Abstract
Several methods of impact assessment have been developed over the years which basically incorporate future climate projections of atmospheric-ocean cir culation based climate models into the simulation o f land surface hydrological processes. This study attempte d to evaluate three methods of climate change impac t assessment: (a) Frequency perturbation method, (b) direct method and (c) delta change method. A wellcalibrated hydrologic model, Soil and Water Assessment Tool (SWAT), was used in watershed simulation for climate projections of mid-century by ten Globa l Climate Models (GCMs). The frequency perturbation method found precipitation decrease by 17% and reduction in temperature by 0.43°C on an average annual basis. The changes when applied through the simulat ion model resulted in 13% reduction in Evapotranspiration (ET) and 25% reduction in water yield. Other two methods produced different set of results. It’s not conclusive to say which method pe rformed better. The frequency perturbation method produced most extreme changes while direct method had the least magnitude of changes projected for the mid-century. Changes in ET and water yield due to c hanges in future climate are likely to have severe implications for the water availability. However, m ore research is needed to evaluate several other im pact assessment methods for more reliable analysis.
Highlights
Hydrological cycle has been found to be significantly impacted by the climate change
This study considered a set of 10 Global Climate Models (GCMs) to hopefully avoid the potential bias that cannot be avoided if considered only one or few climate models
This study evaluated there methods of assessing climate change impact on watershed hydrology
Summary
Hydrological cycle has been found to be significantly impacted by the climate change. Intergovernmental Panel for Climate Change (IPCC) reported evidences of strong correlations between the increasing amount of greenhouse gases and aerosols into the atmosphere and the rising global temperature (IPCC, 2007). Warming is projected to be the greatest over northern latitudes and the least in the Southern Ocean and parts of North Atlantic Ocean. The most warming is likely to occur in winter in northern regions and in summer in the south western USA. The impact of climate change on hydrological processes have been investigated in the United States and across the globe during the last decades (Jha et al, 2004; 2006; 2013; Jha and Gassman, 2013; Takle et al, 2005; 2010).
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