Assessment of the Impact of Big Dams in the Himalayan Mountain Environment System: Management and Sustainability

Dams are an ancient innovation for irrigational and household requirement purposes. Nowadays, it is mainly used for irrigation and hydropower electricity generation. Himalayan rivers have more than 600 dams, adding to the upstream flow velocity and causing significant sediment accumulation around the impoundments. Loss of forest cover, animal species, and human settlements are evident due to the construction of dams and reservoirs. An assessment of the Indian Himalayan Region (IHR) is conducted to evaluate the relationship between various factors and parameters which directly and indirectly affect the dam sites and its periphery. The vulnerability of the ecosystem increases because the study area is a seismically active zone, and anthropological impacts accentuate the possibilities of hazards. The focus is to study the large dams in the Indian States, namely, Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, Assam, and Arunachal Pradesh. The three main river basins, Indus, Ganga and Brahmaputra, are included for better understanding. Major problems like sedimentation, lack of nutrients downstream, and hindrance to the mobility of the riverine species, mainly the fish during their spawning period. The changes have shown differences between the designed and observed rate of siltation (Th.Cu.m/sq. km./Yr). Maps have been generated from QGIS (v3.14) software to represent better the different aspects of the analysis—a graphical data representation was prepared with the help of the data provided by the India Water Resource Information System (WRIS-India) and Central Water Commission (CWC) websites. The entire study is done through secondary data and information.