GROUNDWATER GEOLOGY OF PART OF LATUR DISTRICT, MAHARASHTRA STATE, INDIA

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GROUNDWATER GEOLOGY OF PART OF LATUR DISTRICT, MAHARASHTRA STATE, INDIA Vadagbalkar Shrinivas Krishnaji Department of Geology, D.B.F. Dayanand College of Arts and Science, Solapur-413002, (M.S.), INDIA (Email: vadagbalkar@gmail.

Though the entire district comes under drought area, agriculture is the main source of livelihood. Ground water is predominantly used for irrigation.

However dug wells are the main ground water abstraction structures in the district for domestic and irrigation use. Ground water development depends on many factors viz.

1 GROUNDWATER GEOLOGY OF PART OF LATUR DISTRICT, MAHARASHTRA STATE, INDIA Vadagbalkar Shrinivas Krishnaji Department of Geology, D.B.F. Dayanand College of Arts and Science, Solapur , (M.S.), INDIA ( ) ABSTRACT Latur is one of the drought district of Marathwada regions of Maharashtra State, India. Though the entire district comes under drought area, agriculture is the main source of livelihood. Ground water is predominantly used for irrigation. Ground water in the area is being developed by two type of abstraction structures i.e., bore wells and dug wells. However dug wells are the main ground water abstraction structures in the district for domestic and irrigation use. Ground water development depends on many factors viz., availability, crop water requirement, socio-economic conditions and on the yield of the aquifers existing in that area. The yields of wells are functions of the permeability and transmissivity of aquifer encountered and vary with location, diameter and depth etc. In major parts of the district, declining water level trends have been observed in almost entire Nilanga, Ausa, Latur and Renapur talukas and northern part of Ahmadpur and southern part of Udgir taluka. KEY WORDS: Census of Latur District, Ground water geology, semi-arid climate, INTRODUCTION Latur District Latur district is in the Marathwada region in Maharashtra in India, located between 17 52' North to 18 50' North and 76 18' East to 79 12' East in the Deccan plateau. It has an average elevation of 631 meters (2070 ft) above mean sea level. It covers an area of about 7304 sq.kms, and included within topographic map no. 56/B, 56/C, 56/F of the Survey of India (scale 1: 50,000). Geographically it is divided into 10 talukas namely Latur, Ausa, Ahmedpur, Nilanga, Chakur, Renapur, Udagir, Shirur-Anantpal, Deoni and Jalkot (Wikipedia, 2011) The map of latur District is showed in Figure 1. Almost entire district is underlain by the Basaltic lava flows of upper Cretaceous to lower Eocene age. The shallow Alluvial formation of Recent age also occur as narrow stretch along the banks of major rivers flowing in the area but it does not form potential aquifer. Figure 1. Map of Latur District Meteorological Conditions: The district has a semi-arid climate and is characterized by moderate precipitation of 700 mm per year and a wide range of daily fluctuations in temperature. The district receives rainfall mainly from south-west monsoon which starts from middle of June and lasts up to the end of September. The rainy season is followed by winter, the intensity of Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 4

