Aerial View of 'Old Town' taken April 6, 1999
Project Overview and Goals
The need for a more accurate, timely, and reliable method of predicting floods and their paths was acutely felt after the July 1997 flood in Fort Collins. One of the strategies being developed is called the Real Time Flood Inundation Mapping and Notification System. In simple terms, this system uses computer modeling to predict where flooding will happen and what path it will take, based on data input to the model. The model is dynamic, meaning that as newer data is added to the existing database, the model becomes able to make increasingly more accurate predictions.
The data used to build the computer model is obtained from a variety of different sources. This new and exciting emergency response system integrates information that comes from weather forecasters, hydrology experts, and real time stream and precipitation gages. This information is constantly updated in the computer and the model uses GIS (Geographic Information Systems) topographical mapping to provide instant and real time flood forecasting information to emergency managers during an event. Emergency managers will then be able to take a more proactive stance toward public notification regarding imminent flooding, thus increasing the lead time available for preparation by affected residents and city departments alike.
This system is innovative in that it will integrate technical hydrological and hydraulic runoff modeling with emergency operations in a system that is user friendly and graphically oriented, so that the information can be interpreted and utilized quickly and easily. For example, based on the weather forecast, and knowing that the stream or pond in a neighborhood is rising at a certain rate, the program can predict that the water may go over the banks within an approximate time frame, and begin to flood that neighborhood.
The mapping system will also yield more detailed records after an event, so that we will know more accurately where to concentrate future mitigation efforts.
This project is being funded primarily by FEMA through the Project Impact initiative. However, many city departments and community business are contributing funding, time, and resources to the project. What makes this project so exciting is that this specific type of system has never been used before, and we think it has the potential to change the face of urban planning and post-disaster recovery and rebuilding.
Design Specifications
Database
The system will utilize a database that includes up-to-date geographic information on the city's infrastructure (including streets, private and public critical facilities, bodies of water, irrigation ditches, and stormwater facilities), emergency notification information, aerial photos, digital topographic mapping with two-foot contours, land-use data, and soils information.
Forecasting
Weather forecast information will be available that will show the real time and forecasted weather patterns from the National Weather Service (NWS). Features will include wind patterns, humidity, dew points, radar data, satellite images, and watches & warnings. This information will be displayed graphically using an overlay on a base map showing local streets and physical features. The radar data will be combined with real time streamflow and precipitation data to model the storm runoff. The radar can be calibrated using the real time streamflow and precipitation data.
Real Time Data Collection
Stream and precipitation gages will be located throughout the community to determine the amount of rainfall or level of streamflow at any given time. Each gage will have radio telemetry to send information to a base station. The data will then be accessed remotely or across the city's computer network. In all, approximately 25 precipitation and 53 stream gages are needed. Stream gages will be located along the streams, irrigation ditches, and detention ponds throughout the city. Precipitation gages will be located throughout the Urban Growth Area of the city. Data collected from this segment will also assist in the analysis of long-term rainfall patterns and the calibration of the hydrologic models used in stormwater master planning.
Real Time Data Analysis and Determination of Risk
This feature will develop real time runoff scenarios based on the data received from the gages and from radar. Hydrologic software models incorporated in this feature will develop the runoff estimates. Hydraulic models will develop inundation areas based on the topographic mapping available form the system database and the runoff estimates from the hydrologic modeling. All output information will be displayed in graphical format using a Geographic Information System (GIS). Another feature of the system is that alarms will sound when preset measurements were surpassed. Emergency personnel will have instant information based on the real time data analysis that will define the current risk in the affected area.
Short-Term Flood Forecasting (Prediction Modeling)
In addition to the real time modeling, "what if" scenarios can be run to determine implications of various rainfall amounts based in part on the real time gage data received, and on information entered assuming continued real time rainfall or projected rainfall patterns. This short-term flood forecasting will allow more lead time for responding to an event.
Response Actions
The system will recommend action steps and notification areas for the affected areas of the community based on the results of the real time and prediction modeling. These response actions will be developed before the event based on a vulnerability and damage assessment analysis of potentially impacted facilities. One example would be that when we receive X amount of rain in a specific area, enough runoff is generated that will flood a street intersection. The action associated with that rainfall would be to block-off the affected streets. Another example would be that based on a forecasted modeling run, the inundation mapping shows a residential area being flooded if rains continue for another hour. Evacuation would then begin for the areas that would soon be flooded. These types of pre-planned response actions certainly do not take the place of human judgement and decision making, but they do help to focus response efforts in the appropriate locations.
Notification
Through various notification media the residents of the area potentially affected will be alerted to the pending or occurring event. Examples of notification would include Emergency Auto-Dialing, AM Radio Station broadcasts, Cable TV overrides that include text and maps of impacted areas, Weather Radio, and a Web page that depicts the event and real time information.
Irrigation Gate Activation
Another component that can be incorporated in the system is remote activation of irrigation gate structures. Many of the local irrigation ditches have gates that regulate the flow in the irrigation canals. These gates, in many instances, can direct excess flows into streams, relieving the irrigation system of these increased flows. Remote activation of the gates, based on flow depths and predicted runoff quantities, would allow the gates to be opened or closed, routing flows in the desired direction. This would reduce the impact on downstream property owners who would otherwise be flooded by the overflowing irrigation canals.
Partnerships
Back to Top
|
