Impact of Climate Change on Runoff Generation: An Application to Rift Valley Lakes Basin of Ethiopia

• Published in: Journal of hydrologic engineering 2012-08
• Main Authors: Wagesho, Negash, Jain, M K, Goel, N K
• Format: Article
• Language: English
• Subjects: Bias; Climate change; Climate models; Computer simulation; Mathematical models; Precipitation (meteorology); Runoff; Watersheds
• ISSN: 1084-0699
• DOI: 10.1061/(ASCE)HE.1943-5584.0000647

In the present study, an attempt has been made to investigate the potential impact of climate change on runoff generation at two agricultural watersheds. Climate change and key future signals of its variability are assessed using General Circulation Models (GCMs). Since GCMs are operating at coarser resolution, statistical downscaling method (SDSM) is applied to reduce large-scale atmospheric variables into localized weather variables from BCCR-BCM2.0 and CSIRO MK3.0 GCMs outputs. As precipitation variables are composed of biases, both linear and power transformation bias correction methods are applied to obtain bias corrected daily precipitation. Bias corrected daily precipitation and temperature variables are used to simulate runoff for current and future climate scenarios using Soil and Water Assessment Tool (SWAT) model. The statistical downscaling model, followed by bias correction, effectively reproduced the current weather variables. It is noted that increased extreme daily precipitation and temperature events prevail for future scenarios. Dry-spell length increases during the driest months and remains stable during wet seasons. There is no defined future precipitation change pattern. The simulated runoff varies from - 4% to 18 % at Hare watershed and is within the range of -4 % and 14 % at Bilate watershed. Simulated average annual runoff shows slight variation between GCMs at both watersheds.