DSSAM Model - Development History

Development History

Impetus to derive a quantitative prediction model arose from a trend of historically decreasing river flow rates coupled with jurisdictional and tribal conflicts over water rights as well as concern for river biota. When expansion of the Reno-Sparks Wastewater Treatment Plant was proposed, the EPA decided to fund a large scale research effort to create simulation software and a parallel program to collect field data in the Truckee River and Pyramid Lake. For river stations water quality measurements were made in the benthic zone as well as the topic zone; in the case of Pyramid Lake boats were used to collect grab samples at varying depths and locations. Earth Metrics conducted the software development for the first generation computer model and collected field data on water quality and flow rates in the Truckee River. After model calibration, runs were made to evaluate impacts of alternative land use controls and discharge parameters for treated effluent.

The DSSAM Model is constructed to allow dynamic decay of most pollutants; for example, total nitrogen and phosphorus are allowed to be consumed by benthic algae in each time step, and the algal communities are given a separate population dynamic in each river reach (e.g.metabolic rate based upon river temperature). Sources throughout the watershed include non-point agricultural and urban stormwater as well as a multiplicity of point source discharges of treated municipal wastewater effluent.

Subsequent to the first generation of DSSAM model development, calibration and application, later refinements were made. These augmentations to model functionality focussed on increased flexibility in modeling the diel cycle and also allowed inclusion of analyzing particulate nitrogen and phosphorus. In developing DSSAM III several changes in the model operation and scope were performed.