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1.
Debris flows, debris floods and floods in mountainous areas are responsible for loss of life and damage to infrastructure, making it important to recognize these hazards in the early stage of planning land developments. Detailed terrain information is seldom available and basic watershed morphometrics must be used for hazard identification. An existing model uses watershed area and relief (the Melton ratio) to differentiate watersheds prone to flooding from those subject to debris flows and debris floods. However, the hazards related to debris flows and debris floods are not the same, requiring further differentiation. Here, we demonstrate that a model using watershed length combined with the Melton ratio can be used to differentiate debris-flow and debris-flood prone watersheds. This model was tested on 65 alluvial and colluvial fans in west central British Columbia, Canada, that were examined in the field. The model correctly identified 92% of the debris-flow, 83% of the debris-flood, and 88% of the flood watersheds. With adaptation for different regional conditions, the use of basic watershed morphometrics could assist land managers, scientists, and engineers with the identification of hydrogeomorphic hazards on fans elsewhere.  相似文献   

2.
The Diyung river descends in Nagaon district of Assam. After its confluence with main channel Kopili it causes enormous losses to life and property due to floods. Appropriate watershed treatment measures are, therefore, required for moderating the flood damage. In the present study landscape information viz., the hypsometric integral has been analysed. The Diyung watershed has been subdivided into 23 sub-watersheds for hypsometric analysis. The hypsometric integral for the entire Diyung watershed ranged from 0.14 to 0.56. According to the present study there are two stages of geologic/geomorphologic development, namely equilibrium stage and monadnock stage. The hypsometric integral indicates that surface runoff is the dominant process. Although static, the topographic characteristics indicate response of watershed to various natural phenomenon and dominant processes such as runoff and erosion. Based on the intensity of the processes sub-watershed can be prioritized for taking up appropriate conservation measures. The study also highlights the use of hypsometric integral for prioritizing watershed for planning engineering measures to mitigate the impact.  相似文献   

3.
Land use has changed in the Daqinghe watershed during 1956–2005, and it has influenced the flood peak and volume. In order to reveal the effects of land use change on flood characteristics in Daqinghe watershed, we selected 2 sub-watersheds and used remote-sensed land use data of 1980 and 1996 to analyze changes in land use and also selected several combinations of similar rainfall events and the corresponding flood events to show how changes in land use affect floods. The forest and urban area increased and other types decreased, and flood peaks and volumes tended to decrease under similar rainfall events. To quantify the extent of change in land use affecting floods, a hydrological model incorporating the land use was established. The model combines infiltration excess and saturation excess runoff generation mechanism in each type of land use, and the simulation results agreed well with the measured flood processes in the two selected watersheds. Several floods of different return intervals were selected to be modeled under the 1980 and 1996 land use conditions. The results show that both flood peak and volume decreased under the 1996 land use condition in comparison with the 1980 land use condition in the two watersheds. Most of the flood peaks decreased <5 %, but the volume decreased to a greater extent. This result can be helpful in modifying design flood.  相似文献   

4.
In the last decade, attention has been devoted to the southern part of the Egyptian Red Sea coast due to the large touristic and mining activities. Egypt spares no effort to develop it, to build new urban communities, and to create new job opportunities. Many comprehensive planning studies have been conducted. Many luxurious tourist spots, airports, and harbors have been constructed. These areas are subjected to flash floods, which represent a frequent threat to these urbanization activities that may cause losses in livelihood. By analyzing the geomorphologic features of the study area, intense stream networks are detected that, with the available metrological data, require flood management and analysis to mitigate the possible negative effects and to benefit from the estimation of flood water. Rahbaa basin is a sub-catchment of wadi Hodin. Flash floods within this area threaten the Red Sea coastal plain as well as the main coastal roads. It also directly drained out to the sea, which leads to a loss of huge amounts of flood water that is useful for arid regions. Using geographic information system and remote-sensing tools with the application of a comprehensive graphical modeling (watershed modeling system) supports the hydrological modeling of HEC-1. The total amount of runoff is calculated and the hydrograph of the 50-year return period is computed using rainfall historical data.  相似文献   

