081126 Report AIDECO Version

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ENGINEERS WITHOUT BORDERS

Imi NTizghte

Agricultural project irrigation and boar fences

Stephen Ollier and Clare Wilding

1/1/2008

December 2008


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Agricultural Project- Irrigation and boar fence, Ammeln Valley, Morocco December 2008

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Contents1.0 Introduction ...................................................................................................................................... 4

2.0 Lifestyle and Agriculture in Anbdour and Imi NTizghte ................................................................... 5

3.0 Soil testing ............................................................................................................................................... 8

3.1 Introduction to soil surveys ................................................................................................................ 8

3.2 Factors affecting Soil Fertility, Erosion and Desertification ................................................................ 8

3.3 Methodology Used ............................................................................................................................ 10

3.4 Results Obtained ............................................................................................................................... 11

3.5 Analysis of Results and Recommendations ...................................................................................... 11

4.0 Irrigation System ................................................................................................................................... 13

4.1 Indroduction ..................................................................................................................................... 13

4.2 Khettara ............................................................................................................................................ 144.2.1 History ........................................................................................................................................ 14

4.2.2 Existing Khettara in Imi NTizghte .............................................................................................. 15

4.2.3 Problems with Khettara 1 .......................................................................................................... 16

4.2.4 Khettara Remediation Options .................................................................................................. 17

4.2.6 Recommendation ....................................................................................................................... 18

4.3 Seguia and Water Tanks .................................................................................................................... 19

4.3.1 Existing Infrastructure ................................................................................................................ 19

4.3.2 Problems with existing Infrastructure ....................................................................................... 20

4.3.3 Remediation Options ................................................................................................................. 21

4.3.4 Costs ........................................................................................................................................... 22

4.3.5 Recommendations ..................................................................................................................... 22

4.4 Clothes washing area ........................................................................................................................ 22

4.4.1 Existing usage and problems ...................................................................................................... 22

4.4.2 Remediation options .................................................................................................................. 23

4.4.3 Costs ........................................................................................................................................... 24


4.5 Earth Channels (Earth Seguia) ........................................................................................................... 24

4.5.1 Existing Infrastructure and the problems .................................................................................. 24

4.5.2 Problems with existing infrastructure........................................................................................ 25

4.5.3 Options for re-lining channels .................................................................................................... 25


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4.6 Field Application ............................................................................................................................... 27

4.6.1 Existing Operation Strategy ....................................................................................................... 27

4.6.2 Crop requirements and Irrigation Efficiency .............................................................................. 27

4.6.3 What is the potential?................................................................................................................ 28

4.6.4 A note on Drip by Drip irrigation ................................................................................................ 28

4.6.5 Summary table, costs and Recommendations........................................................................... 29

5.0 Boar Fence ...................................................................................................................................... 30

5.1 Introduction ...................................................................................................................................... 30

5.2 Initial design considerations and materials ...................................................................................... 31

6.0 Crops ..................................................................................................................................................... 38

Different crop typesa critique with respect to Imi nTizghte .............................................................. 38

6.1 Existing Crops .................................................................................................................................... 38

6.2 New crops ......................................................................................................................................... 38

6.3 Future outlook .................................................................................................................................. 40

7.0 Final Recommendations........................................................................................................................ 41

8.0 Project 2009EWB in Imi nTizghte ..................................................................................................... 42

References .................................................................................................................................................. 43

Appendix A: Leaflet, invitation and poster .....................................................................................................

Appendix B: Crops questionnaire and results .................................................................................................

Appendix C: DPA fiche techniques ..............................................................................................................

Appendix D: Soil test results ...........................................................................................................................

Appendix E: Calculations .................................................................................................................................

E1 Flow calcs ............................................................................................................................................

E2 Flow losses ..........................................................................................................................................

E3 Crop Requirements .............................................................................................................................

Appendix F: Drawings .....................................................................................................................................

Appendix G: Bill of Quantities .........................................................................................................................


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Figure 1.1: View of Imi nTizghte

1.0IntroductionA project has been established by Engineers Without Borders with a local NGO, AIDECO, in the

mountainous Ammeln Valley region of Morocco. EWB provided AIDECO with a source of free

engineering consultancy to progress design work on agricultural infrastructure in the village of IminTizghte. AIDECO is likely to be able to source funding to pay for the post design construction costs but

would have been unable to pay for a comprehensive design to be carried out.

The overall goal of the EWB project was to increase agricultural productivity, and thus economic

stability, in Anbdour and Imi nTizghte. One indicator for success would be for the farmers to be less

affected by price fluctuations and to have a more steady income. What was found in the village was that

the majority of the farming is subsistence and many people rely on money sent from relatives living in

the cities for their income. The goal has therefore been extended to have less reliance on money sent

from cities/abroad and to stem the movement of people to the cities by providing better opportunities

in agriculture in the village.

Another goal is to suggest ways for slowing and preventing mass soil erosion and eventual

desertification in the valley. It is clear to see when travelling through the region that many areas of land

which used to be cultivated are now abandoned, leaving a bare and extremely vulnerable soil behind.

This is generally due to lack of water (drought), and possibly lack of labour or inadequate boar

protection. In these areas, mass erosion and desertification are inevitable in this arid/semi-arid climate.


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2.0 Lifestyle and Agriculture in Anbdour and Imi NTizghteImi nTizghte is a small Berber village in the Ammeln valley with a population of about 320. The local

language is Teshleheet and most people also speak Moroccan Arabic. Some more educated people also

speak French. There is mixed primary school in the village. The secondary school and college are inTafraout 10km away and now that there is school transport provided, the girls are able to get there as

well as the boys who used to cycle or catch a lift. This is only a recent change so there are girls in their

twenties who only had primary school education. Most women over the age of about 35 didnt have any

schooling and are illiterate.

The traditional houses are built with stone and earth based mortar however they require yearly

maintenance and many are now in ruins. Newer construction is normally in concrete blocks which are

often rendered and painted, though some are not. The village has mains electricity and a piped drinking

water supply which comes from the same source as the irrigation water and is occasionally treated.

There is also a water supply from ONEP (Office National dEau Potable) but this is expensive and only acouple of houses are connected to this.

Out of 17 households questioned, two had washing machines. Most people use the communal clothes

washing area though some do it at home particularly if they live a long way from the wash area. An

average family uses the wash area 2 to 3 times a week. Some of the girls find that the position washing

on the concrete floor gives them back ache and would prefer sinks, others are happy with the set up but

say that the surface is too rough and sometimes rips the clothes.

There is no municipal waste collection and so all households are forced to burn their rubbish and the

majority of people use the dry river bed for this. This is a poor environmental solution and is

aesthetically very unpleasing particularly in view of the fact that the association would like to increase

tourism. A future project for the Association in collaboration with a Peace Corps volunteer is to set up a

waste collection service providing communal bins and someone to collect the rubbish. Of those

questioned on this they all thought it was a great idea but it will be interesting to see whether people

will actually be prepared to pay for this service. It is hoped that some materials can be separated for

recycling.

Many of the younger generation move to the big cities to work (generally Casablanca), often in family

run shops, or because of marriage. This means that there are less people to work on the land and some

fields are abandoned. Also for those families receiving money from family in the cities there is less

incentive to invest in the land and use it to its full potential. There are currently two family run shops inthe village. There is at least one person employed at a local hotel and two families with edukan

(traditional shoes) shops in Tafraout. Other than this there is little employment opportunity.

There is a womens Co-operative about 12 strong who produce Argan oil. There is also a group of about

10 girls in their twenties and thirties who use the AIDECO building to make crafts. They also receive

French and English lessons.


