FLOOD10391 (2) - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I AYRES a:,SSOtC Ut1::"uIES 4. Estimate a replacement value for each structure. The replacement values will be based on County assessor tax records. If the replacement values are not available, we will commission a local real estate appraiser to estimate the replacement values based on the size and average unit construction cost of the structures. 5. Commission a real-estate specialist to assess the condition of each structure in the inventory. We will then compute depreciated replacement values for each structure, following Corps guidelines. 6. Determine a water surface elevation-frequency function for each structure, ranging from the 2-year through SOO-year events, based on the hydraulic analysis in Task 4. 7. Compute the expected value of average annual flood damage (EAD) at each structure using the Corps' risk-based economic program HEC-FDA. The EA~ will be computed using structure replacement value for risk assessment, and the EAD will be computed using depreciated replacement value following FEMA and Corps guidelines. 8. Compute and report the follow flood risk indices: . Damage incurred at each structure for each design event. . Depth of water at each structure for each design event. . Long term risk of flooding for various durations. . Estimate of the watershed response time for various locations in the watershed. . Estimate of the egress time-time to move from a point within the floodplain to a point outside the floodplain for any given event-for various locations in the watershed. 9. Input the flood risk indices in the structure database and provide a GIS coverage that includes these indices. The team will determine the response (including time parameters) of rainfall in the basin to flooding in order to identify critical and first impacted flooding areas along with the maximum potential impact zones. This will assist in addressing suitable flood preparedness, maintenance, monitoring, warning, and response actions. This analysis involves the multiple applications of incremental and increasing hydrologic data in the hydraulic floodplain model to reflect the performance and increasing hazard of the floodplain. To do so, we will: 10. Compute the watershed response time for areas in the floodplain for the various magnitudes of flood events using the hydrologic and hydraulic models developed in Tasks 3 and 4. This response time will define the maximum hydrologic warning time for those areas: the time difference between when sufficient precipitation falls which would result in flood damage to the time when the flood damage threshold is actually exceeded. 11. Identify areas of greatest potential flood risk based on the risk indices. We will analyze and identify high flood risk areas by ranking the structures in the database by risk indices using various criteria. We will develop notification materials to inform the public about the flood hazard, so that citizens may consider flood insurance, individual response plans, and self-help 25