Assessment and inventory on soil erosion hazard are essential for the formulation of successful hazard mitigation plans and sustainable development. The objective of this study was to assess and map soil erosion hazard in Lesser Himalaya with a case study. 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. The average rate of erosion hazard is 0.68 mm/year or 224 tons/km 2 /year. Anthropogenic and geo-environmental factors have together significantly accelerated the rate of erosion. This reconnaissance study estimates the erosion rate over the period of 3 years (2006-2008) as 1.21 mm/year (398 tons/km 2 /year) in the barren land having geological background of diamictite, siltstone and shale rocks, 0.92 mm/year (302 tons/km 2 /year) in the agricultural land with lithology of diamictite, slates, siltstone, limestone rocks, while in the forest land, it varies between 0.20 mm/year (66 tons/km 2 /year) under dense forest land having the geology of quartzwacke and quartrenite rocks and 0.40 mm/year (132 tons/km 2 /year) under open forest/shrubs land having geological setup of shale, dolomite and gypsum rocks. Compared to the intensity of erosion in the least disturbed dense forest, the erosion rate is about 5-6 times higher in the most disturbed agricultural land and barren land, respectively. The erosion hazard zones delineated following scalogram modelling approach. Integrated scalogram modelling approach resulted in severe classes of soil erosion hazard in the study area with numerical values of Erosion Hazard Index (EHI) ranging between 01 (very low hazard) and 5 (very high hazard).

Assessment and inventory of landslide susceptibility are essential for the formulation of successful disaster mitigation plans. The objective of this study was to assess landslide susceptibility in relation to geo-diversity and its hydrological response in the Lesser Himalaya with a case study using Geographic Information System (GIS) technology. The Dabka watershed, which constitutes a part of the Kosi Basin in the Lesser Himalaya, India, in the district of Nainital, has been selected for the case illustration. The study constitutes three GIS modules: geodiversity informatics, hydro informatics and landslide informatics. Through the integration and superimposing of spatial data and attribute data of all three GIS modules, Landslide Susceptibility Index (LSI) has been prepared to identify the level of susceptibility for landslide hazards. This resonance study, carried out over a period of five years (2007Á2011), found that areas of most stressed geo-diversity (comprising very steep slopes above 308, geology of Lower Krol and Lariakanta formation, geomorphology of moist areas and debris sites, land use of barren land with a very high drainage frequency and spring density) have a high landslide susceptibility because of high rate of average runoff (33 l/s/km 2 ), flood magnitude (307.28 l/s/km 2 ), erosion (398 tons/km 2 ) and landslide density (5Á10 landslides/km 2 ). The areas of least stressed geo-diversity (comprising gentle slopes below 108, geology of Kailakhan and Siwalik formation, geomorphology of depositional terraces, land use of dense forest with low drainage frequency and spring density) have the lowest landslide susceptibility because of the low rate of average runoff (6.27 l/s/km 2 ), flood magnitude (20.49 l/s/km 2 ), erosion (65.80 tons/km 2 ) and landslide density (1Á2 landslides/km 2 ).

Purpose -The main objective of the study is to identify the vulnerable areas for river-line and flash flood hazard and its mitigation through GIS Database Management System (DBMS) of geo-hydrometeorological parameters. 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. Design/methodology/approach -The Dabka DBMS is constituted of three GIS (Geographic Information System) modules, i.e. geo-informatics (consists of geomorphology, soils, geology and land use pattern, slope analysis, drainage density and drainage frequency), weather informatics (consists of daily, monthly and annual weather data about temperature, rainfall, humidity and evaporation) and hydro-informatics (consist of runoff, sediment delivery, and denudation). The geo-informatics and weather informatics modules carried out by comprehensive field work and GIS mapping than both modules used to carry out hydro-informatics module. Through the integration and superimposing of spatial data and attribute data with their GIS layers of all these modules prepared Flood Hazard Index (FHI) to identify the level of vulnerability for flood hazards and their socio-economic and environmental risks. Findings -The results suggest that geo-environmentally most stressed areas of barren land (i.e. riverbeds, flood plain, denudational hills, sites of debris flow, gullies, landslide prone areas etc.) have extreme vulnerability for flood hazard due to high rate of runoff, sediment load delivery and denudation during rainy season (i.e. respectively 84.56 l/s/km 2 , 78.60 t/km 2 and 1.21 mm/year) whereas in geo-environmentally least stressed dense forest areas (i.e. oak, pine and mixed forests) have low vulnerability due to low rate of stream runoff, sediment load delivery and denudation (i.e. respectively 20.67 l/s/km 2 , 19.50 t/km 2 and 0.20 mm/year). The other frazzled geo-environment which also found high vulnerable for flood hazard and their risks is agricultural land areas due to high rate of stream runoff, sediment load delivery and denudation rates (i.e. respectively 53.15 l/s/km 2 , 90.00 t/km 2 and 0.92 mm/year). Research limitations/implications -For hydro-informatics module it is quite difficult to monitor water and sediment discharge data from each and every stream of the Himalayan terrain due the steep and rugged topography. It requires strategic planning and trained man power as well as sufficient funds; therefore representative micro-watershed approach of varied ecosystem followed for a three years (2006)(2007)(2008) period. Practical implications -The study will have great scientific relevance in the field of river-line flood and flash flood hazard and its socio-economic and environmental risks prevention and management in Himalaya and other mountainous terrain of the world.

No abstract

No abstract