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Figure 2.1: Freshly ploughed parcels

Figure 2.2: Local fruit trees

Figure 2.3: Parcels sprouting wheat

Agriculture here is not done on a large scale. Most families own a

few plots of land and these are often shared with extended family.

Up to five households might share land and trees. The plot sizes

are on average 5m x 10m and often a families land is scattered in

many areas. It is mostly the women who work in the fields and all

the work is manual or with donkeys. There is no machinery as even

if it was economically viable it would not suit the small terraced

plots

A lot of the land is covered in trees, the most common being

Argan, Almond, Olive and Date with a few Carob and the

occasional Pomigranite. The majority of the produce is kept for

personal use. Even if a large quantity of Argan oil is produced, any

surplus is usually given as presents to visiting relatives rather than

being sold. Last year the harvest was particularly bad because of

the drought, some trees produced no fruit at all and some evendied. So far in 2008, rainfall has been higher than usual so a better

harvest is hoped for in 2009.

From the information gathered from the questionnaire the only products sold are Carob pods and the

bitter Almonds (edible ones are kept). These can both be sold in Tafraout to someone who then sells on

to factories in Agadir. Carob is sold for 7DH/kg and Almonds for 35DH/kg. Of 17 families asked only two

sell Almonds and, although anyone who has a Carob tree does sell the pods, there were only 4 families

with any trees and a total of only 6 trees amongst these families.

Any crops grown are only for personal consumption. The main one

is wheat and this is something the boars do not eat. This year it

was sown in November after the fields had been ploughed with

donkeys. Some other vegetables are grown but this has diminished

a lot because the boars eat them. The main vegetables that are still

grown are squash, 50% of families questioned continue to grow

them. A very few people also grow onions, tomatoes, potatoes and

other root vegetables. In the past there was a market in the village

where people sold their vegetables. Now most people dont even grow enough for themselves and go to

Tafraout to buy them. The general opinion of people we spoke to was that they would like to be able to

grow their own vegetables again to save money.

On Sunday 23rd October 2008 a presentation was given to the people of Imi NTizghte to present the

work carried out during the EWB project.


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Figure 2.6: Presentation of work

Figure 2.4: EWB and AIDECO meeting

Figure 2.5: The survey team


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3.0 Soil testing

3.1 Introduction to soil surveys

A soil survey was necessary to gain an understanding of the nature of the ground in Imi nTizghte. This

exercise was carried out in order to asses the state of the existing soil and determine its fertility,

suitability to existing/recommended crops and whether desertification and soil erosion are a real

concern. As with most aspects of the project, one of the main aims is to try and establish a baseline

against which future studies can be compared. Since the soil type does not really vary across the site

(apart from the topsoil, which will vary slightly based on crop type, etc) a soil map has not been

produced.

3.2 Factors affecting Soil Fertility, Erosion and Desertification

Soil Fertility

There are many factors which affect soil fertility, and different plant species thrive in different

conditions. The primary factors are listed below with a short text highlighting the indicators;

Aeration - Good free movement of air is essential for a healthy soil (see free drainage).

Moisture content - Should be adequate and balanced. Affects size and texture of soil particles.

Organic content - Relates to moisture content, high organic content gives a fertile soil.

Temperature - Increased temperatures (within threshold


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Soil Erosion

As a general rule, the topsoil is the most fertile part of the soil and simultaneously the most vulnerable.

Simply put, a decrease in vegetation cover, and hence organic content, leads to an increase in soil

erosion. Organic matter fertilizes the soil by binding particles, increasing microbial activity and promotes

permeability and infiltration capacity. The loss of vegetation cover can turn an arid region into desert in

just 10 years! Note an arid region is classified as an area with annual rainfall < 250mm/year. Imi

nTizghte receives 170mm/year and hence is classed as arid. Figure 3.1 shows that Imi nTizghte is right

on the boundary of Hyperacid andDrylands classification (Hyper arid regions receive less than 100mm

of rainfall annually).

Conservation techniques, in principle, are implemented to ensure that the erosion rate equals the rate

of new soil formation. The main aims are to protect the soil from raindrop erosion, increase infiltration

capacity (minimising run-off) and increase ground roughness (retard wind and water erosive forces).

Methods for achieving this include;

Terracing; to reduce effective slope angle and length.Planting crops; provides necessary protection

Contour farming; reduces run-off and promotes soil moisture conservation.

Crop rotation; in 4/5 year cycles. Helps retain moisture by utlising soil retaining crops e.g.

Alfalfa, control pests by eliminating abnormal molds/blights/viruses, control erosion, increase

soil nutrients, and improve soil structure.

Fallow periods; allows the soil to conserve moisture (land must be mulched, tilled and weeded

carefully) and in arid regions can be recommended up to every other year.

Mulching; disturbs capillary action to conserve water and provides soil nutrients to promote

repair after harvest (0.5kg/m2 provides enough cover to protect from wind erosion also). Also

reduces wind and run-off erosion and increases soil surface permeability.Afforestation; increases soil permeability and provides wind and raindrop shelter.

Gullies; to provide run-off with a designated route. Can be grassed, impermeable, etc.

Many of these techniques work by reducing moisture loss from the soil. Another method of doing this is

humid culture where plants are grown in a poly-tunnel. Water is initially provided by irrigation and then

because it is recycled it does not need to be replaced for a few weeks. (1)

Desertification

Defined as the environmental degradation in arid and semi arid

lands causing a critical decrease in the productive capacity of the

soil. Deserts expand and contract naturally over time, the

problem comes when human activity generates unsustainable

demands on already fragile soils ecosystems. The three main

causes are overgrazing, over farming and poor water

management, all of which can lead to desertification of arid and

semi arid lands within 5 10 years!Figure 3.2: Desertification approaches


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Figure 3.5: Cohesion and

plasticity test

Figure 3.4: Basic soil grading

Desertification can be permanent if there is no capital or resources invested. It is without doubt far

cheaper and easier to invest initially in measures to avoid desertification in the first place! Poor

communities may abandon areas once the soil is, in effect, destroyed.

The cause and effects of desertification come hand in hand. Lack

of vegetation, organic matter and moisture leads to soil removalwhich decreases fertility and increases wind erosion. The process

of desertification is difficult to recognise in the field, it is a kind of

creeping disaster. Therefore, effective monitoring is key, this

can be through annual agricultural surveys (production, etc) and

aerial photos.

3.3 Methodology Used

Four sets of tests were undertaken on site, these were soil description, classification, 1-D permeability

and home mineral testing. Samples were also sent to INRA for further testing.

Soil Description

Every soil has its own unique properties and qualities, a soil description is a

qualitative method of explaining the details of a particular soil. The testing

should also include a shear strength test (Standard Cone Penetration Test).

Also useful is the general geography, land use and historical land use if

known. The data is useful in design for estimating bearing pressures, etc. For

this test, the topsoil was removed (top 200mm or so). (2)

Soil ClassificationThis system involves the testing of samples and classifying the soil based on a

list a categories including properties such as particle size and plasticity. For

example, a gravelly silt with little plasticity and a liquid limit of 50%. This data

is useful when using soils as part of a stability design, earth embankments for

example. Again the geography, land use and historical land use is useful and

the topsoil is removed for testing.

Permeability Tests

Permeability coefficient, k, is defined as the as the quantity of unit flow through unit area of soil under a

unit pressure gradient. This is the basis of Darcys L aw. Here, we have only conducted an on site test as

specified by Engineering in Emergencies (3). The macrostructure of soils have a large influence on

permeability, the lack of these features in small laboratory test samples make it difficult to obtain true

values. A field test has its own problems, but in this case it was deemed more appropriate. Simply, a

100mm diameter cylinder (large tin can) was driven into the soil, the top section was filled with water

and the rate at which the water level dropped was recorded over a 60 minute period. Generally the

initial infiltration rate is high and then, as the soil approaches saturation, the rate levels off, it is this rate

that we are most interested in (in m/s).

