Indian Journal of Geo-Marine Science Vol.44(9) , September 2015, pp. 1422-1427

Groundwater flow and fluctuation using GIS in a hard rock region - South

S.Arya1* & T.Subramani2* 1Geological subdivision, Public Works Department, Anna Nagar, Tirunelveli-600011, , India 2Department of Mining Engineering, CEG, Anna University, Chennai-600025, Tamil Nadu, India [Email: [email protected]; [email protected]; [email protected]]

Received 09 December 2015; revised 22 January 2014

Various thematic maps pertaining to groundwater flow and fluctuation were prepared from the Survey of India (SOI) toposheets and satellite imageries using geographical information system (GIS). To understand the topographical variation, three dimensional digital elevation model (DEM) was generated using GIS. Hydrographs were also prepared to understand groundwater fluctuation with respect to space and time. Groundwater level contours were prepared using GIS to understand the water level fluctuation in the basin. Raster based three dimensional groundwater table elevation model was also developed using GIS to understand the depth of occurrence of groundwater. Radial vector map was prepared from the groundwater head data using GIS to understand the groundwater flow pattern. Finally radial vector map was superimposed over the groundwater table elevation model to illustrate the groundwater flow in the basin. [Keywords: Digital Elevation Model; Groundwater table elevation model; Groundwater flow and fluctuation; Thirumanimuthar River basin; South India]

Introduction Average maximum temperature goes to 30.2°C, while the mean minimum drops to 19.2°C. Hydrogeomorphological maps were Average annual rainfall of the basin is about 920 prepared and detailed study was carried out in mm, which is below the average annual rainfall of Kakund watershed, Eastern Rajasthan using Tamil Nadu state. Sixty percentage of total remote sensing and GIS techniques for delineating rainfall is contributed by Southwest monsoon groundwater potential zones1. Various from June to September and the rest by Southwest groundwater potential units were delineated using remote sensing and GIS techniques in Khallikote block of Ganjam District, Orissa, India.2 The previous work in Thirumanimuthar River basin,

Tamil Nadu, India includes identification of groundwater potential zones using Remote Sensing and GIS techniques3 and regular monitoring of groundwater levels and quality by Tamil Nadu Public Works Department4 . However, much importance was not given to understand the groundwater fluctuation and flow. Present study was carried out with the main objective of understanding groundwater fluctuation and flow.

Materials and Methods

Thirumanimuthar River basin is one of the sub- basins of Cauvery River basin. Trunk system of Thirumanimuthar originates in Yercaud hills and it confluences with Cauvery River near Mohanur after a run off nearly 25 Km. The basin lies between the latitudes 1100' N and 1146' N and longitudes 7750' E and 7820' E (Fig. 1). The basin occupies an area of 2,452 Km2. It falls in Salem and Districts. Area is bounded by in north, Kolli hills in east, Fig.1- Thirumanimuthar River basin River Cauvery in south and Kanjamalai iron ore hillock in west. Major settlements in the basin are monsoon from October to December. The study Salem, , Namakkal, Paramathi and area over and adjacent to Shevaroy hills and Kolli Mohanur. Area generally enjoys sub-tropical hills are of dry to moist sub humid climatic types. climate.

S.ARYA & T.SUBRAMANI: GROUNDWATER FLOW AND FLUCTUATION USING GIS IN A HARD ROCK REGION - 1423 SOUTH INDIA The methodology has been divided into two major To understand the spatial variation of depth of categories namely field work and GIS work. occurrence of groundwater in the basin, water Several conventional data like geology, soil, level contour map was prepared using rainfall, and groundwater levels were collected GIS.Groundwater head with respect to mean sea from various government organizations4. Survey level (MSL) was computed for all the wells, and of India 5 toposheets (No. 58I/1, 58I/2, 58I/3, groundwater head contour map was also prepared 58I/4, 58I/5, 58I/6, 58I/7, 58E/14, 58E/15, using GIS.To understand the groundwater flow 58E/16) of 1:50000 scale were used to prepare the pattern, radial vectors were prepared from the base map, drainage map and elevation contour groundwater head using GIS. Finally groundwater map using GIS. Geomorphology map, landuse table elevation model was generated using GIS map and lineament maps were prepared using and the groundwater flow vectors were IRS-1D LISS-III satellite imageries. Digital superimposed. The detailed methodology of the elevation model (DEM) was generated from the study is given in the Fig. 2. elevation contours using GIS to understand the surface undulations. The prepared thematic maps Results and Discussion were verified in the field. Detailed well inventory DEM means digital representation of a was carried out in the basin during March 2011. topographic surface. It is, however, most often Depth of groundwater levels was measured (with used to refer specifically to a raster or regular grid respect to below ground level) with the help of of spot height6 .Thirumanimuthar basin forms part water level recorder and global positioning system of the upland plateau region of Tamil Nadu with (GPS). Hydrographs were prepared integrating many hills and undulating plains. The highest rainfall and groundwater levels to under the peak in Shervaroy hill in north is having an fluctuation. elevation of 1480 m while Kollimalai with an Methodology elevation of 1417 m above MSL is acting as the surface waterside in east. Rajakoil karadu,

