WATER RESOURCES DEVELOPMENT PLANNING UNDER SURFACE WATER AND GROUNDWATER INTERACTION ASSESSMENT IN CON SON VALLEY, CON DAO ISLAND, BA RIA-VUNG TAU PROVINCE, VIETNAM

Abstract

According to the topography, Con Dao Island is considered one of the best tourist area but isolate lands, thus surface water is limited and difficult to be collected properly and it is also very costly to gain support from continent. Therefore, groundwater is the key strategic resources on the island. Along with economic development and population, the demand for groundwater extraction is growing rapidly and gradually affects the land to become drought. In order to satisfy the future demand of water, the evaluation and planning of groundwater is extremely urgent in the present time. From the imperative reasons above, the study on groundwater balance to satisfy for future demand is conducted. The objectives are to assess the interaction between surface water and groundwater, to assess groundwater capability in Con Son valley, as well as to recommend suitable water resources development plan for the future water demand of the island from 2013-2020. This study is divided into three parts: surface water simulation by HEC-HMS, groundwater simulation by Groundwater Modeling System (GMS) with the analysis of the interaction between groundwater and surface water, and water resources development planning under the considerations of construction cost, drawdown, salt water intrusion, and costs without development plan. The study showed the interaction analysis of surface water and groundwater helped to improve the groundwater simulation and groundwater capacity assessment. The study found that the safe yield of the existing pumping scheme is 3500 CM/day and to cope with the future demand of 6000 CM/day, the expansion of lake (no. 2) and additional 5 wells is the best choice for water resources development for the Con Dao Island.