Water Resources Systems-—Water Availability ami Global Change (Proceedinns of symposium HS02a held during IUGG2003 at Sapporo, July 2003). IAHS Publ. no. 280. 2003. 205 Assessment of groundwater quality and climatic water balance studies in the Pageru River basin, Andhra Pradesh, India P. D. SREEDEVI & SHAKEEL AHMED Indo-French Centre for Groundwater Research, National Geophysical Research Institute, Hyderabad-500007,' India shakeelahmed@,satvam.net.in; shakeelahmed@,ngri.res.in Abstract An analysis of the climatic water balance and drought in the Pageru River basin, a chronically drought prone area in south India, has been prepared using rainfall data from eight raingauge stations located in and around the basin. The values of rainfall and temperature have been collected and the water balance parameters have been computed using the Thornthwaite and Mather method. In addition, 99 water samples were collected during both pre- and post-monsoon seasons and analysed for major ions to assess the water quality in relation to agriculture and domestic uses in the basin. The results indicate that the annual water deficit of the basin is 821 mm. The maximum water deficit is observed during the months of March and June and it is minimal in September. The analysis of the data revealed that the annual distri- bution is mainly controlled by the physiography of the region. A comparison of the water balance and cropping pattern used in the villages indicates that the basin area is only suitable for cultivation of drought resistant crops such as Sorghum bicolor, Eleusine coracana and Pennisetum typhoïdes. Assessment of water samples from various methods proved that most of the water is good for drinking as well as for agriculture in both seasons. Key words climate; crops; drought; groundwater quality; Pageru River basin, India; water balance INTRODUCTION The Pageru River basin is situated in the drought prone Rayalaseema region, Andhra Pradesh, India. The river is ephemeral and originates from the Seshachalam range of hills (maximum elevation 449 m) in the western part of the study area. Groundwater has become an important source of water and has an important role in the development of industry and agriculture and for domestic purposes. There are no assured sources of surface water for irrigation such as major and medium irrigation projects. The mainstay of the people living in district is agriculture. The total area of the basin is 480 km 2 and is located on the Survey of India 1:50 000 toposheet numbers 57 J/6, J/7, J/10 and J/11. The basin area lies between latitudes 14°39'04" and 14° 39'51"N, and longitudes 78°19'12" and 78°41'32"E. CLIMATE The general climate of Pageru River basin is semiarid in nature. The temperature gradually rises from January and reaches its maximum in the month of April, then decreases gradually from May and reaches a minimum in the month of December.