Figure 3.3: Desertification complete


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Figure 3.6: pH testing

Mineral Testing

A home tester kit was used to measure pH and nutrient levels. The nutrient

levels are interpreted through levels of Potassium, Nitrates and

Phosphorous. The aim is to gather information on the general quality and

fertility of the soil. It is important to note that nutrient levels vary

significantly throughout the year, depending on the type of crops, the

harvest, the season and application of fertilizer.

3.4 Results Obtained

The site owners, Soltana and Hassin Sain, agreed for their plot to be surveyed 24th September, this was

after the summer harvest so mainly only grass was growing. A flat parcel at the base of the valley, the

plot receives lots of sunlight and irrigation water from the khettara via the earth seguia network. Trees

on the northern edge shade a portion of the plot whilst providing wind protection. The plot had

corn/maize, marrow, mint and grass (for feeding their 5 goats) and carrots. They use fertilizer (cow

manure) every February, also if they plant new crops.

Soil Description

The fines area a brown uncompacted silt. The particles are fine to coarse silt with some clay and sand

particles with frequent fine to coarse gravel. The gravel is angular, possibly Gneiss. The Topsoil is

frequent organic matter. Shear strength was estimated as SPT = 10 (ground is difficult to dig due to

gravel).

Soil Classification

Gravelly SILT (approx 40% fines) with low to intermediate plasticity. The sample showed some cohesion

and a little plasticity. Liquid Limit (LL) estimated at approx 40% (category silt with some clay).

Permeability

A rate of 24mm/hour was taken (varying from 24 to 39mm/hour). A typical sandy loam has a rate of

25mm/hr and a silt loam up to 20mm/hr. Considering the fissures and gravel in the soil, this seems like a

reasonable result. According to Cassagrand and Farram (1940) (4) 24mm/hr (6.7x10 -6m/sec) represents

a low permeability soil with good drainage conditions or a fissured clay modified by the effects of

vegetation.

Results of home testing

The pH result was 7.5 (slightly alkaline). Nitrates levels low/medium to low and Phosphorous levels are

low.

3.5 Analysis of Results and Recommendations

This plot is well looked after, receiving plenty of irrigation water and sunlight. The area is sheltered from

wind and the plot is flat which help to minimize soil erosion and facilitate moisture retention. The

permeability is reasonable also, that value will be more useful later on in the earth seguia chapter. The

low nutrients and slightly high pH are most probably due to the recent harvest and lack of fertilizer. This


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plot is exemplorary for others, it also has a functioning boar fence which allows the user to plant root

vegetables, etc which the boar would otherwise eat.

Recommendations

It is recommended that an annual land use survey is undertaken every year to keep check on

deteriorating or abandoned parcels. All abandoned parcels should be planted with dryland crops toreduce the risk of crop failure and soil deterioration. For example prickly pears survive and fruit without

irrigation water and provide a valuable crop. It is also recommended that some food waste and plant

waste is placed back on the land rather than being fed to the animals, thus increasing organic content

and fertility. The notes given above on increasing fertility and reducing erosion/desertification should

also be considered.


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Table 4.1: Water flow test results

Table 4.2: Summary of flow losses

4.0 Irrigation System

4.1 Introduction

There are two concrete water collection tanks in the village which fill up overnight and are used to

distribute water to the fields during the day. The water source is an underground spring higher up in the

valley. Flow from the source is collected and reaches the tanks via approximately 300 metres of

underground channels (khettara) and then an open channel for 900m (seguia). From these tanks the

water is distributed to the fields via open earth channels and applied to the crops using flood irrigation.

The total flow arriving at the tank was estimated using several methods and the results are summarised

in Table 4.1 below, see appendix E1 for calculations.

Method Flow rate l/s

Measurement of seguia velocity 2.5

Depth of pipe flow (150mm UPVC) 3.5

Mannings equation (5) 4.0

Tank volume 3.3

50mm pipes at full bore 3.4

Average 3.34

One of the main aims of the project is to increase the flow in the irrigation system or, more importantly,

the amount of flow reaching the parcels. It is difficult to increase the amount of flow ebbing from the

springs, therefore the key to increasing water flow is understanding and pinpointing the main losses in

the system and reducing them. There are three main areas where water is lost; the khettara, the

concrete seguia and the earth channels. For each of these three elements, evaporation and infiltrationlosses were calculated. Table 4.2 below summarises the results and the calculations can be found in

appendix E2.

Element Losses (l/s) Losses (m3/day)

Evaporation Infiltration Total Evaporation Infiltration Total

Khettara 0 0.5 0.5 0 43.2 43.2

Seguia 0.017 0 0.017 1.35 0 1.35

Earth channels 0.018 0.6 0.618 1.5 52 53.5Total 0.035 1.1 1.135 2.85 95.2 98.05

The calculations of losses have been based on evaporation and infiltration rates measured on site. The

losses in the earth seguia are based on 300m of channel, this was chosen as an average distance of

each parcel from the supply tanks.


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4.2 Khettara

4.2.1 History

Khettara, or qanats, are underground tunnels that tap the groundwater and lead the water artificially to

a human settlement and agricultural lands using gravity flow conditions. The tunnels can be many

kilometres long and very deep. The longest qanatis more than 40 km long and 100m deep and can befound in Iran. In general a qanat system consists of an underground part and a part above ground

surface. The underground part is divided into the "water production section" and the "water transport

section". In the "water production section", the water is collected, either from a natural source or

infiltration of groundwater. This section is underneath the groundwater level of the surrounding area.

The "water transport section" transports the water to the surface. This section is usually lined on the

sides to prevent leakage of water. The gradient of the tunnel is very precise and should not exceed 5 %

in order not to let the flow erode the rock or sand in which the tunnel is dug. On the other hand, the

gradient should not be too low because then the water can not be transported to the surface as self

cleaning velocity is not achieved. The technique is similar to mining and originates from Old Persia

(present day Iran) around 3000 years ago. (6)

Figure 4.1: Khettara/qanat typical

Figure 4.2: Khettara/qanat typical


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4.2.2 Existing Khettara in Imi NTizghte

The system here uses three different underground springs. The mothershafts are 3m, 3.5m and 6m

deep, each being sited to collect water from the individual underground springs. Each spring is created

by water percolating through the earth and bedrock higher up in the mountains. The groundwatercontinues under gravity down the valley and eventually passes over a shallow section of impermeable

bedrock where the motherwell picks up the flow. Further investigation is required to confirm this which

would be difficult, expensive and at this point unnecessary.

There are two khettara in Imi nTizghte, both of which were built in the 1940/50s by the French. Figure

4.3 below shows the layout. The khettara from source 2 was originally built with 12km of pipe to supply

Tafraout with drinking water. This pipe was destroyed sometime afterwards by the villagers so they

could have retain all the water that they felt was rightfully theirs.

Key

River (Asif)

Khettara 1 (poor condition)

Khettara 2 (UPVC/Dimatit)

Barrage (sub river concrete dam

Seguia (300x300 concrete channel)

Manholes

Figure 4.3: Existing Khettara layout (See drawing 2011 in appendix F)

SOURCE 1

(6m)

SOURCE 2

(3.5m)

SOURCE 3

(3m - TBC)

SEGUIA

FLOW

RIVER


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Figure 4.4: Khettara 1 (MH11)

Figure 4.5: Khettara 2 (source)

Khettara 1

Khettara 1 is a stone lined channel approximately 400mm wide by

900mm high with a gravel and sediment invert. Six years ago, two 75mm

MDPE pipes of approximately 2l/s capacity each were added in the base

of this khettara between MH11 and the seguia to try to increase water

flow. We believe this had an initial impact of increasing flows to approx

3l/s because the total flow from both sources was measured as 6l/s

according to a local engineer in 2001. Today, based on a visual inspection

of the flow at MH06 (manhole 6, see drawing 2011), only one of the

pipes has a significant amount of flow, approx 0.4l/s (just less than half

bore). The khettara runs beneath a river which only flows as a seasonal

torrent during the rare periods of heavy rainfall in the area. During this

time water percolates through the khettara walls and into the channel

temporarily increasing flow. A dam running perpendicular to the river

flow also traps flow and directs it into the khettara. This dam is

supposedly broken, we were unable to confirm.

