Application of Remote Sensing for Water Accounting in Data Scarce Areas: The Case of Wabi Shebelle River Basin

Abstract

Water is a basic necessity for sustaining life and development of society an output of this study is readily available to assist planners and managers to make decision on water resource availability in a catchment and also is to assess and forecast water demand in the basin. The WaterPix model and Remote sensing data were used for the design of surface water potential of WSRB. The research objective is to apply remote sensing products for data scarce areas using water accounting plus (WA+). To assess the water resources situation in WSRB using remotely sensed derived data for the period 2012 to 2021. To explore this methodology water accounting plus (WA+) was done with WaterPix model using WaPOR with 5km resolution data for precipitation, 100m resolution ETa , LULC with 10m resolution from sentinel-2 and ∆S was assessed from GRACE. Precipitation data from WaPOR, on the other hand, significant correlations were observed between these data and rainfall records. In addition, the Sentinel-2 LULC map was reclassified to WA+ classes using World database on protected areas. Application of WA+ to WSRB result for a 10-year analysis shows the net inflow into the basin is 1327.4Mm3 /year with depleted water from evapotranspiration of about 1276 Mm3 /year. The basin has a considerable outflow of 51Mm3 /year and the available exploitable water is 585.9Mm3 /year. The majority of Evapotranspiration incremental (ETinc) total volume of 534.9 Mm3 /year originates from natural withdrawals (429 Mm3 /year) and less from human-made withdrawals (105.9Mm3 /year) the majority of the available water resources go to Utilized Land Use (ULU) and protected Land Use (MLU). Evapotranspiration sheet and Withdrawal sheet was quantified. In this study lack of data, has been overcome by relying on remotely sensed data like WaPOR and other data for water accounting analysis. The results of this study highlights that the satellite datasets can provide a spatial overview of where in the basin water is generated and consumed via ET.WA+ shows the value of hydrological, manageable, utilizable flows, sustainability of water in the resource base sheet, Beneficial & non-beneficial flows in the Evapotranspiration sheet and quantification of the gross and net withdrawals via the withdrawals sheet. To improve understanding of the basin water resources and conditions, and water management achievements in WRSB.