A Study On The Single Debris Flow Monitoring And Warning System And Its Application In The Earthquake-stricken Area Of Sichuan Province

The early warning of debris flow is one of the most important topics in the field of the geological disaster prevention. There are many types of prediction methods that have different accuracies of forecasting. Therefore, it is particularly important to choose and utilize an appropriate early warning method. In this dissertation, the early warning models for the earthquake-stricken area of Sichuan Province are studied. Based on the field investigation and data collection in that area, different types of early warning models are developed, including rainfall models, the physical models which simulate the movement of debris flow, and the real time monitoring models. The models are verified by many debris flow events that happened in the earthquake-stricken area of Sichuan Province. Next, the application range and the advantages and disadvantages of each model are deeply discussed, respectively. Finally, the monitoring and warning system for single debris flow is established, which can transmit information, process data, release early warning information and so on. The main work and research results are concluded as follows:1. The one-dimensional coupling model of surface runoff and infiltration is built, in which the factors of rainfall, infiltration, and lateral flow are added on the basis of the Saint-Venant equations. This model can simulate the movement of the one-dimensional debris flow which can be defined as viscous, rainstorm and valleys type. Moreover, the model can be numerically solved by applying Preissmann four-point linear implicit scheme.2.In order to simulate several debris flows collection, the model of flow concentration is built. The mass continuity equation and the energy continuous equation are set at the confluence of the rivers. The internal boundary condition can be changed by solving the simultaneous equations. With sensitivity analysis, the influences of the longitudinal slope degrees, rainfall intensity and infiltration intensity on the outbreak of the debris flow are respectively discussed.3. The two-dimensional movement model of debris flow is built and can be solved by the improved ADI algorithm in which the different unknown quantities are separated and solved respectively by the well-known Thomas algorithm. The improved ADI algorithm reduces the complexity of solving process and is more suitable for programming calculation. Moreover, this model is verified by the real-world example.4. The effective antecedent rainfall model is developed by establishing the definitive function relationship between rainfall and effective antecedent rainfall. The disaster event and normal event are separated by debugging the function. Next, the dynamic precipitation thresholds are proposed.5. The monitoring and warning system for single debris flow is independently developed. The system includes two main parts, the information database and platform, which are developed by SQL sever 2008 and Delphi XE, respectively. The main functions of the system include data transmission, data processing, information exhibition, and visualized operations.6. The monitoring and warning system for single debris flow is applicated in the earthquake-stricken area of Sichuan Province. Severaltests of this system on real cases show that the following functions can be achieved:updating the real time data, determining the triggering of early warning, and sending early warning information.