floodplain mapping activities on kalona's west ditch - City of Kalona
floodplain mapping activities on kalona's west ditch - City of Kalona
floodplain mapping activities on kalona's west ditch - City of Kalona
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FLOODPLAIN MAPPING ACTIVITIES ON<br />
KALONA’S WEST DITCH<br />
LARRY WEBER<br />
IOWA FLOOD CENTER<br />
DIRECTOR, IIHR – HYDROSCIENCE & ENGINEERING
Ramsey Creek <br />
Flows are input into the computer model to predict water surface <br />
eleva5<strong>on</strong>s. The water surface and land surface are intersected to create <br />
the flood boundary.
Unnamed Tributary 278 <br />
Streams that do not have a name designated in the Na5<strong>on</strong>al Hydrography <br />
Dataset are assigned numbers.
Unnamed Tributary 261
Unnamed Tributary 264
Unnamed Tributary 26
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
The area delineated <strong>on</strong> the <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> map is a combina5<strong>on</strong> <strong>of</strong> all the <br />
river and stream <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundaries in the area.
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek + Unnamed Tributary 278
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek + Unnamed Tributary 278 + Unnamed <br />
Tributary 264
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek + Unnamed Tributary 278 + Unnamed <br />
Tributary 264 + Unnamed Tributary 261
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek + Unnamed Tributary 278 + Unnamed <br />
Tributary 264 + Unnamed Tributary 261 + Unnamed Tributary 26
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> map
100-‐year depth grid <br />
The FEMA c<strong>on</strong>tractor also used the predicted 100-‐year water surfaces to <br />
create a grid <strong>of</strong> flood depths in the Kal<strong>on</strong>a area.
100-‐year <str<strong>on</strong>g>floodplain</str<strong>on</strong>g> boundary <br />
English River + Ramsey Creek + Unnamed Tributary 278
Comparis<strong>on</strong> <strong>of</strong> IFC and STARR Hydrology
STARR Floodplain Boundary
STARR Depth Grid
Comparis<strong>on</strong> with Depth Grid
• West Ditch, <strong>City</strong> <strong>of</strong> Kal<strong>on</strong>a, Iowa: 2.8 mile l<strong>on</strong>g<br />
• Flood pr<strong>on</strong>e areas: flat, low elevati<strong>on</strong><br />
• Objective: Evaluate the result <strong>of</strong> 2D flood-inundati<strong>on</strong> maps by MIKE21
Unit:<br />
Elevati<strong>on</strong>: m<br />
Unit:<br />
Discharge: m 3 /s<br />
Bathymetry Land Use Source Points<br />
• 3-meter DEM (Digital Elevati<strong>on</strong> Model)<br />
generated from 1-meter LiDAR data by IDNR<br />
(Iowa Department <strong>of</strong> Natural Resources)<br />
• 3-meter square grid<br />
• Manning’s n value is assigned to the NLCD<br />
(nati<strong>on</strong>al land cover) 2001 dataset<br />
• 3-meter square grid<br />
• Locati<strong>on</strong><br />
• Magnitude<br />
• Directi<strong>on</strong><br />
The model output is the result <strong>of</strong> steady state simulati<strong>on</strong> that includes:<br />
• Flow depth, free surface grid<br />
• Horiz<strong>on</strong>tal and vertical velocity grid
Culvert<br />
Roadway<br />
Unit:<br />
Elevati<strong>on</strong>: m<br />
DEM Resoluti<strong>on</strong>: 3m
Before the burn <strong>of</strong> DEM
Before the burn <strong>of</strong> DEM<br />
(Top) u/s XS<br />
(Bottom) d/s XS<br />
After the burn <strong>of</strong> DEM<br />
After the burn <strong>of</strong> DEM<br />
(Top) u/s XS<br />
(Bottom) d/s XS<br />
Flow directi<strong>on</strong>: North to South
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