I have been trying to send this message for three days now, but the mail
server doesn't like me since I moved to Colorado state. Hopefully, my
address change has taken effect and you will get this now...LAR
Original Message ---------------------
David, by their very definition, Event Mean Concentrations are computed as
the flow-weighted concentration data. Therefore, if the data are
representative of the area you are studying, using EMCs x runoff is
perfectly valid. But if the concentration data were simply averaged, they
are not EMCs and it is improper to estimate loads by simply multiplying
average concentration x flow.
There is a US spreadsheet model available to do this. It was developed by
Camp Dresser & McKee originally for the State of Florida, but has been
updated and put into Windows format by the Rouge River Program, a large
urban study in the Detroit, Michigan area. (Yes, I know its not a
Mediterranean climate, but the water runs downhill there also -- except when
it freezes).
Anyway if you are interested in a copy, e-mail Steve Rood at <
[log in to unmask] > and ask him for a copy of the Watershed Management Model.
It will help you compare alternative plans with and without BMPs.
...LAR
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]]On Behalf Of Kemp, David
(TSA)
Sent: Thursday, November 04, 1999 3:35 PM
To: [log in to unmask]
Subject: Annual Pollution Loadings
I am currently involved in the review of the production of a stormwater
management plan for townships along the River Murray in South Australia.
The plan focuses on water quality, and makes predictions of annual pollutant
loadings. The climate is Mediterranean.
The methodology is as follows:
- From recorded event mean concentrations on catchments in Adelaide and
Australian Environment Council range of pollutant concentrations determine
average event mean concentrations.
- Apply these average event mean concentrations to each town catchment and
multiply by volumetric runoff coefficient and annual rainfall to get annual
pollutant loads.
The question is this. Is this reasonable given that annual rainfall in
these towns is low (250mm - 300mm compared with Adelaide 600mm). This leads
to lower loadings from catchments having lower annual rainfall. I would
expect that loadings would not be directly proportional to annual rainfall.
What evidence is there to support or otherwise this methodology?
David Kemp
Senior Stormwater Engineer
Transport SA
Phone (08) 8343 2534
FAX (08) 8343 2747
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