RIVER INTERLINKING IN DAKSHINA KANNADA AND UDUPI DISTRICTS OF COASTAL KARNATAKA — A CASE STUDYMohandas Chadaga, Udayashankar H.N., Ganesha A. and Gangandhar Bhat H.
Undivided Dakshina Kannada (DK) district of coastal Karnataka includes Udupi and now Dakshina Knnada (Mangalore) districts and comprises many west flowing river networks with 13 major rivers and hundreds of tributaries and rivulets. These river networks contribute the major share for irrigation and domestic water needs. Due to the increased urbanization and industrialization activities, a growing demand for water is observed in the recent years. Even though the region receives good amount of rainfall (about 3500mm to 4000mm per annum), a large quantity joins the sea as surface runoff due to steep slopes prevalent in the Western Ghats and lateritic terrain in other areas. There is saltwater ingression problem in the coastal region. Therefore, shortage of water during summer season is observed in many places. In this context, a project named "SOUBHAGYA SANJEEEVINI", for linking the rivers of undivided Dakshina Kannada has been proposed (Kum.iaprabha,12-11-2002). This study highlights the feasibility of such a project. The study area comprises rock types of different ages overlaid by Archeans such as Gneisses, Schist, Granites, Volcanogenic metasediments, Dykes, Quartzites, Laterites and Bauxites, Clay, Alluvium and Beach deposits. About 805 lineaments are traced with a length of lkin - 30km of which about 785 are minor and 57 major. Two main soil types observed are laterite and alluvial. Different landforms in the study area include Coastal, Fluvial and structural. Coastal plains, Spits, Estuaries, Bars, Beaches, Beach ridges, Mangroves etc. are the coastal landforms observable while Fluvial landforms include Alluvial Flood- plains, Point bars, Channel bars and River Terraces. Structural landforms comprise Duricrusts, Linear ridges, Mesas, Talus, Residual hills, Pediment slopes, Structural hills, Scarps, Valley fills, Pediplains etc. The different types of river channel patterns observed are Straight, Meandering and Braided. Rivers in the western ghat region are of "Young Flashy" type. Many areas in the Western ghat region are too slopy with elevation rising to 1300m or more within short distances. Thus Geology, Landforms, Soil characteristics and River morphology in the region are varying highly. Keeping in view all these factors, the rivers in the region can be interlinked through their tributaries and rivulets by running artificial channels wherever required, instead of one in North-South direction, at the foothill of Western Ghat. Check dams/barrages/ vented dams are to be constructed across the rivers to divert the water into the interlinking canals. Existing vented dams with some modifications can be made use along with the tanks and natural depressions (Madagas), as temporary reservoirs. The exact amount to be diverted can be estimated based on total water demand and also by considering other collateral factors. Degradation of the deciduous forests in the Western ghat may affect the hydro meteorological characteristics (Orographic Precipitation) of the region. New diversion canals may also pose problems like water logging, increase in the salinity on the downstream, increase in sea erosion in river mouths etc. Hence, it is advisable to divert partial flow trom the natural courses.
Enter your contact information below to receive full paper.