An Environmental System Analysis of Lake Elementaita, Kenya With Reference To Water Quality

Abstract

Lake Elcmentaila, located in the Rift Valley of Kenya is a shallow hyper saline lake, with a mean depth of 0.7 meters and has a fluctuating lake area of betwccn of 15 to 22 km2.The major phytoplankton species is the cyanobacterium 'Spirulina' Arlhrosporia fusiform;s. which is the only food source of lhe lesser flamingo, Phoeniconiconaias minor. Lake Elcmclllaita is hypertrophic with total phosphorus valu.:s ofO.9mg r l and IOlal nilrogen values of 22mg rl.The main sources of inflow are riwrs M.:reroni, Mbaruk and Kariandusi: as well as fresh water and ,aline hot springs, located in the southcm part of the lake. The objective of this study was to find out tbe effect of the hot springs on the lake water chemistry as well as to establish the source of the nUlriems. TIle Generalized Watershed Loading Function (GWLF) model was applied to simulate nutriem transport proccsses in lhe watershed. GWLF model estimates nutricnt loads in strcam flow as wcll aspoint sources. The hot springs wcre imrodueed in tile model as poiru sources. Results indicate that the hot springs arc an imporlanl source of dissolved phosphorus in the lake. The hot springs arc f.:d by fracture flow along faults running on the rift valley 1100r. Spalial varialion of waler qualily was slooit-d as well. The spatial variation of elt>(;lrieal conductivity gave a good indication of the water quality variation. This variation is influenced by winds, springs and surfilce waler inflow (dilution effects). The hydrological link betwcen lakes Elcm~ntaila and Naivasha may explain the source of dissolved phosphorus. The waler type of Lake Naivasha groundwater and rivers Mercroni and Kariandusi was found to be similar. This is due to the similar rock types in the area. This consists of Basalts. Trachytes and Rhyolites.