5.
Boota  Muhammad Waseem  Yan  Chaode  Abbas  Tanveer  Li  Ziwei  Dou  Ming  Yousaf  Ayesha 《Natural Hazards》2021,109(2):1387-1405
Natural Hazards - Prediction of the flash floods in ungauged or poorly gauging watershed is one of the challenging tasks in the field of hydrology and needs implication of advanced techniques to...  相似文献   

6.
Flood of 1997 affected a large number of residents in the Red River Basin. Life disruption, economic damage, lengthy recovery process, physical and emotional trauma motivated a number of main initiatives to improve the level of preparedness in case of future floods. This review will focus on the involvement of the International Joint Commission (IJC). Personal experience is used in this review to emphasize a number of important lessons, of special relevance to Canadian portion of the basin, from the post flood activities. Level of preparedness for, and potential damage from future floods will benefit from focusing very serious effort on the improvement of the Canadian database, exchange of data with the U.S. and standardization of data collection, exchange and use. Tools for sustainable floodplain management are improving. However, the Red River Basin with its characteristics requires a special set of sophisticated tools that will enhance flood flow forecasting, planning of new flood control measures (structural and non-structural) and emergency operations of existing flood protection system. City of Winnipeg, being the largest population centre in the basin deserves a special attention. Additional protection of 670,000 people is required that will take into consideration temporal and spatial distribution of economic and social costs and benefits.  相似文献   

7.
Journal of Earth System Science - Watershed morphometric analysis is important for controlling floods and planning restoration actions. The present study is focused on the identification of...  相似文献   

8.
The Red River valley experienced one of the worst floods in 1997 because of above average snow accumulation, a blizzard during the snowmelt period and high soil moisture conditions. A three-dimensional hydrodynamic modeling system is used to study the impact of the flood on the circulation and contaminant dispersion in Lake Winnipeg. To assess the model performance, we first simulate the circulation and temperature distribution of the lake in 2007 and compare the model results with the observations made in the lake during this period. The model showed considerable skill in reproducing the thermal structure, currents and water levels. The accuracy of these simulations suggests that the model is capable of describing flow and transport of material required for detailed water quality simulations during the flood. During the flood event, Red River plume movement is primarily controlled by the wind-driven currents. The winds from the north confined the plume to a small area near the river mouth.  相似文献   

9.
为高效高精度地模拟流域雨洪过程,应用动力波法求解二维圣维南方程,并耦合水文过程,建立了包含流域降雨产流、汇流、下渗以及洪水演进等过程的高性能流域雨洪数值模型。该模型的优势在于使用非结构网格,可较好地处理不规则边界,准确贴合复杂地形表面,使得模型能精确计算模拟流域雨洪过程,同时引入GPU技术加速计算,使得大尺度流域雨洪计算成为可能。最后,将模型应用于V型经典算例及2个实际流域雨洪算例,所得结果与实测吻合较好,计算所用时间较短,表明该模型可以快速且精确模拟流域雨洪过程。研究结果有助于实现对实际流域雨洪灾害进行合理高效的预测,为应急抢险工作提供有力支撑。  相似文献   

10.
This study investigates how extreme flows in the Grote Nete watershed located in the Flanders region of Belgium will respond to climate change and urban growth using the hydrological model WetSpa. Three climate change scenarios (low, mean and high), three urban development scenarios (low, medium and high) and the nine combined climate–urban change scenarios are considered. The results indicate that extreme low flows would decrease noticeably by climate change, while they would be less sensitive to urban development. On the other hand, extreme peak flows are predicted to increase considerably due to both climate change and urban growth. It is concluded that coupling the effects of land use change with climate change may lead to severe increase in the frequency river floods in winter as well as the frequency of extreme river low flows in summer.  相似文献   

11.
Ras Banas Peninsula is a large triangular tract of land jutting out into the Red Sea. It extends about 40 km eastward out of the general trend of the Red Sea coast of Egypt, covering an area of about 600 km2. Three sandy spits are jutting out from the main body of the peninsula into the Red Sea, possibly representing relics of structural trends, two of which are located at the western part and the third one is extending from the eastern edge forming a further seaward extension of the main body. A series of isometric and contour maps of the whole area under investigation are provided in digitized visual form of geomorphologic features, landforms and slope configuration. According to difference in relief, the study area can be subdivided into three topographic divisions, namely coastal plain (<50 m), medium-height land (50–150 m) and hinterland (>150 m). Drainage and lineament maps of the drainage networks were prepared from the topographic map and satellite images of the area. The prepared lineament map shows four main trends that control the configuration of the drainage system in the study area. These trends are Aqaba trend (NE–SW to NNE–SSW), Red Sea trend (NW–SE to NNW–SSE), Nubian trend (N–S), and Tethyan trend (E–W). It is clear that the structural trends, lithology and general slope are the main controls of developing parallel and dendritic drainage patterns in the area. Both geomorphology and drainage system configuration have great influences on the land use and natural hazards affecting the peninsula especially torrential floods and sea level fluctuations.  相似文献   

