A consolidated reply of experiences and examples shared by various members of the Solution Exchange Water Community
From Lalit Mohan Sharma, Institute of Rural Research and Development, Gurgaon
Posted 28 September 2010
I work with the Institute of Rural Research and Development (an initiative of S.M. Sehgal Foundation) on Natural Resource Management. We have a programme on Integrated Sustainable Village Development (ISVD) in which water Management (WM) is our flagship programme. It is a key component of the Natural Resource Management Center WM that focuses on improving water availability and quality, promoting safe drinking water and its judicious use, wastewater disposal, salinity regression, research and innovation.
The Mewat district of Haryana is one of our primary intervention areas. This is a semi-arid region where groundwater is the main source of water as surface water is scarce. However, even this resource is very limited; only 61 of the 503 villages in Mewat have sweet groundwater and these are mostly situated along the Aravali hills where the land is steep and the soil, sandy. Groundwater recharge is low because of the topography; the shortage of surface storage compounds the problem. These few pockets of sweet water serve surrounding villages as well. People use them for domestic and farming needs. We have seen that rich farmers in the district buy small patches of land in fresh water zones, install a bore well, and pipe the water to their fields many kilometers away. The saline groundwater is slowly spreading as the sweet water gets depleted and many wells that had sweet water earlier have turned saline.
To deal with this problem we built structures to collect the runoff from large catchment areas located uphill in Aravalis to recharge the fresh groundwater pockets. We also have managed to increase the amount of recharging in low lying saline zones to check further advancement. Many wells where the water had turned saline have started yielding sweet water.
We are seeking ways to increase the reach of our recharging interventions and analyse the efficacy of our existing interventions. Can you please provide us the following information:
- How can we determine the salinity levels at different depths in aquifers if there are no test wells?
- What technology can we use to determine this and how reliable is it?
- Please let us know which institutions or individuals work in this area.
This will help us to fine-tune our interventions.
Responses were received, with thanks, from
1. D. Chandrasekharam, Department of Earth Sciences, Indian Institute of Technology, Mumbai
2. N Lakshmi Narayana, Dakshinya Institutes, Guntur
3. Tushaar Shah, International Water Management Institute (IWMI), Anand
4. Shrikant D. Limaye, Ground Water Institute, Pune
5. Yogesh Jadeja, Arid Communities and Technologies, Bhuj
6. Ajit Seshadri, The Vigyan Vijay Foundation, New Delhi
7. Murali Kochukrishnan, Danish Hydrological Institute, Hyderabad
8. Bharti Patel, Svaraj, Bangalore
9. D K Paul, Watershed Association for Training, Employment and Resource Utilisation, Delhi
10. Anil Lalwani, Well Water Works, Pune
11. Natabar Rout, Shristi, Bhubaneswar
12. Shashikant Kumar, Green Eminent Research Centre, Vadodara
13. Jürgen Tümmler, ECHO, New Delhi
14. Satya Prakash Mehra, Rajputana Society of Natural History, Bharatpur
15. J Saravanan, Consultant Hydrogeologist, Chennai
Further contributions are welcome!
Groundwater salinity is a major problem in many parts of India . In Mewat, a semi-arid part of Haryana, groundwater is the main source of drinking water but only 12 per cent of the villages have sweet water; the groundwater in the rest of the villages is saline to some extent. The problem is compounded by unsustainable use of this resource, shortage of recharge options and the geology of the area that further reduces recharge options.
Vertical electrical sounding (VES) is a way to determine the salinity of water as well as its availability in different soil and rock formation. If taken down to a depth of 100 m in reasonable steps, it can give a good idea of the quality of underground water. This can be put into a GIS map and it will be as accurate as the distance between sounding locations. This is usually more reliable than analysis, step by step, to the bottom of wells since most are not built to technical norms.
Such a map can help determine the best locations for groundwater recharge as VES also indicates where water is available. This will help optimize recharge locations and structures, important since there is a shortage of space for putting in these structures in Mewat. In nearby Bharatpur, Rajasthan, the Rajputana Society has tried an alternative method of testing water in wells to determine groundwater flows. In Gujarat , Arid Communities and Technologies have also tried similar approaches to map groundwater availability and its quality.
