Environmental, geological and economic effects of climate change on the Indian hydrology: A review

Over the last few years, global temperature has increased rapidly and continuously at around 0.2 °C per decade. Climate change is expected to have considerable impacts on natural resource systems, which, in turn, can lead to instability and conflict, displacement of people and changes in occupancy and migration patterns. Rise in atmospheric temperature due to climate change will lead to loss of glaciers in the Himalayas, which, in turn, may reduce water availability in the rivers of Indus – Ganga plains, especially in dry seasons. The response of hydrological systems, erosion processes and sedimentation in the Himalayan region could alter significantly due to climate change. During the twentieth century, majority of the Himalayan glaciers have shown recession in their frontal parts, besides thinning of the ice mass. Retreat in glaciers can destabilize surrounding slopes and may give rise to catastrophic landslides and floods. The melting of ice is changing the hydrological cycles and is also affecting the ocean currents. Many of India’s coastal aquifers are already experiencing salinity ingress including Saurashtra coast in Gujarat and Minjur aquifer in Tamil Nadu. Increasing frequency and intensity of droughts in the catchment area will lead to more serious and frequent salt-water intrusion in the estuary and thus can deteriorate surface and groundwater quality and agricultural productivity. A warmer climate will change the patterns of hydrological cycle, which, in turn, can alter the intensity and timing of rainfall. Mahi, Pennar, Sabarmati and Tapi rivers will face water shortage conditions in response to climate change. River basins belonging to Godavari, Brahmani and Mahanadi may not face water shortages, but severity of flood shall increase in these areas. In future, there will be a net reduction of groundwater recharge and greater summer soil moisture deficits because higher temperature can shorten the duration of recharge seasons. Production of rice, maize and wheat in the past few decades has declined in many parts of Asia due to water shortage. Linking the concept of sustainable development to climate change can provide a deep insight into the proper methods of long term societal responses to global environmental change.