... Alexandros A. Ntelekos, Konstantine P. Georgakakos, Witold F. Krajewski. (2006) On the Uncert... more ... Alexandros A. Ntelekos, Konstantine P. Georgakakos, Witold F. Krajewski. (2006) On the Uncertainties of Flash Flood Guidance: Toward Probabilistic Forecasting of Flash Floods. Journal of Hydrometeorology 7:5, 896-915 Online publication date: 1-Oct-2006. Abstract . ...
Proceedings of the Water Environment Federation, 2010
ABSTRACT Central Texas is often called “Flash Flood Alley” because of its frequent, intense storm... more ABSTRACT Central Texas is often called “Flash Flood Alley” because of its frequent, intense storms. While large events seem to happen every decade, lesser events also cause public safety concerns. The City of Austin operates a Flood Early Warning System (FEWS) to reduce public exposure to flash flood hazards. The system is operated and maintained by the Watershed Engineering Division of the Watershed Protection Department. FEWS offers advanced information and warning of urban stormwater flooding based on radar rainfall and distributed physics-based hydrologic modeling. Radar rainfall detection and forecasting leverages rain gauge networks of the City, Lower Colorado River Authority, Upper Brushy Creek and NOAA. An innovative hydrologic information system built upon radar hydrology and Internet information access was implemented in 2004. It has proved to be useful during storms producing heavy precipitation and flooding. This paper describes the off-line configuration and online experience of this approach in Shoal Creek.The Shoal Creek watershed is a thirteen-square mile basin in the heart of Austin. It has a troublesome history of deadly flash floods. The May 1981 flood that took nine lives in this watershed triggered the establishment of the FEWS. The watershed is 43% residential and is home to approximately 65,000 people. A greenbelt path with wooded areas and parks follows much of the eleven-mile channel. The greenbelt path eventually enters into the urbanized mixed-use developments of downtown where businesses and high rise residents co-exist. The greenbelt is then connected to a larger system of greenbelts that run the course of Lady Bird Lake. While citizens enjoy the natural environment, danger can present itself quickly.Late afternoon on May 23, 2009, the Saturday of Memorial Day weekend, FEWS personnel received a text alert that heavy rainfall was moving into the Austin area. One of the team's responses was to check the web-based system for additional information. A steep rise in the hydrograph produced by the real-time continuous Vflo™ model was the basis for notifying the on-duty officer to clear pedestrians and cyclists from the paths and to deploy a photographer to take pictures of the flood's arrival. This photo documentation, radar rainfall data, hydrologic model prediction and verification, display system, and notifications will be presented as a case study in real-time stormwater management.
A modeling strategy has been developed to improve the real-time forecasting of medium to large ma... more A modeling strategy has been developed to improve the real-time forecasting of medium to large magnitude floods in an urban watershed, Brays Bayou (260 km2), in Houston, TX. Severe flooding of downstream areas of the watershed around the Texas Medical Center (TMC) has been an increasing problem over the past few decades, particularly during Tropical Storm (TS) Allison in June
Water quality is a problem in Lake Houston, the primary source of drinking water for the City of ... more Water quality is a problem in Lake Houston, the primary source of drinking water for the City of Houston, due to pollutant loads coming from the influent watersheds, including Cypress Creek. Water quality issues in the watershed that are of concern for the lake include nutrient enrichment bacterial impairment, both of which present operational challenges for the drinking water treatment plant operations. Statistical analysis of the historic water quality data was developed in order to understand the source characterization and seasonality of the watershed. Multivariate analysis including principal component, cluster, and discriminant analysis provided a unique seasonal assessment of the watershed leading to refined loading curves have been analyzed using data collected by the USGS at 3 sites in Cypress Creek with corresponding City of Houston water quality data at the sites for the past 5 years to characterize the behavior of the pollutant source and watershed. A VfloTM hydrologic m...
