Use of Remote Sensing Data in Evaluating the Extent of Anthropogenic Activities and their Impact on Lake Naivasha, Kenya

ABSTRACT

This study investigated the anthropogenic activities in Lake Naivasha Basin and how they are influencing the quality of water resources. The poor quality of water in the lake is seen from the presence of water hyacinth (Eichhornia crassipes) and is a reflection of nutrient rich waters. The water hyacinth in Lake Naivasha is associated with major negative economic and ecological impacts. The intensity of land use within the basin was mapped from multispectral Landsat satellite imagery of 1986 (TM) and 2000 (ETM) and SPOT imagery 10 m (resolution) of 2007. From interpreted data, the surface area of the Main Lake has decreased from 134.9 km2 in 1986 to 117.5 km2 in 2007 (12.9%); that of papyrus and wetland grasslands along the lake shore decreased from 54.6 km2 to 34.3 km2 (37.2%) and that of the horticultural and irrigated farms increased by 103.3% from 45.1 km2 to 91.7 km2 in the same period, placing great pressure on both the quality and quantity of the lake's water resources. Information obtained from the Fisheries Department in Lake Naivasha show that the fishery production declined from 513 to 110 tons in the period considered. The Naivasha Municipal Council records indicate a 30% decline in the water it supplies to Naivasha Town from 10,000 m3 to 7,000 m3 in the same period despite the increase in population. The decline was attributed to many factors among them the presence of water hyacinth and the decline in water quantity due to increased human activities.