我国水资源时空分布不均，夏秋多，冬春少，东南多，西北少。水资源配置工程旨在平衡水资源分布不均的问题，有效解决城市经济发展的缺水矛盾。水资源配置工程取水口突发水污染事件会引发严重水体污染，破坏水体生态环境，影响受水区安全用水，破坏城市正常运行，影响社会和谐。珠江三角洲水资源配置工程建设的根本目的是促使东、西部水资源得到高效配置，具体来讲，从西江水系鲤鱼洲取水口向东引水至东部，以改善南沙区、深圳市等多地区供水不足的现状。工程鲤鱼洲取水口上游周边存在大量潜在风险源。若发生突发性水污染事件，将造成重大影响。

  为预防和应对珠江三角洲水资源配置工程取水口突发水污染事故，本文以取水口所在西江干流水道为研究对象，通过实地勘测和资料收集确定取水口周边潜在风险源。选用EFDC模型，基于研究区域的水文、气象、地形条件，构建西江干流水道水动力模型。使用率定验证后的模型，对取水口附近的河道流场进行分析。在水动力模型的基础上，构建NH₃-N模型、柴油模型及燃油模型。根据取水口周边风险源调查结果，设置多种突发水污染事故情景，并使用NH₃-N模型、柴油模型及燃油模型对突发水污染事故进行模拟。对模拟结果进行分析，探索研究污染物的迁移扩散规律。主要研究成果如下所示：

  （1）对珠江三角洲水资源配置工程取水口周边环境进行实地勘察与调研，识别其环境风险源，确定风险源主要包括工企业废水排放、石化生产及交通航运三大方面。

  （2）利用EFDC模型构建取水口所在西江干流河道的水动力模型，使用甘竹站水位数据对模型进行率定验证。2018年1月到12月的相对误差、绝对误差、均方根误差、纳什系数的平均值分别为0.069、0.059、0.089、0.936，模拟水位与实测水位之间的误差较小，水动力模型精度较高。

  （3）对取水口附近河道流场进行模拟分析可知，取水口上游河道水体流经鲤鱼洲岛后一分为二，分别进入左、右汊河道，右汊河道流速大于左汊河道。流场受水文条件和地形影响：大潮流速大于小潮，丰水期流速大于枯水期，丰水期大潮时流速最大；宽阔河道断面流速小于狭窄河道。风场对取水口所在河道的流场不产生影响，流场与无风时相同。

  （4）利用EFDC模型，在水动力模型的基础上构建NH₃-N模型、柴油模型及燃油模型。根据取水口周边风险源，设置多种突发水污染事件情景。使用NH₃-N模型、柴油模型及燃油模型对突发水污染事件情景进行模拟。模拟结果显示：

   ①不同突发水污染事故对取水口的影响有差异。取水口上游右岸突发NH₃-N污染事故、柴油污染事故，污染物均未经过取水口所在位置：NH₃-N被水体稀释后形成污染带沿着河道右岸流向下游，柴油则在浮在水体表面形成油膜顺着河道向下漂走；取水口上游左岸突发燃油污染事故污染物会影响到取水口，燃油将在河道表面形成油膜，油膜流经鲤鱼洲岛一分为二，一部分经过取水口所在左汊河道，另一部分进入右汊河道。

   ②污染物运移时中心浓度高，周围浓度低。污染物的整体影响范围丰水期比枯水期大，大潮比小潮大。

   ③流量对污染物的运移有重大影响。上游流量增大时，污染物向下游运移更迅速，污染物浓度衰减速度更快。与小潮时相比，大潮时污染物到达、离开同一位置的时间提前，影响时间减少，污染物浓度峰值减小，峰值出现时间提前；与枯水期相比，丰水期相应潮位时污染物到达、离开同一位置的时间提前，影响时间减少，污染物浓度峰值减小，峰值出现时间提前。

  China's water resources are unevenly distributed in space and time, with more in summer and autumn, less in winter and spring, more in the southeast, and less in the northwest. The purpose of the water resources allocation project is to balance the uneven distribution of water resources and effectively solve the contradiction between urban economic development and water shortage. Sudden water pollution incidents at the water intake will cause serious water pollution, destroy the ecological environment of the water body, affect the safe use of water in the water receiving area, disrupt the normal operation of the city, and affect social harmony. The construction of the the Zhujiang Delta Water Resources Allocation Engineering is to promote the efficient allocation of water resources in the east and west. It draws water from the intake of Liyuzhou in the Xijiang River to the east to improve the current situation of insufficient water supply in many areas such as Nansha District and Shenzhen City. There are a lot of potential risk sources around the upstream of the water intake. If sudden water pollution accidents occurs, it will have significant impacts.

