Individual and combined impacts of future climate and land use changes on the water balance

- Impact of climate and landuse changes on water balance in future.
- SWAT model is used to estimate the water yield, ET and its change in the future and Markov Chain used for land use prediction.
- Runoff is affected more by climate change and future rainfall estimated by downscaling climate parameter.
- ET is affected more by landuse change due to changed curve number.
- Integrated effects of climate and landuse project higher runoff and lower ET in future.

Both the climate and land use changes have considerable impact on the water balance of a basin and sub-watersheds influencing various parameters such as water yield, surface runoff, evapotranspiration (ET), etc. Therefore, to predict the trend in the future water balance, individual and combined impact of both should be considered. The major objective of the study is to assess changes in the future water balance by investigating the independent and integrated impacts of climate and land use changes using SWAT (Soil and Water Assessment Tool) model in a part of the Narmada river basin in Madhya Pradesh, India. This includes the sub-objectives of future projection of rainfall and minimum and maximum temperatures by LS-SVM (Least Square Support Vector Machine) and SDSM (Statistical Downscaling Model) models to estimate climate change impact, and prediction of land use change of the basin area by the Markov Chain model. The present and future climate of the 2020s, 2050s and 2080s have been projected along with the past, present and future land use projection (1990, 2000, 2011, 2020 and 2050). The individual and combined effects on water balance have been shown in 12 sub-watersheds (SW) of the basin projecting increased water yield and decreased ET in the future. Individual impact of climate change shows high water yield, surface runoff and ET, while the individual impact of land use change shows increased water yield and surface runoff but decreased ET in the future. The SW 1-7 indicate comparatively higher surface runoff and water yield due to the presence of bare lands, agricultural lands and settlements and lower ET, while southern SW of 8-12 show low water yield and surface runoff but higher ET due to the presence of more vegetation and forest areas. The impact of climate change is found to have a more prominent effect on the water yield while impact of land use change is more on ET.

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