Assessing Water Withdrawals in Scarce-Data Transboundary Areas by Use of Dynamic Precipitation–Flow Relationships: The Case of the Hasbani River Basin

The present study proposes a nonstandard solution to the problem of assessing water withdrawals (AWW) in the scarce-data transboundary basin. The applied AWW method operates with the open-source available data on precipitation and river flow and thereby overcomes the usual restriction due to lack of data on shared water use in the Middle East. Analysis of dynamic precipitation-flow relationships enable to separate the effect of water withdrawals from the total decline of river flow under the decreasing precipitation. This study is the first which provides complete information (1972–2020) on water withdrawals from total, surface, and base flow of the Hasbani River (Lebanon). The resulting values that exceed by far earlier published estimates were confirmed by (i) indirect indices (area of irrigated land and population), and (ii) validation of the AWW method based on independent data on water use (Israel Water Authority). The study results are useful for water balance estimations, as well as for management of water resources in the Jordan River headwaters basin and in the entire Lake Kinneret Basin. The AWW method can be applied to other transboundary basins and enables historical and real-time monitoring of water withdrawals as a necessary database for settlement of riparian water relations.