The Experts below are selected from a list of 34305 Experts worldwide ranked by ideXlab platform
Witold F Krajewski - One of the best experts on this subject based on the ideXlab platform.
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exploring the effects of hillslope channel link dynamics and excess rainfall properties on the scaling structure of Peak Discharge
Advances in Water Resources, 2014Co-Authors: Tibebu B Ayalew, Witold F Krajewski, Ricardo Mantilla, Scott J SmallAbstract:Abstract Several studies revealed that Peak Discharges (Q) observed in a nested drainage network following a runoff-generating rainfall event exhibit power law scaling with respect to drainage area (A) as Q(A) = αAθ. However, multiple aspects of how rainfall-runoff process controls the value of the intercept (α) and the scaling exponent (θ) are not fully understood. We use the rainfall-runoff model CUENCAS and apply it to three different river basins in Iowa to investigate how the interplay among rainfall intensity, duration, hillslope overland flow velocity, channel flow velocity, and the drainage network structure affects these parameters. We show that, for a given catchment: (1) rainfall duration and hillslope overland flow velocity play a dominant role in controlling θ, followed by channel flow velocity and rainfall intensity; (2) α is systematically controlled by the interplay among rainfall intensity, duration, hillslope overland flow velocity, and channel flow velocity, which highlights that it is the combined effect of these factors that controls the exact values of α and θ; and (3) a scale break occurs when runoff generated on hillslopes runs off into the drainage network very rapidly and the scale at which the break happens is determined by the interplay among rainfall duration, hillslope overland flow velocity, and channel flow velocity.
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flood frequency analysis for nonstationary annual Peak records in an urban drainage basin
Advances in Water Resources, 2009Co-Authors: Gabriele Villarini, James A Smith, Francesco Serinaldi, Jerad D Bales, Paul D Bates, Witold F KrajewskiAbstract:Abstract Flood frequency analysis in urban watersheds is complicated by nonstationarities of annual Peak records associated with land use change and evolving urban stormwater infrastructure. In this study, a framework for flood frequency analysis is developed based on the Generalized Additive Models for Location, Scale and Shape parameters (GAMLSS), a tool for modeling time series under nonstationary conditions. GAMLSS is applied to annual maximum Peak Discharge records for Little Sugar Creek, a highly urbanized watershed which drains the urban core of Charlotte, North Carolina. It is shown that GAMLSS is able to describe the variability in the mean and variance of the annual maximum Peak Discharge by modeling the parameters of the selected parametric distribution as a smooth function of time via cubic splines. Flood frequency analyses for Little Sugar Creek (at a drainage area of 110 km 2 ) show that the maximum flow with a 0.01-annual probability (corresponding to 100-year flood Peak under stationary conditions) over the 83-year record has ranged from a minimum unit Discharge of 2.1 m 3 s - 1 km - 2 to a maximum of 5.1 m 3 s - 1 km - 2 . An alternative characterization can be made by examining the estimated return interval of the Peak Discharge that would have an annual exceedance probability of 0.01 under the assumption of stationarity ( 3.2 m 3 s - 1 km - 2 ) . Under nonstationary conditions, alternative definitions of return period should be adapted. Under the GAMLSS model, the return interval of an annual Peak Discharge of 3.2 m 3 s - 1 km - 2 ranges from a maximum value of more than 5000 years in 1957 to a minimum value of almost 8 years for the present time (2007). The GAMLSS framework is also used to examine the links between population trends and flood frequency, as well as trends in annual maximum rainfall. These analyses are used to examine evolving flood frequency over future decades.
Mingfeng Deng - One of the best experts on this subject based on the ideXlab platform.
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glacial lake inventory and lake outburst flood debris flow hazard assessment after the gorkha earthquake in the bhote koshi basin
Water, 2020Co-Authors: Mei Liu, Yong Zhang, Ningsheng Chen, Mingfeng DengAbstract:Glacial lake outburst floods (GLOF) evolve into debris flows by erosion and sediment entrainment while propagating down a valley, which highly increases Peak Discharge and volume and causes destructive damage downstream. This study focuses on GLOF hazard assessment in the Bhote Koshi Basin (BKB), where was highly developed glacial lakes and was intensely affected by the Gorkha earthquake. A new 2016 glacial lake inventory was established, and six unreported GLOF events were identified with geomorphic outburst evidence from GaoFen-1 satellite images and Google Earth. A new method was proposed to assess GLOF hazard, in which large numbers of landslides triggered by earthquake were considered to enter into outburst floods enlarge the Discharge and volume of debris flow in the downstream. Four GLOF hazard classes were derived according to glacial lake outburst potential and a flow magnitude assessment matrix, in which 11 glacial lakes were identified to have very high hazard and 24 to have high hazard. The GLOF hazard in BKB increased after the earthquake due to landslide deposits, which increased by 216.03 × 106 m3, and provides abundant deposits for outburst floods to evolve into debris flows. We suggest that in regional GLOF hazard assessment, small glacial lakes should not be overlooked for landslide deposit entrainment along a flood route that would increase the Peak Discharge, especially in earthquake-affected areas where large numbers of landslides were triggered.
