By -Sanjay Kumar , 25 Sep :Ground Water plays an important role in meeting the water requirements of agriculture, industrial and domestic sectors in our country. Its importance as a precious natural resource can be gauged for the fact that more than 85 % of India’s rural sector water requirements, 50% of its urban sectors water requirements and more than 50 % of its irrigation requirements are being met from ground water resources. It is also a key buffer against drought an abnormal variations in rainfall. The highly diversified occurrence and considerable variations in the availability and the use of ground water in the country makes its management a challenging task.
Ground Water Management Studies are being carried out to have first hand information on the changes in the ground water scenario with reference to time, due to changes in various input and output parameters and due to human interference. This forms the base for developmental activities and policy making. Special priority is being given for Ground Water Management Studies in hilly areas, valley fill areas, tribal areas, drought areas, urban areas, over-exploited areas, low ground water development areas, mining areas, industrial areas, naturally contaminated areas, farmers distress areas, coastal areas, canal command areas, water logged areas and areas having a problem of water quality due to geo-genic sources.
In the annual Action Plan 2007-08, a target of 1.64 lakh sq. km. was assigned. During 2007-08, an area of 1.58 lakh sq. km. was covered during pre-monsoon period and post-monsoon, studies have been completed in 1.59 lakh sq. km.
Central Ground Water Board (CGWB) under Ministry of Water Resources is entrusted with the responsibilities of scientific management studies, exploration, monitoring, assessment, augmentation, and regulation of ground water resources of the country. The data generated from various studies provide a scientific base for user agencies for water resources planning. CGWB has taken initiatives to identify various key issues for Ground Water Management. Keeping in view the need for planned development and management of ground water resources, the main initiatives taken by CGWB are as follows:
Scientific Development of Ground Water – Supply Side Management
Promoting development of Ground Water in areas with prolific aquifers and low stage of ground water development and conservation of fresh ground water resources through development of ground water resources in ground water logged areas has become essential in view of the diminishing fresh water resource and increase in its demand. There is a need for use of saline/brackish ground water in water deficit area. Depending on the hydrological/hydro- geological settings of the area, the strategies for ground water development for increasing the irrigation potential will vary considerably.
CGWB will formulate area specific ground water development and management plans to help State Governments to reorient their strategies for sustained development and management of ground water resources.
Development of Ground Water
The States of Arunachal Pradesh, Assam, Bihar, Chhattisgarh, Jharkhand, Manipur, Meghalaya, Mizoram, Nagaland, Tripura and West Bengal – the Eastern and North-Eastern parts of the country have huge ground water resources both in unconfined and confined aquifers. The annual replenishable resources of 137 bcm have been assessed in these States. The ground water draft is nearly 36 cm and stage of ground water development is 28%.
Ground Water Development in Coastal Areas
Multi-aquifer systems of good ground water potential exist in many parts of the coastal areas of India, which have thick deposits of alluvial sediments. There is considerable scope for development of ground water from such aquifer systems. The development of ground water from such aquifer needs to be done with caution. Care should be taken to ensure that the over exploitation of resources does not lead to seawater intrusion.
Filter point wells, shallow tube wells and large diameter dug wells are best suited for such aquifers. The radial well and infiltration galleries can also be constructed in areas where the requirement of water is large.
Ground Water Development in Hard Rock Areas
The hard rock areas are characterized by considerable heterogeneity and the aquifers are normally discontinuous and have limited ground water potential. These aquifers play an important role in meeting the drinking, agricultural and industrial needs in the peninsular shield areas of the country.
Modern technologies in the fields of Remote Sensing, Geophysical and Geographical Information Systems (GIS), coupled with conventional hydrological and hydro geological surveys are in use for demarcating areas suitable for further ground water development. However there is a need to restrict the development from such aquifers within their recharging capabilities to ensure their long-term sustainability.
Development of Ground Water in Flood Plain Areas
The flood plains in the vicinity of rivers are good repositories of groundwater. A planned management of groundwater in the flood plain aquifers offers an excellent scope for its development to meet the additional requirements of water. The development of ground water in Yamuna flood plain area in Delhi is an example of scientific management of water resources. The flood water spreads over the plains to recharge flood-plain aquifers during rainy season.
CGWB has constructed 100 tube wells in Palla Sector in the depth range of 38-50m for Delhi Jal Board. These tube wells have augmented Delhi’s water supply by 35 MGD. During the year 2008-09, studies of flood plain aquifers of Yamuna and Ganga rivers have been undertaken.
Ground Water Development in Water-Logged Areas
Due to the implementation of surface water irrigation schemes water logging and soil salinity problems resulting from gradual rise of ground water levels, are observed in many canal command areas. About 2.46 million hectare of land under surface water irrigation projects in the country is either water-logged or under threat of it as per the assessment made by the Working Group on Problem Identification with suggested Remedial Measures (1991). Such areas offer good scope for further ground water development as the shallow water table in such areas can be lowered down to six meters or more without any undesirable environmental consequences. The problems related to inferior quality of water in such areas can be solved by mixing them with the canal waters.
Judicious development through integrated use of surface and ground water can greatly reduce the menace of water-logging and salinity in canal irrigated areas. CGWB has completed 13 feasibility studies for conjunctive use of surface water and ground water in canal commands of Indira Gandhi Nahar Pariyojana Stage I and II (Rajasthan), Sharada Sahayaka (Uttar Pradesh), Mahi-Kadana (Gujarat), Hirakund and Rushikulya (Orissa) Tungabhadra, Nagarjunasagar and Sriramsagar (Andhra Pradesh), Ghatprabha (Karnataka), Gandak and Kosi (Bihar) and Western Yamuna (Haryana). These studies have established the need for conjunctive utilization of ground water and surface water in a judicious proportion to address the existing and emergent problems of water logging and salinity in canal command areas. Based on these studies, , sector-wise planning for conjunctive use has been devised including techno-economic feasibility of implementing these schemes by the State agencies in coordination with the Command Area Development Authorities (CADA).
Development of Deeper Aquifers
The existence of deep aquifers having voluminous quantity of ground water in storage has been revealed in the studies carried out by CGWB in the Indo-Gangetic basin in Punjab, Haryana, Uttar Pradesh, Bihar and West Bengal. Fresh ground water has been reported down to a depth of about 700 m in Uttar Pradesh. Studies carried out by ONGC in the Gangetic alluvial plain has indicated the existence of fresh ground water at more than 1000 m depth.
Free flow of ground water due to artesian conditions exists in Tarai and sub-Tarai belt of Uttar Pradesh, Bihar and Jammu & Kashmir. Development of ground water from these auto-flow zones is both economically viable and eco-friendly as no energy is required for extraction of ground water from such aquifers.
Development of Saline/Brackish Aquifers
Many areas in the country are underlain by saline water aquifers. When irrigated with saline or brackish water the yields of many crops, vegetables and fruit plants e.g. barley, dates and pomegranate, are not significantly affected. Such plants can be successfully irrigated by the use of saline/brackish water. Fresh or good quality water can be saved for use of other sensitive crops or for other uses.
Demands and management strategies-to tackle decline of water levels
In the demand side management, socio-economic aspects play an important role to arrest decline in ground levels. With the people’s participation only, the measures for demand side management can be successfully implemented. Therefore the masses should be educated on need and ways for regulation, conservation and augmentation of ground water resources.
*Media & Communication Officer, PIB, New Delhi