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Stephanie Hennelly, Buffalo Creek

Buffalo Creek

Basic Information
Drainage area: 19.6 square miles
Urbanization: medium to low
Topography: generally flat, with occasional hills
Basin shape: elongated
Stream flow: NW (at Lake Zurich) to SE (at Wheeling)
Soils: Mostly Group C soils, silty clay loams (majority Ozaukee, Mundelin and Ashkum silt loams)
Water coverage: roughly 2.9%

Buffalo Creek begins in Lake Zurich, Lake County, Illinois. It flows southeast toward Buffalo Grove, Lake County, Illinois, through the Buffalo Creek Forest Preserve. It continues southeast into Cook County where it becomes the Wheeling Drainage Ditch, eventually ending at the Des Plaines River at Palwaukee Airport, at US-45 (Milwaukee Avenue) south of Hintz Road.

Water Budget (Based on 2010 data):
 INFLOW (in.) OUTFLOW (in.)
 Precipitation35.5 Streamflow14.4
(averaged from two stations)  Lake Evaporation0.023
   Actual Evapotranspiration 21.5
 TOTAL 35.5 TOTAL 35.9

Using the 2010 precipitation record for local Chicago Palwaukee Airport in Wheeling, Illinois, the annual precipitation for the area is approximately 33.35 inches per year.

Using more extensive records from the Chicago O'Hare International Airport (1958-2011), average annual precipitation for the area is determined to be approximately 37.61 inches per year. (Records attached as a file).

The average annual precipitation data from these two stations for year 2010 is approximately 35.5 inches.


-The drainage area of the watershed is 19.6 square miles.
-19.6 square miles = 5.46 x 10^8 square feet
-Annual total discharge of 7602 cubic feet per second

    As calculated for the drainage area of 19.6 square miles, with an annual discharge of 7602 cubic feet/year:
19.6 square miles * (2.7 * 10^7 square feet / 1 square mile) = 5.46 * 10^8 square feet.

(7602 cubic feet/second) = (20.8 cubic feet/s daily average)

(20.8 cubic feet/second) = (1.80 * 10^6 cubic feet/day)

(1.80 * 10^6 cubic feet/day) / (5.46 * 10^8 square feet) = 3.30 * 10^-3 feet per day
=4.0 * 10^-2 inches per day
=14.4 inches per year

The average annual streamflow is 14.4 inches.

Lake Evaporation

Approximately 0.57 square miles of the watershed is open water. The percent of open water in the Buffalo Creek watershed appears to be roughly 2.9%. 

    2.9% * Pan Evaporation Coefficient of 77.5% = 0.023 inches annual       lake evaporation.


Based on pan evaporation data from the Chicago Botanical Gardens in Glencoe, Illinois, the potential evapotranspiration rate (PET) for this area is approximately 27.7 inches per year. Based on a pan coefficient of 77.5%, the actual evapotranspiration rate (AET) would be around 21.5 inches per year for this area.

As calculated from the above data:
    Total Precipitation of 37.6 inches - Annual Discharge of 14.4 inches - Lake Evaporation of 0.225 inches = 23.0 inches total evapotranspiration (estimated).

Stephanie Hennelly,
Mar 15, 2012, 11:40 AM