However, measure to increase recharge need to go hand in hand with a reduction of demand. Farmers need to change their water use in keeping with what is available by changing their crops and switching to more efficient irrigation systems. Groundwater management can be best done at the basin level with aquifers being used for multi-year storage systems and surface storage structures for short term storage. Other corrective mechanisms include moving from a resource development to a resource management mode.
Participation in Community-based Groundwater Quality Assessment, Bharatpur District, Bharatpur (from Satya Prakash Mehra, Rajputana Society of Natural History (RSNH), Bharatpur)
The organization picked a village, Chak Ramnagar, in the Gambhiri river catchment. It assessed the borewells of the village and found sweet water is available up to 45 feet below ground level. It dug wells to a depth of 42 feet drawing on scientific observations and traditional approach/ experiences of the local community. These wells now yield sweet water but a borewell dug next to it to a depth of 45 feet has saline water even after good rains.
Gujarat
Creating Groundwater Quality Map, Kachch (from Yogesh Jadeja, Arid Communities and Technologies, Bhuj)
The arid region faces inherent groundwater salinity. The organisation has generated groundwater data on a half square Km grid and drawn up maps of the local geology, geomorphology, land use, drainage, lineament and slopes. This has helped it prepare long-term groundwater management strategies and explain these to the local community, that has improved groundwater management in this very arid zone.
Delination of Suitable Sites for Artificial Recharging System - Using Remote Sensing and GIS Mapping Techniques (from Murali Kochukrishnan, Environmental Geologist, Danish Hydrological Institute)
Paper; by Mr. K Murali; Danish Hydrological Institute; Hyderabad; Publication date; Permission Required: No
Available at ftp://ftp.solutionexchange.net.in/public/wes/cr/res-28091001.pdf (PDF 950 Kb)
The paper deals with GIS techniques to generate data for the development of water resources and finding out areas for large scale groundwater recharge
A Vertical Electrical Sounding Method for Soil Survey (from Nitya Jacob, UNICEF, New Delhi)
Landviser; USA; 2010; Permission Required: No
Available at http://larisa_pozd.tripod.com/ves/ves.htm
Describes the process of using vertical electrical sounding as a non-invasive method to determine groundwater availability and quality
Recommended Contacts and Experts
Dr. Ajith S Gokhale, Natural Solutions, Mumbai (from Satya Prakash Mehra, Rajputana Society of Natural History, Bharatpur)
Dombivali, Mumbai; Tel: +91 9870423023; ajit.naturalsolutions@gmail.com
Is an expert in water management, from rainwater harvesting to wastewater treatment and also groundwater management
Recommended Organizations and Programmes
Arid Communities and Technologies, Bhuj(from Yogesh Jadeja, Arid Communities and Technologies, Bhuj)
C - 279, Opp. Gunatit Chowk, Mundra Road Relocation Site, Bhuj - 370 001. Kutch. Gujarat; Tel: +919979850931; yogeshjadeja@gmail.com; http://www.act-india.org/
ACT is a voluntary organization that works in a semi-arid part of India. It focusses on research and training for capacity building mainly in water resources and agriculture
Watershed Association for Training, Employment and Resource Utilisation, New Delhi (from D K Paul, Watershed Association for Training, Employment and Resource Utilisation, Delhi)
1234, Sector 12, Ramakrishna Puram, New Delhi 110 022; Tel: +91 11 26166524, +91 11 65465126 ; Contact Mr. D K Paul; WATER; dkpaul47@yahoo.co.in
WATER is a forum for networking of interested government organisations, NGOs and CBOs to come together on watershed management and rural development
Rajputana Society of Natural History, Bharatpur, Location(from Satya Prakash Mehra, Rajputana Society of Natural History, Bharatpur)
Kesar Bhawan, 16/747, P. No. 90, B/d Saraswati Hosp., Ganeshnagar, Pahada, Udaipur, Rajasthan; Tel: +91 294 2470690; http://www.indiawaterportal.org/node/3970;
The society works in north-eastern Rajasthan on issues of natural resource management with an emphasis on water
From J Saravanan, Consultant Hydrogeologist, Chennai
Central Ground Water Board (CGWB), Haryana
NH-IV, Bhujal Bhawan, Faridabad 121001 Haryana; Tel: 91-129-2419075; Fax: 91-129-2412524; chmn-cgwb@nic.in; http://www.cgwb.gov.in/
