Big Creek
Flood Peak Analysis

Landels-Hill Big Creek Reserve

This page displays results of different analyses of peak flood events along Big Creek. See stream studies page for background and descriptive information about the creek.

 Turbidity peaks and changes in relation to the 1999 Kirk wildfire:

 Graphs of recent flood events

 Confluence of Big Creek (right) and Devil's Creek (left) forks of Big Creek. This 2.9' flood was rising from a base of about 1.35' to a peak of 3.9'. Note the marked difference in color between the two creeks: dark "coffee" color for Big Creek and lighter "milky" color for Devil's. 11-8-02
 

 Turbidity measurement tubes showing the water sampled from the above creeks, taken at the same time as the photo above. Note the darker color of Big Creek water on the right (2 JTU) and the lighter, but more opaque, water from Devil's Creek (5 JTU). 11-8-02


Turbidity in relation to the October 1999 Kirk wildfire. In January and February of 2000, flooding included extremely opaque, turbid water with readings up to 4000 JTU. In the winter of 2000-2001 we did not take any measurements, but the water was much cleaner during the smaller floods of that year. On the winter of 2001-2002 we observed further reduction in turbidity (peak value = 40 JTU; see below) and this trend continued in the November 2002 flood (peak value = 6 JTU; see below). However, in December 2002 we experienced a much more intense flood ing event (peak at 6.5' on gauge) and the water bacame quite muddy (JTU=768).

   

On January 2 , 2002 rainfall caused a minor flood in Big Creek. The creek rapidly rose to a level of 4' on the staff gauge. The water became quite dirty and this aspect of the sediment load was measured to be 40 J.T.U. using a standardized turbidity measurement kit. Procedures.

 This graph shows the decline in water level after the flood peak. This flood was preceeded by a month of heavy rains in December, and the creek did not subside as quickly as in the November 2002 flood below.
   
 A similar flood in November 2002 caused a much-reduced peak in turbidity (6 J.T.U.) In this case we had warning and took measurements before as well as after the flood peak.  Graph of stage height, November 2002 flood. This flood was preceeded by extremely dry conditions, and the creek rapidly subsided after the flooding event.
   
 A much larger flood occurred in mid-December 2002. This was an intense storm with strong winds and heavy rain. The water bacame very muddy with a maximum JTU reading of 768. This turbidity subsided to values of 5-10 in 24 hours.  Very intense rainfall was recorded at the gate cabin weather station, with 25mm (about 1") recorded in a 15 minute period at the peak of the flood.