  In order to prevent and respond to the sudden water pollution incidents at the water intake of the Zhujiang Delta Water Resources Allocation Engineering, this paper took the Xijiang main channel as the research object, and determined the potential risk sources around the water intake through field survey and data collection. Based on the hydrological, meteorological and topographic conditions, the EFDC model was selected to construct a hydrodynamic model of the Xijiang main channel. Use the model to analyze the channel flow field near the water intake. Based on the hydrodynamic model, the NH₃-N model, diesel model and fuel model were constructed. According to the investigation results of the risk sources around the water intake, various scenarios of sudden water pollution incidents were set. The NH₃-N model, diesel model and fuel model were used to simulate the scenarios of sudden water pollution. According to the simulation results, the migration and diffusion laws of pollutants are derived. The main research results are as follows:

  （1） Through on-site surveys around the water intake of the Zhujiang Delta Water Resources Allocation Engineering, it was determined that the risk sources mainly include industrial wastewater discharge, petrochemical production and transportation.

  （2） The EFDC was used to construct a hydrodynamic model of the main channel of the Xijiang River where the water intake was located. The water level data of Ganzhu Station was used to verify the model. The average values of relative error, absolute error, root mean square error, and Nash coefficient from January to December 2018 were 0.069, 0.059, 0.089, and 0.936, respectively. The error between the simulated water level and the measured water level was small. The hydrodynamic model has high accuracy.

  （3） By simulating the channel flow field, it can be seen that the water body upstream of the water intake is divided into two parts when passing through Liyuzhou Island, and enters the left and right river channels respectively. The flow velocity of the right river channel is greater than that of the left river channel. Due to hydrological conditions and topographical influences, the flow velocity of the spring tide was greater than that of the dry tide, the flow velocity of the wet season was greater than that of the dry season The spring tide velocity was the largest during the wet season. The velocity of the broad channel was smaller than that of the narrow channel. The wind had no effect on the flow field, and the flow field was the same as when there was no wind.

  （4） The NH₃-N model, diesel model and fuel model were constructed on the basis of the hydrodynamic model by using the EFDC model. According to the risk sources around the water intake, various scenarios of sudden water pollution incidents were set up. The NH₃-N model, diesel model and fuel model were used to simulate sudden water pollution scenarios. Simulation results show:

  ① Different sudden water pollution accidents had different impacts on water the intake. When the NH₃-N pollution accidents and diesel pollution accidents occurred on the right bank upstream of the water intake, the pollutants did not pass through the water intake location: NH₃-N is diluted by the water to form a pollution zone and flowed downstream along the right bank. Diesel oil floated down the river by forming an oil film on the surface of the water. Sudden fuel pollution accidents on the left bank upstream of the water intake pollutants would affect the water intake. The fuel would form an oil film on the surface of the river. The oil film flowed through Liyuzhou Island and divides into two parts. One part passed through the left river channel where the water intake is located, and the other part entered into the right river channel.

  ② When the pollutants were transported, the center concentration was lower than the surrounding concentration. The overall impact’s range of pollutants was greater in the wet season than in the dry season, and the high tide was greater than the small tide.

  ③ Flow had a significant impact on the movement of pollutants. When the flow of upper reaches increased, the pollutants moved to the downstream more rapidly, and the pollutant’s concentration declined faster. Compared with the neap tide’s, during the spring tide, the time of pollutants reaching and leaving the same place was advanced, the impact time was reduced, the concentration peak of the pollutant in the water intake was reduced, and the peak appeared earlier. Compared with the dry season, during the wet season, the time of pollutants reaching and leaving the same place was advanced, the impact time was reduced, the concentration peak of the pollutant in the water intake was reduced, and the peak appeared earlier.

   ④ The impact of the wind field on different pollutants was different, and it was less than the flow. With the wind field conditions, the simulation results of sudden NH₃-N pollution accident was the same as when there was no wind. The oil trajectories of sudden diesel pollution accident and sudden fuel pollution accident were the same as when there was no wind, but the peak thickness was reduced.