OVERVIEW OF GROUND WATER QUAILITY

Monitoring of ground water quality is an effort to obtain information on chemical quality through representative sampling in different hydrogeological units. The chemical quality is being monitored by Central Ground Water Board once in a year through a network of about 15000 observation wells located all over the country, in regular monitoring programme. Apart from these observation wells the quality is also monitored through various studies like ground water management studies, ground water exploration etc. The ground water monitoring activity is aimed at generating background data of different chemicals constituents in Ground water on a regional scale.

GROUND WATER QUALITY SCENARIO IN INDIA

Indian Sub- Continent is endowed with diverse geological formations from oldest Achaeans to Recent alluviums and characterized by varying climatic conditions in different parts of the country. The natural chemical content of ground water is influenced by depth of the soils and sub-surface geological formations through which ground water remains in contact.  In general, greater part of the country, ground water is of good quality and suitable for drinking, agricultural or industrial purposes. Ground water in shallow aquifers is generally suitable for use for different purposes and is mainly of Calcium Bicarbonate and Mixed type. However, other types of water are also available including Sodium-Chloride water. The quality in deeper aquifers also varies from place to place and is generally found suitable for common uses. There is salinity problem in the coastal tracts and high incidence of Fluoride, Arsenic, Iron &  heavy metals etc in isolated pockets have also been reported. The distributions of various constituents present in ground water in different parts of the country have been discussed in following paragraphs.

The main ground water quality problems in India are as follows.

Salinity:- Salinity in ground water can be of broadly categorised into two types, i.e. Inland Salinity and Coastal salinity

INLAND SALINITY

Inland salinity in ground water is prevalent mainly in the arid and semi arid regions of Rajasthan, Haryana, Punjab, Gujarat, Uttar Pradesh, Delhi, Andhra Pradesh, Maharashtra, Karnataka and Tamil Nadu. There are several places in Rajasthan and southern Haryana where EC values of ground water is greater than 10000 mS /cm at 25o C making water non-potable. In some areas of Rajasthan and Gujarat, ground water salinity is so high that the well water is directly used for salt manufacturing by solar evaporation.

Inland salinity is also caused due to practice of surface water irrigation without consideration of ground water status. The gradual rise of ground water levels with time has resulted in water logging and heavy evaporation in semi arid regions lead to salinity problem in command areas.

COASTAL SALINITY

The Indian subcontinent has a dynamic coastline of about 7500 km length. It stretches from Rann of Kutch in Gujarat to Konkan and Malabar coast to Kanyakumari in the south to northwards along the Coromandal coast to Sunderbans in West Bengal .The western coast is characterized by wide continental shelf and is marked by backwaters and mud flats while the eastern coast has a narrow continental shelf and is characterized by deltaic and estuarine land forms. Ground water in coastal areas occurs under unconfined to confined conditions in a wide range of unconsolidated and consolidated formations.

Normally, saline water bodies owe their origin to entrapped sea water (connate water), sea water ingress, leachates from navigation canals constructed along the coast, leachates from salt pans etc. In general, the following situations are encountered in coastal areas

• Saline water overlying fresh water aquifer
• Fresh water overlying saline water
• Alternating sequence of fresh water and saline water aquifers

In India, salinity problems have been observed in a number of places in most of the coastal states of the country. Problem of salinity ingress has been conspicuously noticed in Minjur area of Tamil Nadu and Mangrol – Chorwad- Porbander belt along the Saurashtra coast.

FLUORIDE

85 % of rural population of the country uses ground water for drinking and domestic purposes. High concentration of fluoride in ground water beyond the permissible limit of 1.5 mg/l poses the health problem. Nearly the occurrences of fluoride beyond permissible limit (> 1.5 mg /litre) has been observed based on the chemical analysis of water samples collected from the groundwater observation wells. The name of the districts having spot values of >1.5 mg/l are given in following table.

