assessment of groundwater potential zones using gis

Frontiers in Geosciences (FG)

Assessment of Groundwater Potential Zones Using GIS Senthil Kumar, G.R*1, Shankar, K2 1

Department of Earth Sciences, Annamalai University, Annamalainagar, India Department of Civil Engineering, Kings College of Engineering, Thanjavur, India [email protected]

2

Abstract-Remote sensing and geographical information system (GIS) has become one of the leading tools in the field of groundwater research, which helps in assessing, monitoring, and conserving groundwater resources. A case study was conducted to find out the groundwater potential zones in Lekkur sub basin of Mangalur Block, Cuddalore district, Tamil Nadu, South India. The thematic maps such as geology, geomorphology, soil hydrological group, land use / land cover and drainage map were prepared for the study area. All the thematic maps were converted into grid (raster format) and superimposed by weighted overlay method (rank and weightage wise thematic maps). From the analysis the groundwater potential zones with excellent, very good, good, moderate and poor prospects covering an area of 7.2 km2, 12.63 km2, 38.57 km2, 32.75 km2 & 7.2 km2 respectively.

potentiality of groundwater resources for agriculture and sustainable development. Recent researches have also proved that indigenous knowledge system, rapid and participatory rural / resources appraisal methods could be integrated in GIS. II. EARLIER WORK Hydrological applications such as groundwater for resources assessment, planning, soil erosion and urban drainage system the remotely sensed data derivative has gained popularity with the advent of raster and vector GIS environment (Burrough, 1986, Brown 1995 and Lyon 2003). Several researches have utilized the GIS technology and the remotely sensed derived data for water resources management, groundwater assessment and modeling. This study addresses the strategies for an integrated approach of remote sensing and GIS techniques to delineate groundwater prospective zones. The technique of integrated remote sensing and GIS has proved to be an efficient tool in groundwater studies (Edet et al. 1998; Krishnamurthy et.al 1996 and Murthy 2000). The Remote Sensing and GIS tools have opened new paths in water resources studies. One of the greatest advantages of using remote sensing and GIS techniques for hydrological investigations and monitoring is its ability to generate information in spatial and temporal domain, which is very crucial for successful analysis, prediction and validation (Sarma and Saraf, 2002).

Keywords- ARC GIS; Groundwater; Weighted Overlay; Thematic Maps I. INTRODUCTION Groundwater is a most valuable natural resource and needs judicious use for sustainable groundwater management. Groundwater development programmes require large amount of multidisciplinary data from various sources. Groundwater occurrence being subsurface phenomenon, its assessment is based on indirect analysis of some directly observable terrain features like geological, geomorphological, structural features and their hydrological characteristics. Satellite remote sensing provides synoptic view, which is helpful in identification and delineation of various land forms, linear features, structural elements and terrain characteristics being significant indicators of groundwater potentiality. There are several methods such as geological, hydrogeological, geophysical and remote sensing techniques, which are employed to delineate groundwater potential zones. A systematic integration of these data with follow up of hydrogeological investigation provides rapid and cost-effective delineation of groundwater potential zones.

In recent years the importance of coupling remote sensing and GIS in groundwater potential assessment studies was realised by many workers like Das et al.,(1997); Toleti et al. (2000); Bahuguna et al. (2003); Lokesha et al. (2005); Vijith (2007); Chowdhury et al. (2009); Suja Rose and Krishnan (2009); Pradeep Kumar et al, (2010); Vasanthavigar et al, (2011); Preeja et al, (2011); for identification and location of groundwater resources using remote sensing data is based on an indirect analysis of some directly observable terrain features like geomorphology, geology, slope, land use/ land cover and hydrologic characteristics. With the capabilities of the remotely sensed data and GIS techniques, numerous databases can be integrated to produce conceptual model for delineation and evaluation of groundwater potential zones. An attempt has been made to delineate the groundwater potential zones in Lekkur sub basin of Mangalur Block, Cuddalore district, Tamil Nadu, S.India. The location map of the study area is shown in Fig. 1.

