Investigation of the Mass Movement in Varand Region, Western Ghat of Ha Maharashtra Using Geospatial Technique
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International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 7, July 2018, pp. 20112027, Article ID: IJCIET_09_07_214 Available online at http://iaeme.com/Home/issue/IJCIET?Volume=9&Issue=7 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed INVESTIGATION OF THE MASS MOVEMENT IN VARANDHA REGION, WESTERN GHAT OF MAHARASHTRA USING GEOSPATIAL TECHNIQUE Dattatraya J. Khamkar PhD Scholar, Civil and Environmental Engineering Department, VJTI, Mumbai-400019, Maharashtra, India Sumedh Y. Mhaske Associate Professor, Civil and Environmental Engineering Department, VJTI, Mumbai-400019, Maharashtra, India ABSTRACT Verandha Ghat Section is connecting shield-plateau region with Konkan Coastal Belt (KCB) through Bhor Ghat area. Therefore, it is considered as a lifeline of Bhor (in Pune district) and Mahad (Raigarh District of Konkan), of western Maharashtra corridor. Geologically, this region belongs to Ambenali and Mahabaleshwar – Poladpur formation. The area shows thick flows of the Deccan Trap basalt of Upper Cretaceous to Eocene age. All the rock flows of this formation, exposed along this highway are in the form of rock cutting along the Pandharpur-Mahad Maharashtra State Highway -70, in the 74 km Ghat section from Bhor (part of Sahyadri Uplands, from Pune district) onwards and before Mahad (part of Konkan Coastal Belt from Raigarh district) of Maharashtra, are highly susceptible for landslide activity. A detailed exploration was carried out on all along the road section started from Bhor city and it extends up to the Varandah village, at the foot hill of Sahyadri, in Konkan region. In the present context, detailed investigations of the mass movement were carried out to prepare the map of highly vulnerable locations, in the study area. The remedial measures are suggested to minimize the severity of landslide. Key words: Konkan, Landslide, Mass Movement, Sahyadri, Verandha, Western Ghat. Cite this Article: Dattatraya J. Khamkar and Sumedh Y. Mhaske, Investigation of the Mass Movement in Varandha Region, Western Ghat of Maharashtra Using Geospatial Technique. International Journal of Civil Engineering and Technology, 9(7), 2018, pp. 2011-2027. http://iaeme.com/Home/issue/IJCIET?Volume=9&Issue=7 http://iaeme.com/Home/journal/IJCIET 2011 [email protected] Investigation of the Mass Movement in Varandha Region, Western Ghat of Maharashtra Using Geospatial Technique 1. INTRODUCTION Mass movement is one of the most important processes which can cause enormous changes on the surface of the earth. It is a process, in which sudden downward movement of rock / or loose sediments lead to the formation of slopes. Such movements of slope forming material cause extensive damage to life and property, in which the communication networks such as Highway, Railway, Canals, Tunnels etc. will be generally affected. In most of the time, these processes become most active in the rainy season. They affect at least 15 percent part of India- an area which exceeds 0.49 million km2 (ndma.gov.in). These are the unpredictable natural phenomenon, which causes property and living loss of life. Generally, such process is defined as the probability of occurrence of landslides within a specific period of time and within a given area (Varnes, 1984). While, in according to Schidegger (1994), landslides are the probability, that reasonably stable condition may opaque abruptly. Afterward, Guzetti et al (1999) preferred the definition to include the area, volume and velocity of the expected landslides. The complete hazard assessment and mapping work should be based on where, when, and how large a landslide will occur. An increasing socio-economic interaction between the Konkan Coastal belt and Plateau region has resulted in an increase in the density the lines of communication, by traversing through the Ghat section, which is highly susceptible for mass movements, especially in rainy season. Such activities some at local and regional scale produce large-scale hazard along the ghat section roads. Resulting, highway traffic jam takes place. The term the Western Ghats geographically includes a chain of hill range which trending roughly North-South and run parallel to the west coastline of India. The Sahyadri escarpment is a steep, high-rise west facing, which varying elevation ranging from 500 to 1500m and having regional slopes of wells over 17° (Peshwa and Kale,1987). Rock falls and landslides are localized in those parts of the Ghats with slopes exceeding 35° and the part which directly comes base of the scarp is suffering from slope failure problems. Slope stability studies by various leading workers in this field, for example, Terzagi (1950), Morgenstem and Sangrey (1978) among numerous others indicate that the stability of any slope is primarily dependent upon the Slope angle; Physical properties of the material underlying the slope, e.g. shear strength (s); cohesive strength and the angle of int saturated samples yield weaker strength characteristics while the