Stormwater quality characterization, modeling, and management for the greater Milwaukee area, Wisconsin

Storm sewer pipes in the Greater Milwaukee area collect poluted stormwater runof

Management of uncertainty flood into a large weir system in Thailand

The Upper Yom River Basin in Phrae province, Thailand with the catchment area of 5,500km2 was chosen as a flood study upstream of an existing weir using the Integrated FloodAnalysis System: IFAS. It was calibrated to the large flood in 2011, verified in 2003 and 2006using the global satellite rainfall and ground-based observation rainfall. The results ofsynthesis inflow hydrographs from IFAS showed that it was satisfied on model performancecompared to the observation data during flood period in 2011 with annual flood frequencies of59 years and fitted to the Nash and Sutcliffe Efficiency: NSE of 0.07, R2 of 0.58, RMSE of253.8 m3/s, and the observed peak flood discharge of 1,133.7 m3/s, respectively. The resultwill be benefit to flood management of the weir system in the light of climate change impacts.Keywords: Rainfall-Runoff model; Flood Frequency; IFAS; Weir Operation

The sources, impact and management of car park runoff pollution: a review

Traffic emissions contribute significantly to the build-up of diffuse pollution loads on urban surfaces with their subsequent mobilisation and direct discharge posing problems for receiving water quality. This review focuses on the impact and mitigation of solids, metals, nutrients and organic pollutants in the runoff deriving from car parks. Variabilities in the discharged pollutant levels and in the potentials for pollutant mitigation complicate an impact assessment of car park runoff. The different available stormwater best management practices and proprietary devices are reported to be capable of reductions of between 20% and almost 100% for both suspended solids and a range of metals. This review contributes to prioritising the treatment options which can achieve the appropriate pollutant reductions whilst conforming to the site requirements of a typical car park. By applying different treatment scenarios to the runoff from a hypothetical car park, it is shown that optimal performance, in terms of ecological benefits for the receiving water, can be achieved using a treatment train incorporating permeable paving and bioretention systems. The review identifies existing research gaps and emphasises the pertinent management practices as well as design issues which are relevant to the mitigation of car park pollution

Stormwater runoff characterized by GIS determined source areas and runoff volumes

Runoff coefficients are usually considered in isolation for each drainage area with resulting large uncertainties in the areas and coefficients. Accurate areas and coefficients are obtained here by optimizing runoff coefficients for characteristic Geographic Information Systems (GIS) subareas within each drainage area so that the resulting runoff coefficients of each drainage area are consistent with those obtained from runoff and rainfall volumes. Lack of fit can indicate that the ArcGIS information is inaccurate or more likely, that the drainage area needs adjustment. Results for 18 drainage areas in Milwaukee, WI for 2000-2004 indicate runoff coefficients ranging from 0.123 for a mostly residential area to 0.679 for a freeway-related land, with a standard error of 0.047. Optimized runoff coefficients are necessary input parameters for monitoring, and for the analysis and design of in situ stormwater unit operations and processes for the control of both urban runoff quantity and quality. Stormwater runoff is characterized by source areas and runoff volumes that have been determined accurately by optimization and GIS technology.</p

A washoff model for stormwater pollutants

A washoff rate equation for stormwater pollutants is presented based on linear buildup of pollutant mass in the watershed. The expression was applied to residential and open land areas that have not previously been considered even though these areas are major sources of metals, nutrients, and bacteria in stormwater runoff. The transport coefficient c was determined from the nearly constant portion of the hydrograph at the peak of each runoff event. Values of c (cm- 1) for seven metals, i.e., Zn, Cu, Cd, Ni, Pb, Hg, and Ag (3.03 ± 1.34-6.10 ± 2.55 cm- 1), TSS, BOD5, total phosphorus (TP), E. coli, and fecal coliform (2.12 ± 0.907-7.16 ± 2.72 cm- 1) were estimated using this equation. The washoff rate was developed to reflect mixed land uses based on mass deposition and effective area. The order of transport coefficients for metals is Pb > Ag > Zn > Cu > Ni > Hg > Cd reflecting decreasing particle association. For all parameters this order is TSS > fecal coliform > E. coli > Pb > BOD5 BOD5 > Ag > Zn > Cu > Ni > Hg > Cd > TP. The washoff rate and a related pollutant concentration model are expected to be useful for the development of best management practices for stormwater.</p