Systems Dynamics of Detention/Retention in Ponds

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0003408TorgersenSmall ponds are traditional for control of stormwater and chemical runoff. However, 'events' has been observed that result in significant internal loading, hyper-eutrophication and export of nutrients and contaminants from the ponds. We hypothesize that ordinary bacterial processes within the sediments/benthic-boundary-layer coupled with aperiodic shallow-pond-specific processes are responsible for this internal loading and downstream contamination. Thus, the coupled interactions of physics chemistry and biology in detention/retention ponds control the state of the pond more than any individual processes. This internal loading and coupled dynamics of ponds significantly alters the application of ponds in environmental engineering.We will test hypotheses for internal loading 'events' in ponds with continuous-recording instruments (WEB-addressable) and measure the dynamic responses of ponds to internal loading 'events' (rainfall, spring, accidents, etc.) We will observe and quantify significant bulk processes involved in the removal of nutrients and contaminants from retention ponds as well as the processes that regenerate/release nutrients and metals. With monitored pond response, coupled with direct sampling and wet chemical analyses, we will define a coupled dynamic pond model.We will develop a loading history model of ponds building upon CASC2D as a function of land use to predict when the critical lifetime of a pond has been reached and remediation is required. Development of the 1) pond-loading model and 2) pond dynamics model will contribute to the appropriate use and application of ponds as detention/retention devices in the environment. We will develop the web-addressable monitoring equipment with the possibility of creating an Instrumented Environmental Systems Laboratory for use in undergraduate teaching, honors theses and extensions to high school.. The pond loading and pond dynamics models developed from this study of two ponds can be tested with simplified studies in other ponds. Continuing projects will evaluate pond dynamics across a variety of climatic zones and land use types. The ultimate product will be a database and models that will significantly improve pond design and management.