Flood management in the lower reach of the Yellow River

Abstract

Due to a combination of factors the risk of flooding is increasing significantly in the lower Yellow River. Moreover more and more people settle in the flood plains and the areas prone to flooding. The risk of a large number of casualties becomes serious and the potential damage is high. The Yellow River Conservancy Commission (YRCC) decided to construct the Xiaolangdi dam to face the flood control problems. The Netherlands also faces flood control problems and had to search for new measures to guarantee the safety of the people living in the flood prone areas. The possibility of learning of the Room for the River policy in order to improve the flood control of the lower Yellow River is investigated in this study. The study is carried out in co-operation with the YRCC, within the framework of a project between a number of research institutes and universities in China and the Netherlands. The necessary data of the study are supplied by the YRCC. The data analysis was carried out in China during the summer of 2001, whereas the modelling work and the evaluation of the measures have been carried out in the Netherlands. For the evaluation of measures it is necessary to analyse their impact to the water levels, discharges as well as the morphology of the river. For this purpose an one-dimensional model for the lower Yellow River has been set-up, based on the 1D modelling software package SOBEK of WLDelft Hydraulics. The model simulates the flow, sediment transport and morphological development from Tiexie to Gaocun, a reach of 300 km of the lower Yellow River. The definition of preferable measures to improve the flood control in the lower Yellow River is based on the Dutch Room for the River policy. Before the measures are defined the base case is analysed and the possibility to adapt the Room for the River policy for the lower Yellow River is investigated. The criteria to figure out the usefulness of a measure are the influence of the measure on the water motion and the morphological response of the river. There are differences in the effect between the measures, but all have in common that they lower the water level during a flood with respect to the base case. Based on the results of the evaluation of the measures four strategies have been developed by combining the various measures. All the strategies met the most important objective, i.e. to improve the safety of the lower Yellow River. The strategies show that there are a lot of possibilities to improve flood control. The screening of the impact of the strategies have put forward that one of the bottlenecks for the implementation is the number of people living on the flood plains and in the detention basin. Due to the limited scope of the present study and restrictions of data availability and the reliability of the used model, the results of the study should be considered as indicative, rather than quantitative. Nevertheless the study has shown that the conceptual approach as applied in the Netherlands for the flood control of rivers, can certainly be useful for the flood control of the lower Yellow River.