Impact of urbanization on desert flash flood generation

2020 ◽  
Vol 13 (12) ◽  
Author(s):  
Duaa Almousawi ◽  
Jaber Almedeij ◽  
Abdullah A. Alsumaiei
Keyword(s):  
Flash Flood ◽  
Flood Generation ◽  
Impact Of Urbanization

scholarly journals Convective rainfall in a dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

2017 ◽  
Vol 21 (10) ◽  
pp. 5165-5180 ◽  
Author(s):  
Idit Belachsen ◽  
Francesco Marra ◽  
Nadav Peleg ◽  
Efrat Morin
Keyword(s):  
Red Sea ◽  
Flash Flood ◽  
Eastern Mediterranean ◽  
Stochastic Simulations ◽  
Mean Annual Precipitation ◽  
Runoff Generation ◽  
Radar Rainfall ◽  
Study Region ◽  
Convective Rain ◽  
Flood Generation

Abstract. Spatiotemporal patterns of rainfall are important characteristics that influence runoff generation and flash-flood magnitude and require high-resolution measurements to be adequately represented. This need is further emphasized in arid climates, where rainfall is scarce and highly variable. In this study, 24 years of corrected and gauge-adjusted radar rainfall estimates are used to (i) identify the spatial structure and dynamics of convective rain cells in a dry climate region in the Eastern Mediterranean, (ii) to determine their climatology, and (iii) to understand their relation with the governing synoptic systems and with flash-flood generation. Rain cells are extracted using a segmentation method and a tracking algorithm, and are clustered into three synoptic patterns according to atmospheric variables from the ERA-Interim reanalysis. On average, the cells are about 90 km2 in size, move 13 m s−1 from west to east, and live for 18 min. The Cyprus low accounts for 30 % of the events, the low to the east of the study region for 44 %, and the Active Red Sea Trough for 26 %. The Active Red Sea Trough produces shorter rain events composed of rain cells with higher rain intensities, longer lifetime, smaller area, and lower velocities. The area of rain cells is positively correlated with topographic height. The number of cells is negatively correlated with the distance from the shoreline. Rain-cell intensity is negatively correlated with mean annual precipitation. Flash-flood-related events are dominated by rain cells of large size, low velocity, and long lifetime that move downstream with the main axis of the catchments. These results can be further used for stochastic simulations of convective rain storms and serve as input for hydrological models and for flash-flood nowcasting systems.

scholarly journals Convection-permitting regional climate simulations for representing floods in small and medium sized catchments in the Eastern Alps

2018 ◽  
Author(s):  
Christian Reszler ◽  
Matthew Blasie Switanek ◽  
Heimo Truhetz
Keyword(s):  
Regional Climate Model ◽  
Bias Correction ◽  
Climate Models ◽  
Climate Model ◽  
Flash Flood ◽  
Regional Climate ◽  
Eastern Alps ◽  
Small Scale ◽  
Distributed Hydrological Model ◽  
Flood Generation

Abstract. Small scale floods are a consequence of high precipitation rates in small areas that can occur along frontal activity and convective storms. This situation is expected to become more severe due to a warming climate, when single precipitation events resulting from deep convection become more intense (Super Clausius-Clapeyron effect). Regional climate model (RCM) evaluations and inter-comparisons have shown that there is evidence that an increase in regional climate model resolution and in particular, at the convection permitting scale, will lead to a better representation of the spatial and temporal characteristics of heavy precipitation at small and medium scales. In this paper, the benefit of grid size reduction and bias correction in climate models are evaluated in their ability to properly represent flood generation in small and medium sized catchments. The climate models are coupled with a distributed hydrological model. The study area is the Eastern Alps, where small scale storms often occur along with heterogeneous rainfall distributions leading to a very local flash flood generation. The work is carried out in a small multi-model (ensemble) framework using two different RCMs (CCLM and WRF) in different grid sizes. Bias correction is performed by the use of the novel Scaled Distribution Mapping (SDM) method. The results show, that for small catchments (

scholarly journals Flash-flooding of Ephemeral Streams in the Context of Climate Change

2020 ◽  
Author(s):  
A.M. Camarasa-Belmonte
Keyword(s):  
Climate Change ◽  
River Water ◽  
Flood Control ◽  
Environmental Changes ◽  
Hydrological Cycle ◽  
Flash Flood ◽  
Intermittent Flow ◽  
Ephemeral Streams ◽  
Basin Scale ◽  
Flood Generation

