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Kancheepuram, one of the coastal districts of Tamil Nadu has a total extent of 4432.1 sq.km. and is located in the northeastern part of Tamil Nadu. The normal annual rainfall over the district is 1161 mm of which the major part is received during the months of October to December owing to northeast monsoon. Northeast monsoon is the most important as most of the tanks, irrigation structures receive replenishment and agricultural development gets added impetus. There are 59,102 ground water abstraction structures for irrigation in the district. The net area irrigated is 89.2% of the net area sown, which is about 37.72% of total geographical area. Paddy, groundnut, cholam, cumbu and cotton are the main crops and farmers are shifting towards sugarcane cultivation due to more profit. Land use transition from agriculture to urbanisation and industrialisation has taken place fast in this district causing a drop in agricultural productivity and severe environmental hazards. The district is mainly drained by the Palar, Cheyyar and their tributaries, which are ephemeral in nature. These rivers are mostly controlled by the structural disturbances in their flow traverses. The district is underlain by a wide range of geological formations from the consolidated fissured formations of Archaean age through semi-consolidated formations of Mesozoic and Tertiary age and unconsolidated alluvial formations of Quaternary age. The occurrence of ground water is limited to the granular zones in alluvium and weathered, jointed and fractured rocks of fissured formations. The Gondwana shales and sandstones are compact and contain water in the inter-granular spaces of sandstones and along bedding planes and fractures. The depth to water level lies between 1 and 6.93 m bgl (May 1999). The water table rises 0.885 to 78.46 m amsl from east to west. The general gradient and ground water flow is towards east. The present utility of ground water balance of 0.057 m ha.m/yr is available for further development and this development is possible only in eleven blocks out of the thirteen blocks in the district. The present stage of ground water development in the district as a whole is more than 52%. The stage of ground water development is more than 65% in two blocks viz. i) Madurantakam and ii) Lattur. The number of ground water abstraction structures feasible is 24,279. Almost 100% of the villages are provided with protected water supply and all major towns are getting their drinking water needs from the infiltration wells in the Palar riverbed. Alluvium forms a good aquifer system along the Palar and Cheyyar rivers. The ground water yield prospects are poor in a major part of the district. The yield ranged between 1 and 2 lps in fissured formations whereas in Palar alluvium it ranged between 5 and 10 lps and in Gondwana formations it ranged between 0.5 and 1.2 lps. There is a wide variation in quality of ground water both in lateral and vertical directions. Except in localised pockets, the quality of ground water, in general, is potable and suitable for domestic, drinking, irrigation and industrial purposes. |