Design storms are used in hydrologic and hydraulic modeling for design and rehabilitation of sani... more Design storms are used in hydrologic and hydraulic modeling for design and rehabilitation of sanitary sewer systems. Analysis of regional design storms relies on both rain gauge accumulations and archival radar data during the period of record. Hyetographs, which represent the temporal distribution of rainfall produced by a storm, can be developed from radar or rain gauge data. In the most basic form, hyetograph rainfall rates are applied uniformly over a sewer catchment or basin. Including radar data offers the advantage of determining storm movement and direction, as well as measuring area-intensity reduction factors. Design storms are static if the rainfall does not move over the catchment, and are dynamic when the hyetograph incorporates movement. A gridded dynamic design storm can be produced by specifying the trapezoidal cross-section and movement derived from radar, or by selecting a dimensionless hyetograph derived from rain gauges. This manuscript describes the data analysi...
Several methods have been developed in hydrologic modeling to estimate prediction uncertainty res... more Several methods have been developed in hydrologic modeling to estimate prediction uncertainty resulting from imprecise model parametric settings. It is realized, however, that additional sources of uncertainty may be present in model inputs (i.e., the precipitation estimates), the model structure, and in the observations of streamflow. An ensemble approach is developed in this study to estimate the total prediction uncertainty
Urban flooding is a devastating natural hazard that affects cities globally and is expected to be... more Urban flooding is a devastating natural hazard that affects cities globally and is expected to become worse in the future. To this end, techniques that enable planners and decision makers with more accurate ways to gauge the severity of flood events are key to adaptive planning and management. This presentation addresses research undertaken by faculty at the University of Oklahoma to model and simulate current and projected flood events in five urban watersheds in the cities of Oklahoma City and Tulsa, OK and Austin, Dallas, and Houston, TX. For each of the five urban watersheds, the presentation will discuss the development of site-specific flood models, their visual simulation, and the responses of urban floodplain managers to a Web-based survey used to determine the technique's appeal for future use. The Vflo hydrologic model was used to perform watershed modeling for the target basins. Vflo is a distributed hydrologic model that integrates topography, land-use, soils, and im...
Accurate radar rainfall predictions are necessary for making operational hydrologic decisions eve... more Accurate radar rainfall predictions are necessary for making operational hydrologic decisions even when gauge correction is not available. Many standard Z-R relationships have been developed for estimating rainfall however, it has been found that seasonally and spatially specific Z-R relationships may lead to improved precipitation estimates. The purpose of this project is to derive and evaluate seasonally specific Z-R relationships
... Alexandros A. Ntelekos, Konstantine P. Georgakakos, Witold F. Krajewski. (2006) On the Uncert... more ... Alexandros A. Ntelekos, Konstantine P. Georgakakos, Witold F. Krajewski. (2006) On the Uncertainties of Flash Flood Guidance: Toward Probabilistic Forecasting of Flash Floods. Journal of Hydrometeorology 7:5, 896-915 Online publication date: 1-Oct-2006. Abstract . ...
Proceedings of the Water Environment Federation, 2010
ABSTRACT Central Texas is often called “Flash Flood Alley” because of its frequent, intense storm... more ABSTRACT Central Texas is often called “Flash Flood Alley” because of its frequent, intense storms. While large events seem to happen every decade, lesser events also cause public safety concerns. The City of Austin operates a Flood Early Warning System (FEWS) to reduce public exposure to flash flood hazards. The system is operated and maintained by the Watershed Engineering Division of the Watershed Protection Department. FEWS offers advanced information and warning of urban stormwater flooding based on radar rainfall and distributed physics-based hydrologic modeling. Radar rainfall detection and forecasting leverages rain gauge networks of the City, Lower Colorado River Authority, Upper Brushy Creek and NOAA. An innovative hydrologic information system built upon radar hydrology and Internet information access was implemented in 2004. It has proved to be useful during storms producing heavy precipitation and flooding. This paper describes the off-line configuration and online experience of this approach in Shoal Creek.The Shoal Creek watershed is a thirteen-square mile basin in the heart of Austin. It has a troublesome history of deadly flash floods. The May 1981 flood that took nine lives in this watershed triggered the establishment of the FEWS. The watershed is 43% residential and is home to approximately 65,000 people. A greenbelt path with wooded areas and parks follows much of the eleven-mile channel. The greenbelt path eventually enters into the urbanized mixed-use developments of downtown where businesses and high rise residents co-exist. The greenbelt is then connected to a larger system of greenbelts that run the course of Lady Bird Lake. While citizens enjoy the natural environment, danger can present itself quickly.Late afternoon on May 23, 2009, the Saturday of Memorial Day weekend, FEWS personnel received a text alert that heavy rainfall was moving into the Austin area. One of the team's responses was to check the web-based system for additional information. A steep rise in the hydrograph produced by the real-time continuous Vflo™ model was the basis for notifying the on-duty officer to clear pedestrians and cyclists from the paths and to deploy a photographer to take pictures of the flood's arrival. This photo documentation, radar rainfall data, hydrologic model prediction and verification, display system, and notifications will be presented as a case study in real-time stormwater management.
