1. Flooding in Flathead County and Kalispell, MT
Initiation to Geo-HMS and HEC-HMS
Remi Candaele
Hydrology - CE394K

2. Context & Flood Events Characteristics ArcGIS Process Geo-HMS Process
Outline
Context & Flood Events Characteristics
ArcGIS Process
Geo-HMS Process
HMS Model
Future Work
Evergreen – Kalispell Suburb

3. Context Flathead county subject to flooding
Located in northwest corner of Montana State.
Total area of 13,614 km² (5,256 mi²),
410 km² (158 mi²) of it (3.01%) is water.
As of 2000, the population was 74,471.

4. Motivations
Being familiar with a Hydraulic Model !!!

5. Flood Events Characteristics
Peak Flow : 2 events at 35m3/s
Peak Flow : 2 events > 100m3/s

6. Flood Events Characteristics
Flathead Valley
Occurring mostly during spring time,
Focus on 2 major events :
04/13/1996
04/20/1997
Low Rainfall intensity : computation over a long period,
Difficulty : 1 meteorological station and 2 gauge stations.
Time Series

7. Catchments & Streams Delineation
Projected Coordinate System : NAD1983_StatePlane_Montana
7 Subwatersheds selected
OBJECTID
NAME
BasinSlope (%)
BasinCN
BasinLag (hr)
Area_HMS (km2) 1
W90
24.89
67.02
5.78
476.79 2
W100
20.58
70.21
8.28
498.30 3
W110
22.92
60.90
5.46
211.40 4
W120
6.39
66.50
1.68
3.83 5
W130
22.06
63.12
6.71
557.40 6
W140
10.09
67.78
8.46
282.61 7
W150
13.08
67.39
5.84
115.68
SubWatershed Characteristics

8. Reclassification of Land Cover
Data downloaded from NLCD
Reclassification in 4 main categories thanks to Dr Venkatesh Merwade
Land Use Grid Obtained

9. Soil Data – Characterization of the Soil Type
SSURGO (scale 1:24,000) dataset doesn’t cover the entire watershed: use of the Statsgo dataset (1:250000).
4 types of soil: A/B/C/D. Soil B assigned to the unknown soils
Classification
Type of soil
A (low runoff potential)
Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These soils have a high rate of water transmission. B
Soils having a moderate infiltration rate when thoroughly wet. These soils have a moderate rate of water transmission. C
Soils having a slow infiltration rate when thoroughly wet. These soils have a slow rate of water transmission.
D (high runoff potential)
Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These soils have a very slow rate of water transmission.

10. CN obtained from SCS TR55 (1986)
Curve Number & Grid
CN obtained from SCS TR55 (1986)
Generation of a CN Grid
Statistics
Mean : 66.26
Std Deviation : 11.06

11. Geo-HMS ArcGIS Interface to create input files to HMS
Processes
River Length
River Slope
Basin Slope
FlowPaths,
Basin Centroids
HMS Inputs/Parameters
Loss, Transform methods by SCS,
Route method by Muskingum
Time Lag
Basin Curve Numbers
Selection of the contributing catchments -
GeoHMS Interface

12. Geo-HMS ArcGIS Interface to create input files to HMS
Basin Lag in Hours
Basin Curve Numbers

13. Geo-HMS ArcGIS Interface to create input files to HMS
Schematic
Export to HMS

14. Running the model under HMS
Meteorologic model :
Weight gages,
Muskingum routing,
Time Lag,
Time Series.

15. Results – Calibrating the model
Computations for exercising.
Next steps :
Find accurate numbers for Muskingum routing,
Calibration factor : Streamflow = Model

16. Venkatesh Merwade – Purdue U. Christine Dartiguenave – ESRI
Acknowledgments
Venkatesh Merwade – Purdue U.
Christine Dartiguenave – ESRI
Ron Schlagenhaufer – Flathead County
Folks : Eusebio, Tyler, Brian & others

17. Questions ????