Stormwater Runoff Characteristics and Effective Management of Nonpoint Source Pollutants from a Highland Agricultural Region in the Lake Soyang Watershed

Abstract

Abstract:The dense highland field area in the upstream region of the Lake Soyang watershed is subject to excessive soil erosion during the wet season. In this study, stormwater runoff from the Lake Soyang watershed was monitored during four rainfall events at 10 locations throughout 2016. The maximum SS concentration at Naedongcheon, which is located in the upper part of the Soyang River, reached 4598 mg/L. The event mean concentration (EMC) of SS loads in Naedongcheon ranged from 82.2 mg/L to 926.3 mg/L. We found that, although the first flush events were usually concentrated in highly paved urban areas, a first flush occurred in the agricultural area of the dense highland field region. The first flush phenomenon was identified by a dimensionless cumulative runoff mass and volume curve (M(V) curve), and the intensity of the first flush was analyzed by the coefficient of the nonlinear regression model and the FF 30 and FF 25 values (the fraction of pollution load transported by the first 30% and 25% of runoff, respectively). Nonlinear regression models using the power function were applied to fit the M(V) curve, the FF 30 values were inversely proportional to the coefficient a of the regression model. A long-term seasonal trend decomposition for monthly turbidity and precipitation was performed for the Lake Soyang. Long-term turbidity trend was approximately coincident with the trend in long-term precipitation. In addition, the present status of the best management practices (BMPs) in the upper part of the Soyang River basin was investigated, and a survey of the management and operation of the BMPs was conducted for selected farmers.

Constructed Wetlands as Sustainable Technology for the Treatment and Reuse of the First-Flush Stormwater in Agriculture—A Case Study in Sicily (Italy)

“…However, considering the ecological aspects, it is possible to sustain that FFSW can represent a dangerous source of contaminants for the environment and an excess of nutrients and trace metals in this source of water, for example, can result in eutrophication of downstream water bodies and pollution of aquatic ecosystems and soil [19][20][21]. In urban areas in particular, industrial activities produce a large amount of nutrients, salts and heavy metals which can accumulate on the rough earth surface, pavements and roofs during non-rainy days.…”

Coupling PCSWMM and WASP to Evaluate Green Stormwater Infrastructure Impacts to Storm Sediment Loads in an Urban Watershed

“…It is common for stormwater early in a storm event to have particularly high TSS concentrations due to a first flush effect (Bach et al 2010); though, particularly in urban settings, the first flush effect for TSS is inconsistent and not always observed (Deletic 1998; Deletic and Maksimovic 1998; Lawler et al 2006; Todeschini et al 2019). Peak stormwater TSS concentration is generally not more than three times the EMC for that storm (Bannerman et al 1993; Charbeneau and Barrett 1998; Göbel et al 2007; Peng et al 2016; Cho and Lee 2017); thus, even if measured stormwater TSS values are conservatively considered to be the peak TSS concentration occurring during each storm, these values still exceed the expected range defined by PADEP EMCs by a considerable margin (Figure 4). As a result, during calibration, we chose to raise EMCs to 1, 2, 3, or 5 times the PADEP values (Table ).…”

Multiple Linear Regression Models for Predicting Nonpoint-Source Pollutant Discharge from a Highland Agricultural Region

“…For the remaining points, such as Inbukcheon, Bukcheon, and Soyang River, real-time water level and flow measurements were obtained from the Ministry of Land Infrastructure and Transport and the Korea Water Resources Corporation. The sampled water from the measurement sites was delivered to the laboratory as quickly as possible, and BOD, chemical oxygen demand (COD), SS, TP, TN, and TOC were analyzed using standard methods [2]. In the statistical analysis of this study, the results of stormwater runoff surveys from 2013 to 2016 at nine points in the Jaun, Mandae and Gaha area [31] were used.…”

“…Overall, 670 mm fell over 8 days, with a maximum intensity of 66 mm per hour. The suspended sediment stayed in Lake Soyang for an extended period of time because of stratification; thus, the turbidity of the lake remained high and was measured at over 20 nephelometric turbidity units (NTU) for 168 days [2,3].…”