World over Geographical Information System (GIS) technological applications has now become the common place for the utilities, land information and planning. GIS can be an effective tool in the design and monitoring of groundwater development and its uses. GIS has found a role in the analysis and management of all such areas where ‘variations in local and micro-elements influence the patterns’. There are a vast potential in GIS applications by using remotely sensed data (images) to evaluate the

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Fig.1 Location map of the study area

Several thematic maps necessary for the demarcation of groundwater potential zones were prepared on the basis of information obtained from the toposheets, remote sensing data and field visits are integrated using GIS. Classification involves subdividing the information into several categories to enable zonation of potential into several classes. Thematic maps were prepared for lithology, landforms, drainage, drainage density, soil and land use/land cover are discussed as follows.

III. METHODOLOGY Survey of India (SOI) toposheet 58I/15 and 58M/ 3 on 1:50, 000 scales was used for the preparation of base map of the study area. IRS P6 LISS-III geocoded False Colour Composite, with band combination 2, 3, 4 was procured from NRSA, Hyderabad India. The IRS FCC was visually interpreted based on image interpretation keys and geotechnical elements such as tone, texture, size, shape, association, pattern, drainage, erosion etc (Lillesand and Kiefer, 2002). Interpretation of FCC led to identification and delineation of different hydrogeomorphological units. Subsequently field checks were conducted in important areas to check the veracity of remote sensing data and also to incorporate field knowledge in the map. The drainage map was initially derived from SOI toposheet and subsequently updated using IRS FCC data. Drainage map was digitized as a line coverage showing the entire stream network. The geological map of the study area has been generated through the interpretation of the satellite data keeping in view the geological map prepared by Geological Survey of India (GSI, 2001). The other thematic layers prepared include hydrogeomorphology, geology, drainage density, soil and land use/ land cover of the area. Geographic Information System (Arc/GIS 9.3) was used for the preparation of thematic layers and verified by ground reality.

IV. RESULTS AND DISCUSSION A.Geomorphology According to chambers dictionary the meaning of Geomorphology is “the scientific study of the nature and history of the landforms on the surface of the Earth and other planets, and of the processes that create them”. The geomorphic study was carried out in the study area and the geomorphological map was prepared (Fig.2). The study area geomorphic features have been observed and listed below. i) Duricrust ii) Pediment iii) Shallow pediment iv) Buried pediment v) Flood plain and vi) Pediments covered by reserved forest.



Fig.2 Geomorphological map of the study area

The word duricrust was introduced by an Australian Geologist, Woolnough, in 1927, with four types namely Calcrete, Ferricretes, Silcretes and Alcrete. After woolnough many authors tried to classify the duricrust. However, three types of duri crust (calcretes - caliche zones, Ferricretes - iron oxide, silicates - calcium carbonate) were recognized and in usage. In the study area duricrusts occurs as scattered patches. The prominent patches are occurring near to Nangur forest and Adarnattam village. Pediments are gently sloping smooth surface landforms of erosional bed rock between hills and plains with veneer of detritus. In the study area pediments are surrounded by Nangur forest, Eluthur, Tholudur and Eastern parts of the study area. The shallow pediments covered by block cotton soil. The black cotton soil mainly derived from charnockites. Most of the study area is covered by shallow pediments except in the Nangur forest area and in the central portion. The shallow buried pediments occur in central portion of the study area. The shallow buried pediments occur as a stretch along Periya odai.

forms the southern boundary of the study area. The groundwater potential is high. In shallow depth itself, the groundwater is available; hence the area is suitable for wet crops. The Nangur Reserved Forest is formed in the Northwestern portion of the study area. The Reserved Forest have gentle slope towards east direction. B.Geology and Lineament Density Rock types belonging to early to mid Precambrian represented by charnockite and charnockitic gneiss occupies the study area. Of these, the charnockites are essentially intermediate to acid in composition, coarse to medium grained and form the highland topography. The charnockitic rocks are the oldest and subjected to granulitic facies metamorphism. The gneisses occur as products of retrogression of charnockites indicating an event of retrogression in the metamorphic history of the area. The charnockitic rocks are massive to foliated and the foliations usually trending ENE – WSW with an average dip of 45º towards south. The charnockite shows different depth of weathered zone. The charnockites show well developed foliated fracture in the weathered zones. The geology map of the study area is shown in Fig.3.

