scholarly journals Assessment of at‐site design flood estimation methods using an improved event‐based design flood estimation tool

2021 ◽  
Author(s):  
Ockert Jacobus Gericke
Keyword(s):  
Estimation Methods ◽  
Design Flood ◽  
Flood Estimation ◽  
Site Design ◽  
Event Based

scholarly journals Effects of Probability-Distributed Losses on Flood Estimates Using Event-Based Rainfall-Runoff Models

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2049
Author(s):  
Melanie Loveridge ◽  
Ataur Rahman
Keyword(s):  
Probability Distributions ◽  
Data Sets ◽  
Rainfall Runoff ◽  
Design Flood ◽  
Ungauged Catchments ◽  
Large Dataset ◽  
Loss Data ◽  
Flood Estimation ◽  
Historic Data ◽  
Event Based

Probability distributions of initial losses are investigated using a large dataset of catchments throughout Australia. The variability in design flood estimates caused by probability-distributed initial losses and associated uncertainties are investigated. Based on historic data sets in Australia, the Gamma and Beta distributions are found to be suitable for describing initial loss data. It has also been found that the central tendency of probability-distributed initial loss is more important in design flood estimation than the form of the probability density function. Findings from this study have notable implications on the regionalization of initial loss data, which is required for the application of Monte Carlo methods for design flood estimation in ungauged catchments.

scholarly journals Incorporating climate change in flood estimation guidance

2021 ◽  
Vol 379 (2195) ◽  
pp. 20190548 ◽  
Author(s):  
Conrad Wasko ◽  
Seth Westra ◽  
Rory Nathan ◽  
Harriet G. Orr ◽  
Gabriele Villarini ◽  
...  
Keyword(s):  
Climate Change ◽  
Flash Flood ◽  
Flood Hazard ◽  
Research Effort ◽  
Estimation Methods ◽  
Future Research ◽  
Significant Progress ◽  
Design Flood ◽  
Deep Uncertainty ◽  
Flood Estimation

Research into potential implications of climate change on flood hazard has made significant progress over the past decade, yet efforts to translate this research into practical guidance for flood estimation remain in their infancy. In this commentary, we address the question: how best can practical flood guidance be modified to incorporate the additional uncertainty due to climate change? We begin by summarizing the physical causes of changes in flooding and then discuss common methods of design flood estimation in the context of uncertainty. We find that although climate science operates across aleatory, epistemic and deep uncertainty, engineering practitioners generally only address aleatory uncertainty associated with natural variability through standards-based approaches. A review of existing literature and flood guidance reveals that although research efforts in hydrology do not always reflect the methods used in flood estimation, significant progress has been made with many jurisdictions around the world now incorporating climate change in their flood guidance. We conclude that the deep uncertainty that climate change brings signals a need to shift towards more flexible design and planning approaches, and future research effort should focus on providing information that supports the range of flood estimation methods used in practice. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks'.

The influence of soil moisture conditions on the spatio-temporal variability of event rainfall-runoff coefficients in UK catchments

2021 ◽  
Author(s):  
Yanchen Zheng ◽  
Ross Woods ◽  
Jianzhu Li ◽  
Ping Feng
Keyword(s):  
Soil Moisture ◽  
Temporal Variability ◽  
Estimation Methods ◽  
Runoff Coefficient ◽  
Rainfall Runoff ◽  
Design Flood ◽  
Ungauged Catchments ◽  
Flood Estimation ◽  
Spatio Temporal ◽  
Moisture Conditions

<p>Since the bias and uncertainties of the current design flood estimation methods for ungauged catchments are inevitable, estimation of the design flood in ungauged catchments still remains an unsolved problem. The derived distribution approach appears to be the one of the promising design flood estimation methods, as this method can improve the understanding on which processes contribute most to flood in ungauged catchments. Generally, the distribution of rainfall characteristics and lumped rainfall-runoff modelling was incorporated to estimate the flood magnitude in this method. However, we should note that rainfall is not the only driving factor of flood events. Soil moisture conditions are also an important driving factor affecting the rainfall-runoff transformation, and may even control rainfall-runoff coefficients to a higher degree than does rainfall. Hence, here we perform soil moisture analysis at national scale by employing GLDAS-Noah datasets, and link this to observed event runoff coefficients from a large sample of UK catchments. The relationship between soil moisture conditions and rainfall-runoff coefficient was explored to analyse the spatio-temporal variability of runoff coefficient. This study laid the foundation for further development of a practical derived distribution method, by considering the statistical distribution of rainfall-runoff coefficients and the influence of soil moisture conditions.</p>

scholarly journals Design Flood Estimation Methods for Cascade Reservoirs Based on Copulas

