Estimation of Soil Loss at Tehri Dam Catchment in Uttarakhand, India.

<p>The soil erosion is the most serious environmental problem in watershed areas in Bhagirathi River. The main factors affecting the amount of soil erosion include vegetation cover, topography, soil, and climate. In order to describe the areas with high soil erosion risks and to develop adequate erosion prevention measures in the watersheds of dams, erosion risk maps should be generated considering these factors. “Reduction in the capacity and life of Tehri dam Reservoir was became a major concern. Remote Sensing (RS) and Geographic Information System (GIS) technologies were used for erosion risk mapping in the catchment area of Bhagirathi River. The principal aim of this paper is to utilize spatial-based soil erosion information to assess land suitability at a watershed level. The model integrated with RS and GIS technologies has great potential for producing accurate and inexpensive erosion risk maps.</p><p>Data on Climate (Total precipitation and its frequency and intensity), Geomorphology (Land form, Physiography, Slope and Drainage Characteristics), Soil characteristics (Texture, structure), Land Use/ Land cover (Density of forest or grassland, plant residue, crops etc.) and Soil management were calculated using standard reported methods (Naqvi et al., 2015). Total 6 parameters were calculated i.e. Slope, Slope length, Soil texture, Drainage density, landuse/landcover and Rainfall erosivity. Weightage of each parameters on the basis of value and classes were assign. At last SYI value were calculated using weightage map, Delivery ratio, area of watershed. The sub-watersheds 10, 11 were identified as being very high risk. Intense rainfall and reservoir area of dam coupled with poor soil structure and steep slopes are the main drivers of soil erosion in this area. Therefore, the proper designing of integrated watershed management and conservation strategies is a crucial element to reduce the current rate of environmental degradation and boost up agricultural production in the sub-watersheds.</p>

Geomorphic Changes Related to Anthropogenic Interference Along the Ganga River From Rishikesh to Haridwar, Uttarakhand, India

The authors, in this study, have quantified the changes in the geomorphic activity of the Ganga River between Rishikesh and Haridwar by using Survey of India (SOI) 1:5000 scale topographic sheets, satellite data, digital elevation model (DEM), and hydrological data from published resources. They have also correlated the change in settlement area in Haridwar and Rishikesh and connected it to the changing geomorphic features in the downstream reach of the Tehri dam site. The study finds that the change in geomorphology of the river in the studied reach of the Ganga River is attributable to reduced water and sediment supply. The study area being in the active tectonic zone, bound between MCT in the north and HFT in the south, may have experienced offsetting of the reduction in sediment supply by dam in the post dam era (after 2006) due to massive earthquakes delivering sediment directly delivered to streams through enhanced landslide and other mass wasting processes.

Integrated Hydrological Modelling over Upstream Catchments of Himalayan Rivers and Assessment of Hydrological Events in Tehri Dam and Srinagar Catchments

Flash floods in the Himalayan Rivers result in hundreds of deaths causing a sudden hazard in a minimum period of time. These hydrological events of mostly happen due to cloudburst incidents in the Indian Himalayas, with an unexpected heavy overwhelming of precipitation in a short interval over a small region. These extreme hydrological events are assessed through the analytical hierarchy process for the upper stream catchments of Tehri Dam and Srinagar. The morphometry characteristics of these catchments are collaboratively integrated with the SAC (Space Application Centre) hydro simulated discharge and rainfall data to identify the flash-flood-vulnerable hazard region over the surrounding catchment regions.