12.
Debris flow is one of the most serious and frequent geological disasters that occur in the Loess Plateau. The outbreak of a debris flow is sudden, ferocious, swift, and destructive. The characteristics and mechanism of debris flow were explored in this study via survey, numerical simulation, and simulation analysis in a Loess Plateau area (Huangling County, Shaanxi Province, China). Numerical models and formulas corresponding to the occurrence and movement mechanism were established based on the HEC-RAS, HEC-GeoRAS, and SWAT results. The range of debris flow deposition was determined through capturing the debris flow free surface. A hydrological model and critical rainfall threshold were determined in order to provide technical support for debris flow forecasting in the Loess Plateau. The results suggest that 10-year floods do not submerge any portion of the basin. One village area was affected by the 100-year flood (total area of 0.648 km2) while four villages areas were submerged by the 1000-year flood (total area of 1.39 km2). The method presented here may provide a reliable scientific basis for mitigating loss due to debris flow hazards.  相似文献   

13.
The present paper deals with morphometric analysis of Koshalya-Jhajhara (K-J) watershed, tributaries of Ghaggar in northwestern India. The area forms a rugged topography having elevation range from 399 m to 1810 m MSL. Aster DEM and SOI toposheets have been used to calculate various parameters using Geographic Information System (GIS). Linear, areal and relief aspects for morphometric analysis were calculated using GIS. Total number of streams in the watershed are 991 out of which 543 are of 1st order, 259 are of 2nd order, 124 are of 3rd order, 58 are of 4th order and only 7 are of 5th order. The order of stream determines the chances of flood in the stream. Higher the stream order more the probabilities of flood. The present paper indicates that K-J watershed is of 5th order and less elongated in shape having lower peak flows of longer duration with dendritic pattern and having fine drainage texture. Bifurcation ratio varies from 3 to 5 which indicate that geological structures don’t have dominant influence on drainage pattern. High slope is witnessed in NE part and low slope in SW part with very low gradient ratio. Variables like stream frequency and drainage density determines the volume of the water discharge and its speed of flow in the river channels. Higher the stream frequency and drainage density more will be the probability of floods. These variables also effects temporal variations in the speed at which the water flows in the stream when flood reaches its peak.  相似文献   

14.
Registering a 7.3 magnitude on the Richter scale, the 921 Chi-Chi Earthquake that struck central Taiwan on September 21, 1999 left the island nation with fragile soils, frequent floods, and debris flow, further weakening homeland resources. Taiwan’s dense population had forced its residents to use mountain hills for agriculture and development. The 92-Flood in 2004, which incurred vast monetary losses and human casualties, caused the government to rethink its strategy for land use. In order to use land in a more efficient and in an eco-friendly manner, the Council for Economic Planning and Development, Executive Yuan of the Taiwanese government proposed the “Land Recovery Strategy and Action Plan” in 2006. Its core concept was aimed at “respecting, and adapting to, nature.” To achieve this goal, a hillside watershed management and flood mitigation policy was proposed. Factors of safety, economy, and ecology were included in the policy. Both strategies and practical measures to be implemented were organized in a chart for better understanding and for reference by other countries with similar conditions.  相似文献   

