TASI
Technical Analysis & Services International, Inc.
Integrated Technologies for Sustainable and Prosperous Communities
(New services in PPE, NIOSH Certification & FDA registration in the midst of COVID-19 Pandemic!)
4160 Washington Road, STE 218, McMurray, PA 15317
email: info@tasi-inc.com phone: (724) 288-7467
TASI
4160 Washington Road
Suite 218
McMurray, PA 15317
United States
info
FFM Introduction
TASI provides technical consulting services with its innovative technologies in stormwater management. When you work with us, a world-class technical team will take the ownership of your stormwater management needs and develop the most economical and reliable data and solutions based on a wealth of industry experience.
Demonstration of FFM Features
Among the tools that TASI developed for stormwater management, Flash Flood Management (FFM) is the most major and comprehensive software that is applicable to a wide range of stormwater management needs. Tested with real storm events with success, FFM is versatile and effective in connecting and processing the data from multiple data sources. FFM is demonstrated in the popular user interface ArcMap.
Below is a study case using FFM in a replay of a flash flood event in Connellsville, PA in Auguest of 2016. Connellsville is a small city in Fayatte County, PA located on the famous Youghiogheny River, a scenic area that attracts summer vacationers and white water rafting fans. However, the well developed tributaries and hilly topographic conditions also make this region prone to flash floods. The following replay aims at demonstrating the features and methodology of FFM.
Fig. 1 The purple circles, labelled by numbers in the 20000s are rain gage locations. The gage 29040 is the river gage at Connellsville on the Youghiogheny River. The red line is the boundary of Fayette County, PA. Notice that only a small portion of the county received more than two inches of rain and a very small area received more than 5 inches. The black lines are ridge line boundaries that define small stream watersheds, or river segments of the Youghiogheny River. Blue lines are streamchannels or rivers. ABR is the “average basin rainfall” for each watershed or river segment, computed from radar rainfall estimates. 
Fig.2 Close-up of the heavy rainfall watersheds. AMBER is the Areal Mean Basin Estimated Rainfall program written by Robert Davis. The program matches the WSR-88D rainfall into each defined watershed and computes an Average Basin Rainfall (ABR) in each watershed. The watersheds are assigned a unique number (Black numbers) from 1 to 12000 for small stream basins. And a number from 15000 to 15999 for major river segments, like the Youghiogheny River (15203 to 15208) shown here. Purple shaded circles are rain gage locations. Radar rainfall estimates are calculated for each rain gage locations for comparison with the radar rainfall estimates. All gage locations have a unique ID number in the 20000s. Gage 29040 is the river gage on the Youghiogheny River in the city of Connellsville. Notice that no rain gages are located in the area of the heaviest rainfall. This is typical of most flash floods. The names of the creeks are shown for the areas with the heaviest rainfall and the greatest flash flood damage. A watershed or basin is defined by it’s ridge line boundary. All rainfall falling within the watershed boundary flows down hill and ends up in the stream or percolates into the ground as part of the water table.
Fig. 3 Radar detected Average Basin Rainfall (ABR) in each defined basin. The heaviest rainfall occurred in the two headwaters basins (7.38" in 10644 and 8.39" in 10645) of Breakneck Run.The bulk of the heavy rainfall across Breakneck Run and Whites Run fell in two hours from 7PM to 9PM DST. Serious flash flooding resulted along these two streams withwidespread damage along Breakneck Road from the flooding of Breakneck Run, and the closure of Route 119 for several hours where Whites Run intersects Rt. 119 inConnellsville Township. 
Fig. 4 Mapquest image of the vincinity of Connersville.
Fig. 5 The ESRI ArcMap shapefiles contain a lot of information about each watershed. The following figures show some examples of the basin information. This figure shows the area of each watershed segment in square miles (black numbers). Notice the two basins with the heaviest rainfall, basins 10644 and 10645 have areas of 1.38 and 2.96 square miles. The great majority of flash floods occur on watersheds less than 20 square miles in area. The small basins were defined by going upstream along a stream channel and defining a new watershed where the stream divided into two stream channels. Larger watersheds must be divided into basins down to at least 2.0 square miles to successfully detect flash floods.
Fig. 6 The Flow Accumulation is defined as the upstream contributing area of a basin in square miles. Look at the three basins that make up Breakneck Runbasins 3044, 10644, and 10645. Basins with an area (Fig. 5) and flow accumulation (Fig. 6) equal to the same value are headwaters basins. Basins 10644 and 10645 have the same area and flow accumulation, 1.38 sq miles and 2.96 sq miles. Basin 3044 has an area of 2.38 sq milesbut a flow accumulation of 6.72. This is because basins 10644 and 10645 contribute flow into basin 3044. Therefore basin 3044 is a non-headwatersbasin. The flow accumulation for 3044 is its own area 2.38 plus 1.38 plus 2.96 (the areas of basins 10644 and 10645). So basin 3044 has a flow accumulation of 2.38 + 1.38 + 2.96 = 6.72 sq miles.