A modeling strategy has been developed to improve the real-time forecasting of medium to large ma... more A modeling strategy has been developed to improve the real-time forecasting of medium to large magnitude floods in an urban watershed, Brays Bayou (260 km2), in Houston, TX. Severe flooding of downstream areas of the watershed around the Texas Medical Center (TMC) has been an increasing problem over the past few decades, particularly during Tropical Storm (TS) Allison in June
Water quality is a problem in Lake Houston, the primary source of drinking water for the City of ... more Water quality is a problem in Lake Houston, the primary source of drinking water for the City of Houston, due to pollutant loads coming from the influent watersheds, including Cypress Creek. Water quality issues in the watershed that are of concern for the lake include nutrient enrichment bacterial impairment, both of which present operational challenges for the drinking water treatment plant operations. Statistical analysis of the historic water quality data was developed in order to understand the source characterization and seasonality of the watershed. Multivariate analysis including principal component, cluster, and discriminant analysis provided a unique seasonal assessment of the watershed leading to refined loading curves have been analyzed using data collected by the USGS at 3 sites in Cypress Creek with corresponding City of Houston water quality data at the sites for the past 5 years to characterize the behavior of the pollutant source and watershed. A VfloTM hydrologic m...
Design storms are used in hydrologic and hydraulic modeling for design and rehabilitation of sani... more Design storms are used in hydrologic and hydraulic modeling for design and rehabilitation of sanitary sewer systems. Analysis of regional design storms relies on both rain gauge accumulations and archival radar data during the period of record. Hyetographs, which represent the temporal distribution of rainfall produced by a storm, can be developed from radar or rain gauge data. In the most basic form, hyetograph rainfall rates are applied uniformly over a sewer catchment or basin. Including radar data offers the advantage of determining storm movement and direction, as well as measuring area-intensity reduction factors. Design storms are static if the rainfall does not move over the catchment, and are dynamic when the hyetograph incorporates movement. A gridded dynamic design storm can be produced by specifying the trapezoidal cross-section and movement derived from radar, or by selecting a dimensionless hyetograph derived from rain gauges. This manuscript describes the data analysi...
Several methods have been developed in hydrologic modeling to estimate prediction uncertainty res... more Several methods have been developed in hydrologic modeling to estimate prediction uncertainty resulting from imprecise model parametric settings. It is realized, however, that additional sources of uncertainty may be present in model inputs (i.e., the precipitation estimates), the model structure, and in the observations of streamflow. An ensemble approach is developed in this study to estimate the total prediction uncertainty
Urban flooding is a devastating natural hazard that affects cities globally and is expected to be... more Urban flooding is a devastating natural hazard that affects cities globally and is expected to become worse in the future. To this end, techniques that enable planners and decision makers with more accurate ways to gauge the severity of flood events are key to adaptive planning and management. This presentation addresses research undertaken by faculty at the University of Oklahoma to model and simulate current and projected flood events in five urban watersheds in the cities of Oklahoma City and Tulsa, OK and Austin, Dallas, and Houston, TX. For each of the five urban watersheds, the presentation will discuss the development of site-specific flood models, their visual simulation, and the responses of urban floodplain managers to a Web-based survey used to determine the technique's appeal for future use. The Vflo hydrologic model was used to perform watershed modeling for the target basins. Vflo is a distributed hydrologic model that integrates topography, land-use, soils, and im...
Accurate radar rainfall predictions are necessary for making operational hydrologic decisions eve... more Accurate radar rainfall predictions are necessary for making operational hydrologic decisions even when gauge correction is not available. Many standard Z-R relationships have been developed for estimating rainfall however, it has been found that seasonally and spatially specific Z-R relationships may lead to improved precipitation estimates. The purpose of this project is to derive and evaluate seasonally specific Z-R relationships
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Papers by Baxter Vieux