15.
Overview of some geological hazards in the Saudi Arabia   总被引：2，自引：1，他引：1  
The Saudi Arabia has harsh environmental conditions which enhance some geomorphologic/geological processes more than in other areas. These processes create different geological hazards. The general physiography of the Saudi Arabia is characterized by the Red Sea coastal plains and the escarpment foothills called Tihama, followed by the Arabian Shield Mountains, the Arabian Shelf plateau and finally the Arabian Gulf coastal plains. These types of geological hazards can be categorized into sand accumulations, earth subsidence and fissures, flash floods, problematic soils, slope stability problems, and karst problems. The current study gives an overview of all these hazards with examples, as well as develops a geo-hazard map for the Saudi Arabia. Our findings indicate that the desert environment needs much concern and care. National and international agencies have to join together with other people to keep the system balanced and to reduce the resulting geological hazards. Also, remedial measures should be proposed to avoid and reduce these natural hazards.  相似文献   

16.
2020年长江上游和中下游先后发生特大洪水,其中干流编号洪水全部发生在上游,构成了长江流域洪水的主要部分。首先回顾2020年洪水及洪灾情况,然后根据历史上几次特大洪水过程和历年实测资料,分析长江上游洪水特征、洪灾类型及特点,最后提出新时代长江流域洪水整体防御战略及山洪灾害防治战术。研究表明:金沙江洪水是长江上游洪水基础部分,岷江、嘉陵江和干流区间是洪峰的主要来源,三者洪水遭遇是产生上游特大洪水的主因,上游洪水又是全流域特大洪水的基础和重要组成部分。目前造成洪灾死亡人数最多的是山洪以及山洪引起的地质灾害,财产损失最大的是中下游及湖泊地区。未来堤防仍然是防洪的基础,提高沿江城市防洪标准主要手段是控制性水库的联合优化调度,而减少洪涝灾害损失最有效的途径是给洪水以空间的自然解决方案等非工程措施。  相似文献   

17.
Understanding and improving the public perception has become an important element in the management of flood risk worldwide. In Iceland, studying perception of flood hazard and flood risk is, however, in its early stages. This paper presents a case study on the public perception of flood hazard and flood risk in an Icelandic town prone to ice-jam floods. Awareness of the population regarding historical inundations, self estimation of flood risk and worry is considered. The factual knowledge of the residents is deconstructed in flood hazard parameters accessible to the lay population: number of events, dates, genesis and boundaries. The performance of the respondents is rated for each parameter and the influence of several predictors evaluated. The research shows three significant patterns: there is poor awareness and little worry about historical inundations in the area; experience of the past flooding events in town is the most effective source of knowledge; awareness, risk estimation and worry are not correlated.  相似文献   

18.
Flood mitigation involves the management and control of floodwater movement, such as redirecting flood runoff through the use of floodwalls and flood gates, rather than trying to prevent floods altogether. The prevention and mitigation of flooding can be studied on three levels: on individual properties, small communities, and whole towns or cities. The current study area is located in Hurghada on the Red Sea, which is considered an important area for coastal tourism. The study area is located at distance 7.50 km from El Gouna city along the Red Sea and east of Hurghada–Al Ismaileya road. The aim of this research is to derive the runoff flow paths across the study area and their flow magnitudes under different rainfall events of 10, 25, 50, and 100 year return periods in order to design the flood mitigation measures to protect such important areas. Field data (e.g., topographic data and rainfall intensities) were collected for the study area. The results indicated that the site is exposed to high flash flood risk and protection work is required. In order to protect the area from flood risks, locations of number of drainage channels and dams were selected and designed based on flood quantity and direction. The proposed mitigation system is capable of protecting this crucial area from flood risks and increases the national income from tourism. This study can be applied in different areas of Egypt and the world.  相似文献   

19.
Hashemi  Mahdi  Alesheikh  Ali Asghar 《Natural Hazards》2013,65(3):1895-1911
  相似文献   

20.
新疆河流洪水与洪灾的变化趋势   总被引：32，自引：11，他引：21  
吴素芬  张国威 《冰川冻土》2003,25(2):199-203
在西北气候由暖干转向暖湿的过程中,新疆河流的洪水和洪灾反映明显.对新疆29条河流选取年最大洪水,统计出超标准洪水、20a一遇、50a一遇洪水的出现频次进行分析,结果显示1987年后洪水量级、洪水频次呈增加的变化趋势.通过20世纪90年代以来灾害性洪水出现的频次、灾害损失的变化比较分析,90年代以来灾害性洪水尤其是灾害性暴雨洪水和突发性洪水呈现增加的态势,1987—2000年的灾害损失与1950—1986年相比增加了30倍.  相似文献   

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