Fig. 7 The township boundaries (black line) is a layer of data in FFM. Township boundaries are important for rescue and diaster relief as well as flood prevention projects.
Fig. 8 Overlay of roads with basins near Breakneck Run. This data layer can help the customer to pinpoint the flood damages to roads. In this flash flood, flood from Whites Creek damaged Rt119 and caused transportation block.
Fig. 9 Close-up of State Roads. Overlay of roads with basins near Rt 119.
The Flow Accumulation is defined as the upstream contributing area of a basin in square miles. Look at the three basins that make up Breakneck Runbasins 3044, 10644, and 10645. Basins with an area (Fig. 5) and flow accumulation (Fig. 6) equal to the same value are headwaters basins.Basins 10644 and 10645 have the same area and flow accumulation, 1.38 sq miles and 2.96 sq miles. Basin 3044 has an area of 2.38 sq milesbut a flow accumulation of 6.72. This is because basins 10644 and 10645 contribute flow into basin 3044. Therefore basin 3044 is a non-headwatersbasin. The flow accumulation for 3044 is its own area 2.38 plus 1.38 plus 2.96 (the areas of basins 10644 and 10645).FFM Graphical User Interface
FFM uses ArcMap as the user graphical interface. ArcMap can properly support the layered data structure of FFM.
Fig. 10 The data layers of basins, 6hr ABR and township boundaries are turned on in the graphical user interface.
Fig. 11 The data layers of basins, 6hr ABR and township boundaries are turned on in the graphical user interface.
Fig. 12 The data layers of basins and flow accumulation are turned on in the graphical user interface.Topographic Condition Near Breakneck Creek and Rt 119
Fig. 13 Google Earth view of Basin 3042 where Whites Run crosses Route 119. The severe flash flooding on Whites Run closed Route 119 to traffic in both directions forseveral hours. Similar image shown in Fig. 4.
Fig.14 Google Earth view with the yellow lines showing the entire Mounts Creek watershed, including Whites run and Breakneck Run. The city of Connellsville is in the lowerleft corner. Fortunately the heaviest rainfall fell in basins with very low population density, resulting in serious property and road damage, but no loss of life.
Newspaper Report for Connellsville Flash Flood on August 28, 2017 (courtesy of Pittsburgh Tribune Review)
Normonclature
Fig. N-1 Three types of basins
Fig. N-2 Flash Flood Index 
Fig N-3. BUR examples
Fig. N-4 Flash Flood Index for non-headwaters Basins
Fig. N-5 FFG example
FFM History
Starting from 2008, TASI has engaged in wet weather management and focused on stormwater management in cities. Building upon its internationally recognized flash flood detection expertise and rich engineering analysis experience for complex and interactive systems, TASI contributes significantly in the following areas with its state-of-the-art software tool Flash Flood Management (FFM):
- Weather radar data applications in modern smart city systems
- Hydraulic calculation
- Flash flood detection and warning
- Replay of historic storm events
- Evaluation of flash flood threat due to storm drainage and/or sewer system changes
- Renewable energy through wet weather management
- Insurance risk assessment of flooding
Technical Challenge of Flash Flooding
Flash floods are the root cause of most stormwater management issues internationally.
Flash floods are the most damaging natural disaster in the United States. In 2015, they accounted for 24.7% of weather-related deaths and 43% of property damage. They create severe environmental pollutions, health risks and contribute to economic decline, particularly for economically strained communities.
Flash floods are caused by heavy rainfall (1 to 12 inches) in short time durations (1 to 6 hours) produced by warm season thunderstorms. Several other factors contribute to the flash flood potential. Rainfall history during the days leading up to a flash flood event can result in saturated soil and high stream levels before the onset of the flash flood producing rainfall. The wet soil condition results in greater runoff into the streams, causing a much more rapid rise in stream levels and more severe flash flooding. Another factor is steep topography, as steeper valley walls produce a more rapid overland flow of rain water into the stream. A major factory leading to increases both in the frequency and potential severity of flash flood is urbanization. Impervious ground surfaces such as parking lots and roads, drainage from roofs of homes and buildings, along with storm drainage and sewer systems of limited capacity all contribute to the increased flash flood threat in urban areas. As urbanization continues to increase, the flash flood threat in the urban environment increase as well.
Currently, flash flooding is only addressed by the National Weather Service’s flash flood warning program. The EPA has established a consent decree. Water authorities nationwide implement wet weather management projects to eliminate storm sewer overflow, the direct consequence of flash flooding. These rate-supported capital projects deal with the consequences of flash floods but still need to accurately take into account flash flooding itself.
