RESEARCH ON SYSTEM OF FLOOD DISASTER CONTROL AND REDUCTION SUPPORTED BY GIS IN MEDIUM AND SMALL BASINS

Southeast China coastal areas belong to subtropical monsoon climatic zone, thus easily affected by floods resulted from typhoons and rainstorms. Since the areas of river basins are small, rivers flood regulation capacities are low, and therefore flood hazard is grave. In this paper, taking the Yongjiang basin in southeast China as an example, the approaches and methods of geographic information system(GIS) applied to flood disaster control and reduction research on small basin are explored. On GIS help the rainfall runoff calculation model and the river channel flood routing model are developed. And the evaluating flood submerged area and the damage assessment models are built supported by digit elevation models. Lastly the decision support system on GIS supported for flood control in research basin has been set up. This greatly improves flood proofing decision making capacities in river basin, and provides valuable information and a mode for flood prevention and reduction in the medium and small basin. Meanwhile, the research indicates that technologies of GIS provide a powerful tool for flood disaster control.

Evaluation of Infiltration Capacity and Water Retention Potential of Amended Soil Using Bamboo Charcoal and Humus for Urban Flood Prevention

In Japan, floods occur frequently in urban areas because non-infiltrating areas are seeing increased urbanization. To prevent floods, urban basins must improve the infiltration capacity and water retention of the whole basin. There are several basic technologies for river basin management, such as infiltration trenches or rainwater storage. However, a method of soil amendment that prevents flood disasters has not been established. This study aims to evaluate the infiltration capacity of soil amendments using bamboo charcoal and humus. A constant-head infiltration test and rainfall simulation were conducted to evaluate the properties of the soil amendments. The constant-head infiltration test＇s results showed that soils mixed with 30% humus had the greatest potential for influencing initial and final infiltration rates, and the more the mixing rates of bamboo charcoal and humus were increased, the higher the water retention capacity. The results of the rainfall simulation showed that soils mixed with 30% humus had the highest final infiltration rates and lowest multiplication spillage. To reduce the runoff volume using soil amendment technology, it is important to delay overland flow, and the hydraulic properties of the soils mixed with bamboo charcoal and humus were as effective as those of granite soils.

Geomorphology of the Boao coastal system and potential effects of human activities-Hainan Island,South China

The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods. The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.

With the Measuring Rod against the Floods: Ferdinand Verbiest and His Forgotten Introduction of Benedetto Castelli’s River Hydraulics to China

The monumental Studies to Fathom Principles(Qiongli xue窮理學;1683)by Ferdinand Verbiest S.J.(Nan Huairen南懷仁,1623–1688)was never printed,and its exact content is not known.A section of the only extant,though incomplete,manuscript deals with fluvial flood prevention and river control measures,a subject that until then had not cropped up in any Chinese-language work of the Jesuits.In this section,Verbiest not only described the already well-known Aristotelian theory of the origin of rivers,but also introduced to China new scientific propositions,concepts,and numerical examples originating from the seminal Renaissance work Della misura dell’acque correnti(Of the Mensuration of Running Waters;1628)by Benedetto Castelli(1578–1643).In addition,Verbiest presented to his readers some noteworthy examples of pertinent Western achievements such as the pound-lock with miter gate,and he provided them with a simple economic analysis of flood control options.The significance and possible influence of Verbiest’s text on further developments in Chinese approaches to water engineering are discussed,highlighting a hitherto largely disregarded facet of Western science and technology transfer in the field of river hydraulics and flood management.

Regionalization and the Method for Risk Grading for Flash Flood Disaster in Tibet Region

Flash flood is one of the major meteorological disasters on the Tibet Plateau (TP). Flash flood risk regionalization based on the theory of flash flood occurrence risk is the essential basis for relative risk management. The flash flood risk regionalization and the high-resolution grid mountain flood risk level in TP is carried out by using ArcGIS with the indicators of rainfall, days of heavy rain, vegetation cover, slope, relative elevation difference, river network density, population density, average GDP and traffic density. The areas with high mountain flood risk are mainly located in the middle and downstream of Yarlung, the Nujiang River Valley, the Jinsha River and Lancang River Basin. Besides, the results of flash flood disaster risk regionalization were tested by using historical flash flood disaster data and calamity census data. The disasters occurred in high-risk and sub-high-risk regions are accounted for 73%. Flash floods that cause casualties and economic losses of more than 100,000 CNY (Chinese Yuan) occurred in high-risk areas. Flash flood risk assessment may provide reference for the prevention and control of geological disasters in TP, improve disaster prevention and mitigation capabilities, reduce the hazards of flash floods to social development.

Comprehensive System for Urban Flood Prevention in China and Counter-measures to Reduce Calamities

By reviewing the general state of urban flood calamities of the past 40 years and more, this article tries to explore the causes of urban flood, especitlly the man-made factors. It puts forward the ideas of setting up a comprehensive system for urban flood prevention. This comprehensive system consists of six sub-systems such as: 1) command system; 2) system of flood control and drainage works; 3) system of keeping away of flood and coping with flood; 4) system of flood forecast; 5) flood -fighting and rescue system; 6) flood-preventing legislative and insurance system. This article also puts forward the counter-measures to avert floods and reduce the calamities.I.The General State of Urban Flood Calamities for the Last Few Years in

French Insurance and Flood Risk: Assessing the Impact of Prevention Through the Rating of Action Programs for Flood Prevention

French insurance is part of a public-private partnership with the French State to compensate flood-related damages, and there is growing concern among insurers about damaging climatic events. To promote preventive actions as well as to take them into account in flood risk assessment, insurers have recently expressed the need to develop a rating system of preventive actions. This study identified Action Programs for Flood Prevention (Programme d’Action pour la Prévention des Inondations—PAPI) as the key French public policy instrument: they provide an overview of the diversity of actions that are conducted locally at the relevant risk basin scale. A database of all intended actions in the 145 launched PAPIs was constructed and the actions were coded (88 codes). The analysis consisted of two steps: (1) We conducted an expert valuation using the Analytic Network Process and the Analytic Hierarchy Process, aiming at creating an experimental national rating system. The results show the importance of implementing an integrated strategy that particularly emphasizes land use planning and urban planning. This appears even sounder as individual actions show relatively limited effectiveness. (2) The ratings of actions were applied to each PAPI according to their implemented actions. The resulting scores for individual PAPIs, as local risk coping capacity indicators, show great variance ranging from 8 to 324 points. This confirms the need to take prevention into account in flood risk assessment.

Critical rainfall intensity for safe evacuation from underground spaces with flood prevention measures

Underground space in urban areas has been expanding rapidly during recent decades, and so has the incidence of fatal accidents and extensive damage to facilities resulting from underground flooding. To evaluate the safe evacuation potential of individual underground spaces in flood-prone urban areas, the hydraulic effects of flood prevention measures, e.g., stacked flashboards or sandbags and elevated steps, were incorporated in a proposed formula for estimating the depth of inundation of an underground floor. A mathematical expression of the critical rainfall intensity for safe evacuation from underground space was established and then evaluated for two types of underground spaces, an underground shopping mall and a building basement. The results show that the critical rainfall intensity for any individual underground space can be determined easily using the proposed analytical or graphical solution. However, traditional underground flood prevention measures cannot improve safety if people refuse to evacuate immediately once water intrudes into the underground space.