ASSESSMENT OF CLIMATE-CHANGE IMPACTS ON THE WATER-RESOURCES OF PANAMA- THE CASE OF THE LA VILLA, CHIRIQUI AND CHAGRES RIVER BASINS

The goal of this study is to develop different scenarios of water reso urce availability in Panama under climate change-induced temperature a nd precipitation variability, considering a potential doubling of the atmospheric CO2 concentration in the next 100 yr. The water balance mo del CLIRUN3 was combined with 20 yr of basic climate information recor ds (precipitation, potential evapotranspiration and water flow) to sim ulate monthly river runoff in the Chagres (Panama Canal) river basin. This basin supplies water to 25% of the country's population and is of great importance for international navigation. In the cases of the Ch iriqui and La Villa river basins, 10 yr of records were used. The Chir iqui river basin is the main national source of hydropower, while the La Villa river basin is of agricultural importance. The Chagres river basin is part of the Atlantic watershed while the others belong to the Pacific watershed. The model was calibrated and run for both watershe ds under scenarios with temperature increments of +1 and +2 degrees C, while the precipitation changes considered were +/-15% for the Pacifi c and +/-20% for the Atlantic watershed. It was observed that the mont hly runoff tends to decrease by 3 to 42% of the mean value in both wat ersheds when temperature increases and precipitation decreases. If bot h temperature and precipitation increase, the mean runoff value in the Pacific basins will be reduced by 5 to 35% from November to April and increased by 4 to 40% in the remaining months. In the basin of the At lantic watershed all simulated monthly values are 3 to 50% higher than the actual mean.