Engineering design for storm drain networks are often based on “return periods” of rainfall produced by the National Weather Service. These climatic estimates of rainfall return period are all based on rain gage data. The heaviest rainfall amounts produced by thunderstorms are seldom captured in the rain gage network. The engineering design using the rain gage return periods will generally greatly underestimate both the frequency and amount of the heavy rainfall. If only rain gages were usedto detect flash floods only about 5% of all flash floods would be detected. Using the rainfall from the WSR-88D, the NWS in Pittsburgh detects over 90% of all flash floods. TASI’s FFM programuses WSR-88D data to replay all flash flood events. FFM can also produce the “rainfall history” of rainfall in a specific flash flood watershed for the week prior to the flash flooding. FFM canalso created rainfall in 5 minute time steps through the entire duration of the flash flood producing rainfall. FFM can also show results of historic flash flood events, to show the true spatialand temporal distribution of rainfall that caused the flash flood events. These events include the Johnstown flash flood of 1977, the Etna, PA flash flood of 1986, and the Shadyside, OH flashflood of 1990.
With the advanced and realistic estimates of the spatial and temporal distributions of heavy rainfalls and the rainfall history, TASI will help both the aggressive engineering solutions and green infrastructures to effectively resolve or mitigate the persistent storm sewer overflow, especially the combined sewer overflow (CSO).
Technical Challenge of Flash Flooding
Flash floods are the root cause of most stormwater management issues internationally.
Flash floods are the most damaging natural disaster in the United States. In 2015, they accounted for 24.7% of weather-related deaths and 43% of property damage. They create severe environmental pollutions, health risks and contribute to economic decline, particularly for economically strained communities.
Flash floods are caused by heavy rainfall (1 to 12 inches) in short time durations (1 to 6 hours) produced by warm season thunderstorms. Several other factors contribute to the flash flood potential. Rainfall history during the days leading up to a flash flood event can result in saturated soil and high stream levels before the onset of the flash flood producing rainfall. The wet soil condition results in greater runoff into the streams, causing a much more rapid rise in stream levels and more severe flash flooding. Another factor is steep topography, as steeper valley walls produce a more rapid overland flow of rain water into the stream. A major factory leading to increases both in the frequency and potential severity of flash flood is urbanization. Impervious ground surfaces such as parking lots and roads, drainage from roofs of homes and buildings, along with storm drainage and sewer systems of limited capacity all contribute to the increased flash flood threat in urban areas. As urbanization continues to increase, the flash flood threat in the urban environment increase as well.
Currently, flash flooding is only addressed by the National Weather Service’s flash flood warning program. The EPA has established a consent decree. Water authorities nationwide implement wet weather management projects to eliminate storm sewer overflow, the direct consequence of flash flooding. These rate-supported capital projects deal with the consequences of flash floods but still need to accurately take into account flash flooding itself.
Engineering design for storm drain networks are often based on “return periods” of rainfall produced by the National Weather Service. These climatic estimates of rainfall return period are all based on rain gage data. The heaviest rainfall amounts produced by thunderstorms are seldom captured in the rain gage network. The engineering design using the rain gage return periods will generally greatly underestimate both the frequency and amount of the heavy rainfall. If only rain gages were usedto detect flash floods only about 5% of all flash floods would be detected. Using the rainfall from the WSR-88D, the NWS in Pittsburgh detects over 90% of all flash floods. TASI’s FFM programuses WSR-88D data to replay all flash flood events. FFM can also produce the “rainfall history” of rainfall in a specific flash flood watershed for the week prior to the flash flooding. FFM canalso created rainfall in 5 minute time steps through the entire duration of the flash flood producing rainfall. FFM can also show results of historic flash flood events, to show the true spatialand temporal distribution of rainfall that caused the flash flood events. These events include the Johnstown flash flood of 1977, the Etna, PA flash flood of 1986, and the Shadyside, OH flashflood of 1990.
With the advanced and realistic estimates of the spatial and temporal distributions of heavy rainfalls and the rainfall history, TASI will help both the aggressive engineering solutions and green infrastructures to effectively resolve or mitigate the persistent storm sewer overflow, especially the combined sewer overflow (CSO).
TASI uses FFM to provide design, analysis and product development of highly complex engineering issues in the following areas:
1. Replay of flash flood events for assessment of flash flood vulnerability for locations of interest
-Using data from weather radar, rain gages, flash flood guidance (FFG), topography, and sewer sensors
-Comparing “Average Basin Rainfall” (ABR), computed from radar rainfall estimates, with FFG and actual flash flood severity to establish climatological flash flood baseline
2. Assessment of flash flood vulnerability for locations of interest
-Refining and/or redefining watershed divisions locally for critical locations such as highway intersections, underground garages, bridges, data centers, hospitals, power plants, etc.
-Refining and/or redefining watershed divisions for an entire city's storm sewer system
3. Planning/Renovation Assistance
-Identifying the hidden risks of flash flood areas such as flash flood damage paths, flood plains, and areas affected by flood prone tributaries
-Identifying the impacted areas of pollution due to flash floods
4. FFG Update
TASI
4160 Washington Road
Suite 218
McMurray, PA 15317
United States
info