THE LIMNOGEOLOGY OF THE LAKES SAGARA AND NYAMAGOMA

Abstract

The present study focuses on the limnogeological aspects of the lakes Sagara and Nyamagoma within the MalagarasiWetland Ecosystem. Abiotic parameters from water and sediment samples were determined during the dry and wetseasons using appropriate gears and methods. The data show variation of the abiotic parameters in both lakes from thewater surface to the bottom. Lake Nyamagoma is less turbid (0.7-24 NTU) than Lake Sagara (25 to 65 NTU). The watertransparency was also high at Lake Nyamagoma (0.75-1.5 m) thus supporting the observed turbidity trend. The physicalchemical changes may be attributed to processes such as cooling, dissociation, dissolution, decomposition, adsorption,precipitation, cation exchange and photosynthesis. However, higher nutrient concentration was observed in the wetseason than dry season with the exception of SiO 2 consequent to dilution effect by surface runoff. The mineralogicalcontent (Kaolinite, Smectite, Illite and Quartz) of the lake sediments indicate existence of good drainage conditions at thelakes as supported by the geology of the area. It is recommended that a long-term limnogeological monitoring andevaluation be conducted so as to understand future nutrient hydrodynamics and hydrological functioning of the wetlandecosystem.