REPORT - Nigeria Erosion and Watershed Management Project
Transcript of REPORT - Nigeria Erosion and Watershed Management Project
REPORT ON
CONSULTANCY SERVICES ON GIS –
BASED MAPPING OF EROSION AND
WATERSHED SITES IN KANO STATE
SUBMITTED
TO
KANO STATE NIGERIA EROSION AND
WATERSHED MANAGEMENT PROJECT
(NEWMAP)
WORLD BANK ASSISTED
Project ID: P124905
Credit No IDA 51050
REFERENCE NO:
KNSPMU/CQS/17/2.3
BY
PREPRA NIGERIA LIMITED
222A JIGIRYA, YANKABA, KANO
www.prepraconsult.com
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1. CHAPTER ONE: INTRODUCTION
1.1 Background
The Government of Nigeria initiated the preparation of the erosion and
watershed management project [NEWMAP]. The Project is supported with
financing from the World Bank to the tune of $500 million. The Agency
responsible for the management of the project at the Federal level is the
Federal Ministry Environment (FME), Department of Erosion, Flood and Coastal
Zone Management. In addition, States, local governments, local communities
and CSO‟s are involved in the project, given that the Project is a multi-sector
operation involving MDAs concerned with water resources management,
public works, agriculture, regional and town planning, Earth and natural
resources information, and disaster risk management.
NEWMAP activities currently involve nineteen states, namely: Anambra, Abia,
Cross-River, Edo, Enugu, Ebonyi, Imo, Delta, Kogi, Akwa Ibom, Nasarawa,
Niger, Plateau, Gombe, Borno, Oyo, Kano and Sokoto. NEWMAP is designed
to support participating states and local governments to reduce vulnerability
to erosion and development of watersheds. The overall objective of NEWMAP
is “to restore degraded lands and reduce longer-term erosion vulnerability in
targeted areas. „‟The Project includes four components, namely:
a. Component 1: Investment in Targeted Areas to support on the ground
interventions that address, prevent and reverse land degradation.
b. Component 2: Institutional development and information Systems for
Erosion Management and Watershed planning to address longer term
sustainability by strengthening the enabling Federal and states MDAs
on the environment with a view to addressing erosion and watershed
degradation problems in a comprehensive manner across sectors and
states.
c. Component 3: Climate Change Agenda Support Outcomes focus on
providing tools and approaches for government to become better
equipped to respond to climate change; and on supporting
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demonstration projects on the ground to test the viability and scaling-
up potential of low-carbon development options.
d. Component 4: Project management to support at federal and state
levels to implement this project including (a) procurement and
financial management; (b) social and environmental safeguards issues;
(c) strategic project communications and outreach; (d) project M&E,
including two Mid-Term Reviews; and (e) an impact evaluation fully
integrated into M&E arrangements that will help build replicable
intervention models during implementation.
Against this background, the Project Management Unit of Kano State
NEWMAP commissioned various studies aimed at effectuating successful
implementation of the NEWMAP in the state. One of the assignments is the
Mapping of Gully Erosion/flood Sites and the generation of Land Resource
Inventory data within a geographic information system (GIS) framework. This
will aid in knowing the status of gully erosion sites and land resources in the
State and also underpin project presentation and reporting on key status of
erosion sites especially the sites for the NEWMAP GRASS component.
The scope of work includes the following:
Identification of the sites affected by flood and erosion in the State through
proper ground „truthing‟ and/or field visits which involve appraisals,
observations and measurements (sample/specimen collection).
I. Generation of geological maps for erosion and watershed
management
II. Generate Land Resource Inventory (LRI) data such as soil/land
suitability maps, for erosion and watershed/ catchment management.
III. Mapping of land use land cover including the acquisition of necessary
spatially referenced data of both primary source (such as attributes of
selected sites, comprising of soil types, vegetation types and geo-
ecological characteristics of the area in the state).
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IV. Hydrological analysis for erosion and watershed management in the
state
V. Acquisition of spatial data of secondary origin, such as topographic
sheets and satellite images with 0.5m spatial resolution and other
records for the whole state.
VI. Development of spatial database that can be updated from time to
time and subsequently, build a GIS for erosion and flood information
management from the acquired primary and secondary data arising in
(1-3) above.
VII. Conduct series of spatial analysis and modeling to produce map
documents that can guide key policy and management decision
making.
VIII. Derivation of geo-database on the priority erosion and flood sites in the
State
IX. Identification and delineation of major and minor watersheds in the
State
X. Identification of other potential areas prone to gully erosion and
flooding in the State and the classification of the degree of
vulnerability/risk potentials
XI. Assessment of the socio-economic impact of gully erosion and flood
hazards on the people
XII. Present in easy to read maps:
i. Spatial extent of erosion in the selected area
ii. Spatial extent of flood affected area
iii. Spatial analysis of socio-economic impacts
iv. Predictive models of erosion and flood risk hazard based on
anthropogenic, climatic and environmental factors
v. Land Resource Inventory Map
vi. GIS Catchment Management Plan
vii. Soil Maps
viii. Land use Land cover maps
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ix. Soil Suitability Map
x. Geology maps
xi. Map of a high-resolution satellite image 0.5m covering the
state
1. Proffer best management practices that could mitigate the current
problems and prevent future erosion and flood hazards in the state.
1.2 Location and characteristics of Kano state
Kano state lies within the Sudan Savannah region of Nigeria. It is located on
latitude 110.30N and longitude 80.30E on ( Fig.1) and has a total land area of
20,680 km2 which represents 2.07% of the land mass of Nigeria.
Figure1: Map of Kano state
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1.3 Location of selected sites for intervention
Table 1: location of the Nine selected sites
RARIN - DAWAKIN TOFA
N 12006‟29.80 E 008.19‟ 26.3‟‟
This site is made up of gully heads developed on the
Rarin river . It has encroached and destroyed l
properties and infrastructures. The gullies are l
expanding and will divide Dawakin tofa town into
two sectio. This is a to the socio – economic and
administration of the area being the headquarters of
the local government headquarters, thus disrupting the
livelihood of hundreds of thousands of people. The
existing intervention through concrete stabilization has
only succeeded in pushing the problem to another
location in the town
KAMANDA KIRU
N 110 38‟19.2 E 0080.05‟11.8‟‟
Kamanda river is a 3rd order stream that contributes
water into the Challawa gorge dam. Over he years
human activities along the river and elsewhere
particularly sand mining has increased lateral erosion
that has widened the channel making it increasingly
difficult to cross thereby disrupting the livelihood of
several rural communities. Abridge across will make it
possible the transportation of valuable agricultural
commodities that is abundant in the area, and
movement of people. That is not possible now with
disastrous consequences
YAN SABO - TOFA LGA
N 12003‟18.4 E 0080 18‟41.0‟‟
This is a medium earth dam that potentially can
change the lively hood of several communities. The
dam collapsed as a result of disrepair. Once
rehabilitated the dam can serve as a source of
domestic water supply, fishing, irrigation and recreation
to the many communities in the area. In addition to the
repairs to the dam, there is also the need for access
road and channelization of the water to the field for
irrigation.
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YAR TITI - SHANONO
N 120 03‟53.1 E 0080 00‟25.7‟‟
This is a conservation project to harness the huge
water in the area through impoundment. There are
several communities in the area that currently use the
water during the rainy season. It has rich soil that is used
for rice, sugarcane and vegetable. In addition there is
a need for access road and channelization of the
proposed dam in order for the water to reach the
farmlands
TUDUN FULANI BACHIRAWA - UNGOGO
N 12002‟39.6 E 008028‟06.8
This is a major gully that stretches over several km within
a densely low income area of Kano metropolis.
Already thousands of houses and roads and other
infrastructures have been destroyed. Many families
have been displaced with all their life saving lost. This
project will not only save the remaining properties and
infrastructure in the area, but also help to stem the
growing menace as at the moment the gully is fast
expanding west wards towards Bayero University new
campus.
BULBULA GAYAWA- NASSARAWA LGA
N 12002‟32.5 E 008033‟40.8
This is a major gully within a densely low income area of
Kano metropolis. Already several families have been
displayed with hundreds of houses and roads and
other infrastructures destroyed. This project will not only
save the remaining property and infrastructure in the
area, but also help to stem the growing menace.
KAUYEN ALU - TARAUNI LGA
N11057‟26.60 E 008034‟38.7
This is a major gully within a densely populated area of
Kano metropolis. Already thousands of houses and
roads and other infrastructures have been destroyed.
Intervention already carried out by the state
government and ecological fund is beginning to give
way threatening the community. This project will not
only save the remaining property and infrastructure in
the area, but also help to stem the growing menace as
at the moment the gully is fast expanding southward.
