- An Open Source GIS-Based Decision Support System for Watershed Evaluation
of Best Management Practices
- Authors: Hui Shao; Wanhong Yang, John Lindsay, Yongbo Liu, Zhiqiang Yu, Anatoliy Oginskyy
Abstract: Economic costs, water quantity/quality benefits, and cost effectiveness of agricultural best management practices (BMPs) at a watershed scale are increasingly examined using integrated economic-hydrologic models. However, these models are typically complex and not user-friendly for examining the effects of various BMP scenarios. In this study, an open source geographic information system (GIS)-based decision support system (DSS), named the watershed evaluation of BMPs (WEBs), was developed for creating BMP scenarios and simulating economic costs and water quantity/quality benefits at farm field, subbasin, and watershed scales. This DSS or WEBs interface integrated a farm economic model, the Soil and Water Assessment Tool (SWAT), and an optimization model within Whitebox Geospatial Analysis Tools (GAT), an open source GIS software. The DSS was applied to the 14.3-km2 Gully Creek watershed, a coastal watershed in southern Ontario, Canada that drains directly into Lake Huron. BMPs that were evaluated included conservation tillage, nutrient management, cover crop, and water and sediment control basins. In addition to assessing economic costs, water quantity/quality benefits, and cost effectiveness of BMPs, the DSS can be also used to examine prioritized BMP types/locations and corresponding economic and water quantity/quality tradeoffs in the study watershed based on environmental targets or budget constraints. Further developments of the DSS including interface transfer to other watersheds are also discussed. Editor's note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.
- Spatiotemporal Variability of Snow Depletion Curves Derived from SNODAS
for the Conterminous United States, 2004-2013
- Authors: Jessica M. Driscoll; Lauren E. Hay, Andrew R. Bock
Abstract: Assessment of water resources at a national scale is critical for understanding their vulnerability to future change in policy and climate. Representation of the spatiotemporal variability in snowmelt processes in continental-scale hydrologic models is critical for assessment of water resource response to continued climate change. Continental-extent hydrologic models such as the U.S. Geological Survey National Hydrologic Model (NHM) represent snowmelt processes through the application of snow depletion curves (SDCs). SDCs relate normalized snow water equivalent (SWE) to normalized snow covered area (SCA) over a snowmelt season for a given modeling unit. SDCs were derived using output from the operational Snow Data Assimilation System (SNODAS) snow model as daily 1-km gridded SWE over the conterminous United States. Daily SNODAS output were aggregated to a predefined watershed-scale geospatial fabric and used to also calculate SCA from October 1, 2004 to September 30, 2013. The spatiotemporal variability in SNODAS output at the watershed scale was evaluated through the spatial distribution of the median and standard deviation for the time period. Representative SDCs for each watershed-scale modeling unit over the conterminous United States (n = 54,104) were selected using a consistent methodology and used to create categories of snowmelt based on SDC shape. The relation of SDC categories to the topographic and climatic variables allow for national-scale categorization of snowmelt processes.
- Urban Streamflow Response to Imported Water and Water Conservation
Policies in Los Angeles, California
- Authors: Kimberly F. Manago; Terri S. Hogue
Abstract: Los Angeles has a long history of importing water; however, drought, climate change, and environmental mitigation have forced the City to focus on developing more local water sources (target of 50% local supply by 2035). This study aims to improve understanding of water cycling in Los Angeles, including the impacts of imported water and water conservation policies. We evaluate the influence of local water restrictions on discharge records for 12 years in the Ballona Creek (urban) and Topanga Creek (natural) watersheds. Results show imported water has significantly altered the timing and volume of streamflow in the urban Ballona watershed, resulting in runoff ratios above one (more streamflow than precipitation). Further analysis comparing pre- vs. during-mandatory water conservation periods shows there is a significant decrease in dry season streamflow during-conservation in Ballona, indicating that prior to conservation efforts, heavy irrigation and other outdoor water use practices were contributing to streamflow. The difference between summer streamflow pre- vs. during-conservation is enough to serve 160,000 customers in Los Angeles. If Los Angeles returns to more watering days, educating the public on proper irrigation rates is critical for ensuring efficient irrigation and conserving water; however, if water restrictions remain in place, the City must take the new flow volumes into account for complying with water quality standards in the region.
