Identification of Landslide Hazard Zones in Greater Visakhapatnam Municipal Corporation, Andhra Pradesh, India—A Geospatial Approach

Abstract

The study area, Greater Visakhapatnam Municipal Corporation (GVMC) is the largest one which occupies an area of 545 km2 is also a gateway to industries and tourism in Andhra Pradesh. The area is characterised by hilly terrain with moderate valleys and coastal plains comes under the Eastern Ghats. The area has been covered by reserved forests, within the jurisdiction of GVMC. Owing to industrialisation, urbanisation and migration of rural people encroaching into the Kailasagiri and Yaradakonda thick vegetated hill ranges leading to deforestation. Thatched and asbestos roof houses, single to multi-storied buildings are being constructed in the foothills of these two hill ranges without following the building norms and topographic conditions. Rainfall induced landslides/slips are more common claiming innocent lives. In this study, SOI toposheets, IRS-P6-LISS-III satellite imagery and SRTM-30 data used to generate drainage, geology, geomorphology, land use/land cover, slope revealing fractured and jointed khondalite rocks, altered drainage, erosion, fluvial and marine landforms. Jointed khondalite hillocks, porous and permeable, weathered zones and erosion by different agencies are the potential landslide zones. The Soil Bearing Capacity (SBC) ranges from 28 to 40 t/m2 in the foothill areas. Study suggests, terrain characteristics are to be taken into account besides SBC before taking up of constructions in hilly terrain. Terraced or split level foundation with adequate retaining wall support is a suitable technique which can withstand to the hill slope conditions.