In the study area, the southern part of the region is occupied by the flood plains. The Vellar River flows and



Fig.3 Geology and lineament of the study area

Lineament analysis of the study area was carried out by visual interpretation of remote sensing data (IRS – 1D LIIS – III image) in conjunction with the Survey of India toposheet. The lineament map of the study area is shown in Fig 3. The lineaments of the study area are:

i) NE – SW, and

ii) NW – SE

Of these two types of lineaments, majority of the lineaments are in NE – SW direction, the next is NE – SE direction.

Fig.4 Lineament density map of the study area

The lineament density map was classified into two classes— present and absent based on the number of lineament per km2. The classified lineament density maps are shown in Fig. 4. A major portion (>85%) of the study area is comprised of high lineament density. Fractures are cracks or breaks in rocks. They are openings along which walls of the voids are distinctly separated. The most

important function of fractures in relation to the groundwater is, that they act as conduits for percolation of water to deep sources. Only lineaments could acts as better conduits for descent and ascent of groundwater through any form of opening in the rocks. Well – developed fractures intersecting with each other may hold appreciable quantity of groundwater. The hard consolidated and crystalline rocks


like charnockite represent the fissured and fractured formation and which is occur in the entire study area. C. Land Use/ Land Cover Land use describes how a parcel of land is used such as for agriculture, residence or industry, relates to human activity or economic function associated with a specific piece of land.

A detailed land use map was prepared and shown in Fig. 5. The study area consists following land use pattern. i) Barren lands, ii) Crop land, iii) Dry crops, (BCS) iv) Duricrust, v) Reserved forest, and vii) River / Tank / Pond.

Fig.5 Land use map of the study area

The land nearby hillocks, hills, mountains with steep slope poses problems in forming cultivation. Major portion of the terrain is barren land type. The lineaments are very less in the barren land area. So the groundwater condition is very poor in the barren land area. In the study area, Southern side is covered by crop lands. The flood plain is also having crop lands. Crop lands are along the sides of Vellar river. Due to the flow of Vellar river and Periya odai, the region is fertile and forms crop lands. The lineament is also less in this area. The NW, NE, SW, South and along the Periya odai, dry crops (BCS) are occurring. This area is occupied by the hard rock. The storage capacity is also less. The lineament is also less in this area. Hence, the groundwater condition is also less. The lakes, rivers, tanks, are also less in this area. In the study area the duri crust are found as scattered patches of the entire area. Adarnattam, around Nangur Reserved Forest and Vaithiyanathapuram locations are prominent for duricrust occurrences. The entire Southern boundary of the study is covered by Vellar river. Few irrigation tanks and ponds are presented in the study area. The tanks, Periya odai and river are important sources for irrigation.

D. Drainage The study of drainage is one of the practical approaches to understand the structural and lithological control of land form evolution. In the study area agricultural activities depends on wells, rain fed tanks, canal, river, etc. There are no perennial streams, the seasonal river Vellar and Periya odai (runs in central portion) in the study area. The Vellar river originates at Kalvarayan hills and flows West – East direction, and forms the Southern boundary of the study area. The drainage pattern of the study area is shown in drainage map as Fig.6. The dendritic and subdendritic patterns are characterized by irregular branching of tributary streams in many directions and at almost in all angle, although considerably less than at right angles. Dendritic and sub dendritic patterns are found in the study area. They develop upon charnockite rocks of uniform resistance. E.Drainage Density The development of stream segments is affected by slope and local relief and these may produce differences in drainage density from place to place. The spatial variation of drainage density was estimated by following the

