Author(s): Mohammed Al-Housni; Luminda Gunawardhana; Ghazi Al-Rawas
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Abstract: Oman is vulnerable to the impacts of climate change, the most significant of which are changes in precipitation intensity and frequency. However, the attributed impacts, such as, flash flooding is poorly understood. The objective of this study is to predict the future variation of wadi-flow under changing climate conditions in Al-khoud catchment area in Muscat, Oman. The Tank model was developed to simulate the precipitation and wadi-flow relationship. Precipitation data during1986-2012 were obtained from the Muscat-airport meteorological station. Observed wadi discharges during 26-30, March1997 were used to calibrate the model and observations during 1997-2011 were used to verify our simulations. The MIROC and NCAR general circulation model (GCM) output from the Representative Concentration Pathways (RCPs) 2.6, 4.5, 6.0and 8.5 scenarios were used for assessing changes in climate in the period of 2080-2099 compared to the baseline period of1986-2005. The spatial mismatch between GCM grid scale and local scale was resolved by applying the LARS stochastic Weather Generator (WG) model. Simulated water discharges agreed with the corresponding observations, with the Nash–Sutcliffe model efficiency coefficient equals to 0.79. Predicted wadi-flow under different climate scenarios show clear evidences of extreme wadi-flow in future compared to observations in recent time. When the 90th percentile of the wadiflow during observation time is considered as the threshold to represent the extreme events, predicted total wadi–flow by different scenarios above this threshold in the future are 0.9 to 17.7 times higher than the total wadi-flow above this threshold during observations in recent time. These results highlight the need of improved water infrastructure facilities to store increase wadi-flow for the benefit of agricultural and domestic water supply.
Year: 2014