Water ◽  
2018 ◽  
Vol 10 (5) ◽  
pp. 560 ◽  
Author(s):  
Shenglian Guo ◽  
Rizwan Muhammad ◽  
Zhangjun Liu ◽  
Feng Xiong ◽  
Jiabo Yin
Keyword(s):  
Estimation Methods ◽  
Design Flood ◽  
Cascade Reservoirs ◽  
Flood Estimation

Revisiting design flood estimation of Nam River Dam basin considering climate change

2016 ◽  
Vol 49 (8) ◽  
pp. 719-729
Author(s):  
Hyunseung Lee ◽  
Taesam Lee ◽  
Taewoong Park ◽  
Chanyoung Son
Keyword(s):  
Climate Change ◽  
Design Flood ◽  
Flood Estimation

Flood estimation for ungauged catchments in the Philippines using multiple archival data records

2021 ◽  
Author(s):  
Trevor Hoey ◽  
Pamela Tolentino ◽  
Esmael Guardian ◽  
Richard Williams ◽  
Richard Boothroyd ◽  
...  
Keyword(s):  
Catchment Area ◽  
Daily Rainfall ◽  
The Philippines ◽  
Data Availability ◽  
Estimation Methods ◽  
Annual Maximum ◽  
Ungauged Catchments ◽  
Pearson Type ◽  
Flood Estimation ◽  
Best Fit

<p>Assessment of flood and drought risks, and changes to these risks under climate change, is a critical issue worldwide. Statistical methods are commonly used in data-rich regions to estimate the magnitudes of river floods of specified return period at ungauged sites. However, data availability can be a major constraint on reliable estimation of flood and drought magnitudes, particularly in the Global South. Statistical flood and drought magnitude estimation methods rely on the availability of sufficiently long data records from sites that are representative of the hydrological region of interest. In the Philippines, although over 1000 locations have been identified where flow records have been collected at some time, very few records exist of over 20 years duration and only a limited number of sites are currently being gauged. We collated data from three archival sources: (1) Division of Irrigation, Surface Water Supply (SWS) (1908-22; 257 sites in total); (2) Japan International Cooperation Agency (JICA) (1955-91; 90 sites); and, (3) Bureau of Research and Standards (BRS) (1957-2018; 181 sites). From these data sets, 176 contained sufficiently long and high quality records to be analysed. Series of annual maximum floods were fit using L-moments with Weibull, Log-Pearson Type III and Generalised Logistic Distributions, the best-fit of these being used to estimate 2-, 10- and 100-year flood events, Q<sub>2</sub>, Q<sub>10</sub> and Q<sub>100</sub>. Predictive equations were developed using catchment area, several measures of annual and extreme precipitation, catchment geometry and land-use. Analysis took place nationally, and also for groups of hydrologically similar regions, based on similar flood growth curve shapes, across the Philippines. Overall, the best fit equations use a combination of two predictor variables, catchment area and the median annual maximum daily rainfall. The national equations have R<sup>2</sup> of 0.55-0.65, being higher for shorter return periods, and regional groupings R<sup>2</sup> are 0.60-0.77 for Q<sub>10</sub>. These coefficients of determination, R<sup>2</sup>, are lower than in some comprehensive studies worldwide reflecting in part the short individual flow records. Standard errors of residuals for the equations are between 0.19 and 0.51 (log<sub>10</sub> units), which lead to significant uncertainty in flood estimation for water resource and flood risk management purposes. Improving the predictions requires further analysis of hydrograph shape across the different climate types, defined by seasonal rainfall distributions, in the Philippines and between catchments of different size. The results here represent the most comprehensive study to date of flood magnitudes in the Philippines and are being incorporated into guidance for river managers alongside new assessments of river channel change across the country. The analysis illustrates the potential, and the limitations, for combining information from multiple data sources and short individual records to generate reliable estimates of flow extremes.</p>

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