CLIMATE CHANGE IMPACT ASSESSMENT ON SOIL ORGANIC CARBON AND EROSION USING GEO STATISTICAL APPROACHES

Abstract

In the present study, an attempt has been made to assess the impact of the climatic change on soil organic carbon (SOC) stocks and soil erosion in a hilly region of India (north of Tehri Garhwal district, Uttarakhand) by using geostatistical modelling technique- Regression kriging and Soil Water and Assessment Tool (SWAT) respectively. In this study, the regression – kriging model developed for current SOC has shown good agreement with the R2= 0.98 and predicted a decreasing trend in C content in the year 2050. The Global Climate Models, HadGEM2-AO (RCP 6.0) and HadGEM2-ES (RCP 6.0) for the year 2050 has showed a decrease of 2.016 Mg ha-1 and 2.046 Mg ha-1 in SOC stocks. The study was conducted to determine the soil erosion using SWAT model in the north of Tehri Garhwal district. In case of soil erosion, the SWAT model is simulated from the year 1980- 1993 with a warm-up period of 3 years on annual basis. The sediment data is calibrated and validated with SWAT- CUP 2012 using SUFI-2 algorithm having R2= 0.43 and 0.54, NSE= -0.32 and -0.27 respectively. R2 is set as the objective function for the analysis. From this study it is found that the SWAT model has run perfectly well. From the result it is conferred that the SWAT model does not cater to gully erosion, landslides and mass wasting, which are occurring in the region. There is also lack of sites for the collection of data sample in a watershed of Tehri Garhwal as the sample collection is done at one outlet only. Then, the climate sensitivity analysis is performed for the sediment yield in the study area with respect to perturbations in rainfall and temperature keeping other parameters constant. The change in sediment yield is decreasing when the rainfall is increasing and decreasing with the increasing in rainfall. Maximum decreasing is seen when the smallest change in rainfall is observed with a value of 23.26 % when the rainfall is decreased by 5 % and maximum increase is observed when the increase in rainfall is maximum with a value of 26.68 % when the rainfall is increased by 15%. The change in sediment yield is increasing when the temperature is increasing. Maximum increase in sediment yield is seen having a value of 42.10 % when the temperature is increased by 30C from the baseline temperature.