dry, unaltered samples are considerably stronger. According to Parthsarthi and Shah (1981), the compressive strength of Deccan Trap basalts recorded varying from 1000 and 2600 kg/sq.cm. Their observation again confirms that the saturated and/or weathered samples are considerably weaker. Simple estimates of slope stability would, therefore, suggest that the horizontally stratified, completely unaltered, compact basaltic flows of traps should sustain perfectly stable slopes with inclinations exceeding 30°. The slope failures noted in along the highway in the Ghat section invariably fall in the rock- fall rock-topple category in the classification of Varnes (1978). Therefore, it may be concluded that the slope failures observable in the Western Ghats are due to a combination of factors which are induced as a consequence of the mass-wasting of the trappean rocks. Ansari and et al. (2016) focused on risk consequence analysis for rock fall locations along SH-72of Maharashtra. Singh and et al. (2010) have done the static and dynamic analysis of a landslide of the Amiyan area, near Kathgo dam, Nainital, Uttarakhand. A comparative analysis has been carried out on the basis of factor of safety of slope. Savoikar and Choudhury [2010] considered the effects of cohesion and fill amplification on seismic stability of municipal solid waste landfills. Liquefaction of soil is generally occurs in loose cohesionless http://iaeme.com/Home/journal/IJCIET 2012 [email protected] Dattatraya J. Khamkar and Sumedh Y. Mhaske saturated soil when pore water pressure increases suddenly due to induced ground motion and shear strength of soil decreases to zero and leading the structure situated above to undergo a large settlement , or failure. Mhaske and Choudhury [2010] have developed a methodology for preparation of soil liquefaction susceptibility map of the entire Mumbai city during earthquake using GIS. 2. STUDY AREA The study area is a part of Sahyadri Uplands, which is present between Konkan Coastal Belt bounded to the Arabian Sea in the West and shield - plateau region in the east. It is next to the Bhor, a southwestern boundary of Pune District. The proposed study area is located in Bhor region of Pune district of Maharashtra along SH-70. The area under investigation falls in the - economic interaction between the Konkan Coastal belt and Plateau region has resulted in increase in the density, the lines of communication, by traversing through the Ghat section, which is highly susceptible for mass movement especially in rainy season. Such activity some at local and regional scale produce large- scale hazard along the ghat section roads resulting, highway traffic jam takes place. Location Map of the study area is shown in Fig. 1. Figure 1 Location Map of the study area 2.1. Geology and Geomorphology As stated above, the study area of Ghat section is a part of Deccan Volcanic Provinces (DVP) which formed in Upper Cretaceous to Lower Eocene period. Lithologically, these volcanic igneous rocks are massive (non-vesicular), some time presence of empty cavities (vesicular) / filled gas cavities with secondary minerals (Amygdales), and fine textured. The flows two types of characters, i.e. nonvesicular-compact basalt flows are thick, regular, and extensive and are shows plain tops and bottoms. While, the amygdaloidal basalt flows are thin, irregular, less extensive, chaotic flows and absence of plain tops and bottoms. These individual flows are separated by thin, bands of red / green tachylitic basalt. When they expose to the atmosphere, they rapidly give a response to the weathering action and converted into small fragments, resemble like baked soil and after some period, the baked soil starts to convert into the fine textured clay. http://iaeme.com/Home/journal/IJCIET 2013 [email protected] Investigation of the Mass Movement in Varandha Region, Western Ghat of Maharashtra Using Geospatial Technique At places, the rock shows different divisional planes, viz. columnar (vertical), sheet (horizontal) and irregular (both consistent and inconsistent) type. The block type of joint is comparatively less. These joints are open at the surface at the top portion. As the study area is a part high relief zone of Sahyadri Upland. Therefore, it shows a high rate of precipitation, comparative to the low relief areas of plateau region (Pune District Gazetteer). Therefore, during rain, water seeps through these joints and encircle the nucleus of the. Resulting, separate, isolated blocks are formed. During every rainy season, fine developed loose sediment was washing out and the gaps between two blocks were washing out. In this way, the gaps between two blocks were increased and such blocks become unsupported. In this way, they started to dislodge, in the form of mass movement activity in this area. This formation covers nearly 85% part of Maharashtra state and hence the continuous area of plateau having rocks of trap formation (Gupte, 2005). While the southward extension of the basalt traps origin can be traced a little beyond Maharashtra. Layers of such basalt rock have almost horizontal deposition except for some local deviation.