Design And Verification Of Automatic Saltwater Intrusion Forecasting System In Changjiang Estuary

Saltwater intrusion is ubiquitous phenomenon in estuaries. The development and utilization of fresh water in Changjiang Estuary is interference by saltwater intrusion. So how to establish a real-time automatic forecasting system of saltwater intrusion in Changjiang Estuary is very important. The prediction of salinity of Changjiang Estuary, especially water head site in South Branch has much practical value and scientific significance.First, this paper introduces the triple nested WRF model in Changjiang Estuary. We have verificated the model calculated wind speed with the measured wind speed of Dajishan, Shengshan, Sheshan and Tanhudao during July 2005,November 2005 and May 2006.The validation results show that the WRF model is reliable. Then we collected the latest nautical chart of Changjiang Estuary from Marine Navigation Guarantee Department and calibrated the depth data. Based on the original Changjiang-FVCOM model, we encrypted the grid of South Branch and North Branch according to the depth data, so that the distribution of salinity in South Branch can be described finely. We use the k-s model to calculate vertical mixing instead of MY2.5 model. The results show that the k-s model is more suitable in brackish mixed lot in Changjiang Estuary. Besides the original 8 major constituents, we added 5 shallow water constituents in the open boundary. Then we verificated the water level, the velocity and the salinity to prove that the Changjiang-FVCOM model is reliable.Then we established an automatic saltwater intrusion forecasting system of Changjiang Estuary by combining the well-verificated WRF model and Changjiang-FVCOM model. The forecasting system updates the amount of runoff in Datong, and downloads the boundary conditions for WRF model. The WRF model can calculate the wind speed of next three days accurately, so the forecasting system can better forcast the salinity in Changjiang Estuary for the next three days. The forecasting system downloads the forcing data, runs the WRF and FVCOM model, visualizes prediction results and publishes the results. All the above operations are automatically processed by computer. Lt is convenient to view the output pictures to know the situation of saltwater intrusion. The forecasting system has been installed and tested in National Marine Enviromental Forecasting Center. Then, we hind-casted several saltwater instrusion events during dry season from 2010 to 2012 through the measured data in Baozhen. The results is well. Finally, we runned the forecasting system at January 23,2011 and February 10,2014 to inspect the system. The results of January 23,2011 show that the salinity in South Branch can be well predicted, and the accuracy of salinity in North Branch needs to be improved. We speculate that the transport of high salinity seawater to the shore is mainly through North Channel to South Branch from the results of February 10,2014.