FAJEWA TAKAI LGA
N 110 26‟19.8 E 009012‟00.8
This is a project that will involve the harnessing and
conservation of the huge water in the area through
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impoundment. There are several communities in the
area that currently use the water during the rainy
season. It has rich soil that is used for rice, sugarcane
and vegetable. In addition there is a need for access
road and channelization of the proposed dam in order
for the water to reach the farmlands
DAWAN KAYA - MAKODA LGA
N 12017‟56.0 E 0080 32‟16.8
This is a project that will involve the harnessing and
conservation of the huge water from the Dawon Kaya
stream. The catchment area in Dawon Kaya forest in
which over 20sqkm is a semi virgin land that can
accommodate the reservoir. There are several
communities in the area that can benefit from this
project. It has rich soil that is used for rice, sugarcane
and vegetable. In addition there is a need for access
road and channelization of the proposed dam in order
for the water to reach the farmlands
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CHAPTER TWO: MATERIALS AND METHODS
2.1 Preparing a work plan
In order to accomplish the assignment, a systematic approach was adopted
as illustrated in Fig.2
Figure 2: Schema of work plan
2.2 Mapping of Erosion and watershed sites in the state
The job involves a number of step by step tasks as follows:
2.2.1 Bibliographic Data Review
This involves the following tasks:
Identifying the various data required for the study.
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The sources are of the data
A review of all the available materials in terms of their relevance,
suitability in terms of date/year
The format of the data
Thereafter it is proposed that the project execution shall be carried out
under the following taks:
2.2.2 Survey of the Project sites
The location, alignment of the gully/watershed was traversed to
determine the cross-section and also determine the actual area of the
project. Chain pegs and pillars were used as reference points during the
delineation of drainage location. Appropriate ground controls were
provided for selecting the image of the areas.
Acquisition of coordinates of prominent features and landmarks
In order to carry out delineation of features on land correctly, a high
precision instrument Germain XP Differential Global Positioning System
(DGPS) was used to obtain coordinates of prominent features. A total
Station and Trimble Mobile Mapper was alos used as supplement for the
DGPS. A minimum of twenty field referencing locations would be required
for the study.
2.3 Data acquisition and processing
2.3.1 Process of data acquisition
Figure 3: Shows the step by step tasks that was used in the acquisition.
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Figure 3: Schema of satellite and secondary data acquisition
2.3.2 Data acquired
On the basis of the bibliographic review and field measurements, data the
following were deemed to be the imagery/data for the project.
Quick bird 2016 0.5 m resolution imagery was acquired
SRTM or Aster data to create a digital terrain model for the study area.
Modis dataset was downloaded from Earth explorer USGS which is
used to create Normalised Differential Vegetation Index (NDVI),
Normalised Differential Water Indices (NDWI) and Land Use Land Cover
(LULC) map.
Topographical map sheets of the selected areas at the scale of 1:
25,000.
Cadastre maps, foot prints of the building captured from the geo-
referenced satellite
Geological Maps
GeoNetcast Climate data and In –situ records
Population data of Kano state
Socio – economic impact of gully erosion in the affected sites
2.3.3 Field Verification of acquired imagery
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This was done through acquisition of coordinates of prominent features and
landmarks and Collection of randomly selected spot height by field visits to
the sites. The data obtained from the field verification exercise, such as
coordinates of prominent features was used to further geo-reference the
acquired imagery during image registration process. Both distance and
direction measured on the satellite imagery was confirmed to be accurate.
2.4 Data processing
Figures 4 and 5 show the schematic flow of the processes involved in the
processing of the data acquired.
2.4.1 Digital Elevation Model (DEM)
The Advanced Space borne Thermal Emission and Reflection Radiometer
(ASTER) Global Digital Elevation Model was utilized for various analyses. Six
tiles of AsterDEM that covers the Kano region were mosaic using ENVI
software. The DEM within the boundary of the study area was extracted for
the analysis. This analysis include: generation of drainages, slope and
elevation.
2.4.1.1 Drainage generation
The drainage analysis was carried out using the Arc Hydro extension tool in
ArcGIS.
The DEM was first fill to remove minor artifact. The fill DEM was used create
flow direction grid (fdr) and the flow direction is then as an input to create
the flow accumulation (fac). The fdr and fac were used as input for Stream
definition analysis (str). Finally the stream raster is been convert to drainage
feature.
2.4.1.2 Drainage density
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Drainage density map was created from using Kernel density tool and was
classified into four classes.
Extracted DEM Fill DEM Flow direction Flow Accumulation Stream
definition
Stream features
Drainage
density
2.4.1.3 Identification of flood risk zones
In order to identify disaster risk areas, zones of influence were created around
the erosion sites. This was overlaid on the cadastre map of the study areas.
Flood plains were identified and delineated and a buffer zone of about 45
meters is created around them so as to identify vulnerability zones
2.4.1.4 Elevation
The DEM was used to generate relief map which is categorized into five
classes according to elevation.
2.4.1.5 .Slope
The slope was generated from the DEM which is been reclassified into five
classes based the percentage rise.
2.5 MODIS Dataset
NDVI extracted from Modis data was used to create vegetation map. The
vegetation was been categorized into five classes according to density.
2.5.1 Normalized Differential Water Index (NDVI)
The NDVI indices have been used to generate soil wetness. The Modis Bands
used are: band 1 (RED), band 2 (NIR) and band 7 (SWIR). The soil wetness was
reclassified into four class base on the degree of wetness.
2.5.2 Land Use Land Cover (LULC)
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Land Use Land Cover map was created using Mahalanobis distance
supervised classification using ENVI software. Five classes of land covers were
created which include water bodies, vegetation, built up, sediments and
hard rock.
2.6 SPOT 4 Data
Small water bodies were extracted from the SPOT 4 dataset.
2.6.1 Distance from water bodies
Proximity analysis was carried on the small water bodies using Buffer tool in
ArcMap. Multiple ring buffers of 1000 to 5000meters were performed.
2.7 Rainfall
Rainfall dataset obtained from GEONETcast (EUMESAT) was validated using
In-situ rainfall data.
2.8 Geology
The Lithology of Kano was obtained from Nigeria Geological Survey Agency
(NGSA).
2.9 Weighted overly
The classes of each layer was compared and weights are been assign to
each class according to the degree of preference. Each layer is then ranked
according to the degree of influence. Finally weights sum was used to
produce the final Risk Map.
2.10 Socio- economic survey of the study communities
Focus Group Discussion was undertaken to identify different communities in
each site – tribal, religious, cultural, social and economic as well as to
determine the historical evolution of erosion and the perceived
environmental and socio – economic impact of erosion as well and
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potentials of the intervention from the perspectives of the communities. One
Focus Group Discussion (FGD) was conducted in each of the sites and 86
participants took part in the FGD, which consisted of 47 participants from
communities around gully erosion sites and 39 participants from communities
around watershed conservation sites. The participants involved were heads
of associations and traditional institutions including ward and district heads,
farmers associations, women association, self-help community associations,
religious leaders, traders associations among others. The participants were
selected because both gully erosion and watershed conservation failure
affect their livelihood directly.
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Slope
Drainage
NDVI
AsterDEM MODIS
NDWI
SPOT 4
Small Water
BodiesDEM
Drainage
Density
Distance from
Water Bodies
Geometric &
Radiometric Corr
Elevation
FLOOD RISK POTENTIAL MAP FOR KANO STATE
In-situ
Rainfall
(EUMETSAT)G
GEONETcast
Rainfall Map
Rainfall
Estimate
(RFE)
Validation
Distance from
Drainage
FLOOD RISK POTENTIAL MAP
Weighted Overlay
Figure 4: Flood risk index in Kano state
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LULC
Drainage
NDVI
AsterDEM MODIS
NDWI
SPOT 4
Small Water
BodiesDEM
Weighted Overlay
Drainage
Density
Distance from
Water Bodies
Geometric &
Radiometric Corr
Elevation
Soil
EROSION POTENTIAL MAP FOR KANO STATE
Slope Soil Type
EROSION POTENTIAL MAP
NGSA
Lithology
Figure 5 Erosion potential index in Kano state
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2.11 Delineation of erosion maps
Soil samples based on standard methods was collected from the sites of the
study and laboratory analysis was conducted for erodibility, which was used
to produce a map through spatial interpolation of geo-statistical analysis
function of ArcGIS. This was incorporated in the Revised Universal Soil Loss
Equation (RUSLE)illustrated in figure 6 into GIS for modeling erosion prediction
and control, and to generate erosion risk hazard map.
Figure 6: RULSE Model for soil erosion assessment
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2.12 watershed management
Recently, the use of watershed modeling system (WMS) in combination with
the output of the hydrological models have been used with Digital Terrain
Model (DTM) successfully as illustrated in figure 7.
Figure 7: Model for flood risk assessment and catchment management
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3.0 CHAPTER THREE: PRESENTATION OF DERIVABLES
3.1 Elevation
The elevation of the state is shown in figure 8. Five principal zones of
elevations are found. These are: the south and southeast highlands, the
middle and western high plains and the northeastern low Chad Plains. Table 2
shows the calculated area covered by the five different elevations indicating
clearly the dominance of the plains in the state
Table 2: Calculated area of Elevation in Kano state
S/N Class Area (SqKm) Percent
1 79739 – 1207.927 8,04.7817 3.902915448
2 624.47 – 797.39 2,959.179 14.35100404
3 534.035 – 624.47 5,596.717 27.14215946
4 460.449 – 534.035 5.982.74 29.01423872
5 224.1 – 460.449` 5,276.596 25.58968232
TOTAL 20,620.0137 100
The Highlands occupy a relatively small area to the south (3.9%) and
constitute part of the foot slopes of the Jos Plateau. The elevation is generally
above 650 m and reaches well over 1000 m in the Rishi Hills. Most of the rocky
outcrops in this zone are of Younger Granites.