Apex national level agency responsible for monitoring ground water levels, quality and hydrology across the country, has a network of 18 regional offices
National Remote Sensing Centre (NRSC), Andhra Pradesh
Balanagar, Hyderabad 500625, Andhra Pradesh; Tel: 91-40-23879572-76; Fax: 91-40-23878648; feedback@nrsa.gov.in; http://www.nrsa.gov.in/
Responsible for the acquisition, processing, supply of aerial and satellite remote sensing data and continuously exploring the practical uses of remote sensing technology
Recommended Tools and Technologies
Surfer (from Jürgen Tümmler, ECHO, New Delhi)
Software; by Golden Software; USA; Permission Required: Yes, Priced software.
Available at http://www.goldensoftware.com/products/surfer/surfer.shtml
Surfer is a contouring and 3D surface mapping programme that quickly converts data into contour, 3D surface, 3D wireframe, vector, image, shaded relief, and post maps
D. Chandrasekharam, Department of Earth Sciences, Indian Institute of Technology, Mumbai
Resistivity surveys are reliable to determine the salinity levels at different depths in aquifers if there are no test wells. The problem here seems to be very similar to that existing in Barmer in Rajasthan. There are many professional groundwater consultants in Rajasthan who can do this job and I can provide the contact of people working in Barmer.
N Lakshmi Narayana, Dakshinya Institutes, Guntur
The agency is doing commendable job in harvesting the rainwater. In addition to that, "enhancing the groundwater by way of injection of recharge wells" at suitable sites with required depths which can be decided based on the existing data or by deploying geophysical scanning tools which are cost effective.
The other comments are furnished below the given points:
How can we determine the salinity levels at different depths in aquifers if there are no test wells?
In this situation, geophysical scanning tools like: Electrical Resistivity Survey both Profiling and Vertical Electrical Sounding (VES) and magnetic survey (if the groundwater is controlled by structures like dykes etc.). These tools are cost effective and a large area can be covered with the matching logistics available with in India .
What technology can we use to determine this and how reliable is it?
The technology indicated above can be used effectively with better accuracy. It all needs the suitable equipment for data acquisition and data processing software. The results will be reliable and cost effective.
Please let us know which institutions or individuals work in this area.
All the government both state and central departments dealing with groundwater should be help to solve this problem. In addition, there exist several consultants whose services can be taken for solving the given problem.
As a professional, I have done such mappings and suggested measures have resulted for betterment in the groundwater environment. I will be happy to guide the agency for planning and implementing the problem solving strategies.
Hope this gives you the right direction to move with problem solving strategies for solving the groundwater problem in the given saline environment.
Tushaar Shah, International Water Management Institute (IWMI), Anand
- You should try skimming wells.
- Where there are canals, ponds, check dams, advice farmers to blend saline water.
- But the ultimate answer is more groundwater recharge.
Shrikant D. Limaye, Ground Water Institute, Pune
I have been working on salinity of ground water in coastal and inland regions for past many years.
Sweet water of less density floating over saline water of higher density is a normal condition just like an iceberg floating on seawater. In inland flat terrain, the velocity of ground water is extremely slow and the deeper saline ground water gets enriched in salinity due to longer time for rock-water interaction.
The sweet water lens floating over saline water exists due to infiltration from rainfall, irrigation canal and from irrigated fields. More infiltration means the sweet water lens is thicker. In regions where the subsurface strata are more coarse or sandy, flushing of saline water with sweet water is possible to some extent. Where the strata are more clayey, salinity predominates. Recharging good bores or wells with runoff during the Monsoons ensures sustainable sweet water supply.
