Morphometric and Physico-Chemical Characterization of the Weija Reservoir: Implications for Water Resource Management at the Catchment Scale
dc.contributor.author | Eli, A-H.C. | |
dc.date.accessioned | 2025-02-04T11:21:55Z | |
dc.date.issued | 2023 | |
dc.description | MPhil. Environmental Science | |
dc.description.abstract | The Weija Reservoir, one of Ghana's water resources has been increasingly threatened by pollution in recent years as a result of fast population changes that have coincided with the formation of human settlements. In recent years, activities like as irrigation, nutrient pollution, sand mining, and encroachment on the Reservoir and along its boundary have had major impacts on the Reservoir, causing shortage in water supply. The aim of the study was to combine GIS and measurements of physico-chemical variables along a depth profile to map out the bathymetry and to model nutrient level in the Reservoir. Per that, a 3D (DEM) model of the Reservoir was constructed. Measurements were taken at a total of twenty-five thousand, two hundred and eleven data points with their corresponding coordinates and depths were recorded and processed using ArcGIS to obtain the current surface area and water holding capacity of the Reservoir of 19,330,988.38m2 (19.33km2 ) and 96,900,899.14m3 respectively. In order to assess the temperature variation and dissolved oxygen (DO) distribution along a depth profile, water and sediment samples for physicochemical analysis were obtained from the six sampling points. An echo sounder was then used to determine the depths at which the samples were taken and with a water depth sampler, the samples were taken along the depth profile at 1m intervals till the bottom of the Reservoir was reached. Measurements were taken along the depth profile in order to have a proper representation of the Reservoir. The physico-chemical parameters and nutrient in the samples were determined. A steady decrease in temperature was observed with increasing depth but analysis of variance (ANOVA) indicated that there was no significance in temperature with respect to depth. There was decrease in DO level along the depth profile and ANOVA showed that there was significant difference in DO distribution along the depth profile. This indicated that, the least change in temperature along the depth profile can cause a drastic change in DO which will lead to the thermocline effect. Total phosphorus, chlorophyll a content and Secchi depth were measured from the Reservoir and with the use of Carlson’s Trophic State Index, the TSI for total phosphorus, chlorophyll a and Secchi depth was calculated. Average TSI (TP) was 79.33 making the Reservoir eutrophic. It was also observed that TSI (TP) = TSI (SD) > TSI (CHL) with TSI (SD) having an average value of 68.61 over the study period and TSI (CHL) having an average value of 38.29. This relationship indicates that, the Reservoir is eutrophic as result of heavy siltation rather than phytoplankton abundance. The Utermöhl method for analysis was adopted in this study for analyzing the phytoplankton samples collected. Five (5) Classes were identified and the order of dominance was; Chlorophyceae (green algae) > Bacillariophyceae (diatoms) > Cyanophyceae (blue-green algae) > Euglenophyceae (euglenoids) > Dinophyceae (dinoflagellates). The Chlorophyceae were the most prevalent class (40.38%). Bacillariophyceae (30.77%), Cyanophyceae (23.08%), Euglenophyceae (3.85%), and Dinophyceae (1.92%) followed in declining order of abundance. These findings provide insight on the extent of anthropogenic contamination in the Reservoir and how it affects the distribution and treatment of water as the Reservoir provides water to the populace | |
dc.identifier.uri | https://ugspace.ug.edu.gh/handle/123456789/42791 | |
dc.language.iso | en | |
dc.publisher | University of Ghana | |
dc.subject | Digital Elevation Model | |
dc.subject | Thermocline Effect | |
dc.subject | Trophic State Index | |
dc.title | Morphometric and Physico-Chemical Characterization of the Weija Reservoir: Implications for Water Resource Management at the Catchment Scale | |
dc.type | Thesis |