कᴂ द्रीय भूमम जल बो셍 ड जऱ संसाधन, नदी विकास और गंगा संरक्षण मंत्राऱय भारत सरकार Central Ground Water Board Ministry of Water Resources, River Development and Ganga Rejuvenation Government of India Report on AQUIFER MAPPING AND GROUND WATER MANAGEMENT Upper Cauvery Basin, Tamil Nadu दक्षक्षण ऩूिी तटीय क्षेत्र, चेꅍनई South Eastern Coastal Region, Chennai Foreword Groundwater is the major source of freshwater that caters the demand of ever growing domestic, agricultural and industrial sectors of the country. This renewable resource has been indiscriminately exploited in some parts of the country by several users as it is easily available and reliable. Intensive and unregulated groundwater pumping in many areas has caused rapid and widespread groundwater decline. Out of 6607 ground water assessment units (Blocks/ mandals / taluks etc.), 1071 units are over-exploited and 914 units are critical. These unitshave withdrawal of ground water is more than the recharge (over exploited) and more 90% of recharge (Critical). Central Ground Water Board (CGWB) has taken up largest Aquifer mapping endeavour in the world, targeting total mapable area of country ~ 23.25 lakh sq. km with a vertical extent of 300 m in soft rock area and 200 m in hard rock area. The extent of aquifer, their potential, resource availability, chemical quality, its sustainable management options will be addressed by National Aquifer Mapping (NAQUIM). The NAQUIM programme will also facilitate participatory management of ground water to provide long term sustenance for the benefit of farmers. Currently, focus is on ground water stressed areas of eight states comprising 5.25 lakh sq.km viz. Tamil Nadu, Haryana, Punjab, Rajasthan, Gujarat, Andhra Pradesh, Telangana, Karnataka and Bundelkhand region. South Eastern Coastal Region, Central Groundwater Board, Chennai Under NAQUIM has been envisaged with the Mapping of an area of 70,102 sq.km during 2012-17 (XII five year plan) in Tamil Nadu and UT of Puducherry. This report deals with the Aquifer mapping studies carried out in water stressed upper Cauvery basin covering basin area of 4561 sq .km with 3634 sq.km as mappable area. The basin comprises of drought prone districts of Dharmapuri, Krishnagiri and parts of Salem with 32 firkas (15 Over Exploited and 8 Semi-critical), and is mainly dependent on groundwater (85%) for its agricultural needs. The major issues in the basin include declining groundwater levels, sustainability of wells and high Fluoride concentration in patches leading to risk of dental and skeletal fluorosis. Two aquifer units were deciphered with aquifer Unit - I being the weathered, occurs from ground level to 36 m bgl and Aquifer Unit –II is the fractured/Jointed zone existing from 11 to 140 m bgl (2-5 fractures are encountered). In order to arrest the decling groundwater levels and increase the sustainability of wells groundwater management plans were formulated firka wise. I hope this report will be useful for the district administrators, water managers, stakeholders including farmers in knowing the aquifer and managing it resources effectively. A.Subburaj Head of Office EXECUTIVE SUMMARY Detailed hydrogeological studies were conducted in the study basin of Upper Cauvery and huge existing data pertinent to geology, geophysics, hydrology, hydrochemistry was collected, synthesised and analysed to bring out this report. This report mainly comprises the Aquifer geometry and Aquifer properties of the study area which are considered to be measuring scales for groundwater availability and potentiality. Keeping these parameters in view a sustainable management plan has been suggested through which the groundwater needs can be fulfilled in a rational way. Area experiences semi-arid climate with 875 mm annual normal rainfall covering 4541 km2 area in Dharmapur, Krishnagiri and Salem districts of Tamil Nadu. About 51 thousand hectares of area is under groundwater irrigation in the basin and accounts for 11.6% of the geographical area. The main crops irrigated are paddy, sugarcane, groundnut, maize, cotton, ragi and other minor crops are turmeric, vegetables and flowers. Main aquifers constitute, weathered zone at the topfollowed by a discrete anisotropic fractured/fissured zone at the bottom.Groundwater occurs under unconfined condition in the weathered zone and unconfined to semi-confined conditionsin the fractured/fissured zone and flows downward from the weathered zone into the fracture zone. The predominant water levels are in the range of 5-20 m bgl during pre-monsoon season and 2-10 mbgl during post-monsoon season of 2014. The net annual ground water availability is 282 MCM and the gross ground water draft is 335 MCM and the average stage of groundwater development is of 119%. The fluoride levels in the ground waters of the basin exceed the permissible limit of 1.5ppm in few parts of Dharmapuri and Krishnagiri districts due to geogenic