Mitigation Strategies

through IWRM

By N. Toae –Hydrobiologist, DWA

Introduction

Water is vital for drinking, sanitation, agriculture, industry, generation of hydropower, navigation, recreation, fish farming and countless other purposes.

It is termed “White Gold” in Lesotho because of its economic value.

We need to conserve water and manage it for the benefit of present and the future generations.

• Lesotho’s main Lesotho’s main naturalnatural resource resource export is …export is …

WATERWATER

Introduction cont…Floods cause the destruction of property and

loss of life. Impaired water quality brings disease and

death to humans and aquatic life.Droughts can also be a cause of starvation

and famine.

PRECIPITATIONAnnual rainfall 500mm – 1200mm.

The annual average of 720mm.

85% rainfall in summer (0ct-Apr).

Snowfalls experienced in winter.

RIVER SOURCES IN LESOTHO The wetland (sponge) systems are sources of

rivers in Lesotho, most of which are located in the highlands of the country.

Wetlands are capable of storing water and slowly release this water into small streams that ultimately drain in to river systems.

Over grazing and other development activities threaten the lives and capacities of these wetland systems.

Mohokare6,890 sq.kms

Makhaleng2,911 sq.kms

Senqu28,847 sq.kms

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% Senqu @ Seaka Bridge

Surface Water Resources Of LesothoSurface Water Resources Of Lesotho

RIVER SOURCES IN LESOTHORIVER SOURCES IN LESOTHO

WETLAND AT MOTETE AREA

GroundwaterMost of groundwater is of good quality

because of its natural purification processes.People in the rural areas of Lesotho depend

on it for their daily life.Available data shows that water level in

boreholes responds accordingly to rainy periods and droughts.

Spring yield is also lower during droughts, down to drying up in some springs and it is high in rainy periods.

This simply means Lesotho’s groundwater is dependent on seepage of rainwater.

YIELDS OF NATURAL SPRINGS IN LESOTHOBY DISTRICT

DISTRICTDISTRICT YIELD (l/s)YIELD (l/s)

MokhotlongMokhotlong 0.01 – 8.470.01 – 8.47

Botha-BotheBotha-Bothe 0.01 – 2.90.01 – 2.9

LeribeLeribe 0.01 - 2.570.01 - 2.57

BereaBerea 0.03 – 0.630.03 – 0.63

MaseruMaseru 0.01 – 1.980.01 – 1.98

MafetengMafeteng 0.01 – 1.530.01 – 1.53

Mohale’s Mohale’s HoekHoek

0.04 – 1.570.04 – 1.57

QuthingQuthing 0.01 – 2.70.01 – 2.7

Qacha’s NekQacha’s Nek 0.02 – 1.140.02 – 1.14

Thaba TsekaThaba Tseka 0.03 – 5.410.03 – 5.41

Waiting for Groundwater

Pumping for Groundwater

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WATER QUALITY FOR THREE MAJOR RIVERS OF LESOTHO

PARAMETER SENQU MOHOKARE MAKHALENG WHO

Conductivity (µs/ cm) 50 - 250 70 – 450 0 – 250 1000

Nitrates (mg/ l) 0 – 2.0 0 – 0.08 0 – 1.8 5

Phosphates (mg/ l) 0 – 0.77 0 – 0.12 0 – 1.8 0.02

PARAMETER SENQU MOHOKARE MAKHALENG WHO

Conductivity (µs/ cm) 50 - 250 70 – 450 0 – 250 1000

Nitrates (mg/ l) 0 – 2.0 0 – 0.08 0 – 1.8 5

Phosphates (mg/ l) 0 – 0.77 0 – 0.12 0 – 1.8 0.02

Parameter

Senqu Mohokare

Makhaleng

WHO guidelines

Conductivity (µS/cm)

50-250 70-450 55-250 1000

Nitrates (mg/l)

0-0.08 0-12.6 0-1.8 5

Phosphates (mg/l)

0-0.12 0-0.77 0-1.8 0.02

Cause for concernBecause of the fact that global water

resources are more or less fixed while world population is very rapidly increasing, the competition on water between development and environment may cause local and regional disasters.

Effects of climate change on water resources

Increased temperatureDrying up of water bodiesIntensified pollution of water resourcesIntensity and frequency of storm increasesMore floods and droughts

Prevailing situation – PollutionA water body has capability of cleansing itself

called assimilation capacity.When pollution is beyond the assimilation

capacity of a water body, it causes eutrophication.