- Constraining SWAT Calibration with Remotely Sensed Evapotranspiration Data
- Authors: Kenneth J. Tobin; Marvin E. Bennett
Abstract: Historically, many watershed studies have been based on using the streamflow flux, typically from a single gauge at the basin's outlet, to support calibration. In this setting, there is great potential for equifinality of parameters during the optimization process, especially for parameters that are not directly related to streamflow. Therefore, some of the optimal parameter values achieved during the autocalibration process may be physically unrealistic. In recent decades a vast array of data from land surface models and remote sensing platforms can help to constrain hydrologic fluxes such as evapotranspiration (ET). While the spatial resolution of these ancillary datasets varies, the continuous spatial coverage of these gridded datasets provides flux measurements across the entire basin, in stark contrast to point-based streamflow data. This study uses Global Land Evaporation: the Amsterdam Model data to constrain Soil and Water Assessment Tool parameter values associated with ET to a more physically realistic range. The study area is the Little Washita River Experimental Watershed, in southern Oklahoma. Traditional objective metrics such as the Nash-Sutcliffe coefficients record no performance improvement after application of this method. However, there is a dramatic increase in the number of days with receding flow where simulations match observed streamflow.
- Issue Information
- PubDate: 2017-04-03T07:04:52.067106-05:
- Farm-level Economic and Water Quality Impacts of Comprehensive Nutrient
Management Plan Implementation in the Ohio River Basin
- Authors: Edward Osei; Bing Du, Larry Hauck, Huijun Li, Alexander Tanter
Abstract: In this article, we provide an assessment of comprehensive nutrient management plans (CNMPs) as a tool for addressing nonpoint nutrient and sediment losses from the animal feeding operations (AFOs) in the Ohio River Basin. We employ a macro modeling system to determine the aggregate economic and water quality impacts of CNMP implementation on AFOs in the entire basin. Results of the study indicate that implementing CNMPs on AFOs will help reduce sediment and organic nutrient losses from their current levels at moderate cost. The flexibility inherent in CNMP designs means farmers may be able to achieve water quality and other conservation goals at less cost with CNMPs than with other less flexible policy options.
- Water Prism: A Tool to Assess Water Availability Risk and Investigate
Water Management Strategies
- Authors: Laura H.Z. Weintraub; Hua Tao, Todd M. Redder
Abstract: Water availability risk is a local issue best understood with watershed-scale quantification of both withdrawal and consumptive demands in the context of available supply. Collectively, all water use sectors must identify, understand, and respond to this risk. A highly visual and computationally robust decision support tool, Water Prism, quantitatively explores mitigation responses to water risk on both a facility-level and basin-aggregated basis. Water Prism examines a basin water balance for a 40- to 60-year planning horizon, distinguishes among water use sectors, and accounts for ecosystem water needs. The 2012 Texas State Water Plan was used to apply Water Prism to the Big Cypress-Sulphur Basin (Texas). The case study showed Water Prism to be an accurate and convenient tool to provide fine-scale understanding of water use in the context of available supply, evaluate multi-sector combinations of conservation strategies, and quantify the effects of future demands and water availability. Analyses demonstrated water availability risks for rivers and reservoirs can vary within a basin and must be calculated independently, simulation of water balance conditions can help illuminate potential impacts of increasing demands, and scenario simulations can be used to evaluate relative conservation efficacy of different water resource management strategies for each sector. Based on case study findings, Water Prism can serve as a useful assessment tool for regional water planners.
