# Presentation: 774128

## Kinematic Channel Routing Parameter 

- Estimation for a NEXRAD Cell Based Model
-  pre-processing for HL-RMS
- Hydrology Lab – Research Modeling System
- Seann Reed
- Victor Koren
- Ziya Zhang
- Mike Smith

## Information Required for Each Modeling Element

- HRAP Cell Modeling Elements
- (~ 16 km2 ) for
- the Blue River Basin (1233 km2)

- Flow direction (cell connectivity)
- Channel slope (Sc)

- Channel roughness (nc)
- Channel top width parameter ()
- Channel shape parameter ()

- Hillslope roughness (nh)	Hillslope slope (Sh)
- Channel density (Dd)

**Notes:**
There are 80 bins actually within the Blue 
Althought 
~ 16 km2 at 35 N

## Basic Input Data

- USGS Streamflow
- Measurement Data

- 2

- http://water.usgs.gov/nwis

- http://gisdata.usgs.gov

**USGS Gage **
**07332500**

**Notes:**
/fs/gis/rms/blue30.apr
c:/sreed/rms/agu/example_gsdata.doc

overall relief of basin is about 0.0014

## Deriving Flow Directions for Each HRAP Cell

-   Flow directions are derived from 30-m DEM
-   A starting point for stream tracing is identified in each HRAP cell

- Rules resolve complex situations in which multiple traces pass through the same cell

-   Trace downstream from each starting point and assign flow directions based on a set of rules

**Notes:**
This is a non-trivial exercise because of the large size of the HRAP grid cells and because only one flow direction value can be assigned to each cell.  Of course this limitation could be reduced at the expense of increasing model complexity either through smaller cell sizes or irregularly shaped modeling units.   

## REASONABLE RESULT

- HRAP Flow Directions for the Blue River Basin

**Notes:**
blue30.apr

## Example HRAP Flow Direction Results 

- 1

- 2

- 1.  Illinois River at Tahlequah, OK (2484 km2)
- 2.  Baron Fork at Eldon, OK (795 km2)
- 3.  Cheat River at Parsons, WV (1869 km2)

**Notes:**
Total number of pixels examined in 5 areas:
80 + 135 + 151 + 50 + 114 = 530

3 manual edits required

examples for two additional basins in OK and one in West Virginia

## Channel Slope (Sc)

- Channel Slope (Sc)

-   Channel slope assigned to each HRAP cell based on “main” channel traced from DEM

**Notes:**
lowest slope used when multiple traces pass through the same cell-- based on the assumption that higher order channels carry most of the flow and higher order channels tend to have lower slopes on average

correction for zero slopes and channel slopes in headwaters -- 

check channel slopes in headwaters 

never know for sure what kind of values you will get from a DEM so it is always good to do some visual inspections and check for outliers

 Sc is a key parameter in kinematic routing

## Channel Roughness (nc)

- Channel Roughness (nc)

- At the outlet:  n0 estimated using Manning’s equation and USGS streamflow measurement data
- At an upstream cell c:
- nc = n0Sck1Adk2
- (Ad = drainage area, k1, k2)

**Notes:**
Conceptually, the ArcView/Arc-Info slope function 
fits a plane to the z values of a 3x3 cell neighborhood around the center cell being assigned a slope value.

Tokar, A. S., and P. Johnson, 1995.  Optimization of river characteristics in the Blue Nile watershed, NFS 3.0 Reference manual, No 121.

Perhaps hillslope roughness could be assigned based on land use?  This might be an obvious step although not sure how beneficial this may be in terms of simulation results.  

## Channel Width () and Shape () Parameter Estimation

- 2.  Solve for  and  using streamflow measurement data:

- Channel Width () and Shape () Parameter Estimation

- 1.  Assume relationship between top width and depth:

- Illinois River at Watts, OK

- Example cross section
-  = 36.6,  = 0.6)

**Notes:**
Channel top width parameter  is spatially variable within a basin

Channel shape parameter  is assumed constant

Note: data averaging was used to force low not to have undue influence on the results

## Estimate Channel Width Parameter (c in Each Cell (c)

- 1.  Start with known values of Axo and Qo
- 2.  Solve for Axc using a relationship from geomorphology
- 3.  Assume Qc proportional to drainage area and solve for hydraulic depth using Manning’s equation
- 4.  Solve for Bc and then c

- Estimate Channel Width Parameter (c in Each Cell (c)

**Notes:**
Basically what you are saying is that geomorphology law controls the total cross sectional area but slope and the hydraulic equation for steady-state flow controls the variation in the channel width parameter with space. 

Emphasize that Ax here is cross sectional area of flow 

## Channel Geometry Parameters

- ()

- ()

## Example Simulations

- Flint Creek at Kansas, OK (285 km2)

- Illinois R. at Watts, OK (1645 km2)

- Illinois R. at Tahlequah, OK (2484 km2)

## Summary

-   A method to develop distributed, kinematic channel routing parameters for a basin is described.
-   The method combines topographic information with flow measurement information at the outlet using simple relationships from geomorphology and hydraulics.
-   Initial simulations indicate that the parameter estimates yield reasonable routed flows.

**Notes:**
Although we are initially focused at the HRAP grid cell scale, methods are generally enough to apply to other types of modeling units