38-Growing problem of sedimentation and weeds in reservoirs of irrigation projects in Non Ghat area of Maharashtra

Abstract

Reduced vegetal cover on account of deforestation, rapid urbanization, and developmental activities in the catchment area, faulty agricultural practices etc contribute to rapid erosion of the land in the catchments of reservoirs. The soil erosion in the catchment accelerates the process of sedimentation in reservoirs which poses threat to their useful capacity by rapidly eating away the storage potential created behind the dams. In India every year about 5334 M Tonnes of soil (about 16.35 tlha) is eroded annually out of which about 10 % gets deposited in the reservoirs causing reduction in their storage capacity by 1% to 2% annually. Reduced storage in the reservoir on one side and increased demand for non irrigation use on other side puts the management authorities on edge in making equitable distribution of water. In addition to this, there is an emerging problem of growth of semi aquatic weeds like 1pomoea Carnea (Local name -Morning Glory, Besharam, Behaya etc) in the submergence area of the reservoirs. The most common location for growth of such weeds is the peripheral area of the reservoirs. The growth of such Besharam shrubs is widely observed in many reservoirs in the non Ghat areas of the State, especially in the reservoirs in the Deccan plateau where the topography is flat. Such vegetation grows and spreads profusely forming colonies over long stretches in the reservoir submergence area. Growth of such weeds reduces the storage capacity of reservoirs by trapping the silt, develops marshy areas which create favorable environment for mosquitoes causing spread of disease like Malaria in the nearby places. It also reduces the aesthetic value of the reservoir and also creates bad impact on fisheries development. Regular monitoring of reservoirs for assessing their capacity, preventing growth of such noxious weeds and marshy areas needs to be done. Major reservoirs like Ujjani in Solapur district, Jayakwadi in Aurangabad district, Manjara in Beed district, Lower Terna in Osmanabad district, (in South Maharashtra and Marathwada region), Hatnur in Jalgaon district, Nandur Madhyameshwar in Nashik district, (North Maharashtra) are affected by sedimentation and growth of the semi aquatic weeds like ipomoea carnea i.e. Besharam shrubs. The reservoirs viz. Lower Pus, Arunavati in Yavatmal district, Lower Wunna (Vadgaon and Nand reservoirs), Jam reservoir in Nagpur district, which are less than 15 years of age are also invaded to some extent by growth of such weeds especially near the peripheral shallow water area at the tail and banks,. The above list is just a representative one.