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International Institute for Geo-Information Science and Earth Observation (ITC) 2003

Solute balance modeling of Lake Naivasha, Kenya : application of DMS

Chaweepan Suangkiattikun

Titre : Solute balance modeling of Lake Naivasha, Kenya : application of DMS

Auteur : Chaweepan Suangkiattikun

Etablissement de soutenance : University of Twente International Institute for Geo-Information Science and Earth Observation (ITC)

Grade : Master of Science in Geo-Information Science and Earth Observation 2003

Résumé
The spatial and temporal variation and control of water quality of lake Naivasha is of high interest be- cause the lake body represents the main fresh water resource of economic and environmental importance in the region. In order to study its solute behviour and to be able to predict the impact of water inflows, outflows and abstraction on the lake water quality, a simple dynamic water quality model was built using DMS 1 . The model was designed using a simple conceptual mass balance structure in both quantity and quality constituents. Historical time series of lake levels, river inflows, meteorological data and solute (electrical conductivity) observations, were used to calibrate the modelling system. The lake water balance could be simulated at a monthly time interval with 92% prediction efficiency. The solute balance based on a non-conservative substance concept concerning internal processes of sediment exchange gave a good fit to the observed values. The solute behaviour was further evaluated using different scenarios of man-made water abstractions of the lake. During the field survey campaign, the number of water samples required to monitor water quality of Naivasha lake (e.g. approx. 120 km 2 surface area), was also determined using a spatial sampling de- sign, optimised using simulated annealing, and sub sequent own laboratory analysis and statistical interpretation. Depending on the water quality variable , from 6 to 30 sample points are required for basic parameters to obtain a sound picture of the distribution of the constituent in the lake.

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Page publiée le 4 février 2018