Khettara 2

Khettara 2 is a stone lined channel for the first 20m, it then becomes

simply a buried Dimatit pipeline. Most of the flow in the seguia comes

from this khettara, running at approximately 3l/s. In the 1980s the lower

section of Dimatit was replaced with UPVC. This khettara runs beneath a

smaller river at its upper section. Generally this khettara is in good

condition and will not be considered for renovation as part of this study.

4.2.3 Problems with Khettara 1Consider the khettara as having an upper section and a lower section. The lower section has 2No 75mm

MDPE pipes running along the invert, whereas the upper section is as originally constructed with stone

walls and gravel/sediment invert. The problem with the upper section is that the channel is unlined for

approximately 180m, therefore the infiltration losses are considerable (estimated at 0.5l/s equivalent).

The walls and roof have also deteriorated over time, leaving stones, rocks and debris in the channel

invert which, when not cleared, restrict water flow. To get past these obstacles the flow depth increases

which allows further water to escape through the khettara walls. The upper section has not been

cleaned since the 1980s.

The lower section has two main problems. Firstly the 75mm MDPE pipes have blocked over the last 7

years restricting the amount of flow able to pass down them, this is due to the low flow and lowgradient meaning self cleansing velocities are not achieved. Secondly, the original invert has not been

cleaned often enough, meaning that when flow percolates through the khettara walls it is quickly lost

through the invert due to infiltration as it cannot pass through the blocked channel.


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Figure 4.6: Khettara 1 section

Table 4.3: Khettara remediation Options

4.2.4 Khettara Remediation Options

The main aim of the remediation options are:

- Reduce/remove infiltration losses i.e. all flow gathered at source reaches seguia

- Stop the pipes and khettara silting up and blocking with stones and rocks.

- Retain permeable walls to allow for continued infiltration along the khettara length

All 4 options below include the new silt traps to be built at selected manholes (MH06 and MH11, see

drawing 2011), this will prevent the MDPE pipes silting up and ensure the silt gathers in a manholewhich can be accessed easily.

Option Description Advantages Disadvantages Cost

1

New MDPE pipework

from spring (Source 1)

to MH11

No infiltration losses in upper

section, cheap (pipe already exists on

site)

Does not allow fresh flow percolating

in to join the MDPE flow. Will sediment

up due to lack of flow velocity and

difficult to clean.

Labour

2Concrete lining entire

khettara invert

No infiltration losses, captures

percolating flow also.

Channel can still be blocked by falling

rocks, debris and sediments.

64740

(MDH)

3

Concrete lining entire

khettara invert, walls

and roof (re-build

khettara)

New long lasting infrastructure,

provides safe working and

maintenance area, channel no longer

blocks from falling stones/debris

Expensive, difficult construction (with

very limited access for machinery) and

complete removal of existing

infrastructure.

180000

(MDH)

4New 400mm concrete

perforated pipe.

New infrastructure, easier and safer

construction, allows for percolation

Removal of existing infrastructure, not

a proven technology in the area. Access

into manholes only (like a small sewer)

151900

(MDH)

5

Re-line invert with

perforated UPVC pipe,

gravel and PVC

membrane

Cheaper than concrete lining (option

2), also perforated pipe prevents

channels blocking with large stones

Tricky construction using straight pipe

sections in the meandering khettara.

Fig roots may grow in the perforations

and block the pipe this is TBC.

67710

(MDH)

FLOW LOSSES

FLOW IN


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Figure 4.7: Khettara remediation Options

Option 2 Option 3 Option 5

Option 4

4.2.6 Recommendation

Reline using UPVC pipe with perforations (option 5). It is not confirmed as to whether fig roots will

block the perforations, further study is required here to confirm before construction starts. If fig roots

are deemed a problem, then the pipes should be solid and maintenance improved to ensure thechannel is cleared annually (remove fallen stones/boulders). Regular maintenance will also be

required to remove collected silt as well as roots growing along pipe joints. See drawing 2012 in

appendix F for full details.


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Figure 4.8: Seguia and water tanks layout

4.3 Seguia and Water Tanks

4.3.1 Existing Infrastructure

The concrete seguia and storage tanks were built around 15 years ago. The seguia used to be the earth

channels like the ones seen between the parcels today. The open seguia runs for 900m from the

khettara outlet to the storage tanks.

Water from the seguia is used for irrigation, washing clothes and drinking. There is a pumping chamber

(Manhole C, see AutoCAD drawing) which raises the water to the header tank at the top of the village.

The Seguia details are shown below in figures 4.9 and 4.10. The seguia hugs a steep slope for most of its

course, traversing around regular rocky outcrops and changing in gradient to mirror the natural

contours. There are also several lateral outfalls (generally 100mm DIA holes) which, using stone dams,

can direct flow into parcels running next to the seguia.

N

IMI NTIZGHTE

ANBDOUR

PARCELS

Key

Concrete Seguia

Wash Area

Storage Tanks

Khettara 1

Khettara 2

River

Figure 4.9 Typical section through concrete seguia Figure 4.10 Seguia photo


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Figure 4.11: Tank 2 filling

& emptying via twist valve

Figure 4.12: Cracks and weeds Figure 4.13: Unlined sides Figure 4.14: Steep section

There are two water collection tanks. Tank 1, which is smaller and

higher up so the seguia water reaches it first, is sometimes by-

passed. Tank two, the larger tank shown in the photo, is 17mx 8.5mx

2.15m, therefore having a capacity of 310m. This tank is filled

overnight and discharged to fields each morning. Both tanks

can be bypassed if necessary using steel blanking plates. Tank

2 has three different outlets to serve different areas of

parcels, each controlled by cast iron twist valves. Each tank

has an emergency overflow and both have a build up of

sediment along the invert. Both tanks are in structurally good

condition and will not be considered further in this report.

4.3.2 Problems with existing Infrastructure

The 900m of open channel is all concrete lined but varies in quality with some sections having cracks

along the invert and sides. In general it does not look like there are any significant leakages. Most of the

cracks have allowed plants to cling to and grow within the channel. Therefore, as shown in table 4.2

infiltration losses are negligible. In some areas the walls are falling away or are no longer lined.

The gradient also varies along the length with some very steep sections. These create regions of fast

flowing water which accelerate the degradation of the concrete lining. To date however the lining is still

generally OK. There are also flat sections where flow is deep and slow, this causes deposition of

suspended sediments which slowly block the channel and slow the flow further.

Roots and plants growing within the channel also inhibit the flow and will gradually widen cracks in the

concrete lining, they also use the water. Where there are cracks and the flow is slow, there are oftenmany plants and weeds are growing. There is also lots of debris in the channel, generally dead leaves,

which further inhibit flow and could compromise the quality of the drinking water. Evaporation losses

from the seguia, as shown in table 4.2, are negligible.


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4.3.3 Remediation Options

There are four steps, or options, for remediation discussed here. Whichever scheme is chosen, it is vital

that first the channel is cleaned and all plant life removed. Option 1-Step 2 should not be carried out

with step 1 being carried out first.