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methodology adopted for calculating lineament density. Drainage pattern reflects the characteristic of surface as well as subsurface formation. Drainage density (in terms of km/km2) indicates closeness of spacing of channels as well as the nature of surface material. More the drainage density, higher would be runoff. Thus, the drainage density characterizes the runoff in an area or in other words, the quantum of relative rainwater that could have infiltrated. Hence lesser the drainage density, higher is the probability of recharge or potential groundwater zone. The drainage

density in the area has been calculated after digitization of the entire drainage pattern. The high drainage density area indicates low-infiltration rate whereas the low-density areas are favourable for high infiltration rate. The drainage density values thus obtained were reclassified to prepare a drainage density map and categorized into five categories, namely, Excellent, Very good, Good, Moderate, Poor where more than 75% of the basin belongs to poor drainage density class (Fig.7).

Fig.6 Drainage map of the study area

Fig.7 Drainage density map of the study area



The crops raised are groundnut, gingerly, chilies and millets. Paralithic Ustochrepts soil type covered major portion of the study area overlying and derived from charnockitic suit of rocks. The thickness of the soil is very meager. Charnockite outcrops occur as interiors within the soil. Brown to very dark grayish brown colour indicates their derivation from iron rich mafic minerals.

F.Soil The soil present in the study area was studied and classified upto the sub group level according to the soil taxonomy 1978, by the Soils Survey and Land Use Organization, Tanjavur, Government of Tamil Nadu. Prepared soil map of the study area shown in Fig.8. The distribution of the different soil sub groups are as follows:

2).

i) Paralithic Ustochrept ii) Paralithic Ustorthent iii) Veritic Haplustalf iv) Typic Ustochrept 1).

Paralithic Ustorthent:

These are shallow light textured non – calcareous, dark yellowish brown to dark brown soils. They have rapid permeability and cultivated crops are groundnut, sorghum, cumbu, varagu, and ragi under rain fed condition. Chilies and vegetables under garden land conditions. Paralithic Ustorthent soil occurs in the southern and southeastern parts of the study area.

Paralithic Ustochrept:

These soils are moderately deep, light to medium textured, calcareous, and brown to very dark grayish brown.

Fig.8 Soil map of the study area

3).

Vertic Hapalustalf:

levees of the river on the both sides. They have rapid permeability and slight structured development. They show stratification as they are mostly formed as a result of the fluvial deposition of the river. The crops grown are paddy, sugarcane, vegetables, and millets. Typic Ustochrept occurs the entire southern boundary of the study area. The Vellar river soil of the study area comes under the Typic Ustochrept soil type.

These are deep, light to medium textured, calcareous, brown to very dark grayish brown soils with moderate structural development. The organic carbon content decreases irregularly with the depth. The crops cultivated are paddy, sugarcane, ginger, groundnut, chilies and millets are the other crops grown in these soil. Vertic Hapalustalf occupies the northeastern portion of the study area as an isolated patch, adjacent to Eluthur and near to Nangur Reserved Forest. 4).

V. INTEGRATION OF THEMATIC MAPS THROUGH GIS The integration of various thematic maps describing favourable groundwater zones was brought out as a single groundwater potential zone map with the application of GIS by Prasad et al., (2008). Spatial data analysis an analytical

Typic Ustorchrept:

