Hydrochemical Characteristics of Coastal Aquifers of Kadaladi, Ramanathapuram District, Tamilnadu, India
Total Page：16
File Type：pdf, Size：1020Kb
Appl Water Sci (2013) 3:603–612 DOI 10.1007/s13201-013-0108-z ORIGINAL ARTICLE Hydrochemical characteristics of coastal aquifers of Kadaladi, Ramanathapuram District, Tamilnadu, India P. Sivasubramanian • N. Balasubramanian • John Prince Soundranayagam • N. Chandrasekar Received: 9 October 2012 / Accepted: 27 May 2013 / Published online: 20 June 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com Abstract Geochemical signatures of groundwater in the Introduction coastal aquifers of Kadaladi block of Ramanathapuram District, Tamilnadu, India were used to identify the Groundwater is the backbone of Indian agriculture and chemical processes that control hydrochemistry. The drinking water security. It is a common pool resource, used parameters such as pH, EC, TDS and major ion concen- by millions of farmers across the country. Due to the ever trations Na, K, Ca, Mg, Cl, HCO3,SO4,PO4 and NO3 of increasing demand for potable and irrigation water and the groundwater were analyzed. Abundances of these ions inadequacy of available surface water, the importance of are in the following order Na [ Ca [ Mg [ K and groundwater is increasing exponentially every day (World Cl [ HCO3 [ SO4 [ NO3 [ PO4. Na–Cl is the dominant Bank 2010; Selvam and Sivasubramanian 2012). Ground- hydrochemical facies of the study area. Interpretation of water remains the only drinking water source in most of the hydrochemical data suggests that hydrochemistry of the Indian rural household. With an estimated 30 million study area is controlled by mixing of fresh water with relict groundwater structures, India is fast hurtling towards a saline water, ion-exchange processes, silicate weathering serious crisis of groundwater overuse and quality deterio- and evaporation are responsible for the groundwater ration (World Bank Report 2010). Groundwater is threa- chemistry of the study area. Above statement is further tened by several factors related to its mismanagement. supported by Gibbs plot where most of the samples fall Degradation of groundwater quality in coastal region within the evaporation zone. Good quality groundwater is generally occurs due to natural processes such as saline restricted to coastal sand dunes running parallel to the coast water intrusion, wind driven sea spray and marine aerosols and it is important to conserve these dunes. deposited on the top soil, evaporation and interaction of groundwater with brines and sedimentary formation Keywords Groundwater Á Geochemical facies Á (Sanford et al. 2007). Apart from the natural process, Ionic ratios Á Kadaladi Á Tamilnadu anthropogenic contaminations such as industrial effluents, agricultural fertilizers, municipal waste water, septic tank effluent and landfill are other major causes of water quality deterioration (Mondal et al. 2008; Mondal and Singh 2011; P. Sivasubramanian (&) Á N. Balasubramanian Selvam et al. 2013). Department of Geology, V. O. Chidambaram College, Seawater intrusion is one of the most common problems Tuticorin 628008, India in almost all coastal aquifers around the globe (Melloul and e-mail: [email protected] Goldenberg 1997, 1998; Sivakumar and Elango 2008; J. P. Soundranayagam Chidambaram et al. 2009; Mondal et al. 2010, 2011; Department of Physics, V. O. Chidambaram College, Srinivasamoorthy et al. 2011). This phenomenon can be Tuticorin 628008, India explained by the variety of conditions like gentle coastal hydraulic gradients, tidal and estuarine activity, sea level N. Chandrasekar Centre for GeoTechnology, Manonmaniam Sundaranar rises, low infiltration, excessive withdrawal and local University, Tirunelveli 627012, India hydrogeological conditions (Sarma et al. 1982; Longe et al. 123 604 Appl Water Sci (2013) 3:603–612 1987; Rajmohan et al. 1997, 2000; Barret et al. 2002; Study area Saxena et al. 2004; Kacimov et al. 2009). The common method for assessing seawater intrusion through an aquifer Kadaladi block of Ramanathapuram district, Tamilnadu, in coastal belts is a periodic analysis of groundwater (Todd India lies between the latitude 9° 60–9° 210 N and longitude 1980; Kim et al. 2009; Mondal et al. 2010, 2011 and 78° 180–78° 450 E and covered by the Survey of India Krishnakumar et al. 2012). Chemistry of groundwater is an Toposheets 58 K/7, 58 K/8, 58 K/11 and 12 (Fig. 1). Total important factor determining its use for domestic, irrigation areal extent of the present study area is 623 km2. Presently, and industrial purposes. Interaction of groundwater with Ramanathapuram district is divided into 11 blocks and aquifer minerals through which it flows greatly controls the Kadaladi block is further divided into 60 Panchyat villages. groundwater chemistry. Hydrogeochemical processes that Kadaladi block is mainly covered by sedimentary formation are responsible for altering the chemical composition of and about 70 % of the study area is covered with