Impact of climate change on hydrologic regimes of Western Ghat catchments

Mudbhatkal, Amogh (2013) Impact of climate change on hydrologic regimes of Western Ghat catchments. Masters thesis, Visvesvaraya Technological University.

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Impact of climate change on hydrologic regimes of Western Ghat catchments
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Abstract

The Western Ghats is an environmental and climate sensitive region of India. Livelihood of the population in this region is mainly dependent on agriculture and therefore highly vulnerable to rainfall variability and climate change. For an investigation of the impact of a possible climate change on surface hydrology in the region, the forecasted meteorological parameters through a Regional Climate Model (PRECIS) has been used with a conceptual rainfall-runoff model namely ARNO, to account for soil-atmosphere feedback mechanisms. In order to evaluate the impact of climate change, two river basins in Western Ghats representing two different climatic regimes, i.e., humid and sub-humid are selected, namely, Netravathi river basin in humid climate and the Malaprabha basin under sub-humid climate. This study is carried out with the following objectives viz., (i) to assess the trends in the observed rainfall over the selected river basins; (ii) analyse the variability of evaporation in the forecasted period; (iii) to identify the suitable evapotranspiration method for the region; and (iv) to assess the impact of climate change on hydrological responses from the selected basins. The rainfall, temperature and the evapotranspiration are the intrinsic parameters of the hydrologic cycle. Consequently, these are also the major driving factors of climate change. These parameters have been studied for their shift in regime and trend over the decades in this study.
For the assessment of impact of observed changes in rainfall pattern and the evaporation dynamics on the streamflow responses, a conceptual rainfall-runoff model, the ARNO model, is used. The ARNO rainfall-runoff model has been calibrated using the observed data for a period of 1975 to 2000 and validated with the data from 2001-2005. After the validation of the model, simulation of the hydrological response of these basins has been done for two time slices of 30-years: 2011-2040 and 2041-2070. The simulated hydrological responses for these two basins for the period from 2011 to 2070 indicates that, (i) the peak flows have been shifted from the months of July–August to April-May; (ii) the post monsoon flows have significantly decreased and (iii) the months such as March to May receive a good rainfall and there by contributing to the streamflow. However, the discharge predicted to be below the normal flow in most of the years during 2011-2070. For the selected scenario and time slices, the changing signal in precipitation, as well as surface hydrological variables lies with few exceptions, within the range of inter-annual variability, whereas temperature shows a clear increase.

Keywords:Western Ghats of India, Malaprabha River, Netravathi River, Regional climate models, Indian summer monsoon rainfall, Rainfall-runoff, Hydrology
Subjects:F Physical Sciences > F860 Climatology
F Physical Sciences > F840 Physical Geography
F Physical Sciences > F852 Hydrology
H Engineering > H200 Civil Engineering
Divisions:College of Science > School of Geography
ID Code:49909
Deposited On:22 Jun 2022 13:23

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