2 which is more in the month of January with temperature ranging between 10 0 to 15 0 Celsius. The winter is followed by summer, which is having the months of April and May as hottest, with the average temperature ranging between 40 0 to 45 0 Celsius. Geomorphological Investigations: Geomorphologically, Balaghat plateau running eastwards is the major geomorphological unit (Government of India Ministry of Water Resources Central Ground Water Board, 2009). In general the area of the district shows uneven topography with residual hills belonging to Balaghat ranges. The altitude of the area ranges between 500 to 715 m above mean sea level. Physiographycally, the district can be divided into two parts i.e., Higher Elevated Plateaus, which occurs in the western and southern parts of the district in Latur, Ausa, and Nilanga talukas and Lower Elevated River Valleys, which comprises valley plains of Manyar and Lendi rivers in Ahmedpur and Udgir talukas and valley plains of Manjra and Tawarja rivers and plains of Terna River and its tributaries. The district forms a part of Godavari basin. Manjra River, a tributary of Godavari River flowing south-easterly is the major river in the district. Tawarja and Terna rivers are the main easterly flowing tributaries while Gharni and Rena rivers are southerly flowing tributaries of Manjra River. The rivers shows dendritic and rectangular drainage pattern. The district can be divided into two zones based on soil characteristics i.e., the first zone which occurs in eastern part of the district comprises of Ahmedpur, Udgir and parts of Latur and Ausa talukas. It consists of light and light medium soil of inferior type. They are not retentive of moisture and are therefore suitable for the cultivation of Kharif crops only. The soil in some parts of Nilanga taluka is of Lateritic type and the second zone which occurs in western part of the district comprising parts of Latur and Ausa talukas. They are heavy deep black cotton soils. Owing to the peculiarity of the soil, both Kharif and Rabi crops are cultivated in this zone. The Latur district is situated on plateau and low hills of extended Balaghat ranges of main Sahyadri ranges from Marathwada region which are made up of Deccan Trap basaltic flows. They have NW SE strike direction. Deccan volcanic, being horizontal in disposition. Show the development of flat surfaces. They are very often covered by thick piles of alluvial soil. At places, they are characterized by high degree of weathering and subsequent erosion. All these factors are very important for the occurrence of shallow water table conditions. Drainage Systems The district forms part of Godavari basin. Manjra River is the main river flowing through the district. The precipitation, falling in the term of drops on an uplifted land mass, constitutes the main source of the hydrologic cycle. The principal rivers flowing through the district are Manjara, Tawarja, Terna, Rena, Gharni, Dev, Minar and Tiru.The South West part of the district is made up of Manjara basin within the district the length of Manjara is 130 kms, Terna kms, Tiru 52.8 kms, Tawarja 50 kms, Manar 50 kms, Gherna 38 kms and Dev 35 kms. Manjara forms the major river basin in the district which includes Terna, Tawarja, Rena, Gherni and Dev as tributaries. The big towns such as Latur, Ausa and Udagir are situated on the raised plateau while Ahmedpur and Nilanga lies on sloping ground of these plateau. The results of resistivity surveys carried out by the author for groundwater prospecting in various places in Latur districts is incorporated in Table No.1. The generalized ranges of resistivity values for different flows obtained from soundings and corresponding litho logs are as follows. Table 1. General or Average Resistivity values and Interpreted Geological Litho unit Resistivity in ohm-m Geological Litho unit 3 to 12 ohm-m Soil 12 to 15 ohm-m Alluvium 15 to 25 ohm-m Red beds 25 to 45 ohm-m Weathered fractured or vesicular basalts 45 to 80 ohm-m Hard and jointed basalts >80 ohm-m Hard and massive basalts Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 5

3 MATERIALS AND METHOD Occurrence of the groundwater at any place is directly depending upon the geological formations. The Deccan Volcanics, representing basaltic flows of Cretaceous Eocene age, are the most extensive geologic formations in the Latur district. The author has carried out number of geophysical surveys in the district to assess groundwater potential (Table 2). Table 2: Resistivity (Ohm-M) For Different Lithotypes Interpreted From Representative Villages (I.E. Deccan Trap Area) In Latur District Sr. No. Location Survey Depth In Meters Interpreted Litho units with variability in depth and thickness ( Average Resistivity is given for respective Litho Unit) Soil Alluvium Red bed Weathered vesicular Hard and jointed basalt AUSA TALUKA Hard and massive basalt 1 Ekumba Ekumba Gubbal Killari Killari Killari Killari Killari Killari Killari Killari Killari Killari Ausa Ausa Ausa City Ashiv Ashiv Ashiv Ashiv Ashiv Ashiv Ujjani Ujjani Ujjani Ujjani Ujjani Ujjani Talani Gangakheda Umbarga Malkund These basaltic flows are known for their marked horizontality, characteristics, flat topped hills and step like terraces. The prospects of groundwater in Deccan Volcanics, like any other hard rock, largely depend upon several factors including rainfall, topography, geological features, hydrological properties of rocks etc. The Saucer shaped basins or depressions having varying depth and extent are potential areas for groundwater prospecting in the districts. Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 6