Fluvial, groundwater vary with respect to space and time. The Fluvio-Marine, Aeolian and marine sediments of Quater- hydrogeochemical processes of groundwater system help to nary age. The Fluvial deposits are made up of sand, silt and obtain an insight into the contributions of rock/soil–water clay. The western side of the study area is exposed with interaction (Senthilkumar and Elango 2013). Very few Archaean rocks such as Garnetiferous Biotite Gneiss, research works have been conducted with the aim of Quartzite and Charnockites which are intruded later by Pink assessing the chemical composition of groundwater in the Granite. The Aeolian deposits are made up of red sands and coastal regions of Tamilnadu. When considering the pres- they are in the form of ancient sand dunes. These dunes run ent study area, so far there is no scientific publication *10 km parallel to the coast and extend up to 3 km across. available related to groundwater quality. In this work, a These sand dunes are separated by marshy deposits of black detailed investigation has been carried out to evaluate the clays from the sea coast. The sands are underlain by cal- geochemical process regulating groundwater quality. careous hardpan. The study area enjoys a tropical climate. Fig. 1 Location map of the study area 123 Appl Water Sci (2013) 3:603–612 605 In the plains, the maximum and minimum temperatures good quality drinking water from sea water and supplies recorded are 39 and 29 °C, respectively. Heat becomes them to the surrounding villages. intense in March to September and shoots further up unless The alluvium with alternate layers of sand and clay with a interfered by rains. Humidity is relatively high as 79 % on thickness of 15–25 m and are characterized by floating an average and ranges between 80 and 90 % in coastal freshwater lenses limited to a depth of 6–7 m below ground regions. Coastal areas are flanked by beach ridge complex, level. It can sustain a pumping of up to 2 h and can yield swales, swamps and backwater. The sand flat is another about 2–5 l/s. So people prefer dug wells of 3–6 m depth than feature of the coast comprising clay, silt and often inundated the bore wells of 30 or 50 m and extract good quality by seawater and encrusted with salt. Major rivers flowing groundwater which floats as lens on the saline water. Com- through the study area are Gundar River and Palar River. paratively good quality of water is available in the narrow They flow from northwest to southeast within the study area strip of land between red sand dunes running roughly 10 km and enter into Bay of Bengal. The drainage pattern, in parallel to the coast and the coastline (Fig. 3). Natural general, is dendritic. Both the rivers are seasonal and flow recharge from rainfall elevates the groundwater level and only during monsoon season. In addition to this, a small replenishes the fresh water lens of these sand dune areas. In Kadugusandai Odai also flows through the study area. the study area, there are no deep aquifer has been reported so The district receives rain under the influence of both far. During our reconnaissance survey, we have visited the southwest and northeast monsoons. The northeast monsoon drilling sites of Mineral Exploration Corporation Ltd chiefly contributes to the rainfall in the district. Most of the (MECL) who were in search of lignite beds. They have not precipitation occurs in the form of cyclonic storms caused encountered any hard rock or lignite up to the depth of 400 m. due to the depressions in the Bay of Bengal. The southwest monsoon rainfall is highly erratic and summer rains are negligible. Rainfall data from two stations over the period Materials and methods 1901–2000 were utilized and a perusal of the data shows that the normal annual rainfall over the district is 827 mm Collection of groundwater samples and decreases toward inland. The general practice of peo- ple in the study area is to store rain water in tanks and use Totally 36 wells were identified during our reconnaissance them for their needs throughout the year (Fig. 2). But most survey for the collection of water samples to carry out monsoons fail. To cater the need of the people, Tamilnadu chemical analysis. Due care was given to the distribution of Government has established a desalination plant at Nari- wells throughout the study area during well selection. Dug payur located within the study area. This plant produces well and bore well samples were collected during the Fig. 2 ‘‘Oorani’’ in the study area 123 606 Appl Water Sci (2013) 3:603–612 Fig. 3 Satellite image of the study area pre-monsoon (PRM) period of 2012 (June 2012). Methods generally acceptable. All concentrations are expressed in of collection and analysis of groundwater samples were milligrams per liter (mg/l), except pH, EC and TDS. The EC essentially the same as given by Brow et al. (1983), APHA concentrations were expressed in lS/cm and TDS concen- (1995). The samples were collected in 1 l capacity poly- trations were expressed in ppm.