Hydro-geological observations, inventory of wells and electrical resistivity sounding is helpful to assess the thickness of sweet water lens. Resistivity profiling is also helpful when the quality of water changes in later direction due to irregularities in the strata.
Yogesh Jadeja, Arid Communities and Technologies, Bhuj
Greetings from Arid Communities and Technologies, Bhuj. We are working in arid areas of Gujarat especially on groundwater management. We are facing two types of groundwater quality problems such as inherent salinity in the northern part of the Kachchh district nearer to Great Rann and sea water ingress in the coastal areas in South. To address such issue following suggestions can be made.
- Generation of groundwater data base at closer grid such as 0.5sq km basis
- Preparation various thematic maps such as geology, geomorphology, land-use, drainage map, lineament, slope maps
- Synthesization of thematic map to generate recharge potential and groundwater potential map
- Based on data base generation of trend showing map such as reduced water level and water quality (the parameter may be based on TDS, pH, Fluoride, Iron or dominant problem element in local area) based on maps for pre and post monsoon periods for at least last 10 years and characterize area based on trend such as very severely affected, to no affected areas.
- Closely study lithologs of existing borewells and if required go for test drilling to understand depth/aquifer wise status of water quality
- Prepare long term groundwater management plan on aquifer basis along with community including recharge, to control exploitation, for judicious use of ground water.
- Characterize hydraulic properties of aquifer by holding pump test on specific wells/borewells
- Geophysical investigation, toposheets, existing geological maps of the areas published by GSI can be useful to prepare groundwater management plan
- Close Monitoring and consistency of data are two most important requirements of such kind of initiatives for groundwater management.
Ajit Seshadri, The Vigyan Vijay Foundation, New Delhi
This intervention-ISVD by IRRAD is commendable in which water management is a part of natural resources management is given utmost importance. What we are missing in all these is the overall satisfaction gained by communities living in these watersheds.
If there is satisfaction gained through the intervention, in the quality of living in the hard habitats, and there are some tell- tale signs which have shown that through all this, the situation is improving. Please do get inferences from the community to showcase this and do substantiate this information.
It is good always to recharge the aquifers. But if their yields are very salty, and also too deep for the community to draw the water without using high-powered pumps etc., it makes it harder to source water from these ground aquifers; this is becoming more in common nowadays.
Surface ponds:
It would be in order to harvest rain water by filling up ponds which can be filled easily as surface ponds are utilised widely. These ponds can be evolved in two ways, one which is lined used for potable water and for cooking, and the other could be unlined, or if finances are available, they could also be lined. These unlined ponds are used by live-stock and for agriculture.
Also these ponds in the area could be used for monitoring. Efforts are extended to study and monitor the same.
There will be many old ponds as well, though over the years they would have got silted up and will need desilting and cleaning. It would be appropriate to use some extra efforts to clean them. The water supply board could adopt mechanised dredging if needed to deepen these ponds and they could serve for aquifer recharge.
Old village dug-out wells:
Then another asset which exists on most village farmlands are old dug wells. Most of them have dried up been forgotten; they have become rubbish dumps. If they are located near rainwater channels or streams, they can be restored. They can be cleaned up, desilted, deepened by an additional 10-20 feet and used for recharge of groundwater. Constant monitoring of these wells, would give satisfactory information on groundwater, as well as a source of good drinking water.
Waste-water streams, Nallahs:
Also there are waste-water effluents flowing side by side with rain water in areas where wastewater disposal also is a nuisance. Often, villages discharge their entire effluents into ponds. This water can be cleaned through natural processes and then released into the pond; this would enhance local water security. As water has played a vital part in self sustaining the village, all efforts ought to be made to conserve and regenerate new water using cost-effective means.
Murali Kochukrishnan, Danish Hydrological Institute, Hyderabad
The initiative carried out in recharging groundwater by various methodologies in your project area is highly appreciable. Having conducted quite a number of ground water investigations in the Mewat region for various organizations, I would like to share my experiences and suggest few developmental initiatives to sustain your objective in recharging groundwater.