- Decreased Runoff Response to Precipitation, Little Missouri River Basin,
Northern Great Plains, USA
- Authors: Eleanor R. Griffin; Jonathan M. Friedman
Abstract: High variability in precipitation and streamflow in the semiarid northern Great Plains causes large uncertainty in water availability. This uncertainty is compounded by potential effects of future climate change. We examined historical variability in annual and growing season precipitation, temperature, and streamflow within the Little Missouri River Basin and identified differences in the runoff response to precipitation for the period 1976-2012 compared to 1939-1975 (n = 37 years in both cases). Computed mean values for the second half of the record showed little change (
- Evaluating the Slope-Area Method to Accurately Identify Stream Channel
Heads in Three Physiographic Regions
- Authors: Burak Avcioglu; Christopher J. Anderson, Latif Kalin
Abstract: Estimation of stream channel heads is an important task since ephemeral channels play a significant role in the transport of sediment and materials to perennial streams. The slope-area method utilizes digital elevation model (DEM) and related information to develop slope-area threshold relationships used to estimate the position of channel heads in the watershed. A total of 162 stream channel heads were mapped across the three physiographic regions of Alabama, including the Southwestern Appalachians (51), Piedmont/Ridge and Valley (61), and Coastal Plains (51). Using Geographic Information System and DEM, the local slope and drainage area for each mapped channel head was calculated and region-specific models were developed and evaluated. Results demonstrated the local slope and drainage area had an inverse and strong correlation in the Piedmont/Ridge and Valley region (r2 = 0.71) and the Southwestern Appalachian region (r2 = 0.61). Among three physiographic regions, the weakest correlation was observed in the Coastal Plain region (r2 = 0.45). By comparing the locations of modeled channel heads to those located in the field, calculated reliability and sensitivity indices indicated model accuracy and reliance were weak to moderate. However, the slope-area method helped define the upstream boundaries of a more detailed channel network than that derived from the 1:24,000-scale National Hydrography Dataset, which is commonly used for planning and regulatory purposes.
- Effects of Urbanization on Flow Duration and Stream Flashiness: A Case
Study of Puget Sound Streams, Western Washington, USA
- Authors: Tyler T. Rosburg; Peter A. Nelson, Brian P. Bledsoe
Abstract: The overall influence of urbanization on how flows of different frequency might change over time, while important in hydrologic design, remains imprecisely known. In this study, we investigate the effects of urbanization on flow duration curves (FDCs) and flow variability through a case study of eight watersheds that underwent different amounts of growth, in the Puget Sound region in Western Washington State, United States. We computed annual FDCs from flow records spanning 1960-2010 and, after accounting for the effects of precipitation, we conducted statistical trend analyses on flow metrics to quantify how key FDC percentiles changed with time in response to urbanization. In the urban watersheds, the entire FDC tended to increase in magnitude of flow, especially the 95th-99th percentile of the daily mean flow series, which increased by an average of 43%. Stream flashiness in urban watersheds was found to increase by an average of 70%. The increases in FDC magnitude and flashiness in urbanizing watersheds are most likely a result of increasing watershed imperviousness and altered hydrologic routing. Rural watersheds were found to have decreasing FDC magnitude over the same time period, which is possibly due to anthropogenic extractions of groundwater, and increasing stream flashiness, which is likely a result of reductions in base flow and increasing precipitation intensity and variability.
- Featured Collection Introduction: National Flood Interoperability
- Authors: Jim Nelson
- Book Reviews
- Authors: Richard H. McCuen
- Development and Testing of a Physically Based Model of Streambank Erosion
for Coupling with a Basin-Scale Hydrologic Model SWAT
- Authors: B. Narasimhan; P.M. Allen, S.V. Coffman, J.G. Arnold, R. Srinivasan
Abstract: A comprehensive streambank erosion model based on excess shear stress has been developed and incorporated in the hydrological model Soil and Water Assessment Tool (SWAT). It takes into account processes such as weathering, vegetative cover, and channel meanders to adjust critical and effective stresses while estimating bank erosion. The streambank erosion model was tested for performance in the Cedar Creek watershed in north-central Texas where streambank erosion rates are high. A Rapid Geomorphic field assessment (RAP-M) of the Cedar Creek watershed was done adopting techniques developed by the Natural Resources Conservation Service (NRCS), and the stream segments were categorized into various severity classes. Based on the RAP-M field assessment, erosion pin sites were established at seven locations within the severely eroding streambanks of the watershed. A Monte Carlo simulation was carried out to assess the sensitivity of different parameters that control streambank erosion such as critical shear stress, erodibility, weathering depth, and weathering duration. The sensitive parameters were adjusted and the model was calibrated based on the bank erosion severity category identified by the RAP-M field assessment. The average observed erosion rates were in the range 25-367 mm year−1. The SWAT model was able to reasonably predict the bank erosion rates within the range of variability observed in the field (R2 = 0.90; E = 0.78). Editor's note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.
