Predicting Runoff Chloride Concentrations in Suburban Watersheds Using an Artificial Neural Network (ANN)

Khurshid Jahan,Soni M Pradhanang

doi:10.3390/hydrology7040080

Khurshid Jahan, Soni M Pradhanang

Open Access

https://doi.org/10.3390/hydrology7040080

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Journal: Hydrology	Publication Date: Oct 21, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: University of Rhode Island, Woodward (United States)

Abstract

Road salts in stormwater runoff, from both urban and suburban areas, are of concern to many. Chloride-based deicers [i.e., sodium chloride (NaCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2)], dissolve in runoff, travel downstream in the aqueous phase, percolate into soils, and leach into groundwater. In this study, data obtained from stormwater runoff events were used to predict chloride concentrations and seasonal impacts at different sites within a suburban watershed. Water quality data for 42 rainfall events (2016–2019) greater than 12.7 mm (0.5 inches) were used. An artificial neural network (ANN) model was developed, using measured rainfall volume, turbidity, total suspended solids (TSS), dissolved organic carbon (DOC), sodium, chloride, and total nitrate concentrations. Water quality data were trained using the Levenberg-Marquardt back-propagation algorithm. The model was then applied to six different sites. The new ANN model proved accurate in predicting values. This study illustrates that road salt and deicers are the prime cause of high chloride concentrations in runoff during winter and spring, threatening the aquatic environment.

Highlights

Urban areas require the construction of buildings, roads, and parking areas, yet such urban development causes hydrologic impacts and pollution as pervious surfaces are made impervious [1].For safety, given abundant snowfall during the winter season, most communities in New England use salt or deicing on roads and parking areas
Road salt and deicer applications in a suburban watershed, based on three years of data collected at six study sites
Study sites are close to agricultural land (Sites 1, 2, 3, and 4) and an collected parking at six study sites.5Study are close to agricultural

Summary

Introduction

Urban areas require the construction of buildings, roads, and parking areas, yet such urban development causes hydrologic impacts and pollution as pervious surfaces are made impervious [1].For safety, given abundant snowfall during the winter season, most communities in New England use salt or deicing on roads and parking areas. Urban areas require the construction of buildings, roads, and parking areas, yet such urban development causes hydrologic impacts and pollution as pervious surfaces are made impervious [1]. Road salts or deicing during the winter season are the primary factors for increasing salinity in surface soils, surface water, groundwater, and runoff. In the USA, an average of 24 million metric tons of road salt is applied each year to roads [2]. It is well-established that the application of road salts leads to the accumulation of sodium and chloride in soils and surface waters [3,4,5], with adverse impacts on downstream aquatic ecosystems [6]. When impervious surface areas increase, the areas that need to be deiced increase

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