Water loss due to evaporation from open reservoirs under weather conditions in Vietnam

摘要

Water reservoirs play a significant role in agricultural irrigation systems in Vietnam. It is necessary to quantify and monitor the water storage levels in reservoirs on a timely basis in order to properly forecast the water supply for the local agriculture. For this reason, the amount of water loss due to evaporation at the open surface should be properly quantified. This study evaluated different evaporation models in the literature using published experimental data to select an appropriate model for calculating the evaporation rate at the free water surface under the local weather conditions in Da Nang city and Quang Nam province of Vietnam. Water loss calculations were made for a number of major reservoirs in these two regions, which are located in a tropical monsoon climate region of Vietnam. The results show that water loss for a typical dry day is 11.31 mm/day, whereas it is 6.82 mm/day for a typical rainy day. Estimations of the water loss per day calculated for different reservoirs that may be useful for the agricultural irrigation system management board. The results reported in this study may also benefit the future designs of the irrigation reservoirs.