ASSESSING THE IMPACT OF LAND USE AND LAND COVER ON WATER QUALITY IN THE WATERSHED OF A RESERVOIR

Natural forest of Rio Tercero watershed (Argentina) was replaced by urban expansion and agricultural activities causing negative impacts in water quality of Rio Tercero reservoir. This paper classifies land use and land cover (LULC) in the watershed, trying to find a relationship with nutrient loads of the reservoir's tributaries. Each tributary was analysed during 2006 bimonthly for physico-chemical variables. LULC was determined using a Landsat 5 TM image. Statistical analyses were carried out to identify relationships between water quality and LULC. Results suggest that urban and agricultural activities are the primary driving forces behind the variations in nutrient loads measured in tributaries. Sub-watershed most affected by human activities displayed the highest values of nutrient loads. If agricultural and urban activities continue to increase, water quality at watershed scale will decline. It is recommended the development of a global approach management plan at a watershed scale.