The High Plains occupy more than 50% of the surface area of the state and lie
on elevations ranging between 450 m and 650 m. The plains are developed
on rocks of the Basement Complex and outcrops of these rocks constitute
most of the hills, both grouped and ungrouped.
The Low Chad Plains occupy a small section of the state to the east of the
Hydro-Geological Divide. The elevation of this zone is about 420 m, with a
local relief of about 20 m. The beds of the alluvial channels which are
prominent in this zone lie at elevations 10 to 20 meters lower than the
average given above.
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Figure 8: Elevation of Kano state
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3.2 Slope of Kano state
The slope is a major factor in land use, flood occurrences and erosion as well
as flood hazard identification. Figure 9 shows the slope characteristics of
Kano state. Kano state occupies the southwestern rim of the Chad
depression and shares physiographic divides with the Niger and Benue River
Systems to the south and southeast, and with the Niger System to the
southwest and west, including the Chad-Sokoto Divide. The elevation of the
area above mean sea level ranges from about 400 meters (m) at the
northeast margin to the over 1000 m at the highest southern tip. The state,
except for the section east of the Hydro-Geological Divide, is part of the
popular High Plains of Hausaland. Six landform types are identified in the
state as follows: dissected hilly highlands, high plains with grouped hills,
pediplains, sandy plains, dune fields and alluvial channel complexes.
1. The Dissected Hilly Highlands consist of the Rishi Hills and constitute the most
rugged topography in the state. The mean foothill elevation is between 700
and 800m. The maximum elevation is put at 1230m, with a dominant slope
angle of about 20 degrees.
2. The most distinct ones are: the Dadi and the Dakwat Plains. The mean
elevation is about 700 m. The dominant slope angle is put at 13 degrees and
hill slopes are steeper than 30 degrees.
3.The Garanga Plains occupy an extensive area, starting from Rano in the
north and extending to the south-centra1 boundaries of the state where they
merge with the Ningi Piedmont (outside the state). The mean elevation is
about 550 m, but rocky hills (Older Granites). The dominant slope angle is
between 3 and 5 degrees but hill slopes steeper than 20 degrees are quite
common.
4. The Dakwat Plains are found north of the Gari Plains. The mean elevation of
the flattish plains is about 47Om, but the quartzite ridges, which trend NNE-
SSW, rise up to 120 m above the plains. Hill slopes are steeper than 20
degrees, but the plains slope at a mean angle of 2 degrees.
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5. The Pediplains are developed over the rocks of the Basement Complex.
The Kano Plains are made up of many distinct sections, prominent among
which are: the Gari, the Jakara, the Chalawa, the Kamanda and the Basara
Plains. Most of these pediplains has been covered by a layer of wind drift
material which could be up to 2.5 m thick. The residual hills, usually located
on the upland plain, are of three types:
a) Granitic outcrop which can occur anywhere in the landscape (e.g. the
Tamburawa rock) and a regolith hill, usually capped by laterites, which
occurs usually at the interfluves (e.g. Goron Dutse and Dala Hill. Hill slopes are
generally steeper than 20 degrees.
b) Sandy Plains are great sand sheets occupying the north and central parts
of the low Chad Plains. They are characterized by very gentle slopes and low
relief (usually less than 15 m) and disappearing stream channels.
c) The Dune Fields occupy the rest of the low Chad Plains not utilized by
rivers. They lie to the south of the sandy plains and are traceable to Latitude
11o N where they are believed to mark the southern margin of an extensive
desert during the time of their formation. They are a combination of
longitudinal (ridge-like along wind direction) dunes and transverse (across
wind direction) ones at different stages of conversion into longitudinal types.
Satellite images show them to be multi-linear and aligned NNE-SSW. The
Latenwa Dune fields in the border area of Kano and Jigawa state, on the
Chad Plains. Table 3 shows the calculated area of the state occupied by the
different slope characteristics. More than 71% are plains that are liable to
flooding.
Table 3: Slope characteristics of Kano state
S/N Class Area (SqKm) Percent
1 37.6139 – 259.2310 54.8991 0.266246743
2 17.28207 – 37.6139 277.6324 1.346446887
3 7.1161 – 17.28207 2999.139 14.54506524
4 2.033 – 7.1161 2643.002 12.81789091
5 0 – 2.033 14644.96 71.02435022
TOTAL 20,619.6325 100
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Figure 9 slope of Kano state
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3.3 General Climatic Characteristics
The climate of Kano state is the tropical dry-and-wet type. The seasonal
migration of the Inter-Tropical Convergence zone (ITCz), gives rise to two
seasons, one dry and the other wet. The wet season lasts from June to
September although May is sometimes humid. The dry season extends
properly from mid-October of one calendar-year to mid-May of the next.
Figure 10 shows the rainfall pattern in the state. Clearly five distinct ecological
zone can be identified on the basis of rainfall amount and duration of the
rainy season. Table shows the calculated areas of the five rainfall zones in the
state.
The annual mean rainfall in the state is between 800 mm and 900 mm as
shown in table 4 Variations about the annual mean value are up to ± 30 per
cent. More than 300 mm of the rainfall is received in August alone, while the
truly wet season lasts from June to September. However, it is usual to regard
mid-May to mid-October as the wet season.
Table 4: Long-Term Mean Climate Conditions of Kano
(http://www.worldclim.org/)
Month Temperature oC Rainfall
(mm)
Evaporation
(mm)
Sunshine
(hr/day)
Relative
Humidity
(%) Mean Range
Jan 21.2 17.8 0.0 133.3 9.0 28
Feb 23.7 20.9 0.3 141.1 9.0 25
Mar 27.7 18.5 1.8 182.8 8.6 23
Apr 30.5 16.4 8.9 195.5 8.4 36
May 30.4 13.6 70.2 187.9 8.8 51
Jun 2S.1 13.0 132.7 156.3 8.7 65
Jul 25.7 10.7 210.9 126.4 7.5 7S
Aug 24.9 9.0 314.0 112.7 6.0 S3
Sep 25.9 10.9 132.8 126.5 7.9 79
Oct 26.8 16.5 12.8 144.0 9.5 58
Nov 24.6 19.7 0.0 139.9 9.8 37
Dec 21.7 18.7 0.0 127.4 9.2 32
Year 25.9 15.5 884.4 1771.8 8.5 49.6
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The highlights of the climatic parameters include: the occurrence of peak
rainfall, peak runoff and peak discharge from the last decade of August to
the first decade of September as shown in table 5 which represents the
average conditions for the state. Table 5 shows the calculated area of layers
of rainfall in Kano state
Table 5 Calculated areas of layers of rainfall in Kano state
S/N Value Area (SqKm) Percent
1 667.04 – 757.16 807.4 3.915653886
2 614.04 – 667.44 4,304.6 20.87605117
3 578.80 – 614.04 1,998.4 9.691655593
4 547.82 – 578.80 5,991.3 29.05605292
5 484.81 – 547.82 7,538.1 36.55758058
TOTAL 20,619.80 100
Rainfall intensity is in the range of 40-60 mm hr-1 but it is particularly at the
beginning and end of the wet season when rainfall is characterized by heavy
storms whose average intensity is about 80 mm hr-1. There is the occurrence
of squalls and thunderstorms from April through to August. During the early
part of this period (April and May) squall winds at speeds of up to 100 km hr-1
occur
Apart from the normal (seasonal) variations, there are periodic variations
which are greater than the ±30% stated. These include short-term periodic
cycles (5 to 10 years) and the longer cycles. Major droughts have occurred
in the state this century in 1913-1915, 1940/41, 1948/49 and 1972/73, with
minor ones in 1963, 1967/68, 1977 and in 1983/84. During the most recent
major drought in 1972/73, Kano received only 414 mm of rainfall per year (i.e.
in 1972/73) which is about 48% of the mean value for the station.
Climatic changes are believed to have occurred in the past. There were
pluvial period when climatic conditions were much wetter than the current
ones and large rivers occupied the region, alternating with arid phases when
conditions were very much drier than the current conditions.
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Figure 10: Rainfall pattern in Kano state
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3.4 Population of Kano state
Kano state is the most populous state in Nigeria and accounts for 6.5% of
Nigeria‟s population as shown in table 6. The population of Kano in 1963 was
2,177,467. At present time the estimated population of the state has risen to
14,455,420 in 2016
Table 6: Numerical and Percentage of Nigeria‟s Population by State.
State Population % of Nigeria‟s
population
Abia 2,338.487 2.6
Adamawa 2,1 02,053 2.4
Akwa ibom 2,409,613 2.7
Anambra 2,796,475 3.1
Bauchi 4,351,007 4.9
Benue 2,753,007 3.1
Borno 2,536,003 2.8
Cross Rivers 1,911,297 2.1
Delta 2,590,491 2.9
Edo 2,172,005 2.4
Enugu 3,154,380 3.5
Imo 2,489,635 2.8
Jigawa 2,875,525 3.2
Kaduna 3,935,618 4.4
Kano 5,810,470 6.5
Katsina 3,753,133 4.2
Kebbi 2,068,490 2.3
Kogi 2,147,750 2.4
Kwara 1,548,412 1.7
Lagos 5,725,116 6.4
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Niger 2,421,581 2.7
Ogun 2,333,726 2.6
Ondo 3,452,720 3.9
Oshun 2,452,143 2.4
Oyo 3,452,720 3.9
Plateau 3,312,412 3.7
Rivers 4,309,557 4.8
Sokoto 4,470,179 5.0
Total 73,398,555 100
Source: NPC, 1991.