To start with, the fresh water which may be of lesser density will always float over saline water having greater density. The occurrence of sweet water pockets attributes to the rainfall pattern, infiltration and percolation rate. The sweet water column depends up on the nature of sub-strata forming the aquifer. The areas in the downstream side of the Aravalli’s are more of valley filled sediments/pediments comprising of a coarse strata with sandy water bearing formation. This also helps in flushing/dilution of the saline water to certain extent.
The strata where there is a huge deposition of silt and clayey layer, the recharging aspect is restricted due to the aquiclude nature of the clayey formation and the salinity gets enhanced in those formations.
Hydro-geological mapping, taking well inventories followed by conducting Vertical Electrical resistivity sounding (V.E.S) by schlumberger configuration clearly exemplifies the existence of the sweet and saline water zones. As per our technical study findings, an apparent resistivity reading of less than 10-ohm-m clearly indicates the existence of saline water zones, and reading with 10 ohm-m to 15ohm-m indicates the occurrence of brackish water zones.
Electric Resistivity Profiling survey will also help us in delineating the lateral or horizontal variation in the aquifer system.
To further study the aspect of recharge on a larger scale, secondary data from various government (state/central) and other technical organizations has to be collected and collated for generating various level of information. Remote sensing imageries with various themes viz., geo-morphological features, slope, geology, hydrogeology, water table and water quality contours, etc., for different years will also be helpful in delineating the required information.
A few exploratory bore wells can be drilled and geo-physical logging can be conducted for ground truth and verification. This is followed by continuous monitoring and surveillance of the observation/exploratory wells will also yield copious amount of information.
There are many organizations which provides ample scope for your technical study are available in our nation. There is no dearth of technical organization as such. I am also enclosing a Technical paper of mine titled “Delineation of suitable sites for artificial recharge system- Using remote sensing and GIS technology” for your kind perusal and broad understanding (ftp://ftp.solutionexchange.net.in/public/wes/cr/res-28091001.pdf, PDF, 950 Kb)
Bharti Patel, Svaraj, Bangalore
I would like to add another point to those mentioned by Tushaar Shah:
‘Enforcement of ground water regulation to stop exploitation’. This will require assessment of land and crop use patterns in the area, issues of inequitable distribution and utilisation of water – who gets what, where and for what purpose.
D K Paul, Watershed Association for Training, Employment and Resource Utilisation, Delhi
I would like to add something more to what has been mentioned by Tushaar Shah:
In the business-as-usual scenario in a low per capita income region like MEWAT using low level of technology for water management, the problems of groundwater over exploitation will only become more acute, widespread, serious and visible in the years to come under present rules and regulation of water use system. The frontline challenge is not just supply side innovations (more exploitation of available groundwater) but putting into operation a range of corrective mechanisms involving a transition from the resource “development” to the resource “management” mode. A major barrier that prevents this transition is the lack of information of how much groundwater is there, who withdraws how much groundwater and the consequent regulation mechanism (totally absent).
Policy reform and regulation of groundwater entails major institutional restructuring as local needs; this is a challenging task for water managers (district/state/CADA Haryana) and need much emphasis on self governance (is it possible under existing market oriented policy). For this at least four important steps are needed:
- Information Systems and Resource Planning: Ground water monitoring on regular basis in the Mewat groundwater basin, planning the use of the resource(water) and undertaking systematic and scientific research on occurrence, use and ways of augmenting and managing the resource.
- Demand Side Management: Effective system for bringing down withdrawals to sustainable levels through effective regulations like enforcing compulsory registration of the users, appropriate laws and regulatory mechanisms, pricing for energy and groundwater use, promoting conjunctive use and “precision” irrigation.
- Supply-Side Management: Popularise rainwater harvesting and groundwater recharge programs and activities, optimise surface water use for recharge, improving incentives for water conservation and artificial recharge and suitable policy and regulation for protection against pollution/contamination of groundwater resources.
