Hydrological impacts of climate change on rice cultivated riparian wetlands in the Upper Meghna River Basin (Bangladesh and India)     

《水文科学杂志》2012,57(1):33-56

ABSTRACT

Riparian depressional wetlands (haors) in the Upper Meghna River Basin of Bangladesh are invaluable agricultural resources. They are completely flooded between June and November and planted with Boro rice when floodwater recedes in December. However, early harvest period (April/May) floods frequently damage ripening rice. A calibrated/validated Soil and Water Assessment Tool for riparian wetland (SWATrw) model is perturbed with bias free (using an improved quantile mapping approach) climate projections from 17 general circulation models (GCMs) for the period 2031–2050. Projected mean annual rainfall increases (200–500 mm or 7–10%). However, during the harvest period lower rainfall (21–75%) and higher evapotranspiration (1–8%) reduces river discharge (5–18%) and wetland inundation (inundation fraction declines of 0.005–0.14). Flooding risk for Boro rice consequently declines (rationalized flood risk reductions of 0.02–0.12). However, the loss of cultivable land (15.3%) to increases in permanent haor inundation represents a major threat to regional food security.  相似文献   

基于随机雨型的山洪灾害预警模式          下载免费PDF全文

原文林  宋汉振  刘美琪 《水科学进展》2019,30(4):515-527

针对雨型随机性所导致山洪灾害预警预报空报、漏报率过高问题,为提升山洪灾害预警精度,依据概率分布传递扩散原理,以雨型特征参数为控制条件,提出了基于参数控制的随机雨型生成法,建立了基于随机雨型的山洪灾害临界雨量计算模型及考虑决策者风险偏好的预警模式。以裴河流域为例,对不同雨型集下的临界雨量进行对比分析,并确定研究区6h临界雨量阈值空间。结果表明:雨峰位置、峰值倍比、前期土壤含水量对临界雨量的影响范围分别为32%~34%、33%~34%、15%~22%;雨型较前期影响雨量对临界雨量影响幅度更大;由雨峰位置系数和峰值倍比(r,bmax)双因子雨型集所确定的6h临界雨量阈值空间为98~185mm;考虑决策者不同风险偏好的临界雨量预警模式合理可靠,对更合理地开展山洪灾害预警工作具有指导意义。  相似文献   

河流堰塞的地貌响应   总被引：1，自引：0，他引：1  

周丽琴  刘维明  赖忠平  王昊  曹广超 《第四纪研究》2019,39(2):366-380

堰塞作为一种极端地表过程,深刻影响着河流地貌的变化,特别是河流纵剖面的变化。其对河流纵剖面的影响主要体现在两方面:一方面,堰塞坝将抬高局地的侵蚀基准面,阻碍了上游河道侵蚀,形成河流裂点;另一方面,堰塞坝溃决往往形成大型/巨型洪水,造成下游河道和岸坡的剧烈侵蚀。稳定的堰塞坝形成后,在1~105 a的时间尺度上对河流裂点的发育以及河流纵剖面变化上甚至会超过构造、气候和岩性作用,占据主导。本文在简要概述堰塞地貌相关概念的基础上,介绍了部分河流堰塞的研究方法和案例,以及河流堰塞的发育过程和研究意义。目前多仅从堰塞坝与河流纵剖面的空间关系的相关性来论证其地貌响应,并且发现一些堰塞坝与河流纵剖面的相关性,但是也有一些古堰塞坝对现代河流纵剖面的影响并不显著,原因可能与堰塞坝规模、溃决洪水次数、堵江的持续时间和距今年代的不同有关,目前还缺乏深入研究。  相似文献   

Outburst flood hazard: Case studies from the Tien-Shan Mountains, Kyrgyzstan   总被引：3，自引：0，他引：3  