Option 1 Step 1: Fix cracks and re-line base and walls where necessary

This involves fixing individual cracks by breaking out the cracked section, cleaning and scabbling the

area, then re-applying concrete and finishing until smooth with the existing channel. Sections where the

walls are not lined require new concrete lining, the walls should also be stabilized where they are falling

away due to the steep bank adjacent. This is a quick and cheap solution, however the results will not

last long unless the works are carried out to a high quality.

Option 1 Step 2: Improve gradients locally

There are three sections where the gradient would be unacceptable from a design perspective. These

sections could be removed by introducing new backdrop manholes or a series of steps set into the

existing channel. This would increase the life expectancy of the seguia. However the steps or manhole

would be in reinforced concrete and tricky to construct with limited working space, a dangerous slope

on one side and shallow bedrock.

Option 2 Re-line the whole seguia

This option is to effectively re-built the seguia with new concrete sections cast in-situ. The most cost

effective and quickest solution would be to line the existing channel with membrane and pour concrete

on top. The new concrete section requires expansion and contraction joints (bitumen filled) every 10m

and at each major bend/change in gradient. It is estimated that this could give a lifespan for the seguia

of at least 20 years, however the solution is time consuming and costly.

Option 3 Piped flow

A quick and cheap re-line solution is to pipe the flow for the 900m of seguia. The 150mm UPVC pipe

would sit within the existing channel with regular open sections at major bends, changes in gradient

and lateral connections. The solution is fairly simple to install and cheaper than option 3. However, the

pipe is aesthetically less pleasing, it removes the openness which helps local community trust

(everyone can see where the water is going) and it makes it more difficult to find/remove blockages.

Figure 4.15: Option 2-Backdrop Figure 4.16: Reline option 3 Figure 4.17: Option 2 Concrete Steps


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Figure 4.18: Concrete wash area

Figure 4.19: Contamination in channel

4.3.4 Costs

For full costing details see detail BOQ.

Option Description Cost (MDH)

1 Step 1 Fix cracks and re-line base and walls where necessary 3,800

1 - step 2A Improve gradients locally (backdrop manholes) 12,858

1 - step 2B Improve gradients locally (concrete steps) 11,150

2 Re-line the whole seguia in concrete 100,800

3 Piped flow (900m of new UPVC pipework + open sections) 75,080

4.3.5 Recommendations

Since the seguia is in decent condition, it is prudent that money is invested elsewhere before large

amounts are spent upgrading here. It is recommended that the channel is cleaned first including the

removal of all weeds growing in/near the channel. Then remediation option 1 - Step 1 carried out,which only tackles areas which are in need of repair. It is our understanding that the UPVC pipe

(option 3) has already been decided on in order to improve the quality of the drinking water.

Therefore recommend manholes at significant bends and changes in gradient to allow for access for

cleaning (sediment, etc) and repairs.

4.4 Clothes washing area

4.4.1 Existing usage and problems

The clothes washing area is used by many women in the village.Flow is diverted from the concrete seguia just upstream and runs

through the middle of the wash area in an open channel as

shown. This water is extracted by hand. The used soapy water

then rejoins the main irrigation channel and is used on the fields.

A small treatment section in the channel already exists just

downstream of the wash area. It consists of a series of four stone

dams which are supposed to filter the flow.

However the dams do not work effectively as all the suspended

sediments and soaps pass through the cracks in the rocks. Afterseeing the physical evidence and speaking with the local

population it is clear that contamination is an issue. According to

the DPA this contaminated water doesnt actually do much harm

to the trees but it does damage crops and vegetables.

Table 4.4: Seguia costs


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4.4.2 Remediation options

Option 1 is to make sure that none of the washing wastewater is used for irrigation by diverting the dirty

water into a new septic tank or soakaway. This would only be possible if there was a piece of land close

by available for this. One big disadvantage is the loss of water. Also the effectiveness of a septic tank or

soakaway is compromised by the antibacterial agents in the washing powder, especially when no other

bacteria are added (from a toilet, for example). This option includes new concrete washing sinks and

header tanks.

Option 2, suggested by the DPA, is to move the entire wash area to a position close to the river and to

use the soapy water to irrigate trees only. This option would be costly, require a large piece of land and

the backing of the community because it would change their usual habits, making it much further for

some people to walk. Although the water would be made use of it means less water is available for the

main fields where the crops are grown. It would also be difficult to set up a system where all of the

wastewater reaches trees only, especially if the system is entirely gravity fed.

Option3, is the purchase of washing machines particularly if it could be shown that they were economic

on water usage. It would be important that models chosen were modern energy and water efficient.

This option was chosen in another area of Morocco where they had the same problem, funded by a

French charity Leau de Desert. The used water would still need to be put into a soakaway or sewer.

There are the obvious benefits to the women of the village, giving them more time to work in the fields

for example, but it would take some organisation to avoid disputes and to agree on how much the use

of it would cost. There would need to be a building, electricity supply (possibly solar) and sewer system.

There would also need to be a strategy for the eventual repair and replacement of the machines.

Option 4 is to install a grease trap to remove the contamination. This would need to be cleaned

periodically, perhaps once a day, which would be a fairly quick and simple operation which involves

removing the top scum layer and putting it into a soakaway or cesspit (it is not recommended that the

waste is put into a septic tank as it will affect its operation). The settled sediments could be removed

around once per month depending on wash area usage. It is recommended that a temporary grease trap

is installed first to check the dimensions (the bigger it is, the less cleaning required) and the

effectiveness. This can then be replaced with either a new reinforced concrete unit or a system of

baffles cast into the existing outlet channel (where the stone dams exist today).

Figure 4.20: Temporary grease trap steel drum construction


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4.4.3 Costs

Option Description Cost (MDH)

1 New soakaway and concrete sinks/header yank 4,500

2 New wash area by river TBC

3 New washing machines 4,000 each

4 Grease trap - temporary steel drum Labour only

4 Grease trap Utilise existing concrete channel 1,775

4 Grease trap RC unit 5,050


It is recommended that the temporary grease trap is installed (option 4) and the community to be

consulted to decide the next step.

4.5 Earth Channels (Earth Seguia)

4.5.1 Existing Infrastructure and the problems

There is a network of over 2000m of earth channels delivering irrigation water to over 15ha of

agricultural land. The channels are lined with large stones and gravels. The less used channels have grass

growing in them. There are many steps and drop offs to allow the channels match the parcel terracing.

The channels are aesthetically pleasing and promote trust and openness with the water distribution.

The permeable invert also allows water to infiltrate into the surrounding soil and feed trees which live

adjacent to the seguia.

Figure 4.5: Contamination options - Costs

Figure 4.21: Section through existing earth seguia


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4.5.2 Problems with existing infrastructure

The earth seguias serve their purpose in transporting water to the fields but their efficiency is quite low.

The permeability test (see section 3.4) gave an infiltration rate of 6.7x10 -6m/sec for the soil. This test

was carried out on a dry earth seguia bed. The initial infiltration rate was 1.08x10

-5

m/sec which thensettled to 6.7x10-6m/sec. This means that, over say 300m of channel on average 300mm wide, 0.6l/s

should be lost (see table 4.2). Over a 12 hour day of irrigation that equates to 26m 3 of water wasted

(26,000 litres). If 3.4l/s leaves the tanks and 2.8l/s reaches the field, the efficiency is 82%. This

corresponds to data in The Civil Engineers Reference Book (7) which gives field canal efficiency of 80%

for unlined canals in blocks of up to twenty hectares. If the water has to travel further or the channel is

dry, which is often the case, the losses are greater. Other losses of water have also been observed, they

are hard to quantify but they mean that the total loss could easily be greater than 0.6l/s. The following

list gives the potential sources of inefficiencies which could be tackled:

1. Infiltration losses through channel invert.2. Undersizing of channels (flow spills over the edge).3. Losses at the many unlined steps and drop-offs.4. Wastage at stone dams/junctions which do not function correctly (flow dribbles into adjacent

lines, without actually reaching any fields and even if they did, the fields are not prepared).

