SCLI is an Implementing Agent for invasive alien plant clearing in the Western Cape, with secondary functions in environmental communications.

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H20 WEP

WATER EVAPORATION PREVENTION - WEP Systems

WEP Systems is a South African designed and manufactured solution for the worldwide challenge of reducing the effect of fresh water evaporation.

WEP Systems is a modular (floating) surface cover for large water bodies. The aim of the WEP Systems is to cover as much of the surface exposure, as is feasible, of a fresh water storage body, and in doing so, significantly reduce surface water evaporation.

The modular design of the WEP Systems; allows users to cover as much of the available surface area as they see fit. The WEP Systems is able to survive strong winds and harsh climate conditions.

Water users will have to accept that water scarcity is the new “normal”
he new water-scarce normality implies that water users in general, and agriculture in particular, must have an absolute commitment to use water efficiently , even if that means utilizing innovative, drastic methods and measures to ensure long term viability.
A paradigm shift is required if many farmers are to be viable a decade from now, and many will have to invest now in new technology, such as the Water Evaporation Prevention - WEP system.

Responding to the challenge, a local solution has been developed, for landowners to consider, as a viable and sustainable option to significantly reduce the effect of evaporation.

Box 2

WATER RESOURCES

FACE SEVERE RISK

In water stressed environments, such as South Africa, fresh water loss through evaporation can no longer be ignored. On average, 20% of fresh water is lost through evaporation annually.

AGRICULTURAL & COMMUNAL WATER

RESOURCES FACE SEVERE DEMAND

Both agriculture and communal water resources face severe demand and supply side pressure, restricting production progress and human development.

Box 3

RIVER SYSTEMS & ESTUARIES

CONTINUE TO DETERIOIRATE

River systems, Eco-Systems and estuaries continue to deteriorate because of continuously less available water to sustain them.

INVEST IN WATER FRIENDLY TECHNOLOGY

WATER EVAPORATION PREVENTION – WEP System

The WEP System, designed and manufactured in South Africa, is a solution to the worldwide challenge of reducing the effect of fresh water evaporation.

The WEP System is a modular (floating) surface cover for large water bodies. The aim of the WEP System is to cover as much of the surface exposure, as is feasible, of a fresh water storage body, and in doing so, significantly reduce surface water evaporation.

The modular design of the WEP System allows users to cover as much of the available surface area as they see fit or that is affordable.

The WEP System is able to survive strong winds and harsh climatic conditions. Water saving technology, such as the WEP System, will require investment in the short term, but the return will ensure long term sustainability.

WEP Systems

Water Loss through Surface Evaporation cannot be ignored

ABOUT WEP SYSTEMS

IMPORTANT WATER EVAPORATION FACTS

BELOW ARE SOME OF THE MOST IMPORTANT FACTS ABOUT SURFACE WATER EVAPORATION

SURFACE STORAGE RESERVOIRS

Presently, over 2,000 mm is lost each year through evaporation from surface storage reservoirs. This is estimated to about 7.5% of total capacity in the country, and nearly equal to the volume of water stored in the largest dams in South Africa (Smakhtin et al., 2001).

SURFACE DAMS INEFFICIENT

In addition, evaporation losses cause surface dams to be inefficient for long-term storage, since it has to cope with changes in climate. Water losses due to evaporation equate to 1.2m of depth per surface m2. This means that if a dam is 1.2m deep, it will in fact loose the whole body of water during a year of South African heat and wind.

FARM DAMS

According to SA Weather Services, annual (average) evaporation is between 1600 and 1800mm per year, and it is estimated that evaporative losses from farm dams (2100ML/yr) is greater than the amount of irrigation water that is taken from them. In warmer areas (Karoo etc.) the losses would be even worse.

SALINITY OF WATER

The simple loss of water is not even the whole problem; when the water evaporates, any salt – there is always salt in natural water – is left behind; so the salinity of the remaining water increases. The higher the salinity of water, the more problematic is its use.

REDUCING EVAPORATION

Evaporation can be reduced by either providing some sort of a barrier between the water and the air or by somehow slowing the movement of the air near the water surface. Planting a windbreak of trees and shrubs around the dam will help to some extent.

PLANTING A WINDBREAK

On a calm day, the air close to the surface of the water in storage becomes saturated with water vapour. So long as the layer of saturated air stays put, there will be little further evaporation, but if there is a wind the saturated air layer will be continually mixing with dry air and evaporation will continue.

THE INTERNATIONAL WATER STEWARDSHIP PROGRAMME

Water Stewardship is a collaborative effort by the International Water Stewardship Programme (IWaSP), implemented by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH and WWF SA to address water risks in South Africa.

Through a series of workshops with farmers, as well as the business community across the Western and Eastern Cape, a progression of increased improvement of water use, and a reduction of water related impacts were reviewed. Significant resources are allocated by the entire value chain to reduce identified water risks, which remain high, with increasing challenges, such as climate change, urban development and socio-economic pressure.

Central to Water Stewardship is where the water comes from, how it is used, and where it goes to. Loss of vast amounts of critically scarce water resources are lost to the value chain through evaporation, with seemingly little options available to protect the resource in storage.

Responding to the challenge, a local solution has been developed, for landowners to consider, as a viable and sustainable option to significantly reduce the effect of evaporation.