Bodinayakkanur Karadu, Kunnamalai, Elephant’s tooth rock, Vedampattimalai, Karangan karadu, Data Kusamalai, Namamalai, Jarugumalai, Kallmalai,

Field Work Collection GIS Kanjamalai, Godumalai, Nagarmalai, Nainarmalai, Kambal Karadu and Alagumalai etc are the other hills in this region. The elevation

Well Inventory Survey Preparation of Thematic contour map of Thirumanimuthar basin (Fig. 3) Maps was prepared from the Survey of India (SOI) toposheets. The maximum elevation is 1480 m in

the north, and the minimum elevation is 140 m

Using GPS & Generation above MSL in the south. The digital elevation Water Level of DEM model (DEM) prepared using GIS shows the Measure ment of Water Levels Recorder important hillocks in the basin (Fig. 4).

Integration of Data

Preparation of Hydrographs

Groundwater Level Contour Map

Groundwater Flow Vectors

Overlay

Groundwater Table Elevation Model Fig. 3- Elevation contour map of Thirumanimuthar River Basin

Fig. 2- Flowchart showing methodology

1424 INDIAN J MAR SCI VOL.44, NO.9, SEPTEMBER 2015

On the contrary, a low drainage density area

Shevroys permits more infiltration with more potential for Kanjamalai groundwater. When comparing two terrain types, Namamalai the one that contains the greatest drainage density Jarugumalai is usually less permeable7 The structural analysis Alagumalai of a drainage network helps to assess the characteristics of the groundwater recharge zone. There are about 185 irrigation tanks seen in the Saruvamalai toposheet and many tanks in the basin are used for storing surface water during monsoon period.

Panamarathupatti Lake is the biggest in the basin, which was once used as drinking water source for Salem, Mallur and Rasipuram. Allikuttai in urban areas of Salem is converted into Sericulture research station and partly filled with sewage

water leading to many environmental and land degradation issues. Fig .4- Digital Elevation Model (DEM) of Thamirabarani Most of geomorphic features in River basin Thirumanimuthar basin come under fluvial and The drainage map of the basin (Fig. 5) was alluvial geomorphology. Major geomorphic prepared from the Survey of India toposheets. The features in Thirumanimuthar basin are map indicates that dentritic, sub-dentritic to sub- hills/denudational hills, bazadas, deep pediments, parallel patterns are common while, radial pattern structural hills, pediplain, alluvial plain and valley is noticed in Kanjamalai region. Dentritic fills. The denudational hills mainly consist of drainage pattern indicates the presence of hard highly fractured rocks covered with big pebbles rock terrain and more runoff. Trellis pattern is and sparse vegetation occurring superficially due also seen in linear hill ranges. The drainage to the accumulation of moisture holding soils. density is high in the north and east while it is low Bajada represents geologic conditions that are in south, which is indicative of heterogeneous excellent for obtaining groundwater in large rock characteristics. A terrain with closeness in quantities. Bazada zones are noticed in the foot drainage pattern is proved as zones of poor hills with unconsolidated material. Deep groundwater potential, as a major part of rainfall pediments are mainly due to high weathering of is lost by surface runoff with little infiltration. the gneisses under semi-arid climatic conditions.