- Effects of Spatial Distribution of Prairie Vegetation in an Agricultural
Landscape on Curve Number Values
- Authors: David J. Dziubanski; Kristie J. Franz, Matthew J. Helmers
Abstract: The curve number (CN) method is used to calculate runoff in many hydrologic models, including the Soil and Water Assessment Tool (SWAT). The CN method does not account for the spatial distribution of land cover types, an important factor controlling runoff patterns. The objective of this study was to empirically derive CN values that reflect the strategic placement of native prairie vegetation (NPV) within row crop agricultural landscapes. CNs were derived using precipitation and runoff data from a seven-year period for 14 small watersheds in Iowa. The watersheds were planted with varying amounts of NPV located in different watershed positions. The least squares and asymptotic least squares methods (LSM) were used to derive CNs using an initial abstraction coefficient (λ) of 0.2 and 0.05. The CNs were verified using leave-one-out cross-validation and adjustment for antecedent moisture conditions (AMC) was tested. The asymptotic method produced CN values for watersheds with NPV treatment that were 8.9 and 14.7% lower than watersheds with 100% row crop at λ = 0.2 and λ = 0.05, respectively. The derived CNs produced Nash-Sutcliffe efficiency values ranging from 0.4 to 0.7 during validation. Our analyses show the CNs verified best for the asymptotic LSM, when using λ of 0.05 and adjusting for AMC. Further, comparison of derived CNs against an area weighted CN indicated that the placement of vegetation does impact the CN value. Editor's note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.
- Benefit-Cost Analysis of Integrated Water Resource Management: Accounting
for Interdependence in the Yakima Basin Integrated Plan
- Authors: Jonathan Yoder; Jennifer Adam, Michael Brady, Joseph Cook, Stephen Katz, Shane Johnston, Keyvan Malek, John McMillan, Qingqing Yang
Abstract: Integrated water resource management (IWRM) requires accounting for many interrelated facets of water systems, water uses and stakeholders, and water management activities. The consequence is that project analysis must account for the nonseparability among the component parts of IWRM plans. This article presents a benefit-cost (B-C) analysis of a set of projects included in the Yakima Basin Integrated Plan proposed for the Yakima Basin in south-central Washington State. The analysis accounts for interdependence among proposed water storage projects and between water storage and water market development in the context of historical and more adverse projected future climate scenarios. Focusing on irrigation benefits from storage, we show that the value of a given proposed storage project is lower when other proposed storage projects in the basin are implemented, and when water markets are functioning effectively. We find that none of the water storage projects satisfy a B-C criterion, and that assuring proposed instream flow augmentation is less expensive by purchasing senior diversion rights than relying on new storage to provide it.
