Two days after Hurricane Maria hit Puerto Rico, 70,000 residents in the vicinity of the Guajataca Dam were urged to evacuate as a precaution. Heavy rains were rapidly filling up the island’s 36 dams. Without clearer data, local authorities could only plan for the worst-case scenario. The Guajataca Dam, which holds more than 11 billion gallons of water, was on the verge of uncontrolled overflowing and could cause great devastation to the area downstream.
These are challenges emergency managers face when they do not have reliable information. Several days after the precautionary evacuation order, a more accurate emergency picture of the situation emerged that did not warrant more evacuations. This was the result of a computer simulation system called Simulation-Based Decision Support System for Water Infrastructural Safety (DSS-WISE™) Lite, jointly sponsored by the Department of Homeland Security’s (DHS) Science and Technology Directorate (S&T) and the Federal Emergency Management Agency (FEMA).
The software can generate maps of inundation scenarios caused by dam or levee failures by calculating the speed at which the water would advance, the depths, and the extent of land and infrastructure it would impact. Armed with such information, emergency managers can plan for dam/levee breach incidents. While the original software was released more than a decade ago, new features are continually added to keep it current. Additionally, the development team of DSS-WISE™ Lite has recently entered into a new contract with S&T and FEMA to develop even more capabilities for the software.
Updates to DSS-WISE™ Lite
A dam failure can happen at any time. To address population distribution at different times of the year, week and day, DSS-WISE™ Lite added a new feature called the Human Consequence Module. The module combines flood simulation results with census block population data from the Census Bureau and gridded nighttime and daytime population data from LandScan USA.
“This global population distribution data enables decision makers to prepare more precise emergency plans based on how many people will be impacted and how many will need to be evacuated,” said Mike Matthews, S&T Senior Program Manager. “Knowing the impacted population allows better allocation of resources, especially during larger events.”
In addition to the Human Consequence Module, DSS-WISE™ Lite will also incorporate a flood hazard map.
“The flood hazard map will show the flood hazard levels for different population categories based on water depths and velocities,” said Dr. Mustafa Altinakar, Director of the National Center for Computational Hydroscience and Engineering (NCCHE) at the University of Mississippi, who leads the DSS-WISE™ Lite development team.
The map will be color-coded for different hazard levels ranging from extremely dangerous to not a significant danger. This way, first responders would know how risky the floodwaters would be for search and rescue teams.
Although the program began more than 10 years ago, it has continued to be updated to meet emerging requirement and additional threats. In September 2018, S&T and FEMA signed a new contract with NCCHE to further improve and develop DSS-WISE™ Lite’s analytic capabilities. The state dam safety offices of 34 states are currently using the tool.
“DSS WISE™ Lite can ultimately save lives because it is a great analytic tool that can support decision making before and during disasters,” said James Demby, Senior Technical and Policy Advisor at the National Dam Safety Program, FEMA.
DSS-WISE™ Lite helps emergency managers prepare for breaches
DSS-WISE™ Lite is also being used to inform maps that are part of much-needed Emergency Action Plans specific to dams. These are now required by some states. In fact, after the Oroville Dam incident in California last year during which water had to be released to prevent overflow and dam failure, California issued new laws that require Emergency Action Plans from dam owners.
“Not only are dam owners using DSS-WISE™ Lite to prepare for emergency dam failures, but also The Dam Safety Office in California is using the tool to check the dam owners’ inundation maps,” said Demby. “DSS-WISE™ Lite is invaluable as a decision support tool for the emergency management community because it can do a really sophisticated analysis and simulate a dam break within half an hour, to an hour. That is where the real strength is.”
According to the Association of State Dam Safety Officials, more than 2,000 high-hazard-potential dams are considered deficient due to deterioration, insufficient investment in maintenance, and other issues. This underscores the importance of Emergency Action Plans as well as a tool like DSS-WISE™ Lite that can enrich the data on the maps in the plans that are important for identifying evacuation and shelter-in-place areas.
Usage during the past year
The past year has been punctuated with surges of DSS-WISE™ Lite usage, especially in connection with the hurricane season. One such surge was right after Hurricane Maria hit Puerto Rico.
On Saturday, September 23, 2017, Altinakar received a call from Shudipto Rahman, a civil engineer at FEMA Region II, which includes Puerto Rico. Rahman asked him to register 11 new users from Puerto Rico who needed to rapidly run dam-break simulations for all dams in the island. During that time the storm was still going on, Puerto Rico had no power, and the emergency action plans could not be accessed.
“Within 36 hours, these new users mapped the potential failure of all 36 dams in Puerto Rico,” Rahman said. “They carried out more than 110 simulations with DSS-WISE™ Lite for different types of releases from the dams and the situations created downstream.”
Another surge of usage was related to Hurricane Florence in September 2018. Many high hazard dams were in danger of overflowing and several small dams breached, destroying roads and adding more water to already flooded land. North and South Carolina users were hurrying to run dam breach simulations and plan for evacuations if necessary.
Since the first anniversary of DSS-WISE™ Lite in November 2017, dam-breach simulations have more than tripled – from 3,115 simulations for 876 dams to 10,350 simulations for 2,424 dams as of October 25, 2018. Fortunately, DSS-WISE™ Lite is free for federal and state users, saving them thousands of dollars per simulation..
“As of October 25, 2018, DSS-WISE™ Lite has 644 active users and is handling on average more than 30 simulations per day,” said Altinakar.
“The big success story for everyone is that for the last 11 years DSS-WISE™ has continued to provide valuable life-saving services to local, state, and federal communities and partners. S&T has not only saved taxpayers more than $60 million (thus far) from a meager $1.6 million investment in the research and development of DSS-WISE™ Lite, but S&T, with each iteration of improvements to the system, continues to provide updated and new capabilities for improved emergency planning and preparedness in communities across the nation,” said Matthews.
“The rewarding part for me as a federal program manager is knowing the technology we developed proved valuable for the past hurricane seasons.”
Interested in using the tool? DSS-WISE™ Lite can be accessed here.