Pediplain with meta-sedimentary rock exposures [3,8] is found in the central part of the area. Gneisses are probably the oldest rocks in the area, and are encountered mostly in the plains. Biotite and hornblende gneisses are common. The

rocks are highly weathered and the thickness of weathering often exceeds 30 m. The gneisses are intruded parallel to their foliation by a number of ultramafic and basic intrusive. [9] Charnockites are coarse grained which are younger to the gneisses. They are exposed in Shevaroy and Kolli hills. Kanjamalai hills are known for its magnetite quartzite deposits which are associated with quartzo-feldspathic gneisses, garnetiferous-and grunerite-quartz gneisses. The peridotites and dunites are exposed in the foothills of Shevaroys near Salem, which is known as “Chalk hills”. Pyroxenites are exposed in the Nagarmalai area. [10] They are massive and poorly jointed. Anorthosites are found in the Sittampundi Fig. 5- Drainage map of Thirumanimuthar River basin Complex area. These rocks also are massive and poorly jointed.

S.ARYA & T.SUBRAMANI: GROUNDWATER FLOW AND FLUCTUATION USING GIS IN A HARD ROCK REGION - 1425 SOUTH INDIA A wide range of rocks such as chromites, Thirumanimuthar basin is a hard rock and eclogites, diopsidites, gabbros, hornblendite, also a structurally controlled terrain. So the peridotite etc. are associated with anorthosites as groundwater flow and fluctuation depends upon thin relict layers and lenses. The younger the lineaments, fractures and joints on the rocks. pegmatoidal granites are found in western part of Thirumanimuthar River itself is flowing on the the basin. Thin layers of alluvium (sand and silt) lineament. Hence the geological structures occur along the courses of Cauvery and influence more in this terrain for groundwater Thirumanimuttar rivers. recharge and flow. The Thirumanimuthar basin Lineaments are important from the point consists of several types of rocks with secondary of view of groundwater development in fractured intrusions. The area consists heterogeneous type aquifers. The high lineament zone reflects high of lithology. Gneisses and charnockites are the porosity and hydraulic conductivity of the major rock types in the study area. The underlying materials. In Thirumanimuthar Basin, anorthosite complex of this area occurs as a dyke most of the lineaments are confined to the and this is intruded through a major lineament in locations where pediplain, deep pediment and the granitic terrain. [9] The dyke rock acts as a colluvial plains are exposed. Lineaments trending barrier to groundwater flow. NNE-SSW, NE-SW, NW-SE and NS are The occurrence of rainfall over the identified in the study area indicating regions of Southern Peninsula towards the end of the south- good groundwater occurrence. NE–SW trending west monsoon season was discussed in detail. [11] lineaments are prevalent in Namagiripettai, Hydrographs correlating water level fluctuation Puduchatram and Paramathi Velur areas. N–S and rainfall were prepared for all the observation lineaments are mostly confined to wells in the basin. Monthly rainfall and water Mallasamudram and Elachipalayam regions. level data collected from Tamil Nadu Public NW–SE lineaments are seen predominantly in Works Department (PWD) were used for Tiruchengode and Namakkal regions. Major preparing the hydrographs (Fig. 6), which reveal drainage courses in the basin are structurally that the basin receives maximum rainfall during controlled. The course of Cauvery River is the month of May from southwest monsoon controlled by NW–SE lineament, whereas (average about 350 mm). Northeast monsoon also Tirumanimuttar river flows along a N-S trending contributes significant quantity of rainfall which lineament. [3] These lineaments acts as a good is maximum during October/November(average source for groundwater recharge. Lineament about 175 mm). The average maximum depth interceptions were observed at a few regions in pediplain with potential zones for groundwater.

Groundwater Recharge & Discharge Groundwater Recharge & Discharge

400.00 0.00 400.00 0.00 350.00 1.00 350.00 2.00 300.00 2.00 300.00 4.00 250.00 3.00 Rainfall (mm) 250.00 6.00 Rainfall (mm) 200.00 4.00 200.00 150.00 5.00 WL (m) 150.00 8.00 WL (m) 10.00 100.00 6.00 100.00 .G.L ainfall (mm) ainfall (mm) 12.00 B 50.00 7.00 .G.L 50.00 R R

0.00 8.00 B 0.00 14.00 und Waterlevel in Waterlevel und m July July May May April April June June March March anuary anuary August August J October Gro October J round Waterlevel inround Waterlevel m February February November December November December September September G Well No. 3 Well No. 4

Groundwater Recharge & Discharge G roundwater Recharge & Discharge

250.00 0.00 250.00 0.00 200.00 2.00 200.00 2.00 4.00 4.00 Rainfall (mm) 150.00 6.00 Rainfall (mm) 150.00 6.00 WL (m) 8.00 WL (m) 100.00 8.00 100.00 10.00 10.00

