Assessing the potential impacts of climate change on streamflow in the data-scarce Upper Ruvu River watershed, Tanzania

Abstract

This study assessed the impacts of climate change on streamflow in the data-scarce Upper Ruvu River watershed (URRW). The Long Ashton Research Station Weather Generator (LARS-WG) was employed for generating the future ensemble-mean climate scenario based on six global circulation models (GCMs), under two representative concentration pathways (RCPs: RCP4.5 and RCP8.5). The future projections were made in two periods (2041–2060 and 2081–2100), and the baseline period (1951–1978) was used as a reference. The watershed hydrology was represented by the Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) model, which was calibrated and validated by using 5 and 4 years of streamflow data, respectively. Results indicate that the rainfall and minimum and maximum temperatures will increase in both periods, under both scenarios. This will potentially affect the streamflow that is projected to increase from March to August and decrease from September to February. The mean annual streamflow could potentially change from 48 m3/s in the baseline period to 45.6 and 56.5 m3/s during 2041–2060, and 52.4 and 67.4 m3/s during 2081–2100, under RCP4.5 and RCP8.5, respectively. The minimum and maximum streamflows are also predicted to change in both periods, under both scenarios. Considering these results, the climate change will have significant impacts on the streamflows of the URRW. HIGHLIGHTS The climate change impacts on streamflow were assessed in two future periods (2050s and 2080s) under RCP4.5 and RCP8.5.; The rainfall and temperature are projected to increase in both periods under RCP4.5 and RCP8.5.; The climate change will have significant impacts on the streamflow of the Upper Ruvu River watershed.;

Keywords

• climate change
• hec-hms
• multi-gcms
• rcps
• streamflow
• upper ruvu river watershed