Assessing watershed hydrological response to climate change based on signature indices

Due to the fact that one of the important ways of describing the performance of basins is to use the hydrological signatures, the present study is to investigate the effects of climate change using the hydrological signatures in Azarshahr Chay basin, Iran. To this end, Canadian Earth system model (CanESM2) is first used to predict future climate change (2030-2059) under two Representative Concentration Pathways (RCP2.6 and RCP8.5). Six signature indices were extracted from flow duration curve (FDC) as follows: runoff ratio (RR), high-segment volume (FHV), low-segment volume (FLV), mid-segment slope (FMS), mid-range flow (FMM), and maximum peak discharge (DiffMaxPeak). These signature indices act as sorts of fingerprints representing differences in the hydrological behavior of the basin. The results indicate that the most significant changes in the future hydrological response are related to the FHV and FLV and FMS indices. The BiasFHV index indicates an increase in high discharge rates under RCP8.5 scenario, compared to the baseline period and the RCP2.6 scenario, as well. The mean annual discharge rate, however, is lower than the discharge rate under this scenario. Generally, for the RCP8.5 scenario, the changes in the signature indices in both high discharges and low discharges are significant. HIGHLIGHTS Prediction of future runoff under two RCPs using SDSM and SWAT models. Six signature indices were used to investigate the hydrological behavior of the basin. Annual precipitation, temperature, streamflow and six signature indices of the RCPs were compared. The most significant changes in the future of hydrological response are related to high flows.

Automated summary

This study investigated the effects of climate change on the Azarshahr Chay basin in Iran using hydrological signatures. The results showed that the most significant changes in future hydrological response are related to high and low flow volumes, as well as mid-segment slope.