Design and implementation of saltwater intrusion forewarning system in Pearl River Estuary based on WebGIS

In recent years, increasing marine intrusion into the Pearl River Estuary (PRE) of South China, poses a great threat to water supply of Pearl River Delta and causes drinking water problems of 15 million people. To reduce the influence of saltwater intrusion, engineering measures can be adopted, such as improving the water supply project and the management of water resources of valley. At the same time, it´s essential to adopt non-engineering measures, such as building an effective defense system. Therefore, according to the actual requirement of defense information system of saltwater intrusion in the Pearl River Delta, the paper introduces advanced computer technologies such as WebGIS (ArcIMS), spatial database, network and remote dynamic monitoring technology to build the basic system framework. Microsoft .Net 2003, ArcEngine 9.1, ArcGIS Server, and Microsoft SQL Server 2005 are adopted as system development platform and tools. Based on the real-time upriver river discharge, a saltwater intrusion forewarning system was built to provide decision support for saltwater intrusion defense. The modules in the system framework are as follows: the module for displaying homepage information, the module of basic information query, the module for monitoring real-time weather information, the module of saltwater intrusion forewarning analysis, the module for issuing saltwater intrusion warning, the system management module and so on. In the paper, we laid special stress on designing and implementing the module of saltwater intrusion forewarning analysis. In the module, there are numerical model of experience and remote sensing retrieval model of saltwater intrusion, which were developed in our previous study. And with remote sensing imagery data and real-time weather information obtained during dry season of PRE, magnitude and scope of saltwater intrusion of the Pearl River Estuary can be mapped based on the forewarning System. According to the trial operation and compared w- - ith corresponding measured data, it can be believed that the stability and accuracy of the forewarning system are better.