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Ground Water
  Ground Water
1. What is Ground water?
Part of the precipitation is lost as the interception loss, partly flows as runoff, partly gets evaporated and goes back to atmosphere, partly gets collected in the deeper areas (like lakes and reservoirs) and some used by the plants. The remaining precipitation seeps in the ground. Some amount of the percolated water adheres to the root of the plants and voids between the soils particles. This moisture provides plants the water they need to grow. Water not used by plants moves deeper into the ground. The water keeps on moving down the earth through the spaces or cracks until an impermeable layer of rock is encountered. The water then fills the empty spaces and cracks above that layer. The water thus accumulated in the soil gaps, cracks above that impermeable layer is called the ground water and the top layer of the water is called water table.
Thus the major source of ground water is precipitation (rainfall and slow melt). Some other minor sources are the leaks through the bottom of the lakes and river, the leakage from the water supply system (pipeline and canals) and the irrigated water. The additional water that goes down the earth to meet the ground water is called the recharge water.
2. What is aquifer?
An aquifer is a layer of underground soil which bears the ground water. An aquifer allows the water to seep through it to meet the ground water and also allows the water to get extracted by means of pump. An aquifer is a permeable layer of soil and rock. Contrary to this an aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another. An aquitard can sometimes, if completely impermeable, be called an aquiclude or aquifuge. Aquitards comprise layers of either clay or non-porous rock with low hydraulic conductivity.
Aquifers must be both permeable and porous and include such rock types as sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. Fractured volcanic rocks such as columnar basalts also make good aquifers. The rubble zones between volcanic flows are generally both porous and permeable and make excellent aquifers. In order for a well to be productive, it must be drilled into an aquifer. Rocks such as granite and schist are generally poor aquifers because they have a very low porosity. However, if these rocks are highly fractured, they make good aquifers. A well is a hole drilled into the ground to penetrate an aquifer.
  • Confined Aquifers

  • Confined aquifers are permeable rock units that are usually deeper under the ground than unconfined aquifers. They are overlain by relatively impermeable rock or clay that limits groundwater movement into, or out of, the confined aquifer.

    Groundwater in a confined aquifer is under pressure and will rise up inside a borehole drilled into the aquifer. The level to which the water rises is called the potentiometric surface. An artesian flow is where water flows out of the borehole under natural pressure.

    Confined aquifers may be replenished, or recharged by rain or streamwater infilitrating the rock at some considerable distance away from the confined aquifer. Groundwater in these aquifers can sometimes be thousands of years old.

  • Unconfined Aquifers

  • Where groundwater is in direct contact with the atmosphere through the open pore spaces of the overlying soil or rock, then the aquifer is said to be unconfined. The upper groundwater surface in an unconfined aquifer is called the water table. The depth to the water table varies according to factors such as the topography, geology, season and tidal effects, and the quantities of water being pumped from the aquifer.