Weihong Li - One of the best experts on this subject based on the ideXlab platform.
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response of glacial lake outburst floods to climate change in the yarkant river basin on northern slope of karakoram mountains china
Quaternary International, 2010Co-Authors: Yaning Chen, Changchun Xu, Yapeng Chen, Weihong LiAbstract:Based on the glacial flood events and climate change in the Yarkant River basin during the past 50 years, the study investigated the long-term change of temperature and precipitation, the characteristics of glacial floods, the origin of sudden flood release, the suggested flood mechanism of glacial lakes and the relationship between glacial floods and climate change. Results showed that there was an obvious increase in the temperature of the basin since 1987. Specifically in the mountainous area, the significantly increasing temperature in the summer and autumn seasons accelerated the melting rate of glaciers and caused glacial-lake burst. Sudden flood release occurred frequently. The frequency of glacial-lake outburst floods was 0.4 times/a during the period 1959-1986 and increased to 0.7 times/a during 1997-2006. Peak Discharge also increased. There were seven floods with Peak Discharge over 4000 m(3)/s from 1959-2006, and three occurred after 1997. The increasing frequency and magnitude of glacial outburst floods mirrored the effect of climate warming on glaciers. (C) 2010 Elsevier Ltd and INQUA. All rights reserved.
Efrat Morin - One of the best experts on this subject based on the ideXlab platform.
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controls of flash flood Peak Discharge in mediterranean basins and the special role of runoff contributing areas
Journal of Hydrology, 2018Co-Authors: Yair Rinat, Francesco Marra, Davide Zoccatelli, Efrat MorinAbstract:Abstract During the complex dynamic interactions between rainfall and basin properties, different portions of the basin produce runoff at different moments. Capturing this spatiotemporal variability is important for flood analysis, but knowledge of this subject is limited. The presented research aims at improving the understanding of runoff-contributing areas (RCA; hillslope sections from which water flows, reaches the stream network, and consequently the basin outlet) and at examining their relationship with the magnitude of a flash flood's Peak Discharge. A distributed hydrological model (GB-HYDRA) that enables computing RCA and flood Discharge was developed. The model was applied to four medium-size basins (18–69 km2) in a Mediterranean climate and 59 flash flood events were analyzed. The correlation between basin input flux (basin area multiplied by the basin maximal rain intensity averaged over the time of concentration) and output flux (observed Peak Discharge) was poor (R2 = 0.16). However, using a newly developed index, termed IRCA, to calculate the input flux accounting only for the RCA extent and rainfall intensity over it, resulted in a substantially higher correlation (R2 = 0.64) across a wide range of flood magnitudes. The highest correlation was found using a 50-min time window, which is shorter than the time of concentration. Flood events were categorized according to their magnitude and the differences of several factors among the groups were examined. Pre-storm soil moisture content was found to be similar for all event magnitudes; however, pre-Peak soil moisture content was substantially different between moderate and large–extreme events. Other important properties that differed between magnitudes were: RCA extent and its averaged rain intensity and ratio of convective rainfall. Finally, areas with land-uses characterized by low runoff potential became dominant and contributed mainly during large and extreme events. Although the RCA and its extent full potential is yet to be fulfilled, it is proposed as a significant tool for understanding processes of flash flood generation at the basin scale in future research.
Ioannis K Tsanis - One of the best experts on this subject based on the ideXlab platform.
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a method for estimating flash flood Peak Discharge in a poorly gauged basin case study for the 13 14 january 1994 flood giofiros basin crete greece
Journal of Hydrology, 2010Co-Authors: Aristeidis G Koutroulis, Ioannis K TsanisAbstract:Summary A method for estimating flash flood Peak Discharge, hydrograph, and volume in poorly gauged basins, where the hydrological characteristics of the flood are partially known, due to stage gauge failure, is presented. An empirical index is used to generate missing hourly rainfall data and hydrologic and hydraulic models performs the basin delineation, flood simulation, and flood inundation. The Peak Discharge, hydrograph, and volume, derived from the analysis of measured hydrographs in a number of non-flood causing rainfall events with operating stage gauge, were used for calibration and verification of the simulated stage-Discharge hydrographs. An empirical equation was developed in order to provide the Peak Discharge as a function of the total precipitation, its standard deviation, and storm duration. The Peak Discharge for a flash flood case based on the empirical equation was in close agreement with the results from a number of consolidated methods. These methods involved hydrological and hydraulic modeling and Peak flow estimates based on Manning’s equation and post flash flood measurements of the maximum water level observed at the control cross-section, for the 13–14 January 1994 flash flood in the Giofiros basin on the island of Crete, Greece. This method can be applied to other poorly gauged basins for floods with a stage higher than that defined by the rating curve.