3.4.1Population growth in Kano state
With the persistently high level of fertility accompanied by declining mortality
in the state, the rate of the natural population increase has risen from an
estimated 2.51 per annum in the 1960s to about 3.3% per annum in the 1980s
and 2.9% currently. Table 7 shows projected population growth in Kano state
from 1963 to 2020. All available evidences indicate that the level of
reproduction has been persistently high in Kano state for the last three or four
decades and still remain the same at present. If the present trend in fertility
and mortality condition continue in the future, the rate of growth of
population due to natural increase alone will continue to increase while the
doubling time will be shorter. Urban growth rate is about 5.5% per annum at
present due to internal and external migration. Internal migration within the
state takes the form of rural to rural as well as rural to urban movement.
However, rural to urban migration is the most significant. It is usually
dominated by the young generation in search of empowerment and other
opportunities in especially Kano metropolis and other urban areas.
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Table 7: Projected population growth in Kano state 1963 – 2021
S.No.
LGA
1991
2006
2011
1963
1968
1973 1978 1983 1988 1993 1998 2003 2006 2011 2016 2021
1 Ajingi
172,610 203,580 39,979 45,690 52,217 59,677 71,139 84,803 101,091 120,508 143,655 172,610 211,447 259,023 317,303
2 Albasu 116,603 187,639 221,300 43,460 49,668 56,764 64,873 77,333 92,187 109,893 131,001 156,163 187,639 229,858 281,576 344,930
3 Bagwai 106,645 161,533 190,510 37,413 42,758 48,866 55,847 66,574 79,361 94,604 112,775 134,436 161,533 197,878 242,400 296,941
4 Bebeji 118,833 191,916 226,340 44,450 50,800 58,058 66,352 79,096 94,288 112,398 133,987 159,722 191,916 235,097 287,994 352,793
5 Bichi 182,674 278,309 328,240 64,460 73,669 84,193 96,220 114,702 136,733 162,995 194,302 231,623 278,309 340,929 417,637 511,606
6 Bunkure 122,856 174,467 205,770 40,409 46,182 52,779 60,319 71,905 85,715 102,179 121,805 145,200 174,467 213,722 261,810 320,717
7 Dala
418,759 493,880 96,990 110,846 126,681 144,779 172,587 205,736 245,252 292,358 348,512 418,759 512,980 628,400 769,790
8 Dambatta
210,474 248,230 48,749 55,713 63,672 72,768 86,744 103,406 123,267 146,943 175,167 210,474 257,831 315,843 386,907
9 Dawakin Kudu 163,668 225,497 265,950 52,228 59,689 68,216 77,962 92,936 110,786 132,065 157,432 187,670 225,497 276,234 338,386 414,523
10 Dawakin Tofa 156,443 246,197 290,360 57,023 65,169 74,478 85,118 101,467 120,956 144,189 171,883 204,897 246,197 301,591 369,449 452,575
11 Doguwa 83,365 150,645 177,670 34,891 39,876 45,572 52,083 62,087 74,012 88,227 105,173 125,374 150,645 184,540 226,062 276,926
12 Fagge
200,095 235,990 46,345 52,965 60,532 69,179 82,467 98,306 117,188 139,697 166,529 200,095 245,116 300,268 367,828
13 Gabasawa 152,899 211,204 249,090 48,918 55,906 63,893 73,020 87,045 103,764 123,695 147,453 175,775 211,204 258,725 316,938 388,249
14 Garko
161,966 191,020 37,514 42,873 48,997 55,997 66,752 79,574 94,858 113,077 134,796 161,966 198,408 243,050 297,737
15 Garum Mallam
118,622 139,900 27,474 31,399 35,885 41,011 48,889 58,279 69,473 82,816 98,723 118,622 145,312 178,007 218,059
16 Gaya
207,419 244,630 48,041 54,904 62,748 71,711 85,485 101,905 121,478 144,810 172,624 207,419 254,088 311,258 381,291
17 Gezawa 154,629 282,328 332,980 65,391 74,733 85,409 97,610 116,358 138,707 165,349 197,108 234,967 282,328 345,852 423,668 518,994
18 Gwale
357,827 422,020 82,878 94,717 108,248 123,712 147,474 175,800 209,566 249,818 297,802 357,827 438,338 536,964 657,781
19 Gwarzo 118,778 183,624 216,570 42,530 48,606 55,549 63,485 75,678 90,214 107,542 128,198 152,821 183,624 224,939 275,551 337,550
20 Kabo 90,158 153,158 180,630 35,473 40,541 46,333 52,952 63,122 75,246 89,699 106,928 127,466 153,158 187,619 229,833 281,545
21 Kano Municipal 371,243 437,840
85,985 98,269 112,307 153,003 182,391 217,424 259,185 308,967 371,243 454,773 557,097
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22 Karaye
144,045 169,890 33,363 38,129 43,576 49,801 59,366 70,769 84,362 100,566 119,881 144,045 176,455 216,158 264,793
23 Kibiya
138,618 163,490 32,106 36,692 41,934 47,925 57,130 68,103 81,184 96,777 115,365 138,618 169,807 208,014 254,817
24 Kiru 156,584 267,168 315,100 61,880 70,720 80,823 92,369 110,110 131,259 156,471 186,524 222,351 267,168 327,281 400,919 491,126
25 Kumbotso 166,558 294,391 347,200 68,185 77,926 89,058 101,781 121,330 144,634 172,414 205,530 245,007 294,391 360,629 441,770 541,169
26 Kunchi
110,170 129,930 25,517 29,162 33,328 38,089 45,405 54,126 64,523 76,916 91,689 110,170 134,958 165,324 202,522
27 Kura
143,094 168,760 33,143 37,877 43,288 49,472 58,974 70,302 83,805 99,902 119,090 143,094 175,290 214,730 263,045
28 Madobi 78,924 137,685 162,390 31,890 36,445 41,652 47,602 56,745 67,644 80,637 96,125 114,588 137,685 168,664 206,614 253,102
29 Makoda
220,094 259,580 50,977 58,259 66,582 76,094 90,709 108,132 128,901 153,659 183,173 220,094 269,615 330,279 404,591
30 Minjibir 139,750 219,611 259,010 50,865 58,131 66,436 75,927 90,510 107,895 128,618 153,322 182,771 219,611 269,023 329,554 403,703
31 Nasarawa
596,411 703,400 138,137 157,871 180,424 206,199 245,804 293,016 349,296 416,387 496,363 596,411 730,603 894,989 1,096,362
32 Rano
148,276 174,880 34,343 39,249 44,856 51,264 61,110 72,848 86,840 103,519 123,403 148,276 181,638 222,507 272,571
33 Rimin Gado 60,622 103,371 121,920 23,942 27,362 31,271 35,739 42,603 50,786 60,541 72,169 86,031 103,371 126,629 155,121 190,023
34 Rogo
227,607 268,440 52,717 60,248 68,855 78,691 93,806 111,823 133,301 158,905 189,426 227,607 278,819 341,553 418,402
35 Shanono 84,861 139,128 164,090 32,224 36,827 42,088 48,101 57,340 68,353 81,482 97,133 115,789 139,128 170,432 208,779 255,754
36 Sumaila 164,242 250,379 295,300 57,991 66,276 75,744 86,564 103,191 123,011 146,638 174,803 208,378 250,379 306,714 375,725 460,263
37 Takai 130,007 202,639 238,990 46,934 53,639 61,302 70,059 83,515 99,556 118,678 141,473 168,646 202,639 248,233 304,085 372,504
38 Tarauni
221,844 261,640 51,382 58,722 67,111 76,699 91,430 108,992 129,926 154,881 184,630 221,844 271,759 332,905 407,808
39 Tofa 64,796 98,603 116,290 22,838 26,100 29,829 34,090 40,638 48,444 57,748 68,840 82,062 98,603 120,789 147,966 181,259
40 Tsanyawa
157,730 186,030 36,532 41,751 47,716 54,532 65,007 77,493 92,377 110,120 131,271 157,730 193,219 236,694 289,950
41 Tudun Wada 141,288 228,658 269,680 52,960 60,526 69,173 79,054 94,239 112,339 133,917 159,638 190,301 228,658 280,106 343,130 420,334
42 Ungogo 168,373 365,737 431,350 84,710 96,811 110,641 126,447 150,734 179,686 214,199 255,341 304,385 365,737 448,028 548,834 672,322
43 Warawa 81,666 131,858 155,510 30,540 34,903 39,889 45,588 54,344 64,782 77,224 92,057 109,739 131,858 161,526 197,869 242,390
44 Wudil
188,639 222,480 43,691 49,933 57,066 65,219 77,745 92,678 110,479 131,699 156,995 188,639 231,083 283,076 346,769
9,401,288
2,177,467
2,488,534
2,844,039 3,250,330 3,874,629 4,618,840 5,505,993 6,563,544 7,824,222 9,401,288 11,516,578 14,107,808 17,282,065
3.5 Land use/ land cover maps
Figure 11 shows the vegetation map of Kano state. The typical natural
vegetation of the Kano state is the savanna vegetation, three varieties of
which are identifiable from the south to the north. In the southern fringes from
Tudun Wada is the dry Guinea Savanna. From there up to Ungoogo and
Bichi, is the Sudan savanna while the Sahel thorn bush occupies the
northernmost tips. Indeed, the Sahel incursion is a recent phenomenon in the
Kano state. The normal vegetation has always been the dry Guinea in the
southern fringes and the Sudan in the remaining larger part of the state.
