Development of urban runoff model FFC-QUAL for first-flush water-quality analysis in urban drainage basins

Abstract

An urban runoff model that is able to compute the runoff, the pollutant loadings, and the concentrations of water-quality constituents in urban drainages during the first flush was developed. This model, which is referred to as FFC-QUAL, was modified from the existing ILLUDAS model and added for use during the water-quality analysis process for dry and rainy periods. For the dry period, the specifications of the coefficients for the discharge and water quality were used. During rainfall, we used the Clark and time-area methods for the runoff analyses of pervious and impervious areas to consider the effects of the subbasin shape; moreover, four pollutant accumulation methods and the washoff equation for computing the water quality each time were used. According to the verification results, FFC-QUAL provides generally similar output as the measured data for the peak flow, total runoff volume, total loadings, peak concentration, and time of peak concentration for three rainfall events in the Gunja subbasin. In comparison with the ILLUDAS, SWMM, and MOUSE models, there is little difference between these models and the model developed in this study. The proposed model should be useful in urban watersheds because of its simplicity and its capacity to model common pollutants (e.g., biological oxygen demand, chemical oxygen demand, Escherichia coli, suspended solids, and total nitrogen and phosphorous) in runoff. The proposed model can also be used in design studies to determine how changes in infrastructure will affect the runoff and pollution loads.

Predicting biochemical oxygen demand in European freshwater bodies

“…5) allowed to identify the parameter well. The calibrated parameter is in line with some literature (Rossman and Huber, 2016; Andrés-Doménech et al, 2018; Hur et al, 2018) but is high when compared to estimates by Williams et al (2012), who considered this as part of discharge being treated in WWTPS. The median BOD load from urban wash-off from artificial land was about 4.5 t/km 2 , and accounted for 33% of urban waste (considering also WWTPS emissions).…”

“…Andrés-Doménech et al (2018) reported BOD event mean concentrations of 5–22 mg O 2 /L for Valencia in South Spain. Literature reports large ranges in BOD effective mean concentrations from urban nonpoint sources (Rossman and Huber, 2016; Hur et al, 2018). Given the paucity of data in amount of urban wash off occurrences and BOD mean concentrations, we set a large initial range of this parameter (Table 1).…”

Spatial-temporal variation and modeling of rainwater quality

“…The Storm Water Management Model (SWMM) software was used to model the quality of rainwater flowing into the drainage system, which was developed by the Environmental Protection Agency (EPA). Its use was because of its wide use in hydraulic modeling and water quality of urban drainage systems (Hur et al, 2018;Girão et al, 2017;Rosa et al, 2015). In SWMM, the exponential function was used to describe the accumulation of TSS during the dry period prior to a precipitation event.…”

“…In SWMM, the exponential function was used to describe the accumulation of TSS during the dry period prior to a precipitation event. This function is commonly adopted, as done by Tsuji (2019), Chen (2018), Hur et al (2018) and Girão et al (2017).…”

Flowback verses first-flush: new information on the geochemistry of produced water from mandatory reporting

“…First ush phenomena are common in other environmental process, including stormwater drainage, where sudden inputs of uid and energy disrupt system equilibrium (e.g. 53 ). A characteristic of this model is that earlier samples may be of higher concentration than later samples.…”