- Nitrogen Subsidies from Hillslope Alder Stands to Streamside Wetlands and
Headwater Streams, Kenai Peninsula, Alaska
- Authors: Michael K. Callahan; Dennis F. Whigham, Mark C. Rains, Kai C. Rains, Ryan S. King, Coowe M. Walker, Jasmine R. Maurer, Steven J. Baird
Abstract: We examined nitrogen transport and wetland primary production along hydrologic flow paths that link nitrogen-fixing alder (Alnus spp.) stands to downslope wetlands and streams in the Kenai Lowlands, Alaska. We expected that nitrate concentrations in surface water and groundwater would be higher on flow paths below alder. We further expected that nitrate concentrations would be higher in surface water and groundwater at the base of short flow paths with alder and that streamside wetlands at the base of alder-near flow paths would be less nitrogen limited than wetlands at the base of long flow paths with alder. Our results showed that groundwater nitrate-N concentrations were significantly higher at alder-near sites than at no-alder sites, but did not differ significantly between alder-far sites and no-alder sites or between alder-far sites and alder-near sites. A survey of 15N stable isotope signatures in soils and foliage in alder-near and no-alder flow paths indicated the alder-derived nitrogen evident in soils below alder is quickly integrated downslope. Additionally, there was a significant difference in the relative increase in plant biomass after nitrogen fertilization, with the greatest increase occurring in the no-alder sites. This study demonstrates that streamside wetlands and streams are connected to the surrounding landscapes through hydrologic flow paths, and flow paths with alder stands are potential “hot spots” for nitrogen subsidies at the hillslope scale.
- Measuring Urban Water Conservation Policies: Toward a Comprehensive Index
- Authors: David J. Hess; Christopher A. Wold, Scott C. Worland, George M. Hornberger
Abstract: This article (1) discusses existing efforts to measure water conservation policies (WCPs) in the United States (U.S.); (2) suggests general methodological guidelines for creating robust water conservation indices (WCIs); (3) presents a comprehensive template for coding WCPs; (4) introduces a summary index, the Vanderbilt Water Conservation Index (VWCI), which is derived from 79 WCP observations for 197 cities for the year 2015; and (5) compares the VWCI to WCP data extracted from the 2010 American Water Works Association (AWWA) Water and Wastewater Rates survey. Existing approaches to measuring urban WCPs in U.S. cities are limited because they consider only a portion of WCPs or they are restricted geographically. The VWCI consists of a more comprehensive set of 79 observations classified as residential, commercial/industrial, billing structure, drought plan, or general. Our comparison of the VWCI and AWWA survey responses indicate reasonable agreement (ρ = 0.76) between the two WCIs for 98 cities where the data overlap. The correlation suggests the AWWA survey responses can provide fairly robust longitudinal WCP information, but we argue the measurement of WCPs is still in its infancy, and our approach suggests strategies for improving existing methods.
- Revealing the Diversity of Natural Hydrologic Regimes in California with
Relevance for Environmental Flows Applications
- Authors: Belize A. Lane; Helen E. Dahlke, Gregory B. Pasternack, Samuel Sandoval-Solis
Abstract: Alterations to flow regimes for water management objectives have degraded river ecosystems worldwide. These alterations are particularly profound in Mediterranean climate regions such as California with strong climatic variability and riverine species highly adapted to the resulting flooding and drought disturbances. However, defining environmental flow targets for Mediterranean rivers is complicated by extreme hydrologic variability and often intensive water management legacies. Improved understanding of the diversity of natural streamflow patterns and their spatial arrangement across Mediterranean regions is needed to support the future development of effective flow targets at appropriate scales for management applications with minimal resource and data requirements. Our study addresses this need through the development of a spatially explicit reach-scale hydrologic classification for California. Dominant hydrologic regimes and their physio-climatic controls are revealed, using available unimpaired and naturalized streamflow time-series and generally publicly available geospatial datasets. This methodology identifies eight natural flow classes representing distinct flow sources, hydrologic characteristics, and catchment controls over rainfall-runoff response. The study provides a broad-scale hydrologic framework upon which flow-ecology relationships could subsequently be established towards reach-scale environmental flows applications in a complex, highly altered Mediterranean region.