Ephemeral streams, which are more extended than expected, entail a significant flood risk. Historically they have been underestimated due to their intermittent flow and the lack of knowledge on their hydro-geomorphology. Currently, European legislation recognizes their associated risk and supports research into them, adapting the scale and methodology to their characteristics. Based on the compilation of various works carried out in four Valencian catchments (Eastern Spain), this paper approaches the key questions of rainfall-runoff conversion and flood generation in ephemeral streams, taking into account their hydro-geomorphological specificity. Moreover, the consequences which derive from current environmental changes are addressed in the wider scale of Júcar River Water Authority.The study is based on 5-minute data, registered by the SAIH-Júcar network (Authomatic Hydrological Information System). The investigation has been conducted in two phases. Firstly, key issues determining flash-flood generation at basin scale have been addressed, based on the study of 138 floods, registered between 1989 and 2018, in four Valencian ephemeral streams (Barranc del Carraixet, Rambla de Poyo, Riu Vernissa and Rambla de Gallinera). Secondly, concerning a broader scale (Júcar River Water Authority), the evolution of 698 rain episodes (1989-2007) has been analysed. Finally, the consequences that environmental changes (climatic, anthropogenic and morphogenetic) might mean for flash-flood generation have been discussed.The results show how environmental changes point towards an increase in risk to the detriment of resource. Rain episodes tend to increase in intensity and decrease accumulated precipitation. As a consequence, hydrological connectivity will become more dependent on rain intensity, thus reducing runoff thresholds and basin response times. Anthropic changes enhance this behaviour, reducing infiltration and increasing surface runoff and erosion, while accelerating the hydrological cycle. An increase in process-form disequilibrium in Mediterranean catchments can be expected due to the increase in morphogenetic phases (because of the intensification of events) and a decrease in the efficiency of low-magnitude recovery episodes.Consequently, the behaviour of ephemeral-streams under current climate change conditions points firstly to an increase in intense flash-flood events, which will be difficult to manage with the current flood control measures, and secondly an increase in the general aridity conditions of catchments.

scholarly journals Evaluation of Hydrological and Hydraulic Models Applied in Typical Mediterranean Ungauged Watersheds Using Post-Flash-Flood Measurements

Hydrology ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 12 ◽  
Author(s):  
Aristeidis Kastridis ◽  
Dimitrios Stathis
Keyword(s):  
Goodness Of Fit ◽  
Flash Flood ◽  
Hydraulic Models ◽  
Rain Gauges ◽  
Critical Success ◽  
Small Watersheds ◽  
Flood Simulations ◽  
Flood Generation ◽  
Analysis System ◽  
Ungauged Watersheds

In this paper, three different flash floods episodes were analyzed, which occurred in October 2006, February 2010, and June 2018 in the Chalkidiki peninsula (North Greece). The Soil Conservation Service (SCS) model and a revised assessment of the CN parameter were applied to estimate the flood hydrographs, and Hydrologic Engineering Center’s-River Analysis System (HEC-RAS) software was used for the flood simulations. Initially, hydrological and hydraulic models were calibrated at Vatonias watershed (240.90 km2, North Greece), where three rain gauges and one water level station are located. Vatonias is located very close to the Stavros ungauged watersheds and presents similar geomorphology and land use conditions. The effectiveness and accuracy of the methodology were validated using post-flash-flood measurements. The root mean square error goodness of fit was used to compare the observed and simulated flood depths. Critical success index was calculated for the assessment of the accuracy of observed and modeled flooded areas. The results showed that the dense forest vegetation was not capable of preventing the flash flood generation or reducing the peak discharge, especially in small watersheds characterized by short concentration times. The main cause of flash flood generation was the human interference that influenced the hydraulic characteristics of streams and floodplains. The revised assessment of the CN parameter enhanced the estimation and spatial distribution of CN over the entire watershed. The results revealed that the proposed methodology could be a very useful tool to researchers and policy makers for flood risk assessment of higher accuracy and effectiveness in ungauged Mediterranean watersheds.

scholarly journals Does Population Affect the Location of Flash Flood Reports?

2016 ◽  
Vol 55 (9) ◽  
pp. 1953-1963 ◽  
Author(s):  
Rebecca D. Marjerison ◽  
M. Todd Walter ◽  
Patrick J. Sullivan ◽  
Stephen J. Colucci
Keyword(s):  
New York ◽  
Hydraulic Conductivity ◽  
Flash Flood ◽  
Weather Forecast ◽  
Flash Floods ◽  
Saturated Hydraulic Conductivity ◽  
Storm Events ◽  
Actual Distribution ◽  
Impervious Area ◽  
Flood Generation

