Susceptibility To Flooding Research Articles

Influence of drainage network and compensatory techniques on urban flooding susceptibility.

Urban flooding due to accelerated urbanization and the resulting drainage problems have become a worldwide issue and the subject of several studies in recent decades. Alternative and holistic approaches such as sustainable drainage systems have been gaining prominence. Compensatory techniques represent one of these promising alternatives for managing flooding risk in the transition to regenerative urban environments. The goal of this study is to assess the effect of a drainage network together with compensatory techniques on the susceptibility to urban flooding in Campeche District. This study applies the analytical hierarchy process together with a consistency analysis, using overlapping influential parameters in three scenarios. The results show that introducing a drainage system decreases the susceptibility to urban flooding in approximately 27% of Campeche District. In general, considering the absence of a drainage network, it is concluded that its implementation together with compensatory structures provides a reduction of approximately 32% in the susceptibility to urban flooding. It should be noted that, although costly, interventions for the implementation of a drainage infrastructure associated with compensatory techniques are extremely important for disaster reduction and sustainable development.

Morphometric Analysis of the southern Al Jabal Al Akhdar Watersheds NE Libya

The study aimed to quantify the morphometric characteristics of 11 watersheds in south Al Jabal Al Akhdar area (Green Mountain) located on northeast Libya. Where Digital Elevation Model (DEM) data of 1 arcsec resolution for the study area downloaded from USGS Earth Explorer and processed to extract the watershed attributes using ArcGIS software. In addition, the linear, areal, and relief aspects parameters and indices were computed. The stream number for the watersheds varies from first orders to seventh orders, where a large number of streams was found in the first, second, and third orders. Drainage networks of the watersheds are a dendritic pattern reflects the subsurface lithology. The total lengths of streams in the study area are 35757.8 km. Also, the correlation coefficients which calculated for the relationship between the stream number and the stream count and lengths showed strong inverse relation. Moreover, observed bifurcation ratio for the watersheds considered as low with exception of the seventh order in some watersheds, where the streams tend to be braided due to the stream runoff through the depositional zone that consisting of recent uncompacted fluvial deposits. Drainage densities in the study area are coarse which indicated the much susceptibility to flooding and soil erosion. Where the drainage texture in the study area mostly is very coarse with the exception of some watersheds those are considered as coarse texture. Stream frequencies show very low values. Furthermore, the length of overland flow classified as moderate. The results of relief aspects computation show variation among the watersheds from high to low values. For the ruggedness number values, all watersheds show sharp morphology. Finally, The morphometric characteristics of the watersheds show moderate geomorphologic characteristics, stability in tectonic geology, and homogenous lithology, also the watersheds have intermediate to low flooding susceptibility but in case of heavy rainstorms a very strong flash flood may occur, as the upper stream areas of the watersheds prevail high risk of soil erosion, therefore flood protection ,and soil conservation measures are crucially demanded in the study area especially in the northern parts.

Assessment of Flash-Flood Hazard in Arid Watersheds of Jordan

Flash flood hazard initiated by heavy rainstorms is common in arid Jordan, and often has induced immense damage to life and infrastructures. The current study presents a flash flood assessment for Wadi Rajil (northern Jordan) and Wadi Wuheida (southern Jordan) watersheds using ASTER DEM, GIS, and geomorphic field observation. A total of 23 morphometric parameters of paramount relation to flash flood risk estimation were extracted and calculated using ASTER DEM, GIS, and mathematical formulae developed for this purpose. Two methods were employed to assess flash floods and to generate flooding risk susceptibility maps. The first method is El-Shamy’s approach, and the second is the morphometric hazard degree assessment method. Consequently, sub-basins with high and extreme flooding susceptibility were demarcated and displayed spatially using GIS. The maps so produced are meant to help planners and decision makers to devise appropriate plans to mitigate harmful flooding impacts, and to deal with flooding hazards.

Morphometric Analysis and Flash Floods Assessment for Drainage Basins of the Ras En Naqb Area, South Jordan Using GIS

Morphometric analysis and flash floods assessment were conducted for the watersheds of Ras En Naqb escarpment, south Jordan. The study area comprises of twelve small watersheds occupying the faulted-erosional slopes, and the dip slopes. The drainage network shows that dendritic and sub-dendritic patterns dominated the dip slopes, whereas trellis pattern characterized the faulted-erosional slopes. Stream orders range from fourth to sixth order. The mean bifurcation ratios vary between 4.2 and 5.38 for the dip slope basins, and between 3.5 and 5.0 for the faulted-erosional slope watersheds, indicating a noticeable influence of structural disturbances (i.e., faulting and uplifting), and rejuvenation of drainage networks. All watersheds have short basin lengths, ranging from 23.8 km to 42.2 km for the dip slope basins, and between 15.3 km and 45.4 km for the faulted-erosional slope catchments. This is indicative of high flooding susceptibility associated with heavy rainstorms of short duration. The circularity ratios range from 0.177 to 0.704 which denote that the catchments are moderately circular on the faulted-erosional slopes, and to some extent elongated on the dip slopes. The length of overland flow values ranges from 0.854 to 0.924 for the dip slope catchments, whereas LO values for the faulted-erosional slopes vary from 0.793 to 0.945 denoting steep slopes and shorter paths on both dip slope and faulted-erosional slope watersheds. Values of stream frequency range from 1.509 to 1.692 for the dip slope, and from 1.688 to 2.0 for the faulted-erosional slope catchments. FS values are also indicative of slope steepness, low infiltration rate, and high flooding potential. The watersheds of the dip slopes show lower values of form factor varying from 0.079 to 0.364, indicating elongated shape and suggesting a relatively flat hydrograph peak for longer duration. Similarly, values of Dd are high for catchments on the dip slope basins (1.709 - 1.85) and the faulted-erosional slope watersheds (1.587 - 2.0) indicating highly dissected topography, high surface runoff, low infiltration rate, and consequently high flooding potential. Furthermore, high relief values exist, ranging from 388 m to 714 m for the dip slope basins, and from 421 m to 846 m for the faulted-erosional slope catchments indicting high relief and steep slopes. Morphometric analysis, and flash flood assessment suggest that ten watersheds (83.3%) are categorized under high and intermediate flooding susceptibility, and the faulted-erosional slope catchments are more hazardous in terms of flooding. Thus the protection of Ma’an, El Jafr rural Bedouin settlements, and Amman-Aqaba highway from recurrent flooding is essential to ensure sustainable future development in Ras En Naqb-Ma’an area.