- Hydraulics Near Unscreened Diversion Pipes in Open Channels: Large Flume
- Authors: Ali Ercan; M. Levent Kavvas, Kara Carr, Zachary Hockett, Hossein Bandeh, Timothy D. Mussen, Dennis Cocherell, Jamilynn B. Poletto, Joseph J. Cech, Nann A. Fangue
Abstract: Most of the water diversions on the Sacramento and San Joaquin Rivers (California, United States) and their tributaries are currently unscreened. These unscreened diversions are commonly used for irrigation and are potentially harmful to migrating and resident fishes. A large flume (test section: 18.29 m long, 3.05 m wide and 3.20 m high) was used to investigate the hydraulic fields near an unscreened water diversion under ecologically and hydraulically relevant diversion rates and channel flow characteristics. We investigated all combinations of three diversion rates (0.28, 0.42, and 0.57 m3/s) and three sweeping velocities (0.15, 0.38, and 0.61 m/s), with one additional test at 0.71 m3/s and 0.15 m/s. We measured the three-dimensional velocity field at seven cross sections near a diversion pipe and constructed regression equations of the observed maximum velocities near the pipe. Because the velocity components in three directions (longitudinal, transverse, and vertical) were significantly greater near the diversion pipe inlet compared with those farther from it, they cannot be neglected in the modeling and design of fish guidance and protection devices for diversion pipes. Our results should be of great value in quantifying the hydraulic fields that are formed around fish guidance devices to design more effective protection for fishes from entrainment into unscreened water-diversion pipes.
- SWATMOD-Prep: Graphical User Interface for Preparing Coupled SWAT-MODFLOW
- Authors: Ryan Bailey; Hendrik Rathjens, Katrin Bieger, Indrajeet Chaubey, Jeffrey Arnold
Abstract: This article presents SWATMOD-Prep, a graphical user interface that couples a SWAT watershed model with a MODFLOW groundwater flow model. The interface is based on a recently published SWAT-MODFLOW code that couples the models via mapping schemes. The spatial layout of SWATMOD-Prep guides the user through the process of importing shape files (sub-basins, hydrologic response units [HRUs], river network) from an existing SWAT model, creating a grid, performing necessary geo-processing operations to link the models, writing out SWAT-MODFLOW files, and running the simulation. The option of creating a new single-layer MODFLOW model for near-surface alluvial aquifers is available, with the user prompted to provide groundwater surface elevation (through a digital elevation model), aquifer thickness, and necessary aquifer parameter values. The option of simulating nitrate transport in the aquifer also is available, using the reactive transport model RT3D. The interface is in the public domain. It is programmed in Python, with various software packages used for geo-processing operations (e.g., selection, intersection of rasters) and inputting/outputting data, and is written for Windows. The use of SWATMOD-Prep is demonstrated for the Little River Experimental Watershed, Georgia. SWATMOD-Prep and SWAT-MODFLOW executables are available with an accompanying user's manual at: http://swat.tamu.edu/software/swat-modflow/. The user's manual also accompanies this article as Supporting Information.
- Effects of Impervious Area and BMP Implementation and Design on Storm
Runoff and Water Quality in Eight Small Watersheds
- Authors: Brent T. Aulenbach; Mark N. Landers, Jonathan W. Musser, Jaime A. Painter
Abstract: The effects of increases in effective impervious area (EIA) and the implementation of water quality protection designed detention pond best management practices (BMPs) on storm runoff and stormwater quality were assessed in Gwinnett County, Georgia, for the period 2001-2008. Trends among eight small watersheds were compared, using a time trend study design. Significant trends were detected in three storm hydrologic metrics and in five water quality constituents that were adjusted for variability in storm characteristics and climate. Trends in EIA ranged from 0.10 to 1.35, and changes in EIA treated by BMPs ranged from 0.19 to 1.32; both expressed in units of percentage of drainage area per year. Trend relations indicated that for every 1% increase in watershed EIA, about 2.6, 1.1, and 1.5% increases in EIA treated by BMPs would be required to counteract the effects of EIA added to the watersheds on peak streamflow, stormwater yield, and storm streamflow runoff, respectively. Relations between trends in EIA, BMP implementation, and water quality were counterintuitive. This may be the result of (1) changes in constituent inputs in the watersheds, especially downstream of areas treated by BMPs; (2) BMPs may have increased the duration of stormflow that results in downstream channel erosion; and/or (3) spurious relationships between increases in EIA, BMP implementation, and constituent inputs with development rates.
