Hydrological significance of Himalayan surface water and its management considering anthropogenic and climate change aspects

Water plays a key role in maintaining different ecosystem services. The anthropogenic and climate change impacts studies on Himalayan water resources has been trending in recent years. The Indian Himalayan region cover several states like Jammu & Kashmir, Ladakh (Union territory), Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh and the hilly regions of Assam and West Bengal. Water resources in this region are the life support for humankind and rich biodiversity. Researchers has reported that the warming in the Himalayas is more than the global average, thereby climate change can affect significantly in the mountainous water resources so as the snow and glacial melt is the main lifeline of the perennial rivers' flow. Almost every year, the heavy monsoon rainfall brings floods on the upstream highlands and then the downstream plains causing enormous human suffering, loss of property, loss of life, agricultural crops damage as well as increased economic losses. The main challenges being associated to the frequency and magnitude of extreme weather events like monsoon rainfall which leads to flash floods, landslides and debris flow; and then the drought during dry season also, has had huge impacts on regional water security. Human actions like economic development and population growth have also brought changes in land cover/use to Himalayan watersheds recently. As a result of farming, grazing, tree planting, urbanization, etc., the changes in land cover have altered the water balance and transformed the water-flow paths in the global hydrological cycle. In contrast to freshwater ecosystems, demand is high, but their supply is limited, also depend on the specific flow pattern of rivers. Although, with interference of various infrastructure development upstream results in changes in flow pattern downstream causing non-availability of water to support aquatic life and communities that depend on for livelihoods. Initiation of monitoring and observation system for water resources and use of appropriate hydrological model are preferable to better understand the hydrological processes of the Himalayas.