Rain and groundwater as phosphorus sources of a small reservoir

At Broa hydroelectric reservoir 82% of phosphorus (P) input is from rivers, 12% from groundwater seepage input and 6% from direct rainfall. The reservoir retains 15% of incoming P, corresponding to 73 mg/m²/year sedimentation. Proportions of water input are 36% from groundwater seepage in the dry season and 68% from seepage and 3% from direct rainfall in the rainy season; the remainder comes from rivers. Average P concentration during the 1996 rainy season was 27 μg/L in rain, 6.1 in groundwater, 68.54 in rivers and 33.56 in outflow.