- Probabilistic Flood Inundation Forecasting Using Rating Curve Libraries
- Authors: Caleb A. Buahin; Nikhil Sangwan, Cassandra Fagan, David R. Maidment, Jeffery S. Horsburgh, E. James Nelson, Venkatesh Merwade, Curtis Rae
Abstract: One approach for performing uncertainty assessment in flood inundation modeling is to use an ensemble of models with different conceptualizations, parameters, and initial and boundary conditions that capture the factors contributing to uncertainty. However, the high computational expense of many hydraulic models renders their use impractical for ensemble forecasting. To address this challenge, we developed a rating curve library method for flood inundation forecasting. This method involves pre-running a hydraulic model using multiple inflows and extracting rating curves, which prescribe a relation between streamflow and stage at various cross sections along a river reach. For a given streamflow, flood stage at each cross section is interpolated from the pre-computed rating curve library to delineate flood inundation depths and extents at a lower computational cost. In this article, we describe the workflow for our rating curve library method and the Rating Curve based Automatic Flood Forecasting (RCAFF) software that automates this workflow. We also investigate the feasibility of using this method to transform ensemble streamflow forecasts into local, probabilistic flood inundation delineations for the Onion and Shoal Creeks in Austin, Texas. While our results show water surface elevations from RCAFF are comparable to those from the hydraulic models, the ensemble streamflow forecasts used as inputs to RCAFF are the largest source of uncertainty in predicting observed floods.
- Editor-in-Chief Search
- Pages: 241 - 242
- Impacts of Human Behavioral Heterogeneity on the Benefits of Probabilistic
Flood Warnings: An Agent-Based Modeling Framework
- Authors: Erhu Du; Samuel Rivera, Ximing Cai, Laura Myers, Andrew Ernest, Barbara Minsker
Abstract: Flood forecasts and warnings are intended to reduce flood-related property damages and loss of human life. Considerable research has improved flood forecasting accuracy (e.g., more accurate prediction of the occurrence of flood events) and lead time. However, the delivery of improved forecast information alone is not necessarily sufficient to reduce flood damage and loss of life, as people have varying responses and reactions to flood warnings. This study develops an agent-based modeling framework that evaluates the impacts of heterogeneity in human behaviors (i.e., variation in behaviors in response to flood warnings), as well as residential density, on the benefits of flood warnings. The framework is coupled with a traffic model to simulate evacuation processes within a road network under various flood warning scenarios. The results show the marginal benefit associated with providing better flood warnings is significantly constrained if people behave in a more risk-tolerant manner, especially in high-density residential areas. The results also show significant impacts of human behavioral heterogeneity on the benefits of flood warnings, and thus stress the importance of considering human behavioral heterogeneity in simulating flood warning-response systems. Further study is suggested to more accurately model human responses and behavioral heterogeneity, as well as to include more attributes of residential areas to estimate and improve the benefits of flood warnings.
- AutoRAPID: A Model for Prompt Streamflow Estimation and Flood Inundation
Mapping over Regional to Continental Extents
- Authors: Michael L. Follum; Ahmad A. Tavakoly, Jeffrey D. Niemann, Alan D. Snow
Abstract: This article couples two existing models to quickly generate flow and flood-inundation estimates at high resolutions over large spatial extents for use in emergency response situations. Input data are gridded runoff values from a climate model, which are used by the Routing Application for Parallel computatIon of Discharge (RAPID) model to simulate flow rates within a vector river network. Peak flows in each river reach are then supplied to the AutoRoute model, which produces raster flood inundation maps. The coupled tool (AutoRAPID) is tested for the June 2008 floods in the Midwest and the April-June 2011 floods in the Mississippi Delta. RAPID was implemented from 2005 to 2014 for the entire Mississippi River Basin (1.2 million river reaches) in approximately 45 min. Discretizing a 230,000-km2 area in the Midwest and a 109,500-km2 area in the Mississippi Delta into thirty-nine 1° by 1° tiles, AutoRoute simulated a high-resolution (~10 m) flood inundation map in 20 min for each tile. The hydrographs simulated by RAPID are found to perform better in reaches without influences from unrepresented dams and without backwater effects. Flood inundation maps using the RAPID peak flows vary in accuracy with F-statistic values between 38.1 and 90.9%. Better performance is observed in regions with more accurate peak flows from RAPID and moderate to high topographic relief.
