Ecological Engineering61P (2013) 601– 613 Contentslists availableat ScienceDirect Ecological Engineering j o u r n a l h om e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / e c o l e n g Modeling the eutrophication of two mature planted stormwater ponds for runoff control Tove Wium-Andersen a , Asbjørn H. Nielsen a , Thorkild Hvitved-Jacobsen a , Hans Brix b , Carlos A. Arias a , Jes Vollertsen a,∗ a AalborgUniversity, Department of Civil Engineering, Sohngaardsholmsvej 57,9000Aalborg, Denmark b AarhusUniversity, Department of Bioscience, Plant Biology, OleWormsAllé 1, 8000AarhusC, Denmark a r t i c l e i n f o Articlehistory: Received17 March 2013 Receivedin revisedform 3 July 2013 Accepted4 July 2013 Available online 14 August 2013 Keywords: Eutrophicationmodel Stormwater Wet detentionpond pH Dissolvedoxygen a b s t r a c t A model, targetingeutrophication of stormwater detention ponds was developedand applied to sim- ulate pH, dissolved oxygen and the development of algae and plant biomass in two mature planted wetponds for run off control. The model evaluatedalgal and plant biomass growth into three groups namely; phytoplankton, benthic algae and macrophytes.The study evaluatedlarge data sets from an intensive monitoring campaignof two Danish mature stormwater ponds which were used to calibrate and validatethe model. One generalcalibrationcovering6 consecutivemonths togetherwith two addi- tional short-term calibrationsduring summer (31 days) and winter (56 days) were carried out applying the data series from one of the ponds. The calibrations showed a good agreementbetween measured and modeled data for the time spans evaluated. The calibration showed that growth rates for the three groups of primary producers were approximatelythe same for the two calibrations.The validation for both trends of DO and pH were well simulated,eventhough pond Aarhus showed a better agreement of the absolutevalues. The eutrophicationmodel could be successfullycalibratedto two stormwater ponds and has the potential of providing a tool for improving the design of stormwater ponds by taking into accountthe behavior of the plant ecosystem. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Stormwater runoff from roads and urban surfaces often con- tribute to the deterioration of the aquatic environment. Runoff contains a wide range of contaminants in varying concentrations (NURP, 1983). Among these contaminants are heavy metals, sus- pended solids, nutrients, and organic micro-pollutants like PAH’s and biocides.If dischargedwithout prior treatment,the pollutants can have detrimental impacts on the flora and fauna of surface waters. Thereforetreatmentis often required to protect the receiv- ing aquatic environment. Due to the nature of stormwater runoff, treatment facilities must be robust and capable of handling an intermittent runoff patternaswell asa wide rangeof pollutant con- centrations. One treatment technology which has proven robust and efficient in managingboth flows and pollutants from stormwa- ter runoff is the wet detention pond. A wet detention pond is an artificial lake with a permanent pool of water designed to detain stormwater runoff. While detained,the quality of the stormwater is improved by sedimentation,adsorption, chemical precipitation, ∗ Correspondingauthor. Tel.: +459940 8504; fax: +459940 8552. E-mail address: jv@civil.aau.dk (J. Vollertsen). and biodegradation – hereby mitigating the negative impacts on the receiving waters. The specific load of nutrients to a wet detention pond can be significant and, like in a natural lake, can cause eutrophication of the pond (Mitsch and Reeder,1991; Gelbrecht et al., 2005). In natural lakes the resulting algal bloom will lead to high water turbidity, high pH and periods of low dissolved oxygen (DO) con- centration due to decomposition of deadalgae(Torno et al., 1985). Most stormwater systems are located in urban areas and one of the purposesis to improve the environmental quality of the area. A eutrophic stormwater is not wanted asit leadsto poor estheticcon- ditions, reduced ecological quality as well as decreasedtreatment performance. With respect to wet detention ponds, this process has not beenstudied in details but could potentially lead to low DO concentrationsin the pond. Upon discharge, such water has detri- mental impacts on the receiving water fauna and flora (Magaud et al.,1997).Low DO concentrationsin the pond could furthermore lead to anaerobicconditions at the pond bottom, resulting in mal- odors and lowered redox conditions in the sediments. Thelatter can cause release of phosphorus and heavy metals previously immo- bilized in the pond sediments (Wong and Yang, 1997). The algal biomass can also absorb pollutants, which thereby are removed from the free water phase(Mehta and Gaur, 2005). 0925-8574/$– seefront matter ©2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ecoleng.2013.07.032