Reservoir management model for water supply to rice fields in a context of integrated water resource management - case study: the Nui Coc lake-reservoir in Vietnam
For several years, Vietnam has been recognized in Asia as one of the largest rice exporting countries in the world. This result was made possible through various programs of the Vietnamese government. One of these programs was to invest in irrigation hydraulic infrastructures to develop rice production. Today, several hydraulic infrastructures are built on the catchment of the Cau River and are exploited for several purposes. They serve, among others, industrial and domestic water supply, hydroelectric production, irrigation of rice fields and protection against floods. It is therefore necessary to define rules for the management and operation of these structures in order to satisfy all water needs, especially in the context of integrated water resources management at the watershed scale. The objective of this paper is to model the evolution of the water volumes of a reservoir and to propose a method for managing a reservoir used for several purposes, including irrigation of rice fields. A special case is presented for the Nui Coc lake-reservoir in Vietnam. As part of an integrated water resource management project for the Cau River watershed, on which the Nui Coc reservoir is located, the Hydrotel model was used for hydrological simulations. However, this model did not have a reservoir management sub-model suitable for irrigating rice fields and taking into account various types of water requirements. It was therefore necessary to develop a sub-model including two modules and to adapt it to the problem of irrigation of rice fields from Lake Nui Coc. This sub-model allowed reproducing, with the Hydrotel model modified, the historical variation of the volume of water in Lake Nui Coc then to evaluate the possibilities of expansion of the rice fields.