Results show that some of Lesotho’s water bodies are polluted already.

MOHOKARE DOWNSTREAM OF THETSANE INDUSTRIAL SITE

Prevailing Situation - GroundwaterMost of groundwater is of good quality

because of its natural purification processes.People in the rural areas of Lesotho depend

on it for their daily life.

Greatest ChallengesAvailability of fresh water is one of the greatest

challenges facing humanity at present.Lesotho’s need for water continue to grow

wider in space and bigger in population.Growing developments use water massively

thereby generating considerable wastewater that pollutes water resources.

In the near future Basotho will be affected by shortage of water or pollution of water bodies or both.

Plan If the competition for water is transformed into

partnership, the goal of sustainable development will be attained, as recommended in the world water forum of 2000.

Integrated Water Resources management that includes planning and management of water resources should be employed.

To achieve IWRM, there is a need for coherent national and where appropriate, regional and international policies to overcome fragmentation, and for transparent and accountable institutions at all levels.

Develop new sources of waterIncrease water use efficiency and reduce water

lossesOperational hydrological monitoring and forecast

systems

Integrated Water Resources ManagementThe ways and means of evaluating and

balancing supply and demand for water in a specific region.

The assessment of measures which enable the reduction of demand and increase of available supply should be considered.

Supply could be:Precipitation or flash floodsPermanent or seasonal flowing rivers and

streamsDams, Lakes and reservoirsGroundwaterSoil moisture storage in the unsaturated zone

Other SourcesRecycled treated sewageRecycled treated industrial effluentWater transported from other locations

Parameters to mitigateDrought impactsImpacts on Water qualityFlood impacts

Drought impacts mitigation measuresStorage reservoirs for surface &

groundwater should be constructed to store water to avail it when most needed for the benefit of all water users.

i. Control gates should be regulated to supply according to demand.

ii.Surface water reservoirs should be big enough to cater for siltation over an operational period of 500 years.

iii.Each of the three catchments of Lesotho should have one or two reservoirs depending on their population.

Drought impacts mitigation measures cont…Conservation farming will conserve moisture

& minimize evaporation so that crops don’t need frequent irrigation and also minimize erosion.

Conserved drip irrigation – this method irrigates crop by crop not wasting water on bare land thereby minimizing water loss.

Controlled Allocation of water – consideration of soil type and crop type should guide quantity of water allocated for irrigation

Conservation farming

Conserved drip irrigation

Drought impacts mitigation measures cont…Telemetry system – strict monitoring of

compliance to quantity allocated should be followed, e.g. use of data loggers measuring level upstream & downstream

Water recycling – massive water users should be legally bound to have effective treatment plants and reuse their wastewater in their productions.

Roof water harvesting – use of RWH tanks to store rain water will provide water to many people during times of drought

Water Pollution mitigation measuresPollution sources are mostly sewage related

and in the lowlands.Time bound removal of septic tanks, manholes,

etc. by relevant institution.Transparent and accountable institutional

operationsWet Industries should be placed away from

settlements to have enough land for their wastewater treatment plants

Consolidate all environmental laws of Lesotho and introduce environmental courts dealing with environmental issues solely.

Manhole oozing into Kelekeqe Stream

Pollution mitigation measures cont.Proper disposal of waste according to type

and recycle that which is recyclable.Management of pollution should not be all

penalties, include incentives for compliance.

While implementing the polluter pays principle, charge should be on loads not quantity of effluent based on impact of pollutant, e.g. heavy metals should be more expensive as they are not biodegradable.

Flood impact Mitigation MeasuresUse of remote sensing to estimate rainfall

from satellite images in three different spectral bands; infrared, visible and water vapor.

Flood impact Mitigation Measures cont…Produce and distribute to users a regular

forecast bulletin containing relevant data, information, deterministic and Extended Stream flow predictions forecasts of river flow regime.

Use of other media as early warning on the likelihood of a flood and advise accordingly.

Set different alternatives and scenarios for managing the whole basin in a way that benefits all countries in the basin.

Kea LebohaContacts:Department of WaterAffiarsP.O Box 772 MaseruEmail: toae@dwa.gov.ls Tel: 22314569, 22317516