scholarly journals Numerical investigation of the performance of engineered barriers in reducing flood risk

2021 ◽  
Vol 337 ◽  
pp. 04003
Author(s):  
Alexandros L. Petalas ◽  
Aikaterini Tsiampousi ◽  
Lidija Zdravkovic ◽  
David M. Potts
Keyword(s):  
Flood Risk ◽  
Soil Layer ◽  
Urban Environments ◽  
Water Infiltration ◽  
Natural Soil ◽  
Water Storage Capacity ◽  
Run Off ◽  
London Clay ◽  
Parametric Analyses ◽  
Precipitation Events

In this paper, 2-dimensional, hydro-mechanically coupled finite element analyses are performed to assess the performance of an engineered barrier aimed at reducing flood risk in urban environments. The barrier consists of an unsaturated compacted soil layer and a drainage layer of a coarse granular material, constructed on top of the natural soil, in this case London clay. The barrier is vegetated so that its water storage capacity is renewed after each rainfall event. Sophisticated boundary conditions are used to simulate the effect of precipitation and evapotranspiration. The rainfall water infiltration and the initiation of water run-off during intense precipitation events are simulated. The effect of the hydraulic properties of the unsaturated soil layer on the performance of the system is investigated by means of parametric analyses. The effect of precipitation rate and geometry of the barrier is also discussed. Design recommendations for the properties of the compacted layer and the dimensions of the system are given at the end of the paper.

Physical and bacterial processes affecting suspended particulate matter in a tidal river

1998 ◽  
Vol 38 (6) ◽  
pp. 327-335
Author(s):  
Yasunori Kozuki ◽  
Yoshihiko Hosoi ◽  
Hitoshi Murakami ◽  
Katuhiro Kawamoto
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
River Mouth ◽  
Tidal River ◽  
Natural Soil ◽  
Size Change ◽  
Run Off ◽  
Suspended Particulate ◽  
And Behavior

In order to clarify the origin and behavior of suspended particulate matter (SPM) in a tidal river, variation of SPM in a tidal river was investigated with regard to its size and constituents. SPM was separated into three groups according to size. Change of contents of titanium and organic substances of each group of SPM was examined. SPM which was discharged by run-off was transported with decomposition and sedimentation in a tidal river. Concentration of SPM with a particle size greater than 0.45 μm increased due to resuspension in a tidal river. Origin of SPM with a size of less than 0.45 μm at upstream areas was from natural soil and most of such SPM which had been transported settled near a river mouth. It was determined from examination of the CN ratio and the ratio of the number of attached bacteria to free bacteria that SPM with a size greater than 1.0 μm at upstream areas was decomposing intensively. At the downstream areas, SPM with a size of less than 0.45 μm came from the sea. SPM with particle size greater than 1.0 μm consisted of plankton and substances which were decomposed sufficiently while flowing.

scholarly journals A review of modelling methodologies for flood source area (FSA) identification

2021 ◽  
Author(s):  
Amrie Singh ◽  
David Dawson ◽  
Mark Trigg ◽  
Nigel Wright
Keyword(s):  
Flood Risk ◽  
Risk Mitigation ◽  
Ground Cover ◽  
Source Area ◽  
Urban Environments ◽  
Weather Patterns ◽  
Complex Process ◽  
Average Annual Loss ◽  
Flood Source ◽  
Modelling Approaches

AbstractFlooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises.

Application of run-off model as a contribution to the torrential flood risk management in Topčiderska Reka watershed, Serbia

2016 ◽  
Vol 82 (3) ◽  
pp. 1743-1753 ◽  
Author(s):  
Ana M. Petrović ◽  
Jelena Kovačević-Majkić ◽  
Marko V. Milošević
Keyword(s):  
Risk Management ◽  
Flood Risk ◽  
Flood Risk Management ◽  
Run Off ◽  
Torrential Flood

Study of Digital Surface Data for Soils and Flood Risk Areas Mapping in Sudano-Sahelian Zone (Mayo-Danay Division, Far North Cameroon)