Bohumír Janský  Miroslav Šobr  Zbyněk Engel 《Limnologica》2010,40(4):358-364

More than 2000 of mountain lakes covering more than 0.1 ha exist in a territory of Kyrgyzstan. Nearly 20% of them are dangerous because of instability of lake dams, frequent overflows and melting of buried ice inside the moraine dams. According to the Kyrgyz lake inventory, 328 lakes are at risk of outburst and 12 lakes are considered as actually dangerous. Since 1952 more than 70 disastrous cases of lake outbursts have occurred. The majority of the endangered lakes belong to one of the three genetic types: morainic-glacier, supraglacial and lake dammed by landslides and debris flows. Petrov, Adygine and Koltor lakes were selected and studied in the Tien-Shan Mountains as case studies of the most frequent genetic types of hazardous lakes. Observations were focused on the morphology of the lake basin and the surrounding relief, outflow pattern and processes controlling the development of lake. For the hazard assessment, evolution of glaciers and lakes was reconstructed using historical reports, aerial photographs and satellite images.  相似文献   

我国滨海核电站防护工程设计标准研究     

刘德辅  史宏达  刘桂林  王风清 《海洋工程》2017,35(4):135-146

面对全球极端气候频发的趋势,国内外核电站海岸防护工程普遍采用"可能最大台风暴潮"、"设计基准洪水"等具有含混性的规定作为确定防灾设计标准的依据,其内涵的各种不确定性因素必然会对防灾决策带来重大的致灾隐患。按照国务院核电站安全规划(2011-2020)提出的"必须按照全球最高安全要求",全面开展滨海核电站防护工程设计标准研究己势在必行。使用多维复合极值分布理论及双层嵌套多目标联合概率模式,将核电站水文与气象的研究标准合二为一,对IAEA及我国滨海核电站防护工程设计标准进行了风险评估,供有关部门参考。  相似文献   

Geographical analysis of damage due to flash floods in southern France: The cases of 12–13 November 1999 and 8–9 September 2002     

Freddy Vinet   《Applied geography (Sevenoaks, England)》2008,28(4):323-336

The southern part of France near the Mediterranean Sea is subject to flash floods generated by heavy rainfalls typical of the Mediterranean climate. In November 1999 (the 12th and 13th) and in September 2002 (the 8th and 9th), 5000 km² were touched by rainfalls superior to 200 mm in the departments of Aude and Gard. In both cases, maximum precipitation exceeded 500 mm within 24 h. The damage amounted in the hundreds of millions of euros, and there were numerous fatalities: 35 in 1999, and 23 in 2002. Following a survey of available data, this article details the cost of the damage for both flash flood events. The distribution of the damage is quantified by sector of activity (e.g., industry, agriculture). The average ratio “euros of loss per inhabitant” is quite similar in both cases, but this average hides some geographical discrepancies. Losses in industry can locally worsen the overall toll. The mapping of damage on a local scale and the amount of losses per inhabitant demonstrate that rural areas underwent heavy losses. This was mostly due to the destruction of the public infrastructures (e.g., roads, bridges) that represented more than half of the overall loss. In some rural areas, the cost of flash floods can exceed 15,000 euros per inhabitant. Such flood prevention issues as flood warning systems and land use planning must not focus only on the cities. Death, injury and heavy material losses also disadvantage the rural and mountainous areas where populations and activities are concentrated near rivers.  相似文献   

A grassed waterway and earthen dams to control muddy floods from a cultivated catchment of the Belgian loess belt     

Olivier Evrard  Karel Vandaele  Bas van Wesemael  Charles L. Bielders 《Geomorphology》2008,100(3-4):419-428

