Contribution of Natural Water Retention Measures to Integrated Water Management in Ungauged Basins

Interest in Natural Water Retention Measures (NWRMs) for large river basins is growing rapidly as a result of a wide range of benefits, including improved water retention capacity and regulation of ecosystem services. However, suitable site-specific NWRMs in small ungauged basins prone to flash floods and erosion, such as the Vrutci Reservoir Basin in Serbia, have yet to be evaluated and applied, primarily because of a lack of necessary data. The aim of this study was to design an easy-to-implement approach to evaluating the effects of NWRMs on peak discharge, tailored specifically to small basins with significant data gaps. The approach involves developing and analyzing a synthetic unit hydrograph (SUH) based on the available landscape geospatial data and evaluating the effects of NWRMs on the SUH before and after implementation of site-specific NWRMs. This methodological framework allows for quantification of the NWRMs’ effects on the basin and evaluates the proposed measures’ impact to secure better acceptance among stakeholders and informed decision-makers regarding their location in the basin. The results underscore a peak discharge rate reduction from 5% to 33% and hence indicate a positive impact on basin water retention potential. These results highlight the need for support for improved regulating ecosystem services in integrated water management.