A System Dynamics Model to Improve Water Resources Allocation in the Conchos River

The Conchos river located in Chihuahua state on a semiarid region is the most important Mexican river contributing water deliveries to USA as established by the Water treaty of 1944 signed between Mexico and USA. Historically, Mexico has delivered to UNITED STATES 550 Hm3 (445,549.5 ACF) per year of water since the treaty was established, which is 25% above the yearly water volume Mexico is required to deliver. The Conchos river has contributed with 54% of the historic Mexican water treaty deliveries to the UNITED STATES, which represents the highest percentage of the 6 Mexican rivers considered on the water treaty. However, during drought situations the basin has proven to be vulnerable, for instance, because of the severe drought of the 90's, several cities in 1992 on Chihuahua state where declared disaster areas, and from 1992 to 2001 Mexico had accumulated a water treaty deficit of 2111.6 Hm3 (1,710,586 ACF). This has conduced to economic, social, and political difficulties in both countries. Because of the cited problematic and considering the poor understanding of the relationship between water supply and demand factors on the basin, a decision support system (DSS) has been developed aimed to improve the decision making process related with the water resources allocation process. This DSS has been created using System Dynamics (SD). It is a semi-distributed model and is running on monthly time step basis. For both the short and long term, three important water resources management strategies have been evaluated: several water allocation policies from reservoirs to water users; bulk water rights transfers inside and outside Irrigation Districts; and improvement of water distribution efficiencies. The model results have provided very useful regard to gain more quantitative understanding of the different strategies being implemented. They have also indicated that the different water resources alternatives change its degree of importance according to the different basin's circumstances such as weather conditions, institutional constraints, etc. The DSS is intended to be a simulation tool that facilitates the education and involvement of stakeholders and decision makers on the basin's water resources management process. Consequently, this will help to identify and to support alternatives or combination of them aimed to improve not only the basin's economy but also Mexican water treaty deliveries.