- Groundwater Management in the River Basin Context: Planning and managing groundwater resources for maximum basin-level efficiency, using aquifers as multi-year water storage systems, trans-basin movement or surface water systems exclusively for recharge.
This is the view based on my exposure with in Mewat (the districts of Nuh and Gurgaon) over the last 10-12 years. Presently WATER is involved in a World Bank-funded project 'Strategies to enhance adaptive capacity to climate change in vulnerable regions (Haryana, Orissa, Madhya Pradesh and Maharashtra ).
Anil Lalwani, Well Water Works, Pune
As surface geophysics is a fairly well understood subject, I don’t want to get into it, but when applying such kind of investigation one has to keep in mind that grid spacing, (both vertical, as well as horizontal) generates unnecessary data that is as bad as lack of data.
Another point to be kept in mind is over-exploitation and contaminant plume migration. This means that even if you strike good quality of water you may mis-manage it and will face problems of salt water moving into your wells.
Just using geophyiscs is the simplest part of the problem, I would suggest that a more integrated approach be taken to find a long term solution rather than just temporary short term solutions.
Drilling of a few well at strategic locations is needed both for logging as well as testing and monitoring. Problems due to over-exploitation are far more difficult to deal with as compared to trying to locate fresh water pockets.
There should be a number of consultants who do that kind of work in that area; if not we at Well & Water Works would be glad to help out, only problem is the proximity of the site which makes our intervention in such work a slightly costly affair.
Natabar Rout, Shristi, Bhubaneswar
You have adopted a very strategic initiative to manage the groundwater resources in the region. The concern you have raised is regarding the detection of different aquifers and their characteristics in the region. In this context where there are no test wells, you can go for Geophysical Survey which will give you the details of aquifer positions with saline or fresh water and lithological characteristics. For carrying out such studies you may contact the Central Ground Water Board (CGWB) for further technical guidance.
Shashikant Kumar, Green Eminent Research Centre, Vadodara
To understand the salinity ingress and impact of recharging wells you need to undertake a modeling exercise. The requirement might be as under:
(a) Estimated Salinity levels (if some data is available from past test wells) Sufficient samples would be required to establish the salinity levels.
(b) Existing Salinity Levels - Aquifers (from test wells), Open Wells, Bore wells
(c) Mapping of Estimated and Existing Salinity Levels
(d) Changing Salinity levels at sampled sites - Choose a temporal period 6 months - 1, 2, 5, 10 years. Water Sample analysis
(e) Modeling by using scientific methods - using parameters such as recharging structures, rate of recharge, depletion rate (utilization), set the salinity ingress rate by block or grid.
(f) Use Probability and other statistical tools to model.
These all can be done to set the hydrological and salinity ingress model to estimate future situation under various scenarios. I am sure there are experts available in IITs in India to help in these matters. You cannot go on digging test wells to assess progress of your work. Rather for every region, projects need to be modeled for once and monitored accordingly.
Jürgen Tümmler, ECHO, New Delhi
I wouldn't agree on the harvest of unnecessary data obtained from geophysics in order to detect salinity in groundwater.
If all data from geo-electrical surface soundings (VES, vertical electrical sounding) are taken down to 100 meters, for instance, in reasonable steps (L/2 [m] 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 100) the resolution for interpretation is very good and increases in salinity will be easily discovered. Put into GIS with X, Y and Z data (latitude, longitude, altitude) the mapping will be as precise as the width of the interspaces between sounding locations.
Good GIS applications (e.g., Surfer of Golden Software) can display the saltwater distribution in 3- and 2-dimensonal charts / maps and allow guesstimating with some precision the extension of saltwater plumes and the volumes involved.
Usually, existing wells in the area covered with VES grids can be measured for electrical conductivity to allow fine-tuning of the geophysical data in surface near areas - unluckily most wells are not built up to technical norms, so an analysis step by step down to the bottom will not reveal reliable data of depths of saltwater horizons - VES from the surface will give better results here.