5. Slow flow and pooling due to lack of gradient and high invert roughness (Mannings).

4.5.3 Options for re-lining channels

There are 4 re-lining options, all will reduce infiltration losses and increase water availability by up to

20%.

Option Description Advantages Disadvantages Cost (MDH)1 UPVC pipe lining Longevity and hard wearing Difficult to construct with many the bends, 132,700

2 PVC membrane Easy construction and cheap Vulnerable to punctures if not protected 42,700

3 MDPE pipes Very quick and easy constructionLose openness and aesthetics. Junctions

awkward (many valves would be expensive)115,500

4 Concrete lining Longevity and very hard wearing Expensive and long construction time 107,360

STONE DAM

WASTAGE

MAIN FLOW WASTAGE MAIN FLOW

Figure 4.22: Wastage at dams (4) Figure 4.23: Undersized channel (2) Figure 4.24: Poor drop-off design (3)

Table 4.6: Earth channel re-lining options (labour inc)


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As part of the re-lining there will need to be new junctions built. There are several options for this, the

cheapest and easiest to construction and maintain is as shown below. A concrete section with steel

baffle or piped sections with valves could also be used, though both incur greater costs.


Recommend re-lining with PVC membrane (option 2) with major junctions built as shown in figure

4.29 above. The channel needs to be well bedded and carefully covered with smooth stones to protect

the membrane. Recommend that a 200m section and one junction built first as a pilot (test) scheme.

Figure 4.25OPTION 1, UPVC half pipe Figure 4.26OPTION 2, PVC membrane

Figure 4.27OPTION 3, MDPE pipes Figure 4.28OPTION 4, Concrete lining

Figure 4.29 UPVC/concrete junction


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Figure 4.30 : Flood irrigation

4.6 Field Application

4.6.1 Existing Operation Strategy

The distribution is based on water rights. Each family has the right to a certain amount of water

depending on historic agreements; however this does not necessarily represent current needs. The

scope of this project does not include altering these rights however, only to increase the total quantityof water. The water rights have been the source of many disputes, especially when water levels are low.

Also, now that homes have tapped water without meters, water usage goes unmonitored and people

can be as inefficient as they like (many even use the tap water on their fields). To amplify the problem,

many villagers refuse to pay for the tap water.

During summer, when flow is low, each farmer is allocated certain time slots when they can extract

water from the seguia. This is measured in hours, the ancient method was to used a plate with a hole in

it. A plate full of water would take, on average, 7.5 minutes to empty, therefore they knew 8 plate-loads

was an hour of extraction time. Now the time is used. The distribution cycle during summer runs in 7

day loops (one farm in the morning, another in the afternoon)

During winter, when flows are higher, the time slots still exist,

however there is more water available per person. The distribution

cycle runs in 12 day loops. Winter is considered November to April

and the amount of rainfall varies from year to year, winter 2008 has

already seen more rain than the whole year preceding it (TBC by

DPA, Tafraout). The water is diverted from the earth seguias by

building temporary dams just downstream of their respective

lateral connections. This flow is channeled using stones/gravel

weirs. Once in the fields a variety of irrigation techniques are used

including flood irrigation, furrow irrigation and border irrigation.

4.6.2 Crop requirements and Irrigation Efficiency

As stated previously, the irrigation system is not performing to its full potential with flow losses from

source (khettara outlet) to destination (parcels). Presently, of the 3.4l/s leaving the khettara, only

2.77l/s arrives at the fields (based on EWB preliminary studies, see table 4.2 above). Based on crop

water requirements and irrigation efficiency it is possible to calculate the existing and potential

irrigatable area. The results were as follows; see Appendix E3 for full details.

Based on the Blaney and Criddle method, Crop water requirements in Imi nTizghte = 562mm/year

(based on average monthly temperatures and daily daylight hours, and a summer crop of tomato orsorghum. Millet, for example requires less water and has a shorter crop cycle, hence this value would be

reduced (7)).

This value does not take into account rainfall (8), hence we are assuming drought conditions. It does not

take into account any water added to the field between crops. Finally, this value does not take into

account the efficiency of the water application method. In this case we have an earth canal distribution

system (80% efficient) and flood irrigation (60% efficient). This increases the net annual crop water


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Figure 4.31 : Typical Drip by Drip layout (12)

requirement to 1171mm/year(562/(0.8*0.6)). To verify this, the Engineers In Emergencies design guide

was used (3), giving a value of 1092mm/year. We will work with the higher value.

2.77l/s gives a total water volume of87,355m3/yearavailable (arriving at the fields). The 2.77l/s takes

into account the distribution efficiency (previously taken as 0.8), therefore the crop water requirement

for every parcel becomes 0.937m3

per square metre/year (937mm/year), therefore the area which canbe adequately irrigated is 9.32 Ha. At present, approximately 15ha are irrigated with this 2.77l/s, which

means the crops are receiving around 60% of the water they need. This helps to explain the crop failures

and lack of fruiting trees in the summer 2008 harvest.

4.6.3 What is the potential?

There are two factors which can be looked at. That is to firstly increase the flow (reduce losses) and

hence the application efficiency. Secondly to improve the field application efficiency by, for example,

installing a Drip by Drip irrigation system.

By removing infiltration losses in the khettara and earth seguias, the flow arriving at the fields can be

increased to 3.87 l/s. This increases the annual water available to 122,044m3/year.

With a crop water requirement of 0.937m3 per square metre, it possible to irrigate an area of13.02Ha, a

large increase from 9.32Ha.

By installing Drip by Drip irrigation, field application efficiency increases to 0.8, the potential irrigation

area subsequently increases to 17.37Ha.

4.6.4 A note on Drip by Drip irrigation

Drip by Dip irrigation is an efficient irrigation method, it is a proven technology and many trees and

crops have very been successful under the system. The trickle system transports water through an

extensive pipeline network to the soil near the plant and puts the water directly into the root zone. The

main issue, however, is the cost and difficulty in construction. The most efficient and intricate systems

are generally used only for high value cash crops due to the high setup costs. Setting up a system to

work correctly in Imi nTizghte will

require a professional with the

correct knowledge, skills and

experience. It requires a hands

on approach, training the local

farmers in the process and would

most certainly benefit from a pilot

project on a few parcels (to test

construction methods and

effectiveness). INRA and DPA

involvement are absolutely

necessary here.


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4.6.5 Summary table, costs and Recommendations

SCHEMEAREA POSSIBLE

TO IRRIGATEADVANTAGES DISADVANTAGES

COST

(MDH)

Existing 9.32 Ha Costs nothingPoor efficiency, less crops, more

soils erosion

Free

Fix khettara an line

earth seguias13.02 Ha

Farming practices do not have to change,

more water available and more/better crops.Setup costs 114,210

As above + Drip by

Drip17.37 Ha Maximum efficiency

Difficulty setting up correctly and

high associated costs177,210

As shown in the table above, investment in the irrigation network can have a very significant impact on

the total area which could be effectively irrigated. At present the Boar fence design will contain an area

of 9.75 Ha. The total area covered by the channels is in excess of 15Ha (DPA, Fiche Techniques), it is

therefore recommended that firstly the khettara and earth seguia upgrades are completed. Followingthis, steps need to be taken to improve the irrigation efficiency further, via drip by drip or other forms of

water efficient irrigation. As a quick example, a Carob tree requires 350mm/year to fruit, so a flood

irrigation system (60% efficient) would demand 580mm /year (over the root area). To compare, a drip

by drip irrigation system (80% efficient) would need 438mm/year. This step, very much into the

unknown for many of the local farmers, needs be driven by INRA, DPA, AIDECO and the people of Imi

nTizghte.

