A Conceptual Model for the lower reach of Yellow River

Mr. Cheng Peng

Abstract

Nowadays, due to the climate change, urban development and other human interventions, flood is still a major challenge to humanity. Yellow River is the second longest river in China. Yellow River basin has massive economic significance for the development of the country. Many structural works for protecting city from flood had been built along the downstream of Yellow River for many years. But flood forecasting is still one of the main work points of Yellow River Conservancy Commission all the time especially in the section between Xiaolangdi and GaoCun of Yellow River due to its’many problems, for example, ‘suspended river, wandering river course, flood control, and densely population on flood plain’. The concern of the present research is to use non-structural method— conceptual model developed by Prof.R.K.Price for flood forecasting in this section.

The basic flood routing equation is an approximation of the Saint Venant equations. This equation includes the lateral inflow (or outflow). The equation implies that flood wave propagation through an open channel is a function of the discharge (Q) and two key parameters namely kinematic wave speed (c0) and attenuation parameter (a0) that are themselves functions of Q alone. The main objectives of this study were to find optimum channel dimensions, get parameterised functional forms for the kinematic wave speed and the attenuation parameter using optimisation techniques together with the calculation of a uniformly distributed time dependent lateral inflow along the reach, then obtain the predicted downstream discharge. Optimization was done by GLOBE

software, and minimizing the root mean square error between the calculated downstream discharge and measured downstream discharge. This is done in the case of knowing both the downstream as well as the upstream discharges time series. By this research, it can be seen that the flood-forecasting model can reflect complicated and non-linear dynamic routing rules of flood. The results show that this conceptual model can represent the rules of flood routing, real-time monitoring and forecasting of flood, high precision forecasting.

Keywords: Yellow River, lower reach, flood-forecasting, flood routing, Kinematic wave speed, attenuation parameter, lateral inflow, predicted discharge