Agricultural Engineering Research Journal 1 (1): 12-19, 2011 ISSN 2218-3906 © IDOSI Publications, 2011 Corresponding Author: A. Murugappan, Department of Civil Engineering, Annamalai University, Annamalainagar-608 002, Tamilnadu State, India. E-mail: profam@sify.com. 12 Effects of Lignite Mine Drainage on Irrigated Command Areas - A Case Study A. Murugappan, A. Manoharan and G. Senthilkumar Department of Civil Engineering, Annamalai University, Annamalainagar-608 002, Tamilnadu State, India Abstract: Irrigated agriculture is dependent on an adequate water supply of usable quality. Intensive use of nearly all good quality supplies means that new irrigation projects and old projects seeking new or supplemental supplies must rely on lower quality and less desirable sources. To avoid problems when using these poor quality water supplies, there must be sound planning to ensure that the quality of water available is put to the best use. The mine drainage water pumped out continuously from the open cast lignite mines of the Neyveli Lignite Corporation Limited, Neyveli, Tamilnadu State, India, is received by two system tanks (small reservoirs) used mainly for irrigation. This has encouraged the farmers in the command areas of both tank systems to go for more than one rice crop in a year. Even though, over the years, the farmers have been benefited by this supply of continuous water from mines in addition to rainfall and runoff from respective catchments of the tanks, in recent times, they opine that the coal dust laden mine water used for irrigation had affected the crop yields. Investigations were carried out with the objectives (1) to assess the status of quality of surface waters released from the two tanks for irrigation in the respective command areas and (2) to assess the likely effects of quality of water on soil and on growth and yield of crops grown in the command areas. Key words: INTRODUCTION The quality of the available supply must be evaluated Irrigated agriculture is dependent on a sufficient in using water of different qualities have been gained from water supply of utilizable quality. In the past water quality observations and detailed study of problems that develop apprehensions had often been neglected because good following the use of such waters. The cause and effect quality water supplies had been plentiful and readily relationship between a water constituent and the available. But the situation has changed in many areas. observed problem then results in an evaluation of quality Many irrigation projects have to rely on lower quality and or degree of acceptability. Due to sufficient reported less desirable sources of water supply. In order to avoid experiences and measured responses, certain constituents problems when using such poor quality water supplies, emerge as indicators of quality- related problems. These there must be sound planning to ensure that the quality characteristics are then organized into guidelines related of water available is put to best use. to suitability for use. The guidelines presented in FAO The effect of water quality upon soil and crops must Irrigation and Drainage Paper 29 (Revised 1)[1] give more be better understood in selecting suitable alternatives to practical procedures for evaluating and managing water cope with potential water quality related problems that quality-related problems of irrigated agriculture. might reduce production under prevailing conditions of Two tanks (small sized reservoirs) namely, Walajah use. Tank and Perumal Tank, in Cuddalore District, receive Conceptually, water quality refers to the mine drainage water pumped out continuously from the characteristics of a water supply that will influence its open cast lignite mines of the Neyveli Lignite Corporation suitability for a specific use, that is, how well the quality Limited, Neyveli, Tamilnadu State. This water had been of water meets the needs of the user. Quality is defined by used by the beneficiaries in the irrigated commands of certain physical, chemical and biological characteristics. both Walajah Tank and Perumal Tank for more than three In irrigation water quality evaluation, importance is placed decades. Recently, they had raised apprehensions on the on the chemical and physical characteristics of the water quality of mine drainage waters they were using for and only rarely is any other factor considered important. raising crops in the commands of both the tanks. to see how it fits the intended use. Most of the experience