Helicopter-based geolectrical resistivity measurements may prove more economic if huge areas are concerned and have been successfully done after the tsunami in Northern Sumatra ; the inconvenience is, that there are but a few specialized organizations that are able to do it and that the administrative challenge preparing these campaigns is immense.
Satya Prakash Mehra, Rajputana Society of Natural History, Bharatpur
We (Rajputana Society of Natural History) are working on the same issue in the downstream region of Mewat, i.e., Braj. As per our work experiences in the region on same issue, we would like to share following points on the query circulated:
1. How can we determine the salinity levels at different depths in aquifers if there are no test wells?
Response: one could assess the salinity levels of the borewells of the agricultural fields. Lot of fields have borewells. Along with this assessment of the levels of qualitative water of bores (sweet/saline), we have to analyze water flow pattern (both surface and ground) through toposheets and/or watershed studies. Thus, from these two observations at least one could conclude that the region has certain level where the sweet water turns out to be saline.
Example: We worked similarly for Chak Ramnagar village which is in downstream of River Gambhiri. After assessing all the borewells of the region, we found that the region has the sweet water available up to 45feet down the ground. We dug wells up to 42 feet. Here both the scientific observations and traditional approach/ experiences of the local community were included. Now, the well is full of sweet water and the bore dug up to 45 feet just near it (at approx. 30feet distance) has saline water even after good rain.
2. What technology can we use to determine this and how reliable is it?
Response: Our team of experts studied water flow pattern, ground water level and experiences of the local community of digging deep bores. All the weather reports and meteorological data were also considered before planning the remedial measure to provide qualitative water for the village. Reliability depends on the depth of observations and the information provided by the team of expert. Even differences in one to five feet matter when there is saline water at greater depths.
3. Please let us know which institutions or individuals work in this area.
Response: There are lot of institutions and individuals working in this area. For our work we had Key Expert from "Natural Solutions", Mumbai (Dr Ajith S. Gokhale) along with team of local individuals working on similar aspects.
One most important point which I want to share from our experience in the region is that the availability of surface water is by and large responsible to ground water (up to certain level) to be qualitative. The more the surface water, less the salinity in the region. Further, building filter chambers and conservation of surface water as per conditions of the region play important role in providing qualitative water to the community.
J Saravanan, Consultant Hydrogeologist, Chennai
I went through your query and suggest the following approach:
1. Collect secondary data available with the government agencies. This includes the State Groundwater Department and the Central Groundwater Board (CGWB). The secondary data should include:
a. Borewell Lithology of Observation and Exploratory borewells drilled by these departments
b. Results of the chemical analysis of the above mentioned borewells
c. Pre and Post monsoon water levels - CGWB and the state departments do monitor the water levels at regular intervals
d. Geology, Geomorpholoy, Soil and other thematic maps related to the study area. I believe long back National Remote Sensing Agency, Hyderabad (NRSA) prepared comprehensive recharge maps (topo sheet wise) for several states. Check whether this is available for your state and if available get the same also.
e. Survey of India , Topo sheets pertaining to the study area
2. Integrate the above and analyse on the hydrogeological status of the study area.
3. Data integration can be done using GIS.
4. Superimpose your field data such as fresh water zones, saline zones, locations wherein you have implemented RWH structures, locations wherein you have noticed remarkable improvement in groundwater quality etc., with the above data and prepare an integrated hydrogeological map.
5. This would help us to understand better on the ground conditions first. This would also help us to establish the linkages of geo-hydro-morphic features with groundwater quality.
6. Once the above is established, the next step is to explore for fresh water pockets with the application of Geophysical Survey. Electrical Resistivity Survey is the most common method employed in groundwater exploration. Take reference points for the fresh and saline zones.
7. Once we establish the apparent and true resistivity references through geophysical survey for saline/fresh water zones then the same can be employed in search of fresh water zones in your project area.
The above is an integrated study which involves a Groundwater Consultant, Geophysicist and a GIS expert. You may get in touch with consultancy firms near your project area for the study.
Many thanks to all who contributed to this query!
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