contamination. This problem is addressed through drinking water supply to the affected villages from Hognekal reservoir. Aquifer systems from the area can be conceptualized as weathered zone down to ~36m and fractured zone between ~20-200 m bgl. The weathered zone is disintegrated from the bed rock (upper part–saprolite zone) and partially/semi weathered in the lower part (sap rock zone) with transmissivity varying between 5–20 m2/day and specific yield of 1-3 %. The fractured zone is fractured gneiss or Charnockite which occur in limited extent, associated sometime with quartz vein. The average transmissivity of this zone varies between <1–30 m2/day and storativity varies from 0.00002 to 0.001. Fast growing urban agglomerations shares the groundwater which otherwise is being used for irrigation purpose resulting in either shortage for irrigation needs or creates excessive draft to meet the both demands in groundwater potential areas. The study formulates management strategies for supply side as well as demand side. The supply side measures include construction of artificial recharge structures of 302 Check dams, 421 Percolation ponds, 300 recharge shafts in addition to the 689 ponds earmarked for rejuvenation with recharge shafts in all the 15 OE firkas of the basin. The estimated cost for construction of these structures is to be Rs. 308 Crores. The estimated recharge to groundwater system through these structures will be in the order of 61.75 MCM withan average rise of water levels of 2.28m/year. In addition water conservation plan is proposed through low pressure water distribution system in 1391 Ha irrigation area and digging of 1362 farm ponds which support storage as well as recharge. The expected savings in groundwater through this water conservation plan is estimated as 10.8MCM/year. The existing regulatory measures may be modified suitably for optimal utilization of groundwater as well as for sustainable development of rural agricultural based economy. To achieve this goal opinion pool has to be obtained from more user groups and valid suggestions of may be incorporated in the regulatory acts. REPORT ON AQUIFER MAPPING FOR SUSTAINABLE MANAGEMENT OF GROUNDWATER RESOURCES IN UPPER CAUVERY BASIN, TAMIL NADU CONTRIBUTORS’ PAGE Name Designation Principal Authors Dr.Anandkumar Ars : Scientist -D A. Sreenivas : Scientist -D Hydrogeology & Groundwater exploration Dr. Anandkumar Ars : Scientist-D Dr. K . Rajarajan : Assistant Hydrogeologist A. Sreenivas : Scientist-D M. Panneer : Assistant Hydrogeologist N. Ramesh Kumar : Assistant Hydrogeologist Groundwater Modelling Dr. M. Senthil Kumar : Scientist-C ( Sr. Hydrogeologist) Dr. D. Gnanasundar : Scientist-D (Sr. Hydrogeologist) Groundwater management plan A. Arumugam : Scientist -D S. Piramanayagam : Scientist-D Geophysics T.S.N Murthy : Assistant Geophysicist V.S.T Gopinath : Scientist-B KT Suresha : Scientist-D ( Sr. Geophysicist) Hydrometeorology M. Sivakumar : Scientist-D ( Sr. Hydrologist) Chemical Analysis Dr. K. Ravichandran : Scientist-D ( Sr. Chemist) K. Padmavathi : Scientist-B Map preparation Mrs. M. Navaneetham : Draughtsman Overall Supervision and Guidance A. Subburaj : Head of Office AQUIFER MAPPING FOR SUSTAINABLE MANAGEMENT OF GROUNDWATER RESOURCES IN UPPER CAUVERY BASIN, TAMIL NADU Contents 1.0.Introduction 1 1.1.Objective 1 1.2.Scope of Study 2 1.3.Approach & methodology 2 1.4.Area 3 1.5.Data availability 3 1.6.Data adequaqcy 4 1.7.Data gap analysis & data generation 4 1.8.Rainfall 4 1.9.Physiography 5 1.10. Geomorphology 5 1.11. Landuse 5 1.12. Soils 6 1.13. Hydrology & Drainage 6 1.14. Agriculture 6 1.15. Irrigation 6 1.16. Recharge Practices 7 2.0.Data Collection and Generation 7 2.1.Hydrogeological data 7 2.2.Hydrochemical data 10 2.3.Geophysical data 11 2.3.1. Data acquisition and interpretation 12 2.4.Groundwater Exploration Data 14 3.0.Data Interpretaion, Integration & Aquifer Mapping 16 3.1.Hydrogeological Data Interpretation 16 3.1.1. Groundwater Level 16 3.1.1.1.Depth to water level for Aquifer I (May 2014) 16 3.1.1.2.Depth to water level for Aquifer II (May 2014) 17 3.1.1.3.Depth to water level for Aquifer I (Jan 2015) 17 3.1.1.4.Depth to water level for Aquifer II (Jan 2015) 19 3.1.1.5.Water level fluctuation 19 3.1.1.6.Water table elevation 19 3.1.2. Pumping Tests 21 3.2.Hydrochemical data Interpretation 21 3.2.1. Quality of Groundwater in Phreatic Aquifer 22 3.2.2. Quality of Groundwater in Fractured Aquifer 24 3.2.3. Electrical Conductivity 26 3.2.4. Chloride 27 3.2.5. Nitrate 27 3.2.6. Fluoride 27 3.3.Geophysical Data Interpretation 28 3.3.1. Surface geophysical investigation 28 3.3.2. Data acquisition and interpretation 28 3.4.Groundwater3.3.3. exploration data results 31 3.4.1. Aquifer I 32 3.4.2. Aquifer II 32 3.5.Aquifer Maps 32 3.5.1. 2D Models 32 3.5.1.1.Section along NW-SE dirction 34 3.5.1.2.Section along NNW- SSE direction 34 3.5.1.3.Section along NE – SW direction 35 3.5.2.