Consequence assessment of the La Giang dike breach in the Ca River system, Vietnam

Abstract

Ca River is one of the largest rivers in Vietnam. The river provides water, electricity, and navigation for millions of people living along the banks. Besides these great benefits, the river also poses many potential risks for people. In the case of flooding, this river can cause terrible damage, especially in the case of dike breach. Therefore, this article, by combining a field survey and mathematical simulation, has been conducted to present the results of the dike breach for the La Giang dike of Ca river, in Ha Tinh province, Vietnam. Via the field survey, potential dike breach locations were specifically identified, which helps minimize the number of calculation scenarios. The mathematical model was calibrated and validated with large floods in the area. The results from the mathematical model show that the model is consistent with the observation data, with the Nash index at good to very good levels. Based on the data, a series of simulations was performed to assess the dike breach consequences. In each case, the study provided details on the inundation area, the number of affected residents and the length of flooded road for each inundation level by administrative unit. Based on the calculated results, the degree and scope of consequence varied depending on the locations of the dike breach. The results of the study are the foundation for the building of a local database of flood and storm control. This is very useful information for the decision-makers to establish different response plans for different emergency cases.