A Numerical Framework for Evaluating Flood Inundation Hazard under Different Dam Operation Scenarios—A Case Study in Naugatuck River

Abstract

Worldwide, many river floodplains contain critical infrastructure that is vulnerable to extreme hydrologic events. These structures are designed based on flood frequency analysis aimed at quantifying the magnitude and recurrence of the extreme events. This research topic focuses on estimating flood vulnerability at ungauged locations based on an integrative framework consisting of a distributed rainfall-runoff model forced with long-term (37 years) reanalysis meteorological data and a hydraulic model driven by high-resolution airborne LiDAR-derived terrain elevation data. The framework is applied to a critical power infrastructure located within Connecticut's Naugatuck River Basin. The hydrologic model reanalysis is used to derive 50-, 100-, 200-, and 500-year return period flood peaks, which are then used to drive Hydrologic Engineering Center's River Analysis System (HEC-RAS) hydraulic simulations to estimate the inundation risk at the infrastructure location under different operation strategies of an upstream reservoir. This study illustrates the framework's potential for creating flood maps at ungauged locations and demonstrates the effects of different water management scenarios on the flood risk of the downstream infrastructure. 500 years return period). Distributions used in frequency analysis vary, but in the U.S.A. engineering practice relies on the use of Log-Pearson Type III, which is recommended by the U.S. Water Resource Council [3]. Information regarding magnitude and frequency of occurrence of flooding events gathered through flood frequency analysis (FFA) is instrumental in mitigating losses associated with floods, particularly when designing hydraulic structures such as reservoirs and dams.Hydrologists have developed a number of methods to conduct FFA. These methods can broadly be classified into two groups: statistical approaches and rainfall-runoff modeling. For statistical approaches, statistical analysis or hydrological regionalization are used to analyze hydrological data within a basin, or transfer hydrological information from one or more homogenous gauged catchments to a neighboring or geographically/hydrologically similar basin [4][5][6]. However, the quality of the estimation in the basin is subject to the continuous length of flow observations of the basin or neighboring gauged basins, and potential nonstationarity of the historical flood trend. In an alternate approach, observed precipitation combined with various other meteorological forcing parameters are used to drive physically-based hydrologic and flood routing models to simulate surface flows [7], which can have longer time spans but can be affected by the biased peak estimation. Surface flows are made up of both overland and channel flow routing, which can either be handled separately by two models [8,9], or combined through a coupled model [10,11]. Hydrodynamic routing models simulate surface flows based on solutions to simplified shallow water equations like the kinematic wave [12] or diffusion wave equations [9]. Solutions t...

Sensitivity of flood frequency analysis to data record, statistical model, and parameter estimation methods: An evaluation over the contiguous United States

“…While RFFA offers a potential solution, it has to be highlighted that a fundamental prerequisite for its application is the identification of statistically homogeneous regions, which is far from being a straightforward task for applications at the scale of CONUS, where areas with large variability in climate and watershed characteristics (both natural and anthropogenic) are observed. Alternatively, future research for improving at-site FFA could therefore focus on two possible directions that aim to (a) generate long-term hydrologic information by combining reanalysis data set with distributed hydrological models (Cea & Fraga, 2018;Hardesty, Shen, Nikolopoulos, & Anagnostou, 2018) and (b) investigate new statistical approaches (Marani & Ignaccolo, 2015) that overcome the limitations from shortage of data set and obtain more reliable assessment of high quantiles.…”

Impact of compound flood event on coastal critical infrastructures considering current and future climate

“…To simulate the two synthetic Sandy and Florence hurricane events, we used the Weather Research and Forecasting (WRF) system (Powers et al, 2017;Skamarock et al, 2008). For the synthetic Hurricane Florence event, we used a hurricane track forecast by the National Oceanic and Atmospheric Administration (NOAA) that, as of 6 September 2018, according to the Global Forecast System (GFS) forecasts of the National Centers for Environmental Prediction (NCEP), showed landfall on Long Island and in Connecticut on 14 September as a category-1 hurricane (Higgins et al, 2000).…”

Dam Breach Size Comparison for Flood Simulations. A HEC-RAS Based, GIS Approach for Drăcșani Lake, Sitna River, Romania

“…HEC-RAS is a well-known and successfully used flood analysis tool, which can be applied with high efficiency in dam breach studies [25,34,57]. As is the case of this paper, the freely available HEC-RAS software was used (version 5.0.6), which was developed by U.S. Army Corps of Engineers (USACE).…”

“…Horrit and Bates have compared the simulation algorithms of 1D and 2D variants, by applying an error identification methodology for flood simulations in HEC-RAS, LISFLOOD-FP, and TELEMAC software, and have concluded that all models have proven sufficiently accurate, but have different responses when changing the friction parameters. Furthermore, they emphasize the fact that, no matter the quality of the input data, provided the user does not properly fit the data into the appropriate geometrical description of the model, the final results of the simulation will be considerably lower accuracy [31][32][33][34].…”