Clumps of woodland are common in the guinea savanna zone, while fringing
or gallery forests develop along the banks of most rivers in the state.
The dry Guinea Savanna is a mixture of trees and tall grasses (1.5 to 2 meters
tall). Some of the trees include tropical hardwoods, cotton wool trees which
may be over 20 meters tall, while the grasses include elephant grasses. A few
species of acacias are also found as well as the Baobab tree in areas with
light vegetation. The Sudan Savanna consists of expanse of shorter grasses,
usually 1.0 to 1.5 meters tall and scattered low trees with wide canopies. The
trees hardly rise above ten meters. Several species of acacias and the
baobab dominates the vegetation. A few thorny trees are encountered on
an increasing occurrence as one move northwards. Table 8 shows the
calculated area of the different types of vegetation in Kano state
Table 8 calculated area of Vegetation Cover
S/N Density Area (SqKm) Percent
1 High 2,986.5 14.48372188
2 Moderate 5,945.5 28.83407615
3 Low 6,885.2 33.39136845
4 No Vegetation 4,802.5 23.29083352
TOTAL 20,619.70 100.00
In Kano state, particularly in the zone where continuous cultivation has been
in practice for centuries, natural vegetation does not exist in reality anymore.
Thus, the vegetation has given way to man-made vegetation consisting of his
cropped land, reserved forests, planted forests, shelterbelts and other such
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establishments. Instead of the savanna vegetation with expanse of grasses
and scattered trees, there are the staple crops and scattered tree, some of
them planted, in the rain-supported crop lands during the wet season and a
park-like scenario of bare ground and scattered trees during the dry season,
giving what is known as the “orchard parkland” of scattered trees and
scanty, shrubs or bare ground. Elsewhere, there is the expanse of staple crops
and hardly any tree in the irrigated fields in both the wet and dry seasons.
Where trees have been planted, most of them are exotic ones such as neem,
teak and eucalyptus.
3.6 Soil of Kano state
Soil is an important environmental resource that affects agriculture, civil
engineering, water resources, erosion and flooding among others. Table 9
shows the main soil type in Kano state
Table 9 Soil Type in Kano state
S/N Type Area (SqKm) Percent
1 Lixisols 671.912 3.258603798
2 Gully 442.176 2.144442119
3 Fluviosols 11,09.61 5.381328746
4 Lake 194.678 0.944139218
5 Lixisols/arenosols 31.5609 0.153062408
6 Lixisols/cambiosols 3.9608 0.019208881
7 Arenosols 4,712.21 22.85303046
8 Luvisols/arenosols 46.0906 0.22352779
9 Luvisols 1,335.03 6.474558913
10 Arenosols/cambisols 302.234 1.465758701
11 Luvisols/cambiosols 29.728 0.144173305
12 Arenosols /gleysols 302.907 1.469022581
13 Cambiosols/luvisols 961.677 4.663890992
14 Cambisols 9,668.01 46.887411
15 Cambiosols/rock 270.99 1.314233178
16 Rock 181.741 0.88139803
17 Arenosol/lixisols 356.779 1.730288199
TOTAL 20,619.62858 100
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Figure 11 Vegetation of Kano state
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Most soils in Kano state are developed on the deeply weathered
metamorphic rocks of Basement complex. These, according to CCTA legend
belong to the leached ferruginious tropical soils (FAO; Ferric Luvisols). A few
occupying valley botton positions (hausa, Fadama) are hydromorphic (FAO;
Gleysols), while those around the base of inselbergs and other residual hills
one weakey developed and are lithosols. The characteristics of these soils in
terms of their morphological and analytical properties and agricultural
potentials are largely clayed and loamy to some extent. Figure 12 shows the
distinct soils of Kano state.
3.6.1 Physical Conditions
The color ranges from dark brown in the topsoil to reddish black in the subsoil.
Many soils have faint to prominent reddish mottles at the depth when mottles
will sufficiently high concentration of iron have the capable of irreversible
handering repeating wetting and drying, they form plinthine (US Soil
Taxonomy and when hardened ironstone.
The top horizons are sandy loams with clay content generally between 15 -20
percent. The subsoil is less sandy often sandy clay loams or sandy clays, with
clay loams or sandy clays with clay content between 25 and 40 percent. A
large proportion of the soils are gravelly within 40cm of the surface. The
gravel content, especially at the soil surface, tends to be greater on steep
slopes and at the bluff lines, and also on the locality of settlements where
land is more or less under permanent cultivation.
In terms of consistency, the upper few centimeters of soil are loose even
when slightly moist. They are friable when moist and non-sticky and non-
plastic when wet. Moist sub soils are generally friable but may be firm if they
have high clay content or lose if they have high gravel content. When dry
lower horizons became slightly hand to slightly sticky and moderately plastic.
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Figure 12 soil type in Kano state..
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The top soils develops a weak crumb structure, and the lower horizons are
weak or moderate sub angular blocky structure where Aeolian
contamination is less, the soils are highly porous with common to many, fine
to coarse pores in the upper horizons, these extending down into the subsoil,
the soils are well drained over most of the year, although the presence of
reddish mottles and iron segregation, especially in the middle and lower
slope positions suggests that many do became saturated at depth for at
least brief periods.
3.6.2 Chemical Characteristics
The soils are moderately acid, with pH (in H2O) between and an exception to
this pattern includes the localized slightly calcareous soils. Soils organic
carbon content is highly variable, but generally low, often less than 1.5
percent at the surface and 0.5 percent at the subsoil. Total nitrogen and
available phosphorous are low, less than 0.1 percent and 15ppm,
respectively and slow strong correlation with organic matter contents. The
cation exchange capacity are low to very low, often lss than 15me/100g,
and so the exchangeable cations (Ca2+, Mg2+, K2+, Na+, Al3+.). The clay
mineralogy is dominated by Kolinite type.
3.6.3 FADAMA Soils
These occupy the flood plains of the major rivers. The surface horizons are
dark grey and faintly mottled, becoming well mottled lower down the profile
where the color is dark grey brown to grey brown and were soft iron
concretion are many. The parent materials of these soils are characterized by
a great heterogeneity, as reflected by the satisfactions of the profiles. Some
variations in soil texture are therefore to be expected. Quite often clay loam
top soil overlay clayey or silty clay sub soil, with clay content more than 40
percent. The soils have well developed sub angular blocky to prismatic
structure in the surface horizons but usually massive and permanently moist at
lower horizons. During the dry period, the surface layer often shows weak
polygonal cracking. The soils have poor to very poor drained. The reaction is
38
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ostly slightly acidic and the clay mineralogy mostly kaolinite, but often with
small amount of 2:1 lattice clay.
3.6.4 Weakly developed Soils
These occur principally near the base of inselbergs and crests of ridges, but
may also close to rock out crops in any topographical position. They are poor
in horizon development and are mainly less than 50cm deep. Color ranges
from pale brown to light yellowish brown in the surface layer to yellowish red
at the lower layer. Some prominent mottles, often associated with weathering
rock fragments, may occur at depth, structure are moderate sub-angular
blocking throughout, while texture range from sandy loam in the top layer to
sandy clay loam at lower layer. The soils contain many angular quartz and
feld spar grains, and a few stones. There is usually an irregular boundary to
the underlying granitic rocks and occasional pockets up to 1m. The soils are
moderately acid, with pH of less than 6.0 the level of all exchangeable
cations and CEC are low and so also organic matter content.
3.6.5 Soil wetness index
The emergence of new digital tools and techniques has aided in the
prediction of the behavior of soils and their attributes and has contributed to
a better understanding of the soil-landscape relationships. From digital
elevation models (DEM) it has been possible to create the so-called terrain
attributes, which are environmental variables representative of the relief, such
as slope, curvature and wetness index, information regarding moisture levels
are extremely important in planning the use and management of the area,
because water is a major factor of production. Soil moisture is a key variable
to be initialized in meteorological
models since the partition between sensible and latent heat fluxes depends
on the quantity of water in the soil available in the root zone. The
characterization of soil moisture in deep layers is more important than the
surface soil moisture since the superficial reservoir has a small capacity and
almost no memory features. As the near-surface soil moisture (wg) is
39
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reasonably well correlated with the profile soil moisture content under
specific circumstances, the retrieval of root-zone soil moisture (w2) using
surface observations is possible (Calvet and Noilhan, 2000).
Figure 13 Wetness index of soil in Kano state
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3.7 Geology
Figure 14 shows the geology of Kano state. Generally the state has two
geological regions, the south and central parts of the state are underlain by
crystalline rocks of the basement complex but in the southern part
cretaceous sediments overlap the crystalline rocks.
