Climate Change accelerating hydrological hazards and risks in Himalaya: A case study through remote sensing and GIS modeling

The main objective of the study was to assess the impact of climate change on hydrological hazards through integrated Database Management System (DMS) on three GIS modules i.e. climate informatics and land useinformatics and hydroinformatics. The Dabka watershed constitutes a part of the Kosi Basin in the Lesser Himalaya, India in district Nainital has been selected for the case illustration. Hydroinformatics module consists of comprehensive study on spring hydrology and stream hydrology to assess several hydrological hazards due to climate change. Land use informatics consists of land use mapping and change diction i.e. decadal changes and annual changes whereas the Climate informatics module consists of spatial distribution of climate and its change detection through daily, monthly and annual weather data (temperature, rainfall, humidity and evaporation) of two study periods i.e. during 19851990 and 20052010. The spatial distribution of climate throughout study area suggesting three types of climatic zones i.e. subtropical, temperate and moist temperate which are respectively favorable for mixed forest, pine forest and oak forest in the mountain ecosystem. The results of climate informatics advocating that all these climatic zones shifting towards higher altitudes due to global climate change and affecting the favorable conditions of the existing land use pattern. In order to that the oak and pine forests have decreased respectively by 25% (4.48 km²) and 3% (.28 km²). The nonforest area has increased dramatically due to lopping and cutting of trees, and growing agricultural activities. The nonforest area has mainly been confined to barren land, riverbed and cultivated land. Barren land increased 1.21 km² (56%), riverbed increased 0.78 km² (52%) and cultivated land increased about 0.63 km² (3%) during the period of 1990 to 2010. The results also advocated that the overall accelerating factor of land use degradation in the study area broadly categorizes as dominant factor and supporting factor. Out of the total seven classes of the land use land cover, five classes (i.e. Oak, Pine, Mixed, Barren and Riverbed) are being degraded dominantly due to climate change factor and anthropogenic factors plays a supporting role whereas only two classes (Scrub land and agricultural land) are being change dominantly by anthropogenic factors and climate change factors plays a supporting role. Expansion of mixed forest land brought out due to upslope shifting of existing forest species due to climate change factor only because upslope areas getting warmer than past with the rate of 9°c-12°c/two decades. Consequently the results concluded that the high rate of land use degradation accelerating several hydrological hazards such as land degradation, high runoff, flash flood, riverline flood, soil erosion and denudation and nonseismic landslides during monsoon season and drought during nonmonsoon period as dryup of natural springs and decreasing trends of stream discharge etc.