Study On Three-dimensional Visualization Of Snowmelt Flood

Object: Flood disasters especially the frequency of the spring snowmelt flood in Xinjiang increase with global climate change. The occurrence time and evolution processes have become into the focus of research. With the development of hydrological information in our country, the numerical simulation technology and decision support system have become imperative for water resources regulation, allocation and management. However, the special ecological and geographical conditions in Xinjiang bring severe challenges in handling hydrological information. Based on remote sensing data and a geographic information system monitoring snowmelt flood is significant in practice for water resources management in arid area.Methods: Based on the characteristics of snowmelt flood in spring in Xinjiang basin, we developed a distributed 3D visualization system that integrates energy balance, water balance and river flood routine using the technology of remote sensing, geographic information system and computer. Then this 3D visualization system was used to simulate the spring-snowmelt flood in 2010 in the Urumqi River Basin.Results:(1)A snowmelt runoff model has been intergreted and optimized. Based on the physical process of snowmelt, partial parameters of multi-source retrieval models, power balance theory, and the gauged meteorological data, the algorithm of snowmelt model has been improved.(2)A watershed confluence model has been intergreted and optimized. Based on the multi-source geographic information data(meteorological data, hydrological data, basic geographic data and remote sensing data), the physical processes and the melting snow interception loss module, evapotranspiration loss module and the confluence module, a snowmelt concentration analysis over the entire basin has been realized.(3)A flood visualization system has been developed. Through establishing 3D terrain model based on triangulated irregular network, building environment, converting elevation factor, pasting the texture, rendering in the ArcGIS Engine, using SceneControl interface and Animation class library, the 3D flood routine simulation has been finished.(4)The distributed snowmelt flood 3D visualization system has been developed and applied. C# language compiler system interface, IDL language compiler core algorithm, and the secondary development of ArcGIS and ENVI were adopted in the system. Finally, Urumqi River Basin was taken as a typical research area to test the system.Conclusion: The simulation results show that deep values are higher in the north than in the south, which mainly related to topographic factors. Its south is near the II Peak of Tianger alpine region with low temperature and snow, while the temperature is relatively gentle and high in the North. Through verification using the Landsat 7 image in the same period, the actual runoff is consistent with the simulated flood situation. The flood routine simulation is also accurate. There is a good trend with the measured runoff flow streamline. The Nash-Stucliffe E is 0.72, and the relative error R is 4.36%. These conclusions show us the system simulation of the snowmelt flood in Urumqi River Basin is accurate. The system could couple the hydrological processes, and provide early warning for the snowmelt flood. It is meaningful for disaster prevention and water resources management of river basin.