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IMPACT OF LAND USE LAND COVER WITHIN A MICRO WATERSHED ON WELL WATER QUALITY

The linkages between LULC and water quality in wells are not known. This makes it difficult to control and manage quality of such water sources. Hence, linkage information is required to help the concerned authorities solve and manage water quality at source level.The overall aimof the study was to analyze the effects of the different LULC types within micro watersheds on well water quality. Specifically, the study involved determining pH, EC and TUR of water, mapping the different LULC types within micro watersheds, and determining the linkages between LULC and water quality. 15 purposely sampled wells that had data (pH, EC, TUR) from NWSC were used. Satellite images were acquired from google earth pro, downloaded using smart GIS and imported into ArcGIS 10.3.1 for classification. Unsupervised classification (20 classes) was carried out and then reclassified into 4-5 classes. WQI was obtained by determining the antilog of the product of the weightage factor and quality rating of the parameters. LCI was a ratio of area covered by a given LULCto the total area in the buffer multiplied by the pollution index. SI was obtained by summing 75% of the WQI and 25% of the LCI. Mean and standard deviation for each of the parameters were calculated in Microsoft excel to provide for the statistical analysis. Mean pH was 5.73 with a STDev of 0.39. Mean EC was 291 μS/cm with a STDev of 98.64 μS/cm. Mean TUR was 40.84 NTU with a STDev of 35.66 NTU. Mean WQI was 33.72 with a STDev of 11.21. Cropland had a LCI of 1.68,bare land (0.93), forest (0.4), water (0.29) andbuilt-up (0.13). Mean SI was 18.82.All the wells were acidic in terms of pH and the TUR couldn’t meet both the WHO and UNBS standards while the EC met both standards. This means the water was acidic and turbid. The micro watersheds were mainly covered by cropland and bare land (>70%). 75% of the wells were rated moderate topoor due to the high WQI (>25). Cropland contributed 48.87% to poor quality due to the high LCI (1.68). However, bare land contributed 27.21%, forest–11.68%, swamp-8.39%, built-up-3.79% to poor quality.The low SI (<20) showed that most wells weren’t suitable for consumption.Nevertheless, integrated remote sensing and groundwater quality gave a precise explanation for the influence of LULC on groundwater quality. Alternative LULC patterns for buffers that had low SI was recommendedin order to mitigate poor water quality at source level.In addition, there should also be routine programs for catchment management andcommunity education. Keywords: Water quality index, Land cover index, Suitability index, LULC, Linkages

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Author: aboth jackline
Contributed by: asbat digital library
Institution: makerere university
Level: university
Sublevel: under-graduate
Type: dissertations