State wise details of  distribution of flouride in Ground Water above permissible limit

S. No.	State	Fluoride
		No.of  districts affected	Districts (in parts)
1.	Andhra Pradesh	19	Adilabad, Anantpur, Chitoor, Guntur, Hyderabad, Karimnagar, Khammam, Krishna, Kurnool, Mehboobnagar, Medak, Nalgonda, Nellore, Prakasham, Rangareddy, Vishakhapatnam, Viziangaram, Warangal, West Godawari
2.	Assam	4	Goalpara, Kamrup, Karbi Anglong, Naugaon
3	Bihar	9	Aurangabad, Banka, Buxar, Jamui, Kaimur, Munger, Nawada, Rohtas, Supaul
4.	Chhattisgarh	12	Bastar, Bilaspur, Dantewara, Janjgir-Champa, Jashpur, Kanker, Korba, Koriya, Mahasamund, Raipur, Rajnandgaon, Suguja
5.	Delhi	6	East Delhi, New Delhi, Northwest Delhi, South Delhi, Southwest Delhi, West Delhi
6.	Gujarat	18	Ahmedabad, Amreli, Anand, Banaskantha, Bharuch, Bhavnagar, Dahod, Junagarh, Kachchh, Mahesana, Narmada,  Panchmahals, Patan, Rajkot, Sabarkantha,  Surat, Surendranagar, Vadodara
7.	Haryana	14	Bhiwani, Faridabad, Gurgaon, Hissar, Jhajjar, Jind, Kaithal, Kurkshetra, Mahendragarh, Panipat, Rewari, Rohtak, Sirsa, Sonepat
8.	Jammu & Kashmir	2	Rajauri, Udhampur
9.	Jharkhand	6	Bokaro, Giridih, Godda, Gumla, Palamau, Ranchi
10..	Karnataka	20	Bagalkot, Bangalore, Bellary, Belgaum, Bidar, Bijapur, Chamarajnagar, Chikmagalur, Chitradurga, Devangere, Dharwar, Gadag, Gulbarga, Haveri, Kolar, Koppala, Mandya, Mysore, Raichur, Tumkur.
11.	Kerala	1	Palakkad
12.	Madhya Pradesh	19	Bhind, Chhatarpur, Chhindwara, Datia, Dewas, Dhar, Guna, Gwalior, Harda, Jabalpur, Jhabua, Khargone, Mandsaur, Rajgarh, Satna, Seoni, Shajapur, Sheopur, Sidhi.
13.	Maharashtra	8	Amrawati, Chandrapur, Dhule, Gadchiroli, Gondia, Jalna, Nagpur, Nanded,
14.	Orissa	11	Angul, Balasore, Bargarh, Bhadrak, Boudh, Cuttack, Deogarh, Dhenkanal, Jajpur, Keonjhar, Suvarnapur
15.	Punjab	11	Amritsar, Bhatinda, Faridkot, Fatehgarh-Saheb, Firozpur, Gurdaspur, Mansa, Moga, Muktsar, Patiala, Sangrur,
16.	Rajasthan	30	Ajmer, Alwar, Banswara, Barmer, Bharatpur, Bhilwara, Bikaner, Bundi, Chhittorgarh, Churu, Dausa, Dholpur, Dungarpur, Ganganagar, Hanumangarh, Jaipur, Jaisalmer, Jalore, Jhunjhunu, Jodhpur, Karauli, Kota, Nagaur, Pali, Rajasamand, SawaiMadhopur, Sikar, Sirohi, Tonk, Udaipur
17.	Tamil Nadu	16	Coimbatore, Dharmapuri, Dindigul, Erode, Karur, Krishnagiri, Namakkal, Perambalur, Puddukotai, Ramnathpuram, Salem, Shivaganga, Theni, Thiruvannamalai, Vellore, Virudunagar
18..	Uttar Pradseh	10	Agra, Aligarh, Etah, Firozabad, Jaunpur, Kannauj, Mahamayanagar, Mainpuri, Mathura, Maunathbhanjan,
19.	West Bengal	8	Bankura, Bardhhman, Birbhum, Dakhin Dinajpur, Malda, Nadia, Purulia, Uttar Dinajpur