    Unconfined aquifers are usually recharged by rain or streamwater infiltrating directly through the overlying soil. Typical examples of unconfined aquifers include many areas of coastal sands and alluvial deposits in river valleys.
3. Ground Water Contamination
An aquifer can be contaminated by many things we do at and near the surface of the earth. Contaminants reach the water table by any natural or manmade pathway along which water can flow from the surface to the aquifer.
Deliberate disposal of waste at point sources such as landfills, septic tanks, injection wells and storm drain wells can have an impact on the quality of ground water in an aquifer.
More than 50% domestic water supply is obtained from groundwater in India and, therefore, it is very important to check the purity of groundwater before it is supplied to the public. DDT, BHC, carbamate, Endosulfan, etc. are the very common pesticides used in India both in agricultural and public health sectors. Very little monitoring of water pesticides has been done in India. However, some reports have been published on the presence of organochlorine pesticides in some urban water resources near Calcutta. Groundwater contamination by some arsenic pesticides has been reported in some of the districts of West Bengal. Groundwater contamination has also been reported in some areas near water storage ponds in Gujarat. In these areas, the rain water containing pesticides from agricultural fields, is stored in ponds and during the course of time water (with pesticides) from these ponds enter into the aquifer leading to groundwater contamination by pesticides
4. Can we run out of Ground Water?
We can run out of ground water if more water is discharged than recharged. For example, during periods of dry weather, recharge to the aquifers decreases. If too much ground water is pumped during these times, the water table can fall and wells may go dry.
Ground water can become unusable if it becomes polluted and is no longer safe to drink. In areas where the material above the aquifer is permeable, pollutants can seep into ground water.
5. State Ground Water profile
Click Here to view GW profile of AP state.
6. District Ground Water brochures
Click Here to view GW profile of the districts of AP.
7. Activities carried by CGWB
CGWB carries various activities on the ground water related issues like hydrogeological surveys, GW management studies, GW exploration and management etc. Click Here to view these activities.
8. State-wise Contamination of Ground Water in parts of Districts due to Geogenic Contaminants
10. Ground Water Estimation and Management System (GEMS)
11. Watershed Atlas of India
12. Ground water Purpose Driven Studies (PDSs) undertaken by different State Government Agencies:
PDS No. PDS Name Cost (Lakh) Principal Investigators
Andhra Pradesh
GW-AP-1 R&D Studies on Urban Hydrology, GW Quality, Pollution & Management of Hussain Sagar Micro Basin (In & around twin cities Hyderabad and Secunderabad) Musi sub basin, Krishna basin 150.0 BM M-K Rao, Dir, AP GW Dept & PA Reddy, Dep Dir GW Dept
GW-AP-2 Participatory geo-ecological management in Tettuvanka basin, Rishi valley, Kurbalakota Mandal, Chittoor District 99.97 BM M-K Rao, Dir, AP GW Dept
GW-GJ-1 Ground Water Management in Water logged area of Dharoi Project Command (RBC) and Strategy to maintain harmony on water levels of Perched Aquifer with Deep Aquifer 212.71 SV Patel, Gujarat Wat Res Dev Corp - Geohydrologist, GW Div 5, Deesa
GW-KN-1 Urban Ground Water Hydrology & Ground Water Quality in and around Bangalore city 55 D S Murthy, Dep Dir, Dept Mines & Geol, Bangalore
Madhya Pradesh
GW-MP-1 Applying Aquifer modification techniques like Hydrofraking, bore blasting in existing GW abstraction structures built on various Hydro geological units of Dhasan Basin 107 MS Shah, GWS Dept MP,Bhopal
GW-MP-2 Ground Water Quality in Jabalpur urban areas with emphasis on transport of pathogenic pollutants 32.32 V Dubey, WQ Lab II, Jabalpur
GW-MH-1 Techno Economic Feasibility of Artificial Recharge of aquifer as a mitigatory measures in Fluoride affected area, Distt. Yavatmal 23.19 AB Wadaskar, GW Surveys & Dev Agency, Dist.Yavatmal
GW-MH-2 Study of Ground Water Dynamics in the Earthquake affected area of Manjar sub-basin, Watershed no. MR-35, mini watershed No.2/5 Distt. Lattur. 40.75 SG Kulkarni, GW Surveys & Dev Agency, Dist.Latur
GW-MH-3 Effects of sea water intrusion on Ground Water quality in & around Kelwa- Mahim village, Distt. Thane, Konkan Region 25 VS Deshpande, GW Surveys & Dev Agency, Thane
GW-NIH-1 Study of coastal Ground Water Dynamics and Management in the Saurashtra region, Gujarat 79.7 Dr Anupma Sharma, NIH, Roorkee
GW-NIH-3 Groundwater Management in Over Exploited of Chitradurga & Tumkur Districts of Karnataka 79.7 Dr B Kumar, NIH, Roorkee
GW-NIH-4 Groundwater dynamics of Bist Doab area, Punjab, using isotopes 80.32 Dr B Kumar, NIH, Roorkee
GW-OR-1 Application of remote sensing technique for mapping waterlogged and salt affected areas in coastal tract, Orissa 83 BC Mallick,Dir, GW Survey & Investigation Dept
GW-OR-2 Planning for optimal development of GW in coastal sand pockets of Orissa 105 Dir, GW Survey & Investigation Dept (Shri BC Mallick)
GW-PU-1 To improve the GW potential of drastically affected deep seated cretaceous aquifer (Vanur sandstone) in northern parts of Pundicherry through appropriate recharge techniques 97.45  
GW-Goa-1 Evaluation of downstream consequences of well pumping at Verna Plateau & working out Water Resource Management strategy 70  
GW-CGWB-1 Study of GW dynamics and installation of real-time GW monitoring system in NCT, Delhi 154.5 CGWB
GW-TN-1 CGWB-2 Specific yield studies for planning and designing artificial recharge structures in sub-urban areas of Chennai   Dr N Varadaraj, CGWB, SECR, Chennai