Assessment of the land use/land cover and climate change impact on the hydrological regime of the Kulsi River catchment, Northeast India

The present study has shown the changes in climatic variables and land use/land cover to observe the long-term changes in the hydrological characteristics of the Kulsi River. Mann-Kendall test, Expert Team on Climate Change Detection and Indices Index, t tests, and Analysis of variation were used to analyze the change and variation. The Mann-Kendall test shows a significant declining trend of rainfall at Chamaria (- 26.76 mm/year) annually, the seasonally significant declining trend was noticed in the winter season at the rate of (- 1.47 mm/year) at Ukium, whereas Chamaria showed a declining trend of rainfall in the post-monsoon season at the rate of (- 5.62 mm/year). Among all stations, maximum temperature showed a significant increasing trend at the rate of (0.03 degrees C/year) at Chaygaon, while minimum temperature showed a significant increasing trend at the rate of (0.02 degrees C/year) at Ukium and Chamaria, respectively. Consecutive dry days have shown significant positive trends at the rate of (0.85 days/year), (0.67 days/year) and (1.35 days/year) at Chaygaon, Ukium, and Chamaria. The areas under forest cover and water body have decreased, whereas cropland and transition areas have increased. In the case of the hydrological variables, only the water level has shown significant annual variation (p value is 0.002). However, both water level and discharge show seasonal variation significantly. The water level has shown a significant negative relation with maximum temperature (R and p values are - 0.78 and 0.00 respectively) and a significant positive relation with forest cover (R and p values are 0.6 and 0.01 respectively). On the other hand, water discharge has a significant positive relation with annual rainfall (R and p values are 0.5 and 0.03, respectively). The findings of the research show that increasing maximum temperature and decreasing forest cover are responsible for the decline of water level in the Kulsi River. Whereas, a decrease in rainfall leads to a decrease in discharge and vice versa. The findings of the present research will be helpful to the policymakers and government in preparing a suitable sustainable river management plan to address the declining water resources to mitigate water scarcity issues.