01K050 – Maple Cr. @ mouth
Technical Notes: 2006 Water Year
Chuck Springer

The telemetered stream gaging station on Maple Creek at the mouth operated throughout water 
year 2006 without interruption.  During this time, eight discharge measurements were made and 
33 discrete manual stage readings were taken at this station.

Rating Curve

This station began water year 2006 on rating Table 4.  The rating table covers a range of 
discharge from 0.75 cubic feet per second (cfs) to 478 cfs.  One of the eight discharge 
measurements used to develop this rating was taken during water year 2006.  The measured 
flows for this rating, ranging from 1.5 cfs to 168 cfs, covers only 35% of the rating curve.  
However, flows exceeded the measured range of flows only 6% of the time during water year 
2006.  Five percent of flows were less than the lowest measured flow, and 1% of flows were 
greater than the highest measured flow.  Flows greater than 168 cfs were modeled using a slope-
conveyance model to extrapolate discharge based on the characteristics of measured flows.   
 
Results of this model had to be calibrated or scaled to the measurements taken at this site.  To do 
this, a linear regression of measured versus modeled flows was conducted and the resulting linear 
equation was applied to each of the modeled flows.  On average, scaling the modeled flows for 
this site increased them by about 50%.  However, the difference between measured and modeled 
flows decreased as flows increased, and scaling high flows reduced them by only 5% on average.

A series of storm events between mid-December 2005 and mid-January 2006 caused a moderate 
amount of scour on the section control, shifting the rating curve below 5.4 feet.  This shift was 
pro-rated from mid-December to mid-January and saved as rating Table 5.

The calculated potential error for flows derived from the rating curve used during water year 
2006 for this station is ±13%.

Stage Record

The station logged continuously throughout water year 2006 without interruption.  The staff gage 
at this site is generally readable to within 0.02 ft at low flows, but as variable as 0.05 ft. during 
moderate and high flows.  Conditions surrounding the terminal end of the bubbler orifice are 
similar to those around the staff gage.  The stage height readings during the high flow season 
typically differed from manual staff gage readings by 0.04-0.06 ft, and were as high as 0.17 ft.  
During the summer 2006, the differences were only as high as 0.01 ft.  Time-weighted corrective 
adjustments were made to the continuous stage record whenever the difference between logged 
and measured stage values resulted in a 5% or more difference in discharge.  All adjustments are 
documented in the Hydstra Data Workbench.

The calculated potential error of the continuous stage data for this station is ±3%.

Future Efforts

This station has continued to scour during subsequent storm events.  Further surveying and high 
flow modeling efforts may be necessary.