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TP/Cha Predictive Models

February 18, 2008           
© S.M. Mandaville B.E., Post-Grad Dip., Professional Lake Manage. (limneschebucto.ns.ca)

The citation for this documentation is:

Mandaville, S.M. 2008. TP/Cha Predictive Models. Nova Scotia, Canada. Electronic media.

Contents:

• Introduction

• Selection of Phosphorus Loading Model for Nova Scotia
  • Watersheds modelled (1,000 lakes/ponds completed to date; Work is being initiated on another one thousand (1,000) lakes/ponds and reservoirs elsewhere and abroad!)
  • Example listing of completed lakes/ponds (this list is not complete)

Introduction

Predictive TP modelling was based primarily on the following: extensive decadal research spearheaded by several international peers in limnology under the chairmanship of Richard A. Vollenweider PhD, formerly of the Canada Centre for Inland Waters, Environment Canada, which culminated with the consensus OECD (1982)- Organisation for Economic Co-Operation and Development Report; on the Vollenweider(1976) TP Predictive Model; and the published research of Peter J. Dillon FRSC et al., formerly of the Dorset Research Centre, Ontario Ministry of the Environment.

In addition, the models are being further revised as and when I find the time to incorporate some new regression relationships developed by pioneering scientists, principally in the United States of America, which have proven to be applicable to Nova Scotia lakes as well. This process will take several years for model revisions as well as calibrations!

The natural background (+ direct aerial deposition) concentrations were computed utilizing published export coefficients in generally undisturbed similar natural soils in Nova Scotia (cf., Hart et al, 1978; Mandaville, 2000; Scott et al, 2000; Scott et al, 2003); the post-development concentrations were obtained utilizing published export coefficients (end-of-pipe mean year averages) of typical residential and commercial/institutional developments (cf., Mandaville, 2000; Scott et al, 2003; Vokey, 1998; and typical pollutants in stormwater runoff).

As opportunity presents itself, we are continuing our intensive field sampling, generally at storm sewer outfalls (inclusive of open channels), in order to expand the data base for post-development scenarios and revise the predictive models, if needed!

With respect to areas served by septic systems, our revised models did not incorporate the same assumptions as in Hart et al (1978) and Scott et al (2003) where the authors assumed 50% septic-derived phosphorus retention in Halifax/Wolfville soils. In the Scott et al (2003) report where Mandaville was a co-author, there was an inadvertent omission made by not noting this down (and Mandaville regrets that). Our export coefficients in such areas include all potential sources of phosphorus inputs incorporated into the 50% export assumption; it actually varied from 50% in some watersheds based on local info.

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