Abstract: The objective of this study is to assess the capacity of water supply for
agricultural production and domestic use from Otuksa reservoir in Tinh Bien district, An
Giang province. CropWat model was used to calculate water demand for rice and other
crops according to three production models: model 1 (rice–peanut), model 2 (green bean–
rice), model 3 (green bean–green bean–corn) at present and in the future under three
climate change scenarios (RCP2.6, RCP4.5, and RCP8.5); thereby to assess the ability to
supply water from rain and reservoir for the study area. The results show that, at present
and in the future by 2040s, the water resources from rain and from the reservoir would
ensure water supply for all three production models. However, by 2060s, the reservoir will
not provide enough water for model 1 under the three climate change scenarios with total
water demand, respectively, of 411.4×103 m3, 399.6×103 m3, and 405.8×103 m3.
According to models 2 and 3, thanks to crop conversion, the water demand will be
reduced and the reservoir water would meet the demands. Next study needs to consider the
reservoir operation at each appropriate period in the dry and wet seasons, monthly or each
10-day period in order to optimize the use of water from the reservoir for different water
use purposes.
Keywords: CropWat; Water demand; Production models; Climate change scenarios;
Otuksa reservoir.