Estimation and modeling the surface flow system for irrigation regions

In recent years, the domestic and industrial water demand have got uptrend gradually because of social and economical environment change and the promotion of living standard. Some of the water has always been transferred from agricultural sector to the domestic and industrial sector when facing deficits. Therefore, how to find reliable alternative water resource in current situation will be one of the most urgent issues need to be solved. In this study, a surface flow system-dynamic model that based on water balance was developed to estimate the quantity of the components of flow. The study areawas divided into five categories in accordance with land-use, and considered simultaneously hydrological, meteorological, geology environment factors and crop water requirement in model. Furthermore, the amount and feature of agricultural return flow and how much return flow could be transferred stably to other usage sector in different exceeding probability were discussed. Simulation results show a good agreement between observation and simulated value, and reveals agricultural return flow was the major component in river discharge. The reliable diversions were calculated as: 12,582 CMD, 3,852 CMD, and 38,611 CMD in Sin-Wu stream, Guan-Yin stream, and Da-Ku stream respectively, in 2^nd farming period of 2006, given Q₈₀ exceeding probability of river flow and 50% irrigation water was cut off.