In conjunction with this, it is suggested that steps are taken to encourage people to start using more

dryland crops. For example Pearl Millet (which can replace other grains such as wheat and corn), Carob

trees, and Cactus trees (prickly pear).

Finally, one of the main risks with flood irrigation is salinisation. This is when >0.1% salts (Na) exist in the

top 200mm of soil. Salinisation can be avoided by ensuring adequate surface and sub-surface drainage

to ensure no excess water pools and deposits salts. It is recommended that annual soil tests be carried

out by INRA (this could be organized by AIDECO/DPA/EWB each summer) to monitor salt levels and

irrigation/drainage modified as required. Remediation of salinisation is achieved in several ways, the

most appropriate and simple example is to flood the fields to flush excess salts out.

Table 4.7: Field Application options and costs


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Figure 5.2: AIDECOs sketch of boar fence

5.0Boar Fence5.1 Introduction

In recent years the wild boar population in the region has dramatically increased. A major factor in this is

the absence of natural predators such as wolves and jackels which have been completely wiped out. The

reproductive pattern of the boars has also amplified the problem. The boars are very destructive

because they eat most vegetables, even cactus, and also rummage in the ground for grubs which causes

further damage. Some people have built personal boar fences around their land. Materials seen include

stone walls, brambles, reeds, and wooden posts with chicken wire. Where there are these fences

vegetables seem to be successfully grown, however the vast majority of land remains unfenced.

There has been talk of building a perimeter boar fence for many years and it is something that many

people in the village say is the most important thing they would like to happen. The association had

sketched a suggested outline for the fence and then the EWB engineers surveyed the land to produce a

more accurate map. The total length of the perimeter was measured as 1430m. The terrain is

changeable and quite hilly and there is one length in particular that the slope is very steep,

approximately 30 degrees.

The original design produced by the DPA was a fence with

steel T sections as posts at 5m centres and galvanised steel

mesh (50x50). This design was not accepted by AIDECO who

thought it was excessive. See Appendix C for original fiche

techniques.The cost per metre was given as 80DH and the

total cost based on 1200m of fencing was 96000DH. The aim

of the EWB engineers was to propose a cheaper fence

design.

Figure 5.1: Existing Fence types in Imi nTizghte


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Figure 5.3: Wild Boar and electric fencing

Various options were looked at with each one have advantages and disadvantages in terms of cost,

appearance, effectiveness, time to construct, maintenance required and environmental impact.

5.2 Initial design considerations and materialsOne of the first things that was looked into was an electric fence as this is what is typically used in

France. The cost of this fence would be quite modest, as low as 20Dh/m, based on prices from a French

website (9). However it was decided that it would probably not be appropriate here because the

maintenance is so important for it to work correctly. With a wall or solid fence a small area of damage

might leave an area that can be breached but if an electric fence is not working the entire thing becomes

useless. Given the length of the fence and the relatively high level of maintenance required it was

deemed an inappropriate technology for the village. To back this, there is an electric fence somewhere

else in the valley which has proved ineffective, thought the reasons for the failure are unknown.

It was thought that local materials would be the cheapest

and have least environmental impact. There are fences that

have been built using the trunk of a date palm as the base

and then palm branches to as the barrier. This is ok for the

small fences some people have but there would not be

enough for the kind of lengths necessary.

The British CIRIA Wildlife Fencing Design Guide (10) and all

evidence of fencing seen in the UK is that timber fence posts

are used. This guide does also show examples of steel posts

but says that concrete is not suitable because it does not

perform well under tension. The problem here might be sourcing good quality timber and preservative.

Some of the electricity poles in the village are in timber and this type of timber would be suitable. It

should be found out where this timber comes from, what is its expected lifetime if treated and the cost.

Any timber sourced needs to be from a sustainable resource, a local managed forest is the ideal.

The other obvious local material is stone. All the traditional buildings are built from stone with an earth

based mortar. The advice from the DPA was that this option would be no cheaper because stone would

still have to be bought still that problems could be caused by people taking stone from existing terrace

walls. The opinion of the EWB engineers was that enough stone could be collected from the surrounding

area if there was enough of a volunteer labour force from the village.

Design 1:Dry stone walling with living barrier

EWB and DPA agreed on the merits of the option of dry stone walls along the river where there is an

abundance of stone. It is a traditional technique and could enhance rather than degrade the natural

landscape. There is also the advantage that in some places walls already exist which just need building

up to a suitable height. In addition to the walls prickly branches are placed on top to create a more

effective barrier. These could be Gigibier or Argan. A line of trees can also be planted on the inside of


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Figure 5.4: Section through river stone dry walling with trees

the wall which within a couple of years will grow to a height that the can be pruned to form a living

barrier over the top of the wall. It is hoped that these trees will require no irrigation and can be provided

by the Department dEau et Forets.

Environmental issues: One concern with this is that it may affect the river if too many stones are taken

from it though the DPA assured that this would not be a problem so long as stones are not taken from

the river banks as this could change the course of the river. These rivers actually only flow normally

about once a year and are used by most people to burn their rubbish, therefore the environmental

impact is considered negligible. The embodied energy in this option is almost zero (only the transport

required for labour and trees) and the planting of trees has a positive impact.

Cost: The cost of this wall is very much dependant on the labour since the materials are free. If there is

enough local know-how and people willing to volunteer the cost of the wall would be very low.

Otherwise due to the length of time it takes to build compared to a fence the cost would not be that

much less.

Maintenance: For this length a maintenance strategy would need to be in place with people assigned to

ensure that the Gigibier is intact, to make any repairs necessary to the walls and to prune the trees.

Design 2: Mesh fence

This is similar to the original design by the DPA however it is suggested that timber posts are used

instead of steel to reduce the cost and also as a material with lower embodied energy. Due to the

transparency of the mesh this fenceline would not have a big impact on the landscape. It is most

suitable for terrain which is reasonably flat. Mesh can be placed to a depth of 200mm in the ground and

attached to a tension cable to prevent the boars from digging underneath. On steeper ground masonry

walls could be built to provide to provide a horizontal base on which to place the fence.


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Figure 5.5: Elevation section of Timber post and 50mm mesh

In order for a mesh fence to be effective certain specification should be made and it is recommended

that the following advice is taken:

Posts at the start of a fence line or at a change of direction need to be at least 900mm below ground and

need to be supported with a strut and tie, see the figure.

For a boar fence the guide recommends a minimum of 200mm below ground and 900mm above ground

level. However it suggests that this may need to be increased in certain circumstances. The high

population and determination of the boars here would justify increasing this height.

It is important to specify a good mesh. If it is a woven mesh, the joints should be lock joints rather than

hinge joints so that verticals cant slip on the horizontals.

Foundations are not required if the posts can be driven into the ground without first digging out the soil.

It would be beneficial to source a mechanical post driver if possible to drive the posts into the hard

ground, this is made easier with pointed ended posts.

It is important that the mesh is attached to the outside of the fence, i.e. so that the animal pushes the

mesh onto the post rather than pushing it off.

Environment and Costs

The timber posts MUST be specified from a sustainable forest resource. For this scheme to become a

symbol of best practice then we must invest in protecting the environment wherever possible. The

openness of the mesh also helps to minimise the visual impact. As stated above, using timber also

helps to reduce the cost.

Maintenance

These fence sections will need to be checked regularly for weaknesses and breakages. The tension wire

can be tightened manually so it would be prudent to train a local person how to do this.


