Climate change impacts on river basins of Gujarat

  • Climate change impacts on river basins of Gujarat
  • Climate change impacts on river basins of Gujarat
  • Climate change impacts on river basins of Gujarat

Client: TARU, Ahmedabad

Details:

The study evaluates the impact of climate change on stream flow in the 7 river basins of Gujarat state by using the output of a regional climate model (RCM) as input at daily interval to the hydrologic model, the Soil and Water Assessment Tool (SWAT). The potential impacts of climate change on water yield and other hydrologic budget components were quantified by driving SWAT with current and future climates.

Simulated climate outputs from PRECIS regional climate model for present (1961-1990) and a future period (2071-2100) for two different IPCC SRES socio-economic scenarios both characterized by regionally focused development but with priority to economic issues in one (A2 scenario) and to environmental issues in the other (B2 scenario) have been used. To start with the precipitation analysis was carried using the Baseline and A2, B2 scenarios so as to predict the impact of precipitation changes with respect to the frequency and duration. One day and 2 day maximum rainfall analysis was performed and studied over Gujarat state. It has been found that the intensity of maximum one day and 2 day storms is increasing for A2 and B2 scenarios when compared to baseline for different return periods. The increase in depth is comparatively higher (almost double) in the coastal areas of south west and south east Gujarat. Subsequently it has also been observed from additional analysis that the number of rainy days has also reduced in A2 and B2 scenario when compared with the Baseline scenario.

A total of 60 years of simulation over 7 river basins of Gujarat have been conducted; 30 years belonging to SRES baseline (control) and the remaining 30 years belong to SRES A2 and B2 (GHG) climate scenario. Each river basin has been further subdivided into reasonable sized sub-basins so as to account for spatial variability of inputs in the baseline and GHG scenarios. It has been observed that the impacts of climate change are consistent over the state of Gujarat although are varying in magnitude across the river basins as well as sub-basins. The analyses have revealed that the GHG scenario may deteriorate the conditions in terms of severity of droughts and intensity of floods in various parts of the state of Gujarat. This may be attributed to the increase in intensity of events and the reduction in the number of rain events.

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