Underlying rocks are overlain by sandy drift deposits laid down the last arid
phase about twelve thousand years ago. In the southern part of the state,
covering material largely clayed soil, about five meters in depth and very fine
texture. The soils are different to work, tending to became waterlogged with
heavy rains and to dry out and crack during the dry season. The exact
character of the leached ferruginous soils is dependent on such factors as
nature of parent rock topographical relatives anthropogenic. The properties
point to some of the characteristics soil forming processes that take place in
the area
3.8 Drainage and hydrology of Kano state
The drainage of the Kano state is mainly part of the inland drainage system of
the Chad Basin, except for some pockets in the south and northwest as well
as a small portion in the southeast (all together less than 5% of the surface
area) which drain to the Niger and Benue respectively. The main drainage
consists of the headstreams of the river system known as the Yobe in Borno
State, particularly the Kano, Chalawa and Gaya Rivers as shown in figures 15
16, 17, 18 and 19. Both the drainage and the hydrology of the region are
influenced by the climate, rock and human activities .
The state drains essentially northeastwards to the Lake Chad, although the
headstreams rise from the southeast, south, southwest and west. Two types of
surface drainage can be identified. The principal type is the through-flow
which consists of the Hadejia (know as River Wudil in Wudil) and Jama'are
River Systems and drains the southeast, south and southwest sections of the
region towards the northeast.
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Figure 14; Geology of Kano state
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The important headstreams include the Kano, the Chalawa and the Gaya
(headstreams of the Hadejia River) as well as, the Bunga, the Katagum and
the Fakate (headstreams of the Jama'are).
The second type of surface drainage consists of the disappearing flow. This
type is made up of individual streams such as the Gari, the Tomas and the
Jakara which drain the northwest -and north of the region eastwards. These
streams rise and flow freely over the Basement Complex section only to lose
their channels, at a short distance east of the Hydro-Geological into the
unconsolidated sediments of the Chad Formation.
The climate of the region controls the amount of water that is available both
on the surface and at sub-surface at any given time within a water-year. The
climate also controls the regimen and other characteristics of the rivers. For
example, water is abundantly available during the wet months both on the
surface and at sub-surface. The more humid the micro-climatic zone, the
more water is had. Thus River Kano which rises from a fairly humid zone has a
mean discharge of 39 cubic meters per second (m3/s) over a similar land
area as the River Chalawa which rises from a drier area and has a mean
discharge of 22 m3/s. The streams in the area are characterized by flashy
flows, storm discharges and seasonality. Surface water is not available during
the dry season, except in a few deep ponds and lakes, even on the
Basement Complex structure, while groundwater level falls rapidly through
seepage, extraction by man and high evapo-transpiration. Table 9 shows the
calculated drainage density of Kano state
Table 10: Drainage Density in Kano state
S/N Density Area (SqKm) Percent
1 Very high 5745.571781 27.86352133
2 High 5845.376561 28.34753105
3 Moderate 3004.383598 14.56995224
4 Low 4183.867631 20.28993622
5 Very low 1841.208429 8.929059157
TOTAL 20620.408 100
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The construction of dams which started about 1969 ( Figure 18 and table 11)
marked the beginning of the modification of drainage and hydrology in the
state. More than thirty earth-dams are in existence across the state. The
reservoirs of the dams and the intricate networks of main distribution and field
canals in numerous irrigated sites have created a different type of surface
drainage.The modification is great on the Basement Complex section where
the dams, reservoirs and canals have been concentrated. Minor, but
significant, changes (e.g. perennial flow, flood control) in drainage and
hydrology have occurred in parts of the Chad Formation.
In general, the forms of the channels have been affected and the flashy
flows and storm discharges have been controlled where dams and reservoirs
exist. Water is now available on the surface throughout the year, storm
channels are decreasing in width while the Kano River, in particular, has
become perennial in regime, regulated to a mean discharge of 9.6 m3/s
downstream of the Tiga Dam.
Groundwater retention has been improved in the Basement Complex zone in
the neighborhoods of the reservoirs. Conversely, groundwater depletion is on
the increase in the Chad Formation zone through increased extraction by
boreholes and a lower rate of recharge owing to the impoundments
upstream.
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Figure 15 Minor and Major rivers of Kano state
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Figure 16 Major Rivers of Kano state
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Figure 17 Elevation and drainage pattern in Kano state
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Figure 18: Drainage distance in Kano state
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Figure 19 Drainage density of Kano state
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Table 11: An Inventory of Man-Made Lakes in the Kano Region S/No Location Surface Area of
Reservoir at
Capacity (Km2)
Total
Storage
Capacity
(x 106 m3)
Rank in
ascending
magnitude
Catchment Area (Km2)
1 Brinin Kudu* 0.61 1.19 21 40
2 Bagauda 3.76 22.14 9 207
3 Karaye 1.98 17.22 12 80
4 Kaffin Gana* 1.80 NA 19 NA
5 Tiga 178.10 1,968.00 1 6,641
6 Ibrahim Adamu* 2.63 7.99 16 NA
7 Ruwan Kanya@ 2.50 NA 17 NA
8 Tomir (Tomas) 14.97 60.30 6 585
9 Muhammadu
Ayuba*
1.16 5.54 20 NA
10 Jakara 16.59 65.19 5 559
11 Gari 33.16 214.00 3 1,185
12 Kafin Chiri 8.42 31.12 7 225
13 Warwade* 5.26 12.30 13 106
14 Tudun Wada 3.50 20.79 10 185
15 Watari 19.59 104.55 4 653
16 Guzuguzu 6.35 24.60 8 106
17 Magaga 3.72 19.68 11 119
18 Pada 4.09 12.00 14 62
19 Marashi 2.18 6.77 18 43
20 Kango 2.55 8.73 15 41
21 Rimin Gado 0.10 0.26 22 5
22 Chalawa Gorge 101.17 969.00 2 3,859
TOTAL 415.08 3,571.37+ Variable
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3.9 Flood Risks
Figure 21 shows flood disaster risk areas (vulnerability zones) in Kano state
Flooding phenomenon is a major environmental problem prevalent in Kano
state. It causes ecological havocs: destroying lives and property as well as
agricultural land and social infrastructure. The phenomenon arises as a result
of the following: when rain falls on unsaturated soil, it infiltrates, increasing the
moisture content until the soil becomes saturated, after which additional
rainfall becomes surface runoff. The runoff accumulates into a big flood as it
flows down slopes and erodes the soil. It uses the heavy particles and other
objects it gathers to erode the bed and walls of the flood path causing big
gullies to be created. The gullies continue to grow bigger and multiply, if
adequate measures are not taken to control them. With the increasing value
and high demand for land, due to rapid urbanization and population growth,
there is a compelling need to halt the occurrence of flooding and erosion.
Table 12 shows the calculated extent of areas affected by flooding in Kano
state.
Table 12: Calculated areas for flood risk in Kano state
S/N Class Area (SqKm) Percent
1 Low 6391.99 30.99931231
2 Moderate 9046.72 43.87398896
3 high 5181.07 25.12669873
TOTAL 20619.78 100
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Figure 21 Flood risk areas (vulnerability zones)
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3.10 Soil erosion in Kano
Figure 22 shows the pattern of soil erosion in Kano state. Nowadays one of the
major problems on global scale is the rapidly increasing demand to the food.
This demand is of course totally parallel to the population growth. Even more
land is used for agricultural purposes day by day. Cultivation without using
specific control techniques, unplanned land use, such as establishing
industrial facilities or constructing summer houses on the agriculture land,
uncontrolled urban development and also destroying forests are
fundamental factors of soil erosion. Soil erosion is the systematic removal of
soil particles including nutrients from the land surface by the various agents
and occurs in several parts of Kano state under different local geological,
relief and management conditions. However, the degree of occurrence of
soil erosion varies considerably from one part of the state to the other. Thus,
while soil erosion is one of the most serious on the land surface of Kano state,
only rare occurrences of the phenomenon are recorded in some parts of the
state. Equally varied are the factors responsible for the inception and
development as well as the types that exist in parts of the state. Table shows
the calculated area of the extent of soil erosion over Kano state
Also its severity and frequency, where and when erosion occurs is also
strongly influenced by social, economic, political and institutional factors.
Conventional wisdom favors explaining erosion as a response to increasing
pressure on land brought about by a growing population and the
abandonment of large areas of formerly productive land as a result of
erosion, salinization or alkalization
The "on-site" impacts of soil erosion in Kano state are commonly associated
with shortages of arable land that is capable of supporting agricultural
production. The short and medium term consequences for Kano state are
evidenced by the widespread prevalence of food shortages and
abandonment of agriculture for menial job in the urban centres. In the last
forty years, the combined effects of soil erosion and rapid populations growth
of 3% per anum has meant that a little over a quarter of the arable land per
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capita deemed necessary to ensure people diverse diets, is available in Kano
state.