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Figure 5.6: Timber end post detail

Figure 5.7: Endpost

Design 3: Half blockwork wall half mesh

For the length of fence along the road a robust solution is necessary because

of the possibility of impact from vehicles and the amount of pedestrians

including children who frequent this route. A fence line with posts and mesh is

one option, although it might be subject to damage. There is also a reasonable

slope which is makes it difficult to accommodate the mesh. The DPA suggested

that a wall built in concrete blocks could work out to be cheaper, particularly if

a machine were purchased to produce the blocks in the village using sand

dredged from the river. This seems like a good suggestion however solid

concrete walls would not be very aesthetically pleasing, particularly because

they would block the view and give a closed atmosphere. Therefore the

proposed option is to have a block wall built to a height of 600mm 980mm

with a mesh for the upper half (the height of blockwork varies over each 5mlength according to the slope, 4 courses of blocks suggested as minimum). It is

recommended that the blocks are plastered and painted a similar colour to the

houses for a better look. The mesh required would not need to have such

small squares as the 50x50 suggested for a full height mesh fence because the

boars can exert more force if on the ground rather than if they have tried to

climb up. A mesh size of 100 x 100 is proposed.


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Figure 5.8: Elevation section, half blockwork wall half 100mm mesh

Environmental issues: One disadvantage of this wall is the amount of cement needed to construct it,

with the high embodied energy which that entails. A more environmentally friendly method would be touse earth blocks, or rammed earth. The DPA do not think that the soil here is appropriate for this use

but it is something that should be given more consideration before being completely ruled out,

particularly when earth has been used in the construction of the old houses here.

Cost: The cost depends on whether or not the blocks could be produced locally with a new machine.

This mesh size is cheaper than for the type of mesh required for a full height mesh fence.

Maintenance: Maintenance is quite low. Repainting of the wall every few years would improve the

appearance. The mesh may need some repairs and the posts may need replacing after 10-20 years

depending on the quality of timber and preservative.

Design 4: Masonry wall

This option was decided upon because it offers a stiff, robust solution on steep rocky ground. It is

expensive but it is a well known method used throughout the region and utilises local materials, hence it

fits well with the surrounding environment.

Environmental Issues: Embodied energy from the mortar and reinforced concrete posts. Using local

stones removes the need for quarrying and transportation. The wall fits in well aesthetically and its high

lifespan improve the overall environmental impact.

Costs: Are high due to the concrete and steel volumes. Can be made cheaper if local/volunteer labour is

used.

Maintenance: Low. This is as maintenance free as it gets. This wall will also last longer than any other

fence type discussed here.


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Figure 5.9: Mortared stone wall with concrete posts

Figure 5.10: Typical gate detail

(Timber with mesh infill)

Gates

The position of the gates along the fenceline should be

agreed with the community in order to ensure adequate

access. However the number of gates should be kept to

the minimum required because they represent a

weakness in the fence (continuity) and they can be left

open. They also increase the overall cost. A practical note;

you need to put end posts either side of a gate rather thanusing the gate posts as end posts. This is because the

endposts take the strain of the main cable and will move

over time, therefore the rigid gate would not last very

long under such conditions. The gate consists of timber

cross members with 50x50mm mesh infill and a 200mm

deep concrete footing linking the two gate-posts.

Maintenance issues

Problems are envisaged here because of problems in the community. The evidence of a very small

turnout to a presentation given on the fence and irrigation scheme suggests that a community meeting

to discuss maintenance would be impractical. A more likely outcome is that there will be a few

dedicated people in the village who end up doing all the work. If this were the case it would be fairer for

everyone to pay a small amount to pay these people for the work. Though again getting a consensus on

this would be difficult. In summary this is an area which need a lot more consideration and work from

AIDECO. It would be prudent to assign some budget to the upkeep of the fence.


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Table 5.1: Fence sections cost and appraisal

Figure 5.11: Fence sections and plan of Imi nTizghte

Section TERRAIN FENCE TYPE ADVANTAGES DISADVANTAGES COST MDH

A

235m

Riverside -

flat

Drystone wall (river

stones)

Cheap solution and longevity, also

aesthetically very pleasing and

sustainable material usage

Time consuming

construction, living part

needs maintenance. Takesup space on land.

8225

35Dh/m

B

222m

Roadside -

moderate

slope

Bottom half block work,

top half 100mm mesh

Suits sloping ground, longevity,

strong, keeps open view.High embodied energy.

22270

100Dh/m

C

206m

Roadside -

moderate

slope

As above As above As above19775

96Dh/m

D

72mFlat bare soil

50x50 mesh and timber

fenceposts

Quick and easy construction.

Low visual impact.

Relatively expensive,

vulnerable to vandalism

9479

132Dh/m

E

280m

Riverside

flatAs above (A) As above (A) As above (A)

11100

40Dh/m

F

35m

Steep rocky

section

Mortared wall with

concrete posts (5m c/c)

Longevity, aesthetics and extremely

robust

Costly, time consuming

construction

7685

220Dh/m

G

110m

Linkages

betweenhomes

Mortared wall with

concrete posts (10m c/c)

Longevity, aesthetics and extremely

robust

Getting agreement from

locals to use existing walls

14605

133Dh/m

H

119mFlat bare soil As above (D) As above (D) As above (D)

14426

121Dh/m

J

147m

Stepped Soil,

rocky

terraces

As above (B & C) As above (B & C) As above (B & C)14985

102Dh/m

TOTAL 122550

KEY STATS

1426 m LENGTH

122550 MDH TOTAL COST

86 MDH/m COST/M

98550 MDH MATERIALS


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Figure 6.2: Map showing

Pearl millet in Africa. Photos

of Pearl Millet (top) and Okra

6.0 Crops

Different crop types a critique with respect to Imi nTizghte

A number of different crop types are grown today in Imi nTizghte, this chapter looks at those species

which are grown, those which could be exploited further, and new crops which may not have been

considered before. The hope is to leave the local population with ideas for future agriculture to make

best use of the water whilst bolstering income.

6.1 Existing Crops

There is a limited variety of crops grown in Imi nTizghte today, generally due to the fact that the boars

eat most crops. They do not eat wheat, therefore it is the most popular crop. Some small parcels have

simple self maintained boar fences and they grow Courgettes, Aubergines, Squashes, Peppers and

various root vegetables. Alfalfa is also grown as animal feed.

The vast majority of the oasis is taken up by fruit trees including Argan, Olive, Almond, Date with a few

Carob and the occasional Pomigranite. There are also some fruiting cactus trees.

6.2 New crops

Suggestions for new crops include Pearl Millet, Pistachio tree,

Marama bean and Okra. These are all dryland crops, though

market value in the region requires further assessment. Pearl

Millet is often preferred to maize or wheat because of its

tolerance to difficult growing conditions such as

drought (it can survive on 200mmrainfall /year!), low

soil fertility and pH, high salinity levels and high

temperatures. It can be used as animal feeds, bread

and cous-cous making, and porridges. The Marama

bean is rich in oil and protein (rivaling soya) and

grows well in the Kalahari Desert. Okra is a another

dryland crop. It is a vegetable which grows wild in

Ethiopia and Egypt and is now grown and used for

cooking and making oil throughout the world.

Olive Almond Date Argan

Figure 6.1: Some trees of Imi nTizghte


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Fi

re

.

:T

e

r

ist

c

i

tree


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6.3 Future outlook

It is recommended that an effort is made to increase the numbers dryland cash crops in the area. This

can be in the form of the potential new crops mentioned in 6.2 and increasing numbers of certain

existing crops and trees such as Carob and Cactus. INRA are very interested in driving and monitoring

the use of the Prickly pear cactus. This i

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