Spatio-temporal Variability of Climatic and Hydrological Extremes in River Basins in India

Mandraha, Shivanand (2025) Spatio-temporal Variability of Climatic and Hydrological Extremes in River Basins in India. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Shivanand Mandraha (15RS070)) 15RS070.pdf - Submitted Version Restricted to Repository staff only Download (8MB)

Abstract

Hydro-climatic extremes are expected to increase because of human-induced changes in climate and may cause grave impacts on a nation's socio-economic condition. We investigate the changes in extremes of rainfall, the number of dry days, the maximum and minimum temperature in the river basins of India. We selected 7 river basins experiencing large changes in recent decades for further investigation. We found that the percentage areas of the basins experiencing significant anomalies in these variables has increased in recent decades. We further investigated the variability of extreme rainfall, temperature, and discharge of the Ajay River basin in Eastern India and their implication on groundwater declination. The quantile perturbation and Sen methods were used to analyze the hydro-climatic variables. The second half of the century shows intensified anomalies in the annual extreme rainfall, reaching anomalies up to 70%. The temperature has declined in the past decades, most likely due to an increase in aerosol concentrations which blocks solar incidence. The annual and monsoon extreme daily discharge of the upper basin lies within the natural variability, but the lower basin shows a 7-year-long significant positive anomaly with a maximum value of 34%. The fall in groundwater levels in the Ajay River basin correlated with the extremes of rainfall, annual rainfall, and discharge, suggesting a probable cause of declination in groundwater. In addition, the groundwater level reduction was also correlated with changes in land use and land cover but to a lesser extent compared to the extreme precipitation and the annual river discharge. The analysis suggested that falls in groundwater levels are influenced by the combined effects of climatic and non-climatic factors. Analyzing these trends could aid in the planning and management of upcoming activities.

Actions (login required)

View Item