Hydraulic stream network conditioning by a tectonically induced, giant, deep-seated landslide along the front of the Apennine chain (south Italy)

Abstract. The tectonic stresses that produced the uplift of Apennine chain ridge in southern Italy generated advanced buried thrusts of allochthonous deposits that induced deformations of foredeep deposits. This thrust may cause giant, deep-seated landslides at the front of the chain. Starting from a specific case history in low Biferno Valley, this work presents how giant, deep-seated landslides along the front of the chain may be generated by the thrust of allochthonous nappe of the chain. In addition, the influence that these huge phenomena may have on landslide and flood susceptibility and on natural hazards of the involved area is analysed. The work presents an interpretation of local morphology and stream network paths of low Biferno Valley as a consequence of a giant, deep-seated landslide affecting the right side of the valley. The proposed interpretation is supported by numerical geomorphological analyses of the area at stake. It is shown how both the morphologies of the catchments of the river Biferno and its tributary Cigno and stream paths are strongly conditioned by this large, deep-seated landslide. This landslide deviates the stream paths affecting both the flooding susceptibility of low Biferno Valley and landslide susceptibility on the left side of Biferno Valley.

The use of elevation models to predict areas at risk of groundwater flooding

Abstract Groundwater flooding, which occurs when the groundwater table rises in response to exceptional recharge rates either to the ground surface or to a point where subsurface infrastructure is affected, has been recognized as a significant issue with real economic impacts. A methodology has been developed to produce maps of groundwater flooding susceptibility, using geological and hydrogeological data. While good geological map data are available in digital form for England and Wales, there are much less data on water levels. These levels are usually measured during the construction of water boreholes, and while there is a national groundwater level monitoring network for regulatory purposes, at a national level data are sparse. To assist in developing a comprehensive map of water levels, the British Geological Survey (BGS) has adopted a number of strategies for data interpolation for areas with limited water level data and a surface has been derived from a terrain model by considering interactions between groundwater and surface water in rivers and lakes. When comparing the calculated levels against the available field measurements, a high correlation was found to exist. However, it was considered that in areas where bedrock aquifers dominate, this interpolated surface was probably inaccurate, and so refinements were developed to improve the modelled water levels surfaces. The resulting groundwater levels have been used to develop maps of areas where shallow groundwater may pose a risk. With potential changes in groundwater recharge postulated as a result of global climate change, identifying areas prone to flooding from groundwater, or areas where groundwater is likely to increase the impact of surface water flooding, is increasingly important.

Interferência do excesso de água no solo e componentes de produção em beterraba

O experimento, realizado no Laboratório de Hidráulica e Irrigação da UFC, em Fortaleza, de julho a setembro de 2002, utilizou tanques de drenagem de nível freático constante para verificar a relação existente entre o Índice Diário de Estresse (IDS) e componentes de produção em beterraba, cultivar Early Wonder. O delineamento experimental foi inteiramente casualizado, com cinco tratamentos (0; 120; 180; 240 e 300 cm de soma de excesso de água no solo (SEW30)), quatro repetições e parcelas de 48 plantas úteis. O coeficiente de suscetibilidade da cultura (SC) ao encharcamento foi calculado para o primeiro, segundo e terceiro estádios de desenvolvimento, submetendo-se as plantas a um encharcamento de quatro dias de duração com lençol freático à profundidade de 0,10 m, em cada um desses estádios. Avaliou-se o diâmetro médio do hipocótilo (DM), o comprimento da maior folha (CMF) e a produtividade (PT). Somente DM apresentou variação significativa em função do excesso de água, passando de 5,51 quando não houve estresse para 4,71 quando o estresse foi aplicado no último estádio de desenvolvimento. Os valores obtidos para SC para o primeiro, segundo e terceiro estádios de crescimento foram de 0,10; 0,16 e 0,28, respectivamente. O produto do valor ponderado de SC (0,17) juntamente com os respectivos valores de SEW30 (0; 120; 180; 240 e 300 cm) permitiu calcular, para cada tratamento, os valores de índice diário de estresse (IDS), de 0; 20,4; 30,6; 40,8 e 51,0, respectivamente. Somente o tratamento com maior nível de estresse (lençol freático a 5 cm de profundidade) diferiu estatisticamente (p<0,05) da testemunha sem estresse: DM passou de 5,51 na testemunha para 4,00; CMF foi reduzido 43,35 para 26,10 e; a produtividade caiu de 40,4 para 15,8 t ha-1). A estimativa de IDS que produziu os maiores valores para produtividade (41,8 t ha-1) foi de 12,8 cm, obtida através de regressão quadrática (r² = 0,87).