Prevention and Control of Water and Sediment Disasters

Author:admin | published date:2013-11-30 | click:1074

Serious water and soil erosion, frequent disasters of debris flow and landslide occur frequently in the upstream and middle reach of rivers in China. At the same time, serious river sedimentation, high sediment concentration and high risk of river dike break are also threatening the lower reaches. Therefore, in recent years, water and sediment disasters featured by “small water flow, high water level” or “small flood but severe disaster” are frequently observed in many rivers in China. Water and sediment coupled disasters have become a serious issue for the two largest rivers in China, Yangtze River and the Yellow River. To efficiently prevent and control water and sediment disasters, it is critical to address the following technical issues: (1) how to describe the new characteristics of the coupled disasters of water and sediment; (2) how to describe the coupled mechanism of water and sediment disaster; (3) how to simulate water and sediment processes under complicated water and sediment conditions in lowest computational time; and (4) how to rapidly assess and zone water and sediment disasters.

Figure 5 Water and Sediment Disaster

In order to systematically prevent and control of water and sediment disasters, great efforts have been devoted to addressing the above four important issues and significant progress have been achieved.

Figure 6 Prevention and Control for Water and Sediment Disaster

Preliminary theoretical systems on sediment disaster in rivers have been established. The concept, properties, classification and grading, formation mechanism, and disaster effect of sediment disaster have been proposed. The methods for the dynamics process simulation, rapid assessment and forecast of sediment disaster have been developed. A series of approaches were synthesized for monitoring, forecast, prevention, control and management water and sediment disasters. These achievements provide scientific basis for prevention and control of water and sediment disasters in rivers.

Key technologies for “multi-dimensional and large-area” rapid assessment and zonation of water and sediment disasters have been developed. Significant improvements have been achieved to improve the modeling precision while reducing the computational time. Specifically, the rapid assessment of water and soil erosion can be obtained by utilization of “minimum information polygons” of multi-source data from soil erosion environmental factors under various dimensions. The method has certain advantages, including short assessment period, low cost, low requirement for data integrity, and effective isolation the effects of human activities. Compared to the widely used Universal Soil Loss Equation (USLE), this method can reflect the characteristics of water and soil erosion more effectively. On the other hand, as for the sudden water and sediment disasters such as debris flow, landslide and collapse, the method can achieve rapid zonation even when the data was incomplete by selection of the reference point, establishment and matching of reference groups.

Technology for rapid forecast of hyper-concentrated sediment-laden flood process in hanging rivers and risk control of dike collapse has been developed. This technology, for the first time, couples water and sediment two-phase flow model with artificial neural network (ANN) algorithm, which greatly improves stimulation speed for flood process. Forecast of hyper-concentrated sediment-laden flood therefore can be more rapid and accurate.

Comprehensive assessment methodology for hazard level of flood disasters has been established. Systematic evaluation for the regional impact and spatial effects of flood disasters in China has been evaluated. Significant differences between the short and long-term impacts of the flood disasters were revealed. The areas with significant differences were found to be the key areas for strategic shift of flood control and disaster reduction. These findings are of great significance for decision-makers to make sustainable comprehensive measures for flood control and disaster relief.

        These research outputs have been adopted by the government and some research agencies, such as the Yellow River Conservancy Commission of the Ministry of Water Resources, the Yangtze River Water Resources Commission of the Ministry of Water Resources, and China Institute of Geo-Environment Monitoring. It has gained significant social, economic and environmental benefits. Moreover, the above scientific and technological achievements had won the First Prize for Science and Technology Progress, Ministry of Education in 2008, and the Second Prize of National Science and Technology Progress in 2010.