2021 ◽  
Vol 10 (1) ◽  
pp. 3473-3491
Author(s):  
TIKI Denis ◽  
◽  
BITOM Mamdem Lionelle ◽  
IBRAHIM Achille ◽  
SOUNYA Jean Boris ◽  
...  
Keyword(s):  
Spatial Data ◽  
Flood Risk ◽  
Multicriteria Analysis ◽  
Urban Environments ◽  
Careful Study ◽  
Risk Areas ◽  
Vertic Soils ◽  
Flooding Risk ◽  
Hazard Level ◽  
Excellent Tool

In general, living close to a river is advantage, but there is always of flooding risk, that recurrence in recent decades provokes serious material damage and loss of life. Thus, in order to protect environmental health, economic viability and human activity zones of Mayo-Danay, a careful study of components of natural environment, mainly soil, has proved essential. Clearly, use of GIS in management of natural disasters is most relevant method, designed on integration, Multicriteria Analysis (MCA) and spatial data. Thus, Digital Elevation Model is obtained by manual digitization of contour lines, in order to define the large pedological sets on which wells have been opened, profiles described, soil samples taken and analyzed in laboratory. Main results reveal that soils are sandy to clayey, with neutral and basic pH (7 to 8), high CEC and low organic matter. While, quartz is predominant, associated with smectites, illites, feldspars and iron oxyhydroxides. Updated soil map shows five soil units (1) vertisols with hydromorphic characters (26%), (2) tropical ferruginous soils (32%), (3) less evolved hydromorphic soils (15%), (4) halomorphic vertic soils (9%), and (5) hydromorphic vertic soils (18%). It is an excellent tool for work and research, that responds to agronomic and development problems. It is therefore an excellent tool for work and research, which responds to agronomic and development problems. The multi-criteria spatial analysis establishes hazard and vulnerability, crossing of which gives of flood risk areas map, according to hazard level, very high (12%), high (16%), moderate (14%), low (30%) and very low (28%) risks. For this purpose, it emerges that rainfall is relatively low (700 mm/year), but falls very abruptly during short periods, at high intensity with flows exceeding the infiltration capacities. Morphology of low-slope "yayrés" (280 m) (2‰) is bordered by high landscape (500 to 1400 m) that prevent flow of many rivers that converge into plain. Sandy soils dominated by quartz favor fast rising in water table, while very clayey soils governed by 2/1 clayey (smectites) whose behavior induce waterproofing and intense surface runoff that generate flooding. Evidently, land use change leads to transformation of natural spaces into agricultural and urban environments, which makes soils more compact and impermeable, favorable to flooding. Keywords Soil; Flood risks; Mapping; Mayo-Danay Division; Spatial data DOI: https://doi.org/10.23953/cloud.ijarsg.501

scholarly journals Organic Matter Clogging Results in Undeveloped Hardpan and Soil Mineral Leakage in the Rice Terraces in the Philippine Cordilleras

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3158
Author(s):  
Tomoyo Kurozumi ◽  
Yasushi Mori ◽  
Hiroaki Somura ◽  
Milagros O-How
Keyword(s):  
Organic Matter ◽  
Soil Analysis ◽  
Influencing Factor ◽  
Soil Layer ◽  
Organic Matter Content ◽  
Matter Content ◽  
Water Infiltration ◽  
Soil Conditions ◽  
Infiltration Process ◽  
Soil Nutrition

Rice terraces in Cordillera, Philippines, a world cultural heritage site, are threatened by the risk of collapse. It is crucial to manage these rice terraces for their conservation, while simultaneously practicing traditional farming. We examined the soil environment and investigated its effects on rice terrace conservation, by focusing on the hardpan condition; infiltration process, which is related to the collapse of rice terraces; and soil nutrition conditions in these sites. Field survey and soil analysis revealed that in areas where the hardpan was not sufficiently developed and water infiltration was effectively suppressed, organic matter content was significantly high, suggesting organic matter clogging. In these rice terraces, the amounts of P, K, Ca, and Mn were significantly low, showing the mineral leaching under reductive soil conditions. Therefore, hardpan formation, rather than organic matter clogging, is essential for the suppression of infiltration and prevention of potential terrace collapse. Because hardpan formation or organic matter clogging cannot be identified from the surface of flooded rice paddies, it is difficult to identify the influencing factor. Thus, we suggest that the hard soil layer should be checked before the planting season and drainage is allowed after the cropping season in the rainy season.