The "off-site" or downstream impacts of soil erosion are associated with for
instance, eroded sediment that are deposited in reservoirs, which caused
reduction in the flow of water supplies for irrigation and residential uses. Also,
the use of large amounts of fertilisers, pesticides and irrigation to help off-set
the deleterious effects of soil erosion have the potential to create pollution
and health problems, as well as destroying natural habitats, and contribute
high energy consumption and unsustainable agricultural system
The "off-site" or downstream impacts of soil erosion are associated with for
instance, eroded sediment that are deposited in reservoirs, which caused
reduction in the flow of water supplies for irrigation and residential uses. Also,
the use of large amounts of fertilisers, pesticides and irrigation to help off-set
the deleterious effects of soil erosion have the potential to create pollution
and health problems, as well as destroying natural habitats, and contribute
high energy consumption and unsustainable agricultural system
3.10.1 Causes of soil erosion in Kano state
Many processes have been found to exert an influence on soil erosion. In
Kano state, there appear to be four possible causes of erosion. First, the
removal of vegetation cover by overgrazing has been observed to be the
primary factor which initiates soil erosion in Kano state. We found many
erosion hotspots that develop where the vegetation cover has been
disturbed by livestock. Other causative factors include cultivation and
grazing practices as a principal cause of erosion. The removal of vegetation
by fire has been shown to reduce infiltration and increase surface erosion
especially in the southern part of the state.
Second, land use changes particularly in urban areas and construction which
has led to excavation of earth as a cause of accelerated erosion in Kano
state. Many local people had said trucks from Kano that had started
extracting sand from a site adjacent to the village as the initiator of erosion
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Indeed, as the demand for building materials in Kano has steadily grown in
recent years, this has become a more common practice.
Third, climate fluctuations have also been cited as cause of accelerated
erosion. A shift to either drier or wetter conditions may trigger episodes of
erosion. A shift to drier conditions can lead to a reduction in vegetation
cover. A decrease in vegetation cover may reduce infiltration and increase
surface runoff which may produce incision in channels.
Conversely, a shift to wetter conditions may lead to an increase in vegetation
cover and infiltration. However, this increase in infiltration may not
adequately compensate for the volume of runoff produced by the increase
in precipitation. Therefore, an increase in surface runoff due to either an
increase or decrease in precipitation may cause increased erosion
Fourth, increased erosion may result from natural adjustments within a
geomorphic system. In most parts of Kano state alternating cycles of erosion
and deposition have occurred in the past and this episodic erosion may be a
normal part of the erosional evolution in areas of high relief and high
sediment production
In Kano state surface and subsurface flows are dominant hydrological
processes but other factors such as material and morphological
characteristics also influence the activity of processes. Different mass failure
processes have been found in the gully channels observed suggesting mass
failure as the main source of sediment in erosion . Mass failure processes
could be grouped into three categories of slumping, block failure, tensile
failure and spalling, and desiccation debris avalanches, based on the factors
controlling speed of movement and the shape of failure.
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Figure 22 Soil erosion risk hazard zone
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3.1 1 Maps of the study sites showing impact to houses and infrastructures
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3.12 Assessment of the socio-economic impact of gully erosion and flood
hazards on the people
Table 13 Erosion sites
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S/N
EROSION SITES
KAMANDA KAUYEN ALU RARUN BULBULA GAYAWA
TUDUN FULANI
1 Historical Background
a. Kamanda erosion started over sixty years ago
a. For the past fifty years KauyenAlu had no erosion, but had a stream used by the community for both watering of animals and domestic uses.
a. Erosion in Rarun started more than thirty five years ago with a stream used for farming activities in the community
a. Erosion started in the last ten years in the area.
a. For the past twenty five years ago, had no Erosion, but started with a narrow pass like gutter for draining wastewater.
2 Causes a. Erosion was caused by increase in water volume during rainy season b. Sand mining for Chalawa gorge dam’s construction c. Deforestation along the stream
a. Construction of drainage system in 1978 by NNPC depot facilitated erosion process at KauyenAlu, Walawai and eastern bypass in Kano metropolis
a. Gully Erosion at Rarun was caused by sand mining
b. Change in the stream course
c. Lack of adequate drainage systems
d. Failure of embankment made at the upstream locations of Rarun.
a. Erosion was caused by lack of drainages
b. Indiscriminate waste disposal by the people in the limited available drainages
c. Sand mining in the area
d. Looseness of the soil in the area
a. Sand mining activities
b. Erosion was facilitated by looseness of the soil in the area
c. Being a water collection point where water from different locations converged facilitated the erosion also.
d. Human activities along water channels and drainages such as local fishing also accelerated the erosion in the area.
3 Social Effects
a. Loss of lives
b. Displacement of people
c. Physical injuries, Trauma and illness
d. Effects on social activiti
a. Loss of lives of many children and causes physical injuries to people among others
b. Effects
a. Loss of lives of children
b. Affects social interaction
c. Affects social relation such as frequency of visits to friends
a. Loss of lives of both children and adults
b. Destruction of cemetery by exposing some buried human bodies.
a. Erosion affects accessibility to nearby schools, and led to transfer of some pupils and students to other schools
b. It affects access to cemetery for burial of dead people
c. It led to the loss lives of people and animals.
d. Many people sustained injuries as
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es e. Occurr
ence of thief and criminal activities
f. Effects on school attendance
on frequency of visits and social interactions among people .
and relatives
d. It causes trauma and psychological stress among people
c. Destruction of social interaction between people and among others inneighbouring communities
d. Erosion sites harvoured thieves and other criminals.
e. It also affects school attendance by pupils and students during rainy season
f. The erosion resulted in serious trauma and psychological disturbance among inhabitants
g. It affected access to mosques, hospital, and other social institutions.
a result of the erosion.
e. Erosion sites became hiding places for thieves and criminals.
4 Economic Effects
a. Loss of public
a. Loss of propert
a. Loss of farmlan
a. Loss houses,
1. The erosion
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facilities such as electricity poles and utility cables, bridges and roads
b. Loss of houses, farmlands, crops and trees
d.Isolation of villages and towns e. Displacement of villages f. High transportation costs.
ies such as farmlands, plots of land and houses
b. Destruction of some water wells and water pipes
c. Collapse of bridges and roads
d. Loss of a famous Gangara market
ds,
b. Loss of properties such as roads, houses, and plots of lands in the area
roads, shops and plots of land.
b. Loss of properties including electrical poles, and cable wires, bridges and drainages
affects trading activities.
2. Loss of public facilities such as bridges, roads, schools
3. Loss of properties such as houses, farmlands, and farm produce
4. The erosion also affects transportation and its costs.
5 Livelihood Changesafter Erosion
a. Practiced Farm activities including irrigation and rainy season cultivation of sorghum, rice, maize, cowpea, cotton, and cassava before erosion
b. Presently, changed to non-farm activities such as trading and marketing of farm produce in addition to only rainy season crop farming
a. Residents were farmers before the gullies, but changed to non-farm activities such as brick laying, plumbing, house painting, carpentry, local land and house valuation after the erosion
a. The participants cultivatedcrops such as sugar cane, mango, guava, lemon, and banana in the past.
b. Presently, their farmlands were washed away by erosion and the soil became barren.
a. Livelihood of the people changed.
b. In the past, the inhabitants were traders having shops.
c. Presently, most of them lost their shops to the gullies.
a. Erosion changed the livelihood of the people from farming and trading to purely non-farm activities such as petty trading activities and housing and land valuation.
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.
6 Erosion Threat
a. Became threat since 1990 to 1992 following sand mining for dam construction
a. Became threat immediately after the construction of drainage systems BY NNPC’s Deport in 1978.
a. The erosion became a threat to the community for about twenty five to thirty years ago.
a. The erosion became threat to the community over six years ago.
a. The erosion effect became a threat for the last twenty years.
7 Community Efforts
a. Construction of temporary bridges
a. Used sand to fill the affected areas through community participation
b. Construction of local bridges made up of wood and rock materials
c. Construction
if drainages and bridges by local authority and federal Government
a. Community to fill erosion affected areas with sand
b. Community constructs drainage systems and concrete barriers to prevent erosion
c. Local authority also constructed some drainages
a. Community use to fill some sections of the erosion sites with sand and waste materials.
b. Also, they constructed drainages and local bridges to link up many areas.
a. The community constructed many bridges and drainages in the area
b. Community bought sand to fill some erosion sites
c. Community also participated in filling the erosion sites weekly using solid waste materials.
d. Local authority also constructed a bridge at the site to ease hardship faced by the community.
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8 Expected Intervention Benefit
a. Will boost agricultural production and marketing of farm produce
b. Boost Trading
c. Improves transportation services,
d. Increases communication and linkages between towns and villages
e. Provision of public facilities such as electricity poles and utility cables
f. Creation of job opportunities
a. Intervention would boost their livelihood by providing bridges
b. It will reduce the effects of the erosion on their lives and valuable properties.
a. Intervention would boost livelihood of the community through revival of agricultural activities,
b. Expansion of the villages by coming to together of different communities
c. It will also strengthen relationship and accessibility among people.
a. The intervention would enhance their livelihood, and reduce loss of lives.
b. It will also allow for improving accessibility of the people to various places such as mosques and schools.
c. Intervention will overcome the erosion in the cemetery and other important places like schools, and
d. It will also reduce further effects on lives and valuable properties.
a. The intervention would boost their income level and ease accessibility to school and cemetery
b. It will reduce illness caused by mosquitoes.
c. It will also reduce pollution caused by waste materials used for filling the gully sites
d. The intervention will also boost trading and save lives as well as properties communities
9 Suggestions a. Need
for quality projects especially on bridges and roads
a. Appealed for quality work in the constructions of bridges and culverts
a. The community appealed for the control of the gully erosion
b. Advised for
the use of quality materials in
a. Community advised that quality work should be done on the constructions of bridges and culverts b. Appealed
for incorporating
a. The participants appealed for the use of quality materials in the construction of bridges and culverts.
b. They also emphasized on the involvement of
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constructions
b. Need for employing professionals from the communities such as brick layers, plumbers and carpenters.
the projects that will be sustainable
local community members who are professionals such as bricklayers, plumbers, and carpenters in the project
professional local people in the project.
