Evaluating gabion performance in sediment yield reduction of basin under current and future conditions (case study: Dehbar basin)

Climate change exerts a considerable impact on the hydrological cycles. Relying on the Long Ashton Research Station-Weather Generator (LARS-WG) statistical model and the Soil & Water Assessment Tool (SWAT), the present study discusses the effects of climate change and gabions on sediment yield of Dehbar drainage basin, Khorasan Razavi Province, Iran, over the next three decades. First, meteorological data were generated for the study period by calibrating the LARS-WG for the basin. Then, meteorological data for the 2020–2050 interval were downscaled using the Hadley Centre Global Environment Model version 2 (HadGEM2) under three Representative Concentration Pathway scenarios, namely RCP8.5, RCP4.5, and RCP2.6. The SWAT was then used to investigate the effects of climate change on runoff and sediment transport in the drainage basin. LARS-WG results were suggestive of a decline in precipitation and a rise in temperature by 2050. The SWAT calculated runoff variations at −21.8%, −17.5%, and −17.1% and sediment yield variations at −4.6%, +9.3%, and +3.1% under RCP8.5, RCP4.5, and RCP2.6, respectively. Removing gabions increased the sediment load by 57% at the basin outlet.