Activities

The CGWB, Regional Office is well equipped with men and machinery in tackling various groundwater related issues of the State. Scientists belonging to different scientific disciplines such as Hydrogeology, Geophysics, Hydrometeorology, Hydrology, Hydrochemistry, Drilling etc. work in unison to find out solutions for groundwater related problems of the State. The activities can be summarized as follows;

Exploration Drilling	Photo geology & Remote Sensing
Ground Water Management Studies	Surface Geophysical Surveys
Ground water level monitoring	Rajiv Gandhi Technology Mission Programme
Artificial Recharge Studies	Work done in Lakshadweep Islands
Estimation of Ground water Resources	Technical Documentation and Publication
Short term water supply investigations

1. Exploration Drilling:

CGWB has about 100 rigs (DTH, Rotary and Percussion) of 300 to 700 m drilling capacity located at different areas of the country. Drilling is performed in different geological formations like hard rocks, bouldary formations, sedimentary and unconsolidated sediments. Drill cuttings are collected to prepare lithological logs and are standardized based on geophysical logs to demarcate aquifer zones. The Board is imparting guidance to State Government and other user agencies about the development of ground water structures including depth, design and spacing. The Board has the capability of deep drilling in coastal areas by grouting.

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2. Ground water Management Studies

Ground Water Management studies have been completed in the entire Kerala State and reports have been circulated to different user departments, administration and planning departments of the State. District Groundwater management studies are taken up every year in one or two districts. These surveys are carried out to assess the progressive developmental status of ground water resources for future availability and quality status.

The Board closely monitors the ground water situation in Kerala State through a network of 615 observation wells and 241 piezometers. The water levels are regularly monitored 4 times a year. The water samples are collected in pre-monsoon period (April – May). From this data, maps showing ground water level fluctuations are prepared to determine the long term water level trend, which helps delineating the areas of critical and overdeveloped nature.

CGWB has pioneered the methodology of rainwater harvesting in the country. CGWB, Kerala Region constructed a roof-top rain water harvesting structure at Mayyil Harijan Colony, Kannur district. Another scheme of artificial recharge using roof top rain water has been completed by CGWB at the Naval Academy, Ezhimala, Kannur. Both these schemes have proved to be highly successful.

CGWB, Kerala Region is carrying out artificial recharge studies in high water demand areas with critical stage of ground water development. It involves augmenting the natural movement of surface water into underground aquifers by some method of construction like sub-surface dykes, spreading of water or changing natural conditions artificially.

The sub-surface dam constructed at Odakkali in Ernakulam district by CGWB proved that it is one of the best methods for conservation of ground water resources in Kerala. Later, a few more sub-surface dams were constructed by CGWB, Kerala Region at Alanallur, Bavajinagar (Palghat district), Sadanandapuram (Quilon district), Ayilam (Trivandrum district), Njeezhur (Kottayam district). It was observed that, there was considerable rise of ground water levels in the up streamside of these sub-surface dams, thus preventing the decline of water table in the areas.

The Ministry of Water Resources, Government of India constituted a Ground water Estimation (G.E.C.) Committee in 1984 consisting of experts in the field to recommend a methodology for ground water estimation. Accordingly, the total and block-wise ground water resources of Kerala have been computed as on March, 1999.

The exercise was jointly done by the Scientists of CGWB and State Ground Water Department. According to the estimation, the total ground water resources of Kerala comes to 7,049 MCM (March 1999).

CGWB, Kerala Region is regularly taking up water supply investigations on request from Central/State organizations.

Photogeological and remote sensing data is extensively used for hydrogeological investigations. These are used to identify geomorphological features and map the fracture zones that control the occurrence and movement of ground water in the hard rocks. Data is primarily used for source finding to demarcate the area and sites suitable for ground water development. Real time use of satellite data in research and investigation for ground water, aerial data and application of G.S.I. made by the CGWB have proved to be of immense value for quick and positive results.

During the second SIDA project, Panchromatic aerial photographs of 1:60,000 scale of various periods of 1968 to 1979 were used for interpretation of regional geomorphic and structural features which were transferred to a base map of 1:50,000.

The black and white prints of Landsat imageries of Band 5 and 7 on 1:1 million as well as 1:2,50,000 scales were visually interpreted and the data were used in the preparation of Morpho-structural maps. Also, image processing and analysis were carried out using computer compatible tapes.

Advanced surface geophysical methods are used as source finding technique in the hard rock terrains and these have proved to be indispensable to decipher saturated fractures or situations suitable for ground water occurrence. The techniques in use area; Electrical Resistivity, Seismic Refraction, Electromagnetic, VLF and Magnetic measurements. The equipments are mostly digital with computer facilities for data transfer, storage, retrieval and processing.

During the second SIDA project, surface geophysical surveys comprising electrical, electromagnetic and magnetic methods were conducted at 192 sites of the State. Multiple logging of 92 boreholes and visual analysis of the fracture pattern in 28 borehole columns through closed circuit television (CCTV) were carried out. The surface geophysical studies were limited to the hard rock areas across the inferred lineaments in order to identify the fracture zones where surface geological evidence was too inadequate.

Electromagnetic surveys (VLF) and Slimgram aided in tracing thin, split or intersecting fractured zones even in uneven topography.

VLF measurements were made at a number of sites and it was found that the in-phase component was strong over the highly conducting part of the fractured zone. Slingram measurements with cable separation of 40, 60 and 100 m were carried out across the photo lineaments to delineate the fracture zones.

Electrical resistivity profiling with multi-electrode separations, vertical electrical soundings and gradient resistivity profiles were carried out to select favourable sites for exploratory drilling in the State, bringing out the existence of narrow, vertical deep-seated fracture zones in the basement rocks at most of the sites.
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CGWB, Kerala Region took up the challenging task of micro level source finding for water supply to problem villages under this scheme carried out in Palghat district of Kerala. Nearly 1800 sites were examined and 1710 sites were cleared for drilling in 146 villages and a total of 1457 bore wells were drilled under this programme. Almost 88% of these bore wells proved to be highly successful with very good yields. Nearly 57% of the drilled wells yielded up to 10,000 lph, 15% of the wells yielded between 10,000 and 20,000 lph and 13% yielded above 40,000 lph.

The Lakshadweep Islands also fall under the jurisdiction of CGWB, Kerala Region. For the first time in the history of these islands, exploratory drilling was carried out under the supervision of Scientists of CGWB, Kerala Region. The Board completed detailed hydrogeological studies in 9 out of the few inhabited islands. Under exploratory drilling, 15 shallow tube wells spread over 5 sites were drilled in Kavaratti island, having depths varying from 6 to 38 m were constructed. These boreholes were electrically logged to decipher the depth of interface and quality of w2ater. The studies proved that the thickness of fresh water lens in the island varied between 6 to 16 m only.

Results of the investigations carried out by the Board are documented as technical reports, scientific papers, maps, manuals, and Atlases. CGWB, Kerala Region is regularly issuing technical reports based on the results of hydrogeological, hydrometeorological, hydrological, geophysical, hydrochemical and exploration programmes. These technical reports are distributed to various user agencies, Universities, planners and administrators, which will be immensely helpful for the optimum development and judicious management of ground water resources of the State.