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HAZUS-MH Unit 3: Flood Riverine Hazard Analysis

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**1. **HAZUS-MH Unit 3: Flood (Riverine) Hazard Analysis

**3. **Inventory: Menu

**4. **Inventory: General Building Stock

**5. **Inventory: General Building Stock This is an example of the distribution of the number of buildings in a typical census tract. Of all the buildings in that tract, most of them are Wood-Residential type.This is an example of the distribution of the number of buildings in a typical census tract. Of all the buildings in that tract, most of them are Wood-Residential type.

**10. **HAZUS-MH Unit 3: Flood Model (Riverine) Hazard Analysis

**12. **HAZUS Flood Hazard Model

**15. **Add Screen Shots for the 4 major Menu OptionsAdd Screen Shots for the 4 major Menu Options

**16. **Flood Hazard Model (Riverine) Step 1: Define Topography

**19. **Define Topography The DEM [National Elevation Dataset (NED)] can be downloaded from USGS Web site
as a seamless dataset using the default, automated functions in HAZUS
HAZUS-USGS default download: 1-Arc Second resolution (approx. 22-27 meters)

**21. **Define Topography

**22. **Flood Hazard (Riverine) Model Step 2: Generate Stream Network

**23. **Step 2: Generate Stream Network User defines drainage area (to generate stream density)
Larger drainage area generates fewer, larger streams
Smaller drainage area generates more, smaller streams, but still includes the larger streams
A drainage area is the total surface area upstream [of a point on a stream] where the water flows over the ground surface and back into streams to finally reach that point

**24. **Based on “steepest slope”, each cell is assigned a flow directionBased on “steepest slope”, each cell is assigned a flow direction

**25. **Based on the flow direction, the Cell values now = the accumulation of the neighboring/upstream cells pouring into it (using 8-direction pour point model).
The cells with the largest flow accumulation values are the ones w/ the most water is flowing, hence the “stream channels”
Based on the flow direction, the Cell values now = the accumulation of the neighboring/upstream cells pouring into it (using 8-direction pour point model).
The cells with the largest flow accumulation values are the ones w/ the most water is flowing, hence the “stream channels”

**26. **Threshold Streams Cell values now meeting the “threshold” value (drainage area/Sq Mi. input in Step 2/Generate Stream Network) will now be used to create this dendritic pattern (our synthetic stream network)Cell values now meeting the “threshold” value (drainage area/Sq Mi. input in Step 2/Generate Stream Network) will now be used to create this dendritic pattern (our synthetic stream network)

**27. **Generate Stream Network

**28. **Flood Hazard (Riverine) Model Step 3: Define Scenario (Study Case)

**29. **Step 3: Define Scenario (Study Case) Select the stream reach(es) to analyze
Reaches are sections (line segments) of streams between two nodes created by a junction from another reach

**31. **Flood Hazard Analysis Step 4: Run Hydrology

**32. **Step 4: Run Hydrology

**33. **If the Reach is considered a Main Stream (originating outside of the Study Region DEM area) the flow rates/discharge are found in a pre-calculated table in HAZUS.
If #1 is not applicable, perform regression equation calculations AND make necessary adjustments if there are any gages w/ flow rate/discharge values that are applicable.
If no applicable gage data in #2, just use regression equations.If the Reach is considered a Main Stream (originating outside of the Study Region DEM area) the flow rates/discharge are found in a pre-calculated table in HAZUS.
If #1 is not applicable, perform regression equation calculations AND make necessary adjustments if there are any gages w/ flow rate/discharge values that are applicable.
If no applicable gage data in #2, just use regression equations.

**34. **Which process happens first? USGS Regression Equations or USGS Stream Gaga adjustment?Which process happens first? USGS Regression Equations or USGS Stream Gaga adjustment?

**35. **Which process happens first? USGS Regression Equations or USGS Stream Gaga adjustment?
Which process happens first? USGS Regression Equations or USGS Stream Gaga adjustment?

**38. **Flood Hazard (Riverine) Model Step 5: Compute Hazard (Run Hydraulics)

**39. **What odes Stream Channel “morphology” mean?What odes Stream Channel “morphology” mean?

**41. **Delineate Floodplain (Run Hydraulics)

**42. **Delineate Floodplain (Run Hydraulics) Floodplain Boundary
(horizontal data)
Flood Depth Grid
(vertical data)
* Both data layers are computed w/ Spatial Analyst and output in raster format

**43. **Flood Hazard Model

**44. **Exercise 3: Flood Model Hazard Analysis