4 Table 2. Continued NILANGA TALUKA 1 Kokalgaon Kokalgaon Ambalga Kusur Balkunda Kusur Balkunda Kusur Balkunda Kusur Balkunda Kasarshirshi Kasarshirshi Jevari Jevari Badur Badur Utasari Utasari Shirdhon Shirdhon Panchinehali Panchinehali Ramling Mudgad Ramling Mudgad Ramling Mudgad Ramling Mudgad Ramling Mudgad Sangavi Sangavi Telgaon Devani Ahmedpur Taluka 1 Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Wadwal Nagnath Andhora Nalegaon Nalegaon Nalegaon Himpalner Anandwadi Chakur Chakur LATUR TALUKA 1 Ekurga Ekurga Please note: (Based on this obtained scientific data by adoption of Electrical Resistivity Method survey techniques in the fields - Bore wells drilled (Between 70 to 100 meters - maximum up to the depth of 120 meters) are successfully working either for drinking or / and irrigation, for public or private use) Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 7

5 Rolling and flat areas are moderately favorable whereas hill tops and rugged hilly areas are unfavorable for the occurrence of groundwater. It has been a practice in the districts, to dig open wells in topographic lows or depressions to obtain groundwater from shallow aquifers. These wells are obviously confined to the soil covered or weathered basaltic flows. Groundwater at deeper levels on the other hand is held only in joints and fissures and can be tapped by drilling bore wells. Recharge to such deeper aquifers is mainly controlled by percolation through overlying flows. Permeability, the ability of rock to transmit water, in the Deccan Volcanics, mainly depends upon the inter connections of either pores or joints. Partly decomposed and fractured zones are favorable permeable zones for groundwater movement. The ground water potential at different places distributed in parts of Latur District is determined by adopting Geological and Geophysical methods of prospecting. Of the different methods of electrical resistivity, a method suggested by Wenner has been followed due to its simplicity, ease of operation and also immediate applicability to draw the interface, in the basaltic terrain, for prospecting under groundwater conditions. Based on the experiments attempts are made for assessing the groundwater potential at different places. RESULTS AND DISCUSSION The results of resistivity surveys and subsequent drilling of borewells for village drinking water programme and for irrigation of agriculture lands shows that good amount of groundwater is available in Ashiv, Ujjani and Killari villages in Ausa taluka while moderate amount of water is available in Nilanga taluka in Kasarshirshi, Ambalga and Balkunda villages, and in Ahmedpur Taluka Chakur, Wadwal Nagnath areas are noteworthy. In Latur district taluka Ekurga area proved to be promising for groundwater exploration. The Udgir taluka has moderate water potential. The average aquifer depth lies between 40 and 70 mtrs., from ground level and it is constituted of hard but well jointed basalt formations. The average yield of these borewells is about 1800 LPH. The maximum yield of LPH is noticed in Ashiv village of Ausa taluka. Slope analysis of the Latur district demarcates the areas of permanent source of groundwater resources. These are as follows. Latur Taluka:- Central, Northern and North-eastern areas lying in Manjara and Rena river basin and Southern and South0-western part of Tawarja basin. Ausa Taluka:- Northern and southern part of the taluka which lying in Tawarja and Terna basins. Nilanga Taluka:- Northern, eastern and south-eastern part laying in Manjara and Gharni basin and southern portion of Terna basin. Ahmedpur Taluka:- Central, northern and north-eastern portion of Mannar basin and a small area of Tiru basin. Udagir Taluka:- North eastern portion lying in Tiru basin and southern area lying in Dev basin. Good scope is available for the systematic and planned exploration of groundwater resources in different parts of all talukas of Latur district. The government departments, Zilla Parishad and any other Semi-Government organizations should come forward for financial assistance in research and development programme to solve water resource problems which the farmers are facing in different part of the district. However it is equally important to note that modern techniques of water conservation, storage of rain water in lakes /ponds, natural and artificial recharging of dug well, bore well and ground, adaption of modern methods of irrigation to minimize the wastage and to protect from evaporation, selection of crop pattern suitable as per availability of ground water, understanding of soil and permeability characters etc must be implemented to preserve the ground water storages. Groundwater movement in hard rock s like basalts is very sluggish, erratic, haphazard, discontinuous and gravity driven, below the surface. Its occurrence and movement may or may not synchronize with surface flows. It is important to note that the today s available groundwater at shallow and deeper depths is stocked by natural processes, which operated continuously for past thousands of years. SUGGESTIONS FOR FUTURE DEVELOPMENT PLAN FOR GROUNDWATER PROSPECTINGS: Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 8

