Supplementing Farm-level Water Productivity Assessment by Remote Sensing in Transition Economies

Abstract Increasing water scarcity in the downstream areas of several river basins demands improved water management and conservation in the upper reaches. Improved management is impossible without proper monitoring at various levels. In the Aral Sea Basin, monitoring is carried out, albeit largely by under-paid staff; however, the water flows to farms and fields remain largely unmeasured due to poor infrastructure and lack of proper measurement facilities. Any conclusions drawn, and therefore the policies devised for water conservation, remain largely ineffective. Contrary to the prevalent human methods of monitoring, the potential for standard monitoring of large areas at field- or farm-level in terms of water depletion and yield, using the Surface Energy Balance Algorithm for Land (SEBAL), and eventually leading to water productivity calculations, is explored here using multi-source public and non-public remote sensing data combinations. The results show reasonable levels of accuracy and indicate areas needing improvements and further investigation and refinement. Farm-level maps of various water depletions and productivities provide a practical view of the performance for the mesolevel. Finally, the link between the field, farm, district, and province is briefly addressed in order to provide a methodology using water depletion assessment at smaller level to upscale it to a sub-basin scale.

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