scholarly journals Development of an Apparent Recharge Coefficient (ARC) for Estimating Groundwater Storage Changes due to Precipitation Events Using Time Series Monitoring Data

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1675
Author(s):  
Jae Min Lee ◽  
Sunjoo Cho ◽  
Hyun A Lee ◽  
Nam C. Woo
Keyword(s):  
Water Resources ◽  
Groundwater Level ◽  
Global Climate ◽  
Soil Layer ◽  
Monitoring Data ◽  
Specific Yield ◽  
Groundwater Storage ◽  
Hydrogeological Characteristics ◽  
Sustainable Water Supply ◽  
Precipitation Events

Significant variation in the precipitation events caused by global climate change has made it difficult to manage water resources due to the increased frequency of unexpected droughts and floods. Under these conditions, groundwater is needed to ensure a sustainable water supply; thus, estimates of precipitation recharge are essential. In this study, we derived an apparent recharge coefficient (ARC) from a modified water table fluctuation equation to predict groundwater storage changes due to precipitation events. The ARC is calculated as the ratio of the recharge rate over the specific yield (R/Sy); therefore, it implicitly expresses variation in Sy. The ARC varies spatially and temporally, corresponding to the precipitation events and hydrogeological characteristics of unsaturated materials. ARCs for five monitoring wells from two basins in Korea in different seasons were calculated using a 10-year groundwater level and weather dataset for 2005–2014. Then, the reliability of the ARCs was tested by the comparison of the predicted groundwater level changes for 2015 and 2016 with observed data. The root mean square error ranged from 0.03 to 0.09 m, indicating that the predictions were acceptable, except for one well, which had thick clay layers atop the soil layer; the low permeability of the clay slowed the precipitation recharge, interfering with groundwater level responses. We performed a back-calculation of R from the Sy values of the study areas; the results were similar to those obtained via other methods, confirming the practical applicability of the ARC. In conclusion, the ARC is a viable method for predicting groundwater storage changes for regions where long-term monitoring data are available, and subsequently will facilitate advanced decision making for allocating and developing water resources for residents, industry, and groundwater-dependent ecosystems.

scholarly journals Influence of Living and Dead Roots of Gansu Poplar on Water Infiltration and Distribution in Soil

2020 ◽  
Vol 10 (10) ◽  
pp. 3593 ◽  
Author(s):  
Dashuai Zhang ◽  
Yao Dai ◽  
Lingli Wang ◽  
Liang Chen
Keyword(s):  
Preferential Flow ◽  
Storage Capacity ◽  
Water Storage ◽  
Infiltration Rate ◽  
Water Infiltration ◽  
Soil Porosity ◽  
Soil Permeability ◽  
Rapid Urbanization ◽  
Water Storage Capacity ◽  
Porosity And Permeability

During rapid urbanization, it is necessary to increase soil permeability and soil porosity for reducing urban runoff and waterlogging risk. Woody plants are known to increase soil porosity and preferential flow in soil via living roots growth and dead roots decay. However, the primary results of dead woody plant roots on soil porosity and permeability have been discussed based only on the hypotheses or assumptions of different researchers. In this study, living and dead roots (decayed under natural conditions for more than 5 years) of Gansu poplar trees (Populus gansuensis) were selected. They were selected to compare the influence between living and dead roots on water infiltration rate and soil porosity in a cylindrical container (diameter = 20 cm, height = 66 cm) under laboratory conditions. Results indicated that the steady-state water fluxes at the bottom of the containers without roots (control), with living roots, and with dead roots were 54.75 ± 0.80, 61.31 ± 0.61, and 55.97 ± 0.59 cm d−1, respectively. Both living roots and dead roots increased the water infiltration rates in soil and also increased the water storage capacity of soil. The water storage capacities of soil without roots, with living roots, and with dead roots were 0.279, 0.317, and 0.322 cm3 cm−3, respectively. The results from SEM indicated that smaller pores (30–50 μm) were in living roots and larger pores (100–1000 μm) were in dead roots. The soil permeability was increased by living roots possibly due to the larger channels generated on the surface of the roots; however, water absorbed into the dead roots resulted in greater water storage capacity.

