| The information service system for flood control in Jilin Province is to enable automatic inquiry about flood control information and real time monitoring of precipitation rainfall. With the system, which uses modern information technology to modernized flood control information system construction, we can get information about rains and water projects vividly and visually through various graphs and forms. It also enables us to share flood control information to the largest extent, thus ensuring the punctuality and accuracy of rainfall and flood information and improves the efficiency and function of flood control information service in Jilin Province. The flood control information service system that has three layers is based on Sybase 11.0 real time precipitation rainfall general database and SQL ERVER7.0 flood control projects database. It is built on the ArcMS geographic information system net and the one two hundred thousandth electronic map of Jilin Province. It is operated on local area net and provides inquiry and analysis service on information about rain, flood and water projects through the browser in the form of WEB service. The paper introduces the further developments of ARCIMS by using VB with COM technology. I, the writer of the paper, has taken part in the project and designed and developed functional modules like the ones used to put in maps and the one to mark the points. Besides, I have also selected a Algorithm dealing with rainfall Contour and designed WebGIS processing models. The further development has reduced repeated uses of codes and decreased the difficulty of professional development and make it more suitable to be used in irrigation works and water conservancy. The achievements our work has made are as follows:It has developed a interface lab to supplement ARCIMS functions., most important of all, it helps solve the difficult problem that ARCIMS fails to in point marking. Before the further development, pictures in ARCIMS are read-only files, no marks and notes can be added to them. With the improvement we have made on it, flood control information such as real time precipitation rainfall, real time water level of a reservoir and its capacity, real time flux of a watercourse and so on can be added to a map. Under our newly developed TopArc, first, the browser issues a command for an inquiry or an analysis. Then we put out those maps that do not need any notation directly. If notation is needed, TopARC will process the requirement and send the result to the browser through its own map service and ARCGIS map service. It has realized the Algorithm of rainfall Contours in TopARC system. In TopArc, irregular grid multi-side function is used in rainfall Contours analysis. Contours generated from the distributed points are used in the making of rainfall charts. But in the geographic system, there are some shortcomings in using irregular grid multi-face function to deal with rainfall Contours. For stance, there are three rainfall observatories, two of which reports the precipitation rainfalls in the local areas as five and two respectively and the third reports that there is no rain. By using multi-face equal value analysis, we will assume the rainfall in the third area to be 10 because the values increase from the left to the right. But, as a matter of fact, there is no rain in the third area and an error is made. On the contrary, the method proposed in the paper uses the irregular grid multi-side function that has got a reduction check, thus solving the above-mentioned problem. The first step of the method is to divide grids according to the distribution of the points and then add values to the nodes of the grids. Then the last step is to index the points of various sides and connect equal value lines by following certain index calculating procedures. It enables better choice of WebGis models. Gis system usually has to deal with a large amount of geographic information. Thus how to reduce the amount of data transfer on the net and improve the...
|
PDF Full Text Request