These are very deep; light textured non – calcareous, dark yellowish brown to dark brown soils occurring on the


technique associated with the study of locations of geographic phenomena together with their spatial dimension and their associated attributes (like table analysis, classification, polygon classification and weight classification). The various thematic maps as described above have been converted into raster form considering 100 m as cell width to achieve considerable accuracy. These were then reclassified and assigned suitable weightage following the methods used by Srinivasa Rao and Jugran (2003), Aravindan et al (2006), Krishnamurthy et al. (1996). These are given in Table 1. The occurrence and movement of groundwater in an area is controlled by various factors. The influence of all factors need not be the same in an area. Therefore, each parameter is assigned a weightage depending on its influence on the movement and storage of groundwater. For instance, the area being underlain by sedimentary rocks, the lithological control is less compared to the topographical control. Therefore, higher weightages are given to geomorphology and geology. On the other hand,

the influence of land-use and drainage density in the area is comparatively less, lower weightages are given to these themes. After assigning the weightages to the themes and features, all the themes were converted to raster format using ‘Spatial analyst’, extension of Arc/GIS software. Spatial analyst extension of Arc GIS 9.3 was used for converting the features to raster and also for final analysis. In this method, the total weights of the final integrated map were derived as sum or product of the weights assigned to the different layers according to their suitability. Further, different units of each theme were assigned knowledgebased hierarchy of ranking from 1 to 5. On the basis of their significance with reference to groundwater prospects, where 1 denotes poor prospects and 5 denotes excellent prospect of groundwater. The technical guidelines prepared by National Remote Sensing Agency (NRSA, 1995, 2000) were made use for the preparation of various thematic maps and final groundwater potential zone map.

TABLE I RANKS AND WEIGHTAGES FOR VARIOUS PARAMETERS FOR GROUNDWATER POTENTIALITY

Thematic layers

Map weights (%)

Individual features

Rank

Groundwater potentiality

Geomorphology

10

Flood Plain

5

Excellent

Pediment

3

Good

Shallow Pediment

4

Very good

Buried Pediment

1

Poor

Geology

Landuse/Land cover

Soils

Drainage density

Lineament density

35

10

5

10

30

Duri Crust

2

Moderate

River/ water Bodies

4

Very good

Tanks

3

Good

Charnockite

2

Moderate

River

4

Very good

Barren land

1

Poor

Crop land

5

Excellent

Dry crop

2

Moderate

Dry crop (BCS)

1

Poor

Duri Crust (Salinity)

2

Moderate

Reserve forest

2

Moderate

River / Tanks

4

Very good

Paralithic Ustorcthent

3

Good

Paralithic Ustochrept

2

Moderate

Typic Ustochrept

5

Excellent

Vertic Haplustalf

4

Very good

Reserve Forest

2

Moderate

River

4

Very good

Poor

5

Excellent

Moderate

4

Very good

Good

3

Good

Very good

2

Moderate

Excellent

1

Poor

Present

5

Excellent

Absent

2

Moderate



has been categorized into five zones, from groundwater potential zone map.

A.Data Integration Each thematic maps such as geology, lineament, geomorphology, Landuse / landcover, drainage density, soil provides certain clues for the occurrence of groundwater. In order to get all these information unified, it is essential to integrate these data with appropriate factor. Although, it is possible to superimpose this information manually, however it is time consuming and error may occur. Therefore, this information is integrated through the application of GIS. Various thematic maps are reclassified on the basis of weightage assigned and brought into the ‘‘Raster Calculator’’ function of Spatial Analysist tool for integration. The weightage for different layers have been assigned considering similar work carried by many workers such as Srinivasa Rao and Jugran (2003), Krishnamurthy et al. (1996) and Saraf and Choudhary (1998). A simple arithmetical model has been adopted to integrate various thematic maps by averaging the weightage. The final map

VI. CONCLUSIONS Remote sensing and Geographic Information System (GIS) approach is very constructive because this integrates various geospatial informations especially for groundwater potential zone mapping. Study has focused on the effectiveness of remote sensing and GIS in the identification and delineation of groundwater potential zones of study area. All the thematic maps were converted into grid (raster format) and superimposed by weighted overlay method (rank and weightage wise thematic maps). From the analysis the groundwater potential zones with excellent, very good, good, moderate and poor prospects covering an area of 7.2 km2, 12.63 km2, 38.57 km2, 32.75 km2 & 7.2 km2 respectively (Fig.9) were brought out.

Fig. 9 Groundwater prospects of the study area

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