‘Are you prepared?’ Representations and management of floods in Lomanikoro,Rewa (Fiji)

The islands of Fiji, in the Western Pacific, are exposed to a wide range of natural hazards. Tropical storms and associated floods are recurring natural phenomena, but it has been regularly alleged that Fijians lack preparation, over‐rely on state assistance in post‐disaster situations or engage in risky behaviours that aggravate the negative impact of floods. Risk reduction strategies, which are now implemented by government authorities and international organisations, heavily promote the principle of ‘community preparedness’. Both community awareness programmes and capacity‐building programmes are conducted throughout the country in the most vulnerable communities. This paper analyses how the inhabitants of Lomanikoro village, in the low areas of the Rewa Delta, perceive and manage existing flood risks. It examines social and cultural factors that contribute to shape risk response locally—in particular, why villagers may be reluctant to adopt some recommended preparedness measures and resettle in higher, safer zones.     

采用保护性耕作对减少水稻产量损失的实证分析——基于4省1080个稻农的调研数据

干旱和洪涝是造成水稻减产最主要的自然灾害,稻农通过采用保护性耕作可以减少其对水稻的产量损失。基于2013—2015年中国水稻主产区1 080个水稻农户的调研面板数据,论文采用内生转换模型,实证分析了稻农通过采用保护性耕作应对干旱或洪涝的效果,并分别估计了采用者和未采用者的水稻单产情况。实证结果表明:1)采用者的水稻单产远远高于未采用者的水稻单产;2)在反事实假设情况下,如果采用者未采用保护性耕作,其水稻产量将相应减产457.95 kg/hm~2(约7%);如果未采用者采用保护性耕作,其水稻产量将相应增产225 kg/hm~2(约4%);3)户主种植经验、受教育年限和公共服务可得性正向影响稻农的采用行为。最后,论文建议政府应大力推广保护性耕作技术,加大对抗逆水稻品种的培育,加强对农业生产资料的投入和管理,扩大公共服务的覆盖范围。     

STREAMFLOW TRENDS IN WISCONSIN'S DRIFTLESS AREA1

ABSTRACT: Trends in streamflow characteristics were analyzed for streams in southwestern Wisconsin's Driftless Area by using data at selected gaging stations. The analyses indicate that annual low flows have increased significantly, whereas annual flood peaks have decreased. The same trends were not observed for forested areas of northern Wisconsin. Streamflow trends for other streams in southeastern Wisconsin draining predominantly agricultural land were similar to trends for Driftless Area streams for annual low flows. The causes for the trends are not well understood nor are the effects. Trends in annual precipitation do not explain the observed trends in streamflow. Other studies have found that erosion rates decreased significantly in the Driftless Area, and have attributed this reduction to a change of agricultural practices, which increase infiltration, decrease flood peaks, and increase low flows.     

Stimulating flood damage mitigation through insurance: an assessment of the French CatNat system

Flood risk has increased in France in the last 20 years and is projected to increase further in the future due to climate change and increase in exposure. Since 1982, France has had a natural disasters insurance system (‘CatNat’) in place that covers flood damage. This insurance system has been combined with what are called ‘Risk Prevention Plans’ (PPRs) in order to stimulate the undertaking of flood risk mitigation measures by communities and households. However, these schemes do not provide optimal incentives for flood damage reduction. This is confirmed by the results from a survey about flood preparedness of 885 households who live in flood-prone areas in France, which are presented in this paper. Moreover, this study provides suggestions for improvement, which are assessed on their potential economic, social and political implications. Among these suggestions are increasing the effectiveness of PPRs and increasing the incentives to apply and implement PPRs; improving the monitoring of the implementation of damage mitigation measures; and the possibility to differentiate premiums and deductibles according to flood risk.     

Simulated interior floods and the flood experience in urban communities

The Hydrologic Engineering Center (HEC-1) model was used to construct synthetic hydrographs for isolated interior urban floods. Flood peak and lag time were very well preserved in simulated flows. Total volume was not adequately expressed. Lag time varied inversely with both urban development and storm intensity. Peak discharge varied with storm intensity, but this variability was well defined only at very high urbanization levels. An 175% increase in storm intensity produced a change of about 15% in peak discharge. Claims for flood damage correlated well with estimates of peak flow and lag time combined. Other measures of flood experience also correlated with the two features. Within the range of storms utilized, urban development factors consistently outranked storm intensity as a determining factor in flood damage.     

HYDROLOGICAL APPLICATIONS OF LANDSAT IMAGERY USED IN THE STUDY OF THE 1973 INDUS RIVER FLOOD,PAKISTAN1

ABSTRACT: During August and September 1973, the Indus River Valley of Pakistan experienced one of the largest floods on record, resulting in damages to homes, businesses, public works, and crops amounting to millions of rupees. Tremendous areas of lowlands were inundated along the Indus River and major tributaries. Landsat data made it possible to easily measure the extent of flooding, totaling about 20,000 km² within an area of about 400,000 km² south from the Punjab to the Arabian Sea. The Indus River data were used to continue experimentation in the development of rapid, accurate, and inexpensive optical techniques of flood mapping by satellite begun in 1973 for the Mississipi River floods. The research work on the Indus River not resulted in the development of more effective procedures for optical processing of flood data and synoptically depicting flooding, but also provided potentially valuable ancillary information concerning the hydrology of much of the Indus River Basin.     

APPLICATION OF RORB MODEL TO A CATCHMENT IN SINGAPORE1

ABSTRACT: Runoff Routing model (RORB) is a general model applicable to both rural and urban catchments. The performance of the model is illustrated through its simulation of flood runoff hydrographs in an urban catchment in Singapore. The essential feature of the model is the routing of rainfall excesses on subareas through some arrangement of concentrated storage elements, which represent the distribution of temporary storage of flood runoff on the watershed. This nonlinear routing procedure of the storage elements has two common parameters, k_c and m. With the limited data available, these two parameter values were determined through calibration runs. The same set of values of k_c and m were then used in the model to determine the runoff hydrographs of five other storms selected from the rainfall events between 1979 and 1981. It was found that the simulated runoff hydrographs matched reasonably well with the recorded hydrographs.     

CATCHMENT RESPONSE TIME AS A PREDICTOR OF FLOOD QUANTILES1

ABSTRACT: A regression analysis using a generalized least squares approach on flow data from the driftless area of Wisconsin indicates that the ratio of drainage area to time-to-peak is a good predictor of flood quantiles. The estimation of time-to-peak (or some other measure of basin response time) requires direct measurement of river stage and possibly rainfall at the site of which the quantiles are to be estimated. The cost-effectiveness of such an approach must yet be determined.     

1994年华南城市水灾的经验教训

本文概述了1994年华南洪灾的情况,指出水灾反映出城市防洪中存在的有关问题,并总结了防洪成功的经验,作为今后的借鉴。     

水灾害治理对种植业生产的影响

为了应对水灾对我国种植业生产的破坏，国家每年要投入大量资金用于防灾减灾工作，在对1980年以来我国种植业生产、自然灾害和水利建设的统计数据进行描述性分析的基础上，通过建立模型，定量分析了26年来我国救灾工作和各种防灾水利建设对种植业增长所起的作用，为我国进一步制定科学有效的国家防灾减灾政策提供参考。