6 The author suggests following important guideline in future planning of groundwater requirement in the District Systematic hydro geological mapping of each watershed is to be carried out and displayed publically for information and planning strategies To measure precipitation accurately, installation of rain gauges at every selected stream basins is urgently needed. Water balances studies are to be carried out at regular intervals of seasons and year in the district. Selection of sites for major and minor surface reservoirs should be carried out purely on scientific basis. Study of replenishment of groundwater by percolation tanks is to be carried on selected sites to measure the aquifer parameters such as Storativity, Transmissivity and Specific yield. The entire district is underlain by the Deccan Trap Basalt where only dug wells are most feasible structures for ground water development. Hence proper geologically feasible sights must be recommended. The sites for bore wells need to be selected only after proper scientific investigation. Bore wells generally tap deeper fractures, which may not be sustainable. Besides, the bore wells should only be used for drinking water supply and not for irrigation. The scope exists for constructing of suitable artificial recharge structures in the district. The structures recommended for the hilly-basaltic area are: contour bunds, gully plugs, nala bunds and check dams. For other Basaltic areas, particularly in Nilanga, Ausa, Latur, Renapur and Ahmedpur talukas, where water levels are deep and falling water level trends are also observed, the nala bunds, check dams, inverted dams, and KT weirs are suggested. Farm ponds, percolation pits, trenches and contour bunds are to be implemented on local level. The existing dug wells may also be used for artificial recharge of ground water provided source water is free of silt and dissolved impurities. These sites need to be located where the hydrogeological conditions are favourable, i.e., where sufficient thickness of unsaturated/de-saturated aquifer exists and water levels are more than 5 m deep. The existing village ponds need to be rejuvenated to act both as water conservation and artificial recharge structures. Proper care should be taken for protecting the water bodies from any kind of pollution. Public awareness campaigns must be organized regularly for protection, conservation and management of private and public water bodies. CONCLUSION Deccan Traps occurs as Basaltic lava flows, which are normally horizontally disposed over a wide stretch and give rise to tableland type of topography, on weathering also known as plateau. These flows occur in layered sequence ranging in thickness from few meters to 50 m. Flows are represented by massive portion at bottom and vesicular portion at top and are separated from each other by marker bed known as bole bed. Ground water in Deccan Trap Basalt occurs under phreatic conditions at shallow depths up to 15 to 20 m. At deeper levels, the ground water occurs under semi-confined to confined conditions. The weathered and fractured trap occurring in topographic lows, form the main aquifer in the district. The vesicular portion of different lava flow varies in thickness from 15 to 25 m and forms the potential zones. The yield of dug wells tapping upper phreatic aquifer, range from 25 to50 m3/day and that of bore wells varies from 0.50 to m3/day; depending upon the local hydro geological conditions. REFERENCES Census, Latur District (2011). CGWB Report (2009). Ground Water Information, Latur District, Maharashtra-(1615/DBR/2009) Official website of Collector & District Magistrate, LATUR Government of India Ministry of Water Resources Central Ground Water Board (2009). URL: Wikipedia (2011). URL: Volume- 1 Issue-2 (2014) ISSN: X (Print); (Online) 2014 DAMA International. All rights reserved 9

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