AbstractFlash floods cause more fatalities than any other weather-related natural hazard and cause significant damage to property and infrastructure. It is important to understand the underlying processes that lead to these infrequent but high-consequence events. Accurately determining the locations of flash flood events can be difficult, which impedes comprehensive research of the phenomena. While some flash floods can be detected by automated means (e.g., streamflow gauges), flash floods (and other severe weather events) are generally based on human observations and may not reflect the actual distribution of event locations. The Storm Data–Storm Events Database, which is produced from National Weather Service reports, was used to locate reported flash floods within the forecast area of the Binghamton, New York, Weather Forecast Office between 2007 and 2013. The distribution of those reports was analyzed as a function of environmental variables associated with flood generation including slope, impervious area, soil saturated hydraulic conductivity ksat, representative rainfall intensity, and representative rainfall depth, as well as human population. A spatial conditional autoregressive model was used to test the hypothesis that flash flood reports are made more frequently in areas with higher populations, even when other flood-generating processes are considered. Slope, soil saturated hydraulic conductivity, and impervious area are significant predictors of flash flood reports. When population is added as a predictor, the model is similarly robust, but impervious area and ksat are no longer significant predictors. These results may challenge the assumption that flash flood reports are strongly biased by population.

Initial soil moisture effects on flash flood generation – A comparison between basins of contrasting hydro-climatic conditions

2016 ◽  
Vol 541 ◽  
pp. 206-217 ◽  
Author(s):  
M.G. Grillakis ◽  
A.G. Koutroulis ◽  
J. Komma ◽  
I.K. Tsanis ◽  
W. Wagner ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Flash Flood ◽  
Climatic Conditions ◽  
Initial Soil Moisture ◽  
Moisture Effects ◽  
Initial Soil ◽  
Flood Generation

scholarly journals Convective rainfall in dry climate: relations with synoptic systems and flash-flood generation in the Dead Sea region

2017 ◽  
Author(s):  
Idit Belachsen ◽  
Francesco Marra ◽  
Nadav Peleg ◽  
Efrat Morin
Keyword(s):  
Red Sea ◽  
Flash Flood ◽  
Eastern Mediterranean ◽  
Stochastic Simulations ◽  
Mean Annual Precipitation ◽  
Runoff Generation ◽  
Radar Rainfall ◽  
Study Region ◽  
Convective Rain ◽  
Flood Generation

Abstract. Space-time patterns of rainfall are important characteristics that influence runoff generation and flash-flood magnitude and require high-resolution measurements to be adequately represented. This need is further emphasized in arid climates, where rainfall is scarce and highly variable. In this study, 24 years of corrected and gauge-adjusted radar rainfall estimates are used to identify spatial structure and dynamics of convective rain cells in a dry climate region in the Eastern Mediterranean, to determine their climatology, and to understand their relation with the governing synoptic systems and with flash-flood generation. Rain cells are extracted using a segmentation method and a tracking algorithm and are clustered into three synoptic patterns according to atmospheric variables from ERA-Interim reanalyses. On average, they are 90 km2 in size, move 13 m s−1 from west to east, and live 18 minutes. Cyprus low accounts for 30 % of the events, low to the east of the study region for 44 % and Active Red Sea Trough for 26 %. Active Red Sea Trough produces shorter rain events composed of rain cells with higher rain intensities, longer lifetime, smaller area and lower velocities. The area of rain cells is positively correlated with topographic height. The number of cells is negatively correlated with the distance from the shoreline. ‎Rain cell intensity is negatively correlated with mean annual precipitation. Flash flood related events are dominated by rain cells of large size, low velocity and long lifetime that move downstream with the main axis of the catchments. These results can be further used for stochastic simulations of convective rain storms and serve as input for hydrological models and for flash-flood nowcasting systems.

“Land fever” and “Bankruptcy”: Social Problems in Hanoi’s Urbanizing Peri-urban Communities

2019 ◽  
Vol 5 (5) ◽  
pp. 550-562
Keyword(s):  
Rural Communities ◽  
Urban Communities ◽  
Agricultural Production ◽  
Social Problems ◽  
Social Issues ◽  
Field Research ◽  
Credit Market ◽  
Urbanization Process ◽  
Impact Of Urbanization ◽  
The Impact

Drawn upon field research in two peri-urban villages of Hanoi in 2014 and short re-visits recently, the research examines the widespread of gambling and other social issues in Hanoi’s urbanizing peri-urban communities which happened concurrently with the phenomenon of “land fever,” and at the time local villagers received compensation from land appropriation. The article aims to understand the impact of urbanization on these communities and the interface between urbanization and the increase of social problems. It argues that gambling, drug use, and other social problems have been existing in Vietnamese rural communities long before; however, when urbanization came, some people have higher chances to engage in these activities. Those are villagers who want to transform quickly into entrepreneurs or bosses by joining the “black credit” market and gambling. Together with middle-aged and old farmers who greatly relied on agricultural production and face difficulties in transforming their occupation, they formed the group of losers in the urbanization process. Received 6th January 2019; Revised 26th April 2019; Accepted 15th May 2019

Sign in / Sign up

Export Citation Format

Share Document