scholarly journals Urban Flood Hazard Modeling Using Self-Organizing Map Neural Network

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2370 ◽  
Author(s):  
Rahmati ◽  
Darabi ◽  
Haghighi ◽  
Stefanidis ◽  
Kornejady ◽  
...  
Keyword(s):  
Neural Network ◽  
Flood Risk ◽  
Goodness Of Fit ◽  
Flood Hazard ◽  
Characteristic Curve ◽  
Urban Environments ◽  
Hazard Mapping ◽  
Self Organizing Map ◽  
Urban Flood ◽  
Self Organizing

Floods are the most common natural disaster globally and lead to severe damage, especially in urban environments. This study evaluated the efficiency of a self-organizing map neural network (SOMN) algorithm for urban flood hazard mapping in the case of Amol city, Iran. First, a flood inventory database was prepared using field survey data covering 118 flooded points. A 70:30 data ratio was applied for training and validation purposes. Six factors (elevation, slope percent, distance from river, distance from channel, curve number, and precipitation) were selected as predictor variables. After building the model, the odds ratio skill score (ORSS), efficiency (E), true skill statistic (TSS), and the area under the receiver operating characteristic curve (AUC-ROC) were used as evaluation metrics to scrutinize the goodness-of-fit and predictive performance of the model. The results indicated that the SOMN model performed excellently in modeling flood hazard in both the training (AUC = 0.946, E = 0.849, TSS = 0.716, ORSS = 0.954) and validation (AUC = 0.924, E = 0.857, TSS = 0.714, ORSS = 0.945) steps. The model identified around 23% of the Amol city area as being in high or very high flood risk classes that need to be carefully managed. Overall, the results demonstrate that the SOMN model can be used for flood hazard mapping in urban environments and can provide valuable insights about flood risk management.

Recommended urban storm water infiltration devices for different types of run-off under varying hydrogeological conditions

2008 ◽  
Vol 8 (4) ◽  
pp. 231-238 ◽  
Author(s):  
Patricia Göbel ◽  
Julia Zimmermann ◽  
Christoph Klinger ◽  
Holger Stubbe ◽  
Wilhelm G. Coldewey
Keyword(s):  
Water Infiltration ◽  
Storm Water ◽  
Hydrogeological Conditions ◽  
Run Off ◽  
Different Types ◽  
Urban Storm

scholarly journals Traffic and Tillage Effects on Soil Water Conservation and Winter Wheat Yield in the Loess Plateau, China

2013 ◽  
Vol 20 (3) ◽  
pp. 507-517
Author(s):  
Hao Chen
Keyword(s):  
Soil Water ◽  
Loess Plateau ◽  
Crop Yield ◽  
Water Conservation ◽  
Wheat Yield ◽  
Soil Layer ◽  
Water Infiltration ◽  
No Tillage ◽  
Yearly Variation ◽  
Controlled Traffic

Abstract In semi-humid Loess Plateau of northern China, water is the limiting factor for rain-fed crop yields. In this region, long-term traditional ploughing with straw removal has resulted in poor soil structure, water conservation and crop yield. Controlled traffic, combined with no-till and straw cover has been proposed to improve soil water conservation and crop yield. From 1999 to 2007, a field experiment on winter wheat was conducted in the dryland area of Loess Plateau of northern China, to investigate the effects of traffic and tillage on soil water conservation and crop yield. The field experiment was conducted using two controlled traffic treatments, no tillage with residue cover and no compaction (NTCN), shallow tillage with residue cover and no compaction (STCN) and one conventional tillage treatment (CK). Results showed that controlled traffic system reduced soil compaction in the top soil layer, increased soil water infiltration. The benefit on soil water infiltration translated into more soil conservation (16.1%) in 0-100 cm soil layer in fellow period, and achieved higher soil water availability at planting (16.5%), with less yearly variation. Consequently, controlled traffic system increased wheat yield by 12.6% and improved water use efficiency by 5.2%, both with less yearly variation, compared with conventional tillage. Within controlled traffic treatments, no tillage treatment NTCN showed better overall performance. In conclusion, controlled traffic combined with no-tillage and straw cover has higher performance on conserving water, improving yield and water use efficiency. It is a valuable system for soil and water conservation for the sustainable development of agriculture in dryland China.

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