Sediment dredging as a restoration tool in shallow tropical lakes: Cross analysis of three freshwater lakes of Udaipur, India

Abstract

The effects of massive sediment dredging on water quality, trophic status and on bottom sediment characteristics of three lakes of Udaipur (India) was studied for a period of five years. The lakes (Fateh Sagar, Baghdara and Udai Sagar) differ with respect to the nature and magnitude of anthropogenic perturbations. During dry periods (May-June, 2001; May-June, 2003; AprilJune, 2004), about 4,205.6 and 2,147.1 tons of bottom sediments were removed from Udai Sagar and Fateh Sagar respectively. During the course of study (from Year 2000 to 2004), N and P concentrations declined significantly both in sediment and in water column of Fateh Sagar and Udai Sagar. The declining nutrient concentration caused reduction in chlorophyll biomass (up to 41.4%) and primary productivity (up to 32.2%) reflecting a reversal of trophic status towards oligotrophy. A comparison with Baghdara further indicate that sediment removal have strong influence on water chemistry and trophic status of Fateh Sagar and Udai Sagar. We suggest that the sediment dredging which help reversing trophic status may be used as an effective tool for restoration of freshwater tropical shallow lakes.