Muddy floods, i.e. runoff from cultivated areas carrying large quantities of soil, are frequent and widespread in the European loess belt. They are mainly generated in dry zero-order valleys and are nowadays considered as the most likely process transferring material eroded from cultivated hillslopes during the Holocene to the flood plain. The huge costs of muddy flood damages justify the urgent installation of control measures. In the framework of the ‘Soil Erosion Decree’ of the Belgian Flemish region, a 12 ha-grassed waterway and three earthen dams have been installed between 2002–2004 in the thalweg of a 300-ha cultivated dry valley in the Belgian loess belt. The measures served their purpose by preventing any muddy flood in the downstream village, despite the occurrence of several extreme rainfall events (with a maximum return period of 150 years). The catchment has been intensively monitored from 2005–2007 and 39 runoff events were recorded in that period. Peak discharge (per ha) was reduced by 69% between the upstream and the downstream extremities of the grassed waterway (GWW). Furthermore, runoff was buffered for 5–12 h behind the dams, and the lag time at the outlet of the catchment was thereby increased by 75%. Reinfiltration was also observed within the waterway, runoff coefficients decreasing by a mean of 50% between both extremities of the GWW. Sediment discharge was also reduced by 93% between the GWW's inflow and the outlet. Before the installation of the control measures, specific sediment yield (SSY) of the catchment reached 3.5 t ha^− 1 yr^− 1 and an ephemeral gully was observed nearly each year in the catchment. Since the control measures have been installed, no (ephemeral) gully has developed and the SSY of the catchment dropped to a mean of 0.5 t ha^− 1 yr^− 1. Hence, sediment transfer from the cultivated dry valley to the alluvial plain should dramatically decrease. Total cost of the control measures that are built for a 20 year-period is very low (126 € ha^− 1) compared to the mean damage cost associated with muddy floods in the study area (54 € ha^− 1 yr^− 1). Similar measures should therefore be installed to protect other flooded villages of the Belgian loess belt and comparable environments.  相似文献   

Late Quaternary fluvial activity in the dry valleys (mekgacha) of the Middle and Southern Kalahari,southern Africa     

Paul A. Shaw  David S. G. Thomas  David J. Nash 《第四纪科学杂志》1992,7(4):273-281

Kalahari dry ‘fossil’ valleys (mekgacha) have been little used in palaeoenvironmental reconstruction, partly because the origins and functions of the valleys are a subject of debate, and partly because they contain few datable sediments. In the Middle Kalahari the valleys are endoreic, and, following a decline in ground-water tables owing to human interference over the past 150 years, rarely contain water. Evidence from three sites suggests that the valleys contained standing water between 15000 and 12000 yr BP, and that the main Okwa-Mmone system flowed into palaeolake Makgadikgadi at 920 m a.s.l. during this period. The Southern Kalahari contains the exoreic Molopo network which is hydrologically more active, being prone to surface flows in response to extreme rainfall events. The spring—fed Kuruman valley has two terraces, the lower composed of a series of flood deposits of late Holocene age. The flood of February 1988 provides a useful analogue for the conditions under which these deposits were formed, and of the temporal regime of the Kuruman River. Comparison with adjacent sites suggests that evidence put forward to indicate cycles of climatic amelioration in the last 4000 yr may, in part, represents the effect of extreme precipitation events. Historical floods show a strong correlation to Southern Oscillation high-phase (cold event) episodes, suggesting possibilities for extension of the Southern Oscillation record through palaeoflood studies.  相似文献   

陕西省山洪灾害特征及防治对策   总被引：5，自引：1，他引：4  

张茂省  薛富平  王晓勇 《西北地质》2004,37(3):96-102

界定了山洪灾害的概念．分析了陕西省山洪灾害的形成条件和影响因素。在时域上,具有多期性和同期群发性,与泥石流、滑坡等灾害形成灾害链,每年7～9月是山洪灾害的高发季节,4～6月偶有发生;在地域上．受暴雨中心和流域地形控制,具有相对集中性和成片成带性。划分了山洪灾害易发区,分区提出了相应的防洪减灾措施。  相似文献   

Recognition of debris flow,debris flood and flood hazard through watershed morphometrics   总被引：4，自引：2，他引：2  

D.?J.?WilfordEmail author  M.?E.?Sakals  J.?L.?Innes  R.?C.?Sidle  W.?A.?Bergerud 《Landslides》2004,1(1):61-66

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