50.00 ainfall (mm) 50.00

12.00 .G.L ainfall (mm)

12.00 .G.L R B R 0.00 14.00 B 0.00 14.00 Waterlevel in Waterlevel m Waterlevel in Waterlevel m July May July May April June April June March March anuary anuary August August J October October J February February November December Ground November December September September Ground Well No. 13 Well No. 20

Groundwater Recharge & Discharge G roundwater Recharge & Discharge

250.00 0.00 450.00 0.00 1.00 2.00 400.00 200.00 350.00 2.00 4.00 300.00 3.00 150.00 6.00 Rainfall (mm) 250.00 4.00 Rainfall (mm) 8.00 200.00 5.00 100.00 WL (m) 6.00 WL (m) 10.00 150.00 7.00 infall (mm)

12.00 100.00 .G.L

.G.L 8.00

ainfall (mm) 50.00

50.00 B Ra 14.00 B 9.00 R 0.00 16.00 0.00 10.00 July May und Waterlevel in und Waterlevel m July April May June April June March March anuary August anuary round Waterlevel roundin Waterlevel m August October J J October February Gro G February November December November December September September Well No. 21 Well No. 24

Fig. 6- Groundwater fluctuation Vs rainfall recharge

1426 INDIAN J MAR SCI VOL.44, NO.9, SEPTEMBER 2015 of groundwater level in the weathered zone varies direction and magnitude of groundwater flow, from 14 to 16 m during April/May. Maximum vector diagram was prepared using surfer recharge occurs during the month of software and then it was superimposed over the July.Groundwater fluctuation observed in most of water table elevation model. The model indicates the wells reveals that there is an immediate that the direction of groundwater flow is found to response of water level to the rainfall occurrence. be north to south. The topography of the study This shows groundwater recharge is faster in most area highly influences the groundwater flow in the of the areas (eg. Well Nos. 3, 4 & 13). However, basin. in some areas (eg. Well No. 24) there is a considerable delay in recharge after the rainfall. Conclusion Few hydrographs also indicate that water level does not respond to the rainfall (eg. Well Nos. 20 Digital elevation model of & 21). Thick weathered and soil zones promote Thirumanimuthar River basin indicates that the good recharge in the basin. Recharge rate is also basin consists of so many hills and all are high in Bajada and alluvial formations. Lineament structurally controlled. General slope track of the zones also facilitate good recharge. Recharge rate basin is found to be NE-SW direction. The is poor in clayey soil, and almost negligible in northern and north-eastern parts of the basin barren rock areas. consist of several hills and the southern part is Groundwater table elevation model of almost plain. Because of the influence of those Thirumanimuthar River basin was created using structurally controlled hills the river and drainages Surfer software (Fig.7). Initially depth of are flowing on lineaments. The occurrence of groundwater levels was measured in many open lineaments acts as a good source for groundwater wells spread over the basin with respect to ground recharge. Plain areas in the basin consist of very level. GPS coordinates of all well locations were low density of lineaments when compare with noted. Height of the water table (Head) at each hills. The rainfall infiltration is comparitively less well location was calculated with respect to datum in those regions. Drainage analysis indicates that (MSL). Finally three dimensional groundwater dentritic pattern is very common while, radial table elevation model was generated by plotting pattern is noticed in Kanjamalai region. This the GPS coordinates and head. To indicate the indicates more runoff take place in hills. The drainage density is high in the north and east while it is low in south. Geomorphological studies indicate that bajadas are located along the eastern side in the foot hills. Deep pediments are mainly due to high weathering of the gneissic rocks. Borehole lithology indicates deep pediments are noticed as detached patches throughout the basin. About 40% of the basin area is covered with Legend Pediplain. Groundwater occurrence is good when it is associated with lineament interaction. Wells Pediplains with lineament interaction are noticed Flow in the center part of the basin. Gneisses and charnockites are the major rock types in the basin. Biotite and hornblende gneisses are commonly seen in most of areas. The rocks are highly weathered and the thickness of weathering often exceeds 30 m in many locations. Hydrographs indicate that groundwater fluctuation is not uniform in the basin. Open wells become dry in many areas during summar due to over exploitation and less rainfall. Groundwater fluctuation is more in the central and northern part Fig.7 Groundwater table elevation model of when compare with the southern part. Depth of Thirumanimuthar River basin occurrence of water table is comparatively shallow in the southern part.

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