- Conceptual Framework for the National Flood Interoperability Experiment
- Authors: David R. Maidment
Abstract: The National Flood Interoperability Experiment is a research collaboration among academia, National Oceanic and Atmospheric Administration National Weather Service, and government and commercial partners to advance the application of the National Water Model for flood forecasting. In preparation for a Summer Institute at the National Water Center in June-July 2015, a demonstration version of a near real-time, high spatial resolution flood forecasting model was developed for the continental United States. The river and stream network was divided into 2.7 million reaches using the National Hydrography Dataset Plus geospatial dataset and it was demonstrated that the runoff into these stream reaches and the discharge within them could be computed in 10 min at the Texas Advanced Computing Center. This study presents a conceptual framework to connect information from high-resolution flood forecasting with real-time observations and flood inundation mapping and planning for local flood emergency response.
- A Comprehensive Python Toolkit for Accessing High-Throughput Computing to
Support Large Hydrologic Modeling Tasks
- Authors: Scott D. Christensen; Nathan R. Swain, Norman L. Jones, E. James Nelson, Alan D. Snow, Herman G. Dolder
Abstract: The National Flood Interoperability Experiment (NFIE) was an undertaking that initiated a transformation in national hydrologic forecasting by providing streamflow forecasts at high spatial resolution over the whole country. This type of large-scale, high-resolution hydrologic modeling requires flexible and scalable tools to handle the resulting computational loads. While high-throughput computing (HTC) and cloud computing provide an ideal resource for large-scale modeling because they are cost-effective and highly scalable, nevertheless, using these tools requires specialized training that is not always common for hydrologists and engineers. In an effort to facilitate the use of HTC resources the National Science Foundation (NSF) funded project, CI-WATER, has developed a set of Python tools that can automate the tasks of provisioning and configuring an HTC environment in the cloud, and creating and submitting jobs to that environment. These tools are packaged into two Python libraries: CondorPy and TethysCluster. Together these libraries provide a comprehensive toolkit for accessing HTC to support hydrologic modeling. Two use cases are described to demonstrate the use of the toolkit, including a web app that was used to support the NFIE national-scale modeling.
- Continental-Scale River Flow Modeling of the Mississippi River Basin Using
High-Resolution NHDPlus Dataset
- Authors: Ahmad A. Tavakoly; Alan D. Snow, Cédric H. David, Michael L. Follum, David R. Maidment, Zong-Liang Yang
Abstract: As a key component of the National Flood Interoperability Experiment (NFIE), this article presents the continental scale river flow modeling of the Mississippi River Basin (MRB), using high-resolution river data from NHDPlus. The Routing Application for Parallel computatIon of Discharge (RAPID) was applied to the MRB with more than 1.2 million river reaches for a 10-year study (2005-2014). Runoff data from the Variable Infiltration Capacity (VIC) model was used as input to RAPID. This article investigates the effect of topography on RAPID performance, the differences between the VIC-RAPID streamflow simulations in the HUC-2 regions of the MRB, and the impact of major dams on the streamflow simulations. The model performance improved when initial parameter values, especially the Muskingum K parameter, were estimated by taking topography into account. The statistical summary indicates the RAPID model performs better in the Ohio and Tennessee Regions and the Upper and Lower Mississippi River Regions in comparison to the western part of the MRB, due to the better performance of the VIC model. The model accuracy also increases when lakes and reservoirs are considered in the modeling framework. In general, results show the VIC-RAPID streamflow simulation is satisfactory at the continental scale of the MRB.