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Table 14 : Watershed Conservation sites
S/N
WATERSHED SITE
YAR TITI YAN SABO FAJEWA DAWAN KAYA
1 Historical Background
1. a.Constructed more thirty two years ago, but for the past sixteen years (1999 or 2000) ago the conservation site ceased to retain water because of its failure in 1999 to 2000 as a result of erosion.
a. Yan Sabo stream was more than one hundred years ago.
b. The stream was dammed five to six years ago
c. Erosion led to its collapse a year after damming because of serious flooding
a.Fajewa watershed conservation was constructed more fifty years ago along a small water stream
a.Dawan Kaya watershed was more than forty years ago, presently affected by erosion
2 Causes/Purposes
a. Need for domestic uses, irrigation and animal watering in the communities
b. It was affected by gully erosion
a. Yan Sabo was dammed at one section of the stream for conserving the water for farming activities, animal watering, and fishing
a. The purpose of the watershed conservation was for irrigation and watering animals such as cattle, sheep, goats, and camels.
a. Commercial sand mining activity facilitated erosion at Dawan Kaya watershed
3 Social benefit of watershed
a. Maintenance of good
a. The watershed led good
b. a. The social benefit included
a. In the past, the site
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relationship between the people and visitors who used the water in the past
b. Presently, there is loss of the good relationship between the community and the visitors because of failure of the watershed conservation.
relationship between the people of the area and users of the watershed from other communities.
strengthening of relationship with neighbouring villages and other people coming to water,fishing, domestic uses and feed their cattle.
allowed for good relationships and interaction between people and neighbouring villages
b. Presently, after the erosion at the site, there was loss of such relationships enjoyed before and communication linkages were lost between villages due failure of roads and bridges.
4 Economic benefit of watershed
a. Communities around YarTitiplanted some orchard trees and crops such as maize,
a. The watershed was used for irrigation and fishing, but its failure affects the
b. Community used the site for domestic uses, farming, watering of animals, washing
a. Growing of economic trees and crops such as maize, sorghum,cowpea, and raised animals
b. After the erosion, their economicactivities changed
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sorghum, rice and vegetables with grazing land in the past
b. Presently, the participants believed that presently economic trees such as orchard trees and crops are affected and removed from the watershed site
farming and fishing potentials of the site
of clothes and body.
c. It reduced migration of people especially youth to the cities for economic reasons
to commercial cutting for firewood and petty trading.
5 Changes in the land use Patterns
a. In the past, the site boosted the income level of the community because of irrigation farming and rearing of animals before the failure,
a. The land was used for farming activities such as crop farming and watering of animals, but after the conservation the expectation on the stream
a. In the past, the watershed was used for watering of animals, fishing, and domestic uses and conservation of tree species,
b. Presently, the land use had changed because the water could not remain in the dam for long time during dry season for
a. The land was used for irrigation farming, sand mining and fishing before the erosion, Presently, it is no longer
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b. Presently, farming and rearing of animals are affected, consequently the level of income fall, thus change in landuse. .
was not realised because of the failure of the embankment.
b. There was no change on land use pattern before and after the watershed conservation.
irrigation
used as before
6 Erosion Threat of Watershed
a. Erosionbecame at the site became a threat to the community for the past sixteen years (1999). Since then, the conservation site has not been fully utilised.
a. Erosionat the site became a threat to the community a year after its construction five to six years ago because of its failure
b. Visits to relatives and friends and going to the mosques became difficult
a. Watershed conservation failure becomes a threat to the community after two year of its utilization.
b. And after the drying off of the watershed during dry season
a. Erosion at the watershed became a threat to the community for the past thirty five years.
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after the failure of the dam.
c. Loss of lives among members of the community, especially among guest and strangers
d. Destruction of roads and bridges because of erosion.
7 Community Efforts on Conserving and Maintaining Watershed
a.Bags of sand were used as barriers to block the failed section of the watershed to prevent further erosion effects and for continuous utilisation in the area.
a. Community made efforts in blocking affected section of the dam with big rocks and bags of sand to block the failed section of the dam, though became eroded
b. Community raised some funds to dredge reservoir of the watershed and physical efforts were by the members of the community to do the work
a. Bags of sand were used to fill erosion affected section by the community
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again
8 Expected Intervention Benefit
a. Intervention will reduce emigration young people for economic reasons to other places.
b. The Fulani shedsmen that used the watershed for watering their animals such as cattle, sheeps and goats that left the watershed for watering and feeding and will return back.
c. Intervention would boost economic status of the communities.
d. In addition to rain fed agricultur
a. The expected benefit of watershed conservation intervention would discourage emigration of young people to other areas job seeking.
b. The Fulani shedsmen in the community and neighbouring villages will utilised the dam for watering.
c. Irrigation farming and fishing activities will be boosted, if the interven
a. Intervention would improve the livelihoods of the people using the watershed
b. Intervention on the watershed will prevent young people from migrating to the cities for economic reasons.
a. Intervention would in merging some villages near the watershed.
b. Economic status of the community and neighbouring areas will rise
c. Relationship between people in the community and neighbouring areas will be increased
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e, irrigation activities, and fishing also would be boosted.
e. The livelihood of the people in the neighbouring villages and communities also will improve, when the interventions come.
tion is done.
9 Suggestions a. Participants suggested for quality construction at the site to conserve the watershed in a sustainable manner.
b. The participants also appealed for provision of adequate channels
a. Participants appealed for high quality materials and construction of conservation measures
b. Appealed for better dredging of the floor of stream for
a. Participants appealed for the rehabilitation and expansion of the existing dam so that their lives will be renewed
b. Participants also appealed to the authority concern for better
a. Channels need to be constructed for irrigation purposes
b. Appealed for quality construction of Watershed conservation project
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for irrigation farming.
collection of more water for irrigation farming purposes
c. They appealed foradequate compensation for the farm owners to be affected by the project
way of conserving the watershed.
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Plates showing interaction with communities during focus group discussions
Plate 1: Discussion at Fajewa
Plate 2 Group picture with participants in D/tofa
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Plate 3 Discussion at Dawan Kaya
Plate 4: Discussion at Kauyen Alu
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Plate 5 : Discussion at Kamanda
Plate 6: Group photograph with participants at Kamanda
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Plate 7 Group photographs with participants at D/tofa
Plate 8: Group photographs with participants at Fajewa
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3.13 Information System for Integrated Watershed Management
Soil, water and vegetation are the most vital natural resources for sustainable
development and management of any watershed, and hence should be
handled and managed effectively, collectively and simultaneously. A
watershed has been taken as the smallest planning unit, as it conveniently
and efficiently represents continuum of three vital natural resources i.e. soil,
water and vegetation. Managing the natural resource with sustainable
approach is a rational phenomenon and is proposed in this project. In this
approach, the natural watershed are conceptualized in terms of the flow of
water, which influences almost all fields of the environment.
Figure 32 Information system for watershed management
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3.14 Information system for soil erosion management
Figure 32 Model of information system for soil erosion management
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3.15 Information system for soil erosion assessment
Figure 33 Model of information system for soil erosion assessment
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3.16 Information system for flood assessment and management
Figure 34 Model of information system for soil erosion assessment
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Conclusion
There is considerable concern worldwide about the impacts of
environmental change induced by human activity. Hydrological issues
include the effects of large scale deforestation and climate change on soil
erosion and flow regime and the dispersal of contaminants from agricultural
and industrial activities. Increasingly, therefore, it is accepted that the
development of river basins for economic purposes should be tempered by
the maintenance of an acceptable environmental quality. Establishing the
necessary trade-off between economic development and environmental
quality is a decision-making process involving many elements, one of which is
an appreciation of how environmental systems respond to imposed change.
In particular, there is a need to assess the impacts of different levels of
development on basin hydrology, soil erosion and contaminant
concentrations, in advance of any development taking place. Environmental
impact and economic return can then be weighed against each other for
different levels of development, providing a rational basis for selecting an
optimum development strategy.
Efforts to balance economic development with environmental protection
have increased the demand for simulation tools which enable predictions of
the human impact on the landscape. In order to prevent irreversible changes
and avoid costly, ineffective solutions, the simulation tools should provide
detailed spatial and temporal distributions of modeled phenomena.
Statistical averages for entire study areas or predictions only for a certain
point, such as a watershed outlet, are often insufficient. Effectiveness of land
management decisions aimed at preventing negative impacts of soil erosion
in complex landscapes can be significantly improved by detailed predictions
of erosion and deposition patterns for proposed land use alternatives.
Development of improved soil erosion prediction technology is required to
provide conservationists, farmers and other land users with the tools they
need to examine the impact of various management strategies on soil loss
and sediment yield and plan for the optimal use of the land. Additionally, soil
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erosion prediction technology allows policymakers to assess the current status
of the land resource and the potential need for enhanced or new policies to
protect soil and water resources. Erosion prediction is most needed by
conservationists at the field level who work directly with farmers and other
land users, which has large implications for development and adoption of this
technology.