Abstract Flood disasters frequently occur in the flat river network region of eastern China. The current flood risk management concentrates only on the analysis of water quantity, and lacks in water quality investigations. In this study, the MIKE11 NAM module was used for the simulation of the rainfall-runoff processes, the MIKE11 HD module was used to simulate the hydrodynamic processes, and then the MIKE11 AD module was used to simulate the water quality processes. The coupled model was adequately calibrated using observed data, and then applied to simulate the processes of flood and water quality under four different rainfall conditions. The results indicate that rainfall has a significant influence on flood and water quality in a flat tidal river network, which can provide some assistance for flood and water quality management. Introduction Flood disasters frequently occur in the flat river network area of eastern China. Abundant rainfall, flat terrain and fertile soil bring about a lot of agglomeration of cultivated land, large population and a lot of industries in this region (Xu, 2012). In combination with global climate change and rapid economic development in recent years, rainstorm and flood have caused complicated and changing hydrological characteristics in the flat river network areas (Han, 2014). Meanwhile, the problem of water environment is increasingly serious. In response to these concerns, new demands for flood forecasting and water resources management should be taken into consideration. Nowadays, hydrodynamic and water quality characteristics of the flat river network area are studied by mathematical models. Some hydrodynamic models of Shanghai in China were established by the MIKE11 modeling system, however, the model couldn't be applied to flood forecasting without a rainfall-runoff model (Xu, 2003; Yan, 2007). Using the same numerical software, a detailed model of the Rideau Valley Watershed was constructed, and is being used for various purposes of watershed management (Ahmed, 2010). More than that, the water environmental mathematic model of Pinghu city in China provided an effective method to simulate the effect of reducing pollution load on water quality (Qian, 2013; Yin, 2011). The above indicates that appropriate numerical models have positive practical performance of flood forecasting and controlling river pollution. In this paper, a coupled hydrodynamic and water quality model was constructed using the MIKE 11 modeling system, and then four cases were used to simulate the process of flood and water quality in the Hangjiahu (HJH) region.

Abstract Jiaxing area as a typical plain tidal river network area, is threatened by flood. And to the flood processes, downstream tide is one of the three major influencing factors. Hence, in order to investigate the influence of downstream tide on the flood processes, a coupled hydrologic and hydrodynamic model is established. And different flood processes under four different tidal processes are calculated in this model. Through comparing the different water level change processes, the relationship between flood processes and downstream tide is summarized. Finally, some relevant suggestions on Jiaxing flood control and drainage planning are put forward.

ABSTRACT: In order to meet the demand of local economic development, Fujian Province will implement a shipyard project in Min River Estuary recently. During the shipyard construction period, in Min River Estuary the potential oil spill risk will greatly increase. Based on a 2-D hydrodynamic model of Min River Estuary, an oil spill numerical model by using MIKE is developed, taking into account the variables of wind, the spilling position and the occurrence moment. The results show that the sweeping range and the trajectory of the spilled oil are closely related to the spilling position and the wind condition. 1.Introduction The rapid development of economy makes energy demand grow intensely, which promotes oil exploration industry and the seagoing oil transportation, at the same time also increases the potential risk of the oil spill accident. A major oil spill can contaminate the shoreline, cause long-term damage to the aquatic environment for fishery and wild-life. When the liquid oil is spilled on the surface of the sea it spreads, forming a thin film, the so-called oil slick. Under surface wave action and upper layer turbulence, a coherent oil slick will break up into small particles. The oil particles move horizontally on the surface owing to current, wind-induced surface speed, wave drift and horizontal diffusion. Because of sea-surface agitation, some particles entrain and diffuse in the water column. Once in the water column, the entrained droplets move in the three spatial directions. Vertical displacements are due to buoyancy and turbulent diffusion (Wang and Shen, 2010). Oil spill model is the core part of the oil spill emergency response system, which can predict the change of oil composition, property, stage and fate of the spilled oil and provide scientific information for decision-making such as choosing the proper cleaning method and evaluating the damage.