Inland Flood: Shows cost and savings from Inland flooding from a Hurricane Harvey
Storm Surge: Shows cost and savings from storm surge induced flooding from a Hurricane
Mitigation Budget: Hypothetical amount of money allotted for buyouts or property
elevation for each census block group.
The results show the associated cost and benefit from a mitigation budget ranging from $10
million to $750 million per census block group.
Buyout Cost: Cost of purchasing residential property at the appraised market value, plus
the cost of demolishing the property and returning it to undeveloped open space.
Buyout Savings: Net present value of all NFIP flood claims, and the discounted annualized
losses from flood damages throughout the remaining economic life of the property.
Elevation Cost: Cost of elevating the first finished floor of a property to a level where
it is unaffected by the selected storm event (Harvey or Ike).
Elevation Savings: Net present value of all NFIP flood claims, and the estimated flood
damages avoided from a hurricane Harvey or Hurricane Ike flood event as a result of elevating
Benefit-Cost Ratio: Savings divided by cost expressed in ratio for the display extent
shown in the dashboard.
The coastal spine or "Ike Dike" is a proposed barrier that would extend the existing Galveston
seawall from [blank] to [blank]. For more information, see [link].
The sea level rise option (available only in combination with the 2080 economic development
scenario) shows how 2.4 ft of sea level rise would affect local property damage and inundation.
National impacts are not modeled for sea level rise.
Hurricane severity is considered in terms of the return period for associated surge events.
Over a given time period, weaker surge events are more likely, while stronger surge events
are less likely. The explanatory text describes the likelihood of surge events over the next
Hurricane Harvey Inundation: Federal Emergency Management Agency (FEMA).
Hurricane Ike Storm Surge Inundation: US Army Engineer Research and Development Center, Jackson
Hurricane Harvey Flood Damages: FEMA’s National Flood Information Program (NFIP)
Flood Damage Functions: United States Army Corps of Engineers (USACE) Galveston District.
Building and Property data: Harris and Galveston County Appraisal Districts.
Average Annualized Loss (AAL): AIR Worldwide Corporation, a pioneer in the catastrophe modeling
This dashboard explores the benefits of buying out or elevating residential homes in reducing major
flood damages as well repetitive flood loss.
Click on the buttons at the left side of the dashboard to change between costs/savings or elevation and
buyouts of residential properties.
You can change the budget using the drop down above the map.
The analysis in this dashboard apply four major methodological steps in estimating costs and savings
from inland and storm surge flooding in Harris and Galveston Counties: (1) hydrologic modelling of
Hurricane Harvey and Hurricane Ike, (2) computation of average annualized flood losses and historic
flood claims from previous flood events, (3) flood damage estimation to residential properties for
selected storm events, and (4) a benefit-cost analysis which compares cost of flood mitigation to
savings accrued from the flood damages prevented.
The analysis is at the parcel level and results are aggregated to show estimated costs and benefits at
the block group level. Parcels were chosen based on the Benefit/Cost Ratio. Those with the highest
benefit/cost are purchased first. Parcels must at least have a 1 Benefit to Cost.
Users should interpret the results with caution and treat the values only as
estimates. Decision makers should perform additional analysis to enable them to select the appropriate
flood mitigation measures, in addition to a suite of other non-structural flood risk reduction methods
that cross jurisdictional boundaries. You may find additional recommendations for flood risk reduction
from the Commission to
Rebuild Texas Report.