ASFPM - Rapid Floodplain Mapping

Transcription

1 ASFPM - Nicole Cominoli Hydraulic Engineer USACE - Omaha District mary.n.cominoli@usace.army.mil June 3, 2015 US Army Corps of Engineers

2 Mitigation = Risk Informed Decisions 2

3 The National Flood Insurance Act of 1968 Directed the Federal Insurance Administration (FIA) to: Identify ALL flood prone areas within the United States Establish flood-risk zones within flood prone areas 3

4 Zone A versus Zone AE Mapping Zone A (Approximate Study): Areas subject to inundation by the 1-percentannual-chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been performed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply. Zone AE (Detailed Study): Areas subject to inundation by the 1- percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply. 4

5 Approximate Studies (Zone A) Because the FIA was to map the entire United States, they could not conduct detailed studies everywhere. Instead they used the following existing information to identify areas that are likely to be flooded. Highwater marks Aerial photos from previous floods Topographic maps Soils maps Shown on maps as Flood Hazard Boundary Maps Served as the official NFIP floodplain maps 5

6 Detailed Studies (Zone AE) Gage data records Hydrologic modeling Hydraulic modeling LiDAR data and surveys Histroical flood information Structure surveys Budget: High risk of flooding Significant development or potential to develop in the future. 6

7 Coordinated Needs Management System (CNMS) A FEMA initiative to update the way FEMA organizes, stores, and analyzes flood hazard mapping information for communities. Studied Stream Lines Unmapped Stream Lines 7

8 Coordinated Needs Management System (CNMS) Unmapped Stream Lines Studied Stream Lines 8

9 There is a need for floodplain mapping in the United States. There is a need to rapidly create this data. $$$$$ $ 9

10 A Need for New/Updated Mapping The Omaha District has developed automated scripts that: Setups up the HEC-RAS (Hydraulic Model) data Manages the data (such as the flow and geometry data) QA/QC tool So 100% manual review is not needed The Iowa Floodplain Mapping project is a Section 22 project that develops floodplain modeling and mapping for 8 HUC 8 watersheds within Iowa. This effort is similar to modeling and mapping activities associated with the National Flood Insurance Program. It is the objective of the Iowa Floodplain Mapping project to develop data applicable for a Zone A approximate study incorporated into the NFIP. Through the application of statewide LiDAR data and GIS automation tools, HEC- RAS models are used to develop this data. Automated methods has been developed to assist hydraulic modelers in verifying that engineering products meet specified requirements. 10

11 Large Data Set Entire Watershed/HUC 2,000 of these 8 of these 11

12 Terrain Data and Flow Data 12

13 Cross Sections 13

14 Bank Station Lines 14

15 Flowpath Lines 15

16 Python Scripts #1 Create Directories Script: Breaks up a large area (ie: watershed) into individual stream folders #2 Hydraulic Preprocessing Script: (1) Creates HEC-GeoRAS Geodatabase (2) Creates Hydraulics Folder (3) Clips Mannings' N Land Use Shapefile (4) Exports Flow Points (5) Created Station Points (6) Extracts DEM (7) Creates Hillshade (8) Clips Contour Shapefile (9) Adding Stream to River_Tarr_Creek (10) Adding Stream to Flowpaths_Tarr_Creek (11) Exports Banklines (12) Adding Cross Sections to XSCutlines_Tarr_Creek (12a) Ran Hydraulic Flow Change Points Script (13) Loading Data (13a) Updating HydroID (14) Creating float file 16

17 Individual Stream 17

18 Video Video 18

19 QA/QC No real criteria for Zone A mapping USACE Omaha District QA/QC automated tool checks: Completeness Review: Is the project title correct? Are there only one plan, geometry and flow file? Are the plan, geometry, flow title correct? Geometry Review: Model units Are the reach lengths correct? Is the cross section stationing in line with the reach lengths? Are the cross sections long enough to include the flooded areas? Are the overbank Mannings values correct? Are the channel Mannings values correct? Flow Review: Does the model contain each profile Are the discharges for each profile correct? Do the flows increase in the downstream direction? Is the slope acceptable for boundary conditions-normal depth? Results Review: Are any of the profile crossing or contain dips? 19

20 Online Tracking Tool 20

21 Online Tracking Tool 21

22 Online Tracking Tool 22

23 ?Questions? Nicole Cominoli US Army Corps of Engineers Omaha District Flood Risk and Floodplain Management Special Thanks: Michelle Schultz Programmer and GIS Specialist Tony Krause Iowa Floodplain Mapping Project Manager Iowa Flood Center Technical Partner Iowa Department of Natural Resources Project Sponsor 23