Evapotranspiration Mapping for Poverty Analysis and Irrigation Management in Morocco
Client: The World Bank
Location: Morocco
Period: 2008 – 2010
Project Summary
Agricultural area in Morocco.
Current irrigation demands are depleting surface water supplies and have increased groundwater use beyond sustainable aquifer recharge rates. Riverside Technology, inc. developed physically based, spatially distributed evapotranspiration (ET) estimates using energy balance-based remote sensing techniques. The ET data were used as inputs to a water balance model to estimate groundwater use and to serve as baseline conditions for evaluating World Bank funded irrigation rehabilitation and improvement measures.
Project Details
Morocco’s agriculture consumes 85 percent of available water resources. In the last four decades, the development of reservoirs and irrigation infrastructure have greatly improved Morocco’s ability to store and efficiently distribute water, however, population pressures and drought have substantially offset these improvements.
Many irrigators are relying increasingly on groundwater pumping for their water supply and, as a result, water tables are declining rapidly. Information on when, where and how much irrigation water is consumptively used is becoming more important with increased pressure on Morocco’s limited water supplies.
Riverside Technology, inc. (Riverside) teamed with AGMIR, a Moroccan engineering and rural development firm, to evaluate specific components of the water balance and categorize the components by uses and associated productivity. Riverside used remote sensing techniques, meteorological data, and surface water data, provided by Moroccan water management agencies, to assess irrigation performance. This approach offered a substantial improvement in spatial resolution and an unbiased and more comprehensive accounting of all water contributing to the budget.
Riverside used the METRIC surface energy balance methodology for estimating and mapping ET. METRIC requires satellite imagery with thermal (surface temperature) information, as well as high quality weather data from one or more weather stations located in an agricultural area within the satellite image. Water balance models were developed for the study areas, using monthly and seasonal ET estimates from METRIC along with irrigated acreage and surface water records from the Moroccan government, to estimate monthly groundwater extraction.
Results are used as a baseline condition for monitoring trends in water use and for assessing the impacts of irrigation system improvements.