Namibian Land Use Changes and Nutrient Water Quality of the Okavango River
Andrea Vushe, Erasmus Panduleni Haimene, Damas Mashauri

Over the past twenty years, the Kavango Region in Namibia has experienced a ninety percent population increase, land use change from forests and grasslands into settlements and agricultural lands, which included increased irrigated commercial farming activities along the Okavango River. These human activities were expected to cause some impact on the water quality of Okavango River. Landsat TM images for years 1990 and 2011 were classified using unsupervised classification process to determine the changes in land use. Water quality parameters measured for three months at six sampling points along the river, and climatic data was obtained. Eleven percent land use change from shrub and grasslands into settlements and agricultural lands was observed. Irrigated area increased by over hundred percent and area under forest, shrubs and grass have decreased by over eleven percent between 1990 and 2011. Linear regression was used to analyse correlation between reach length and water nutrient concentration. A high negative correlation between nutrient load and reach length indicated that the reach was attenuating the inflow nutrient load. Analysis of variance showed statistically significant differences in oxidized nitrogen levels between 1993 and 2012, but there were no statistically significant differences in total phosphorus and total nitrogen during the same period. The study showed that the land use changes in the Kavango Region had low impact on the water quality of the Okavango River.

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