Rainstorms Inducing Shifts of River Hydrochemistry during a Winter Season in the Central Appalachian Region

Abstract

Rainstorms rapidly change catchment conditions which can alter river flow and water constituents due to the transport and fate of suspended and dissolved solids and the river water chemistry. To understand river water chemistry changes, this investigation relies on field data collected during a winter season. The Kanawha River in West Virginia was monitored using grab water samples and continuous readings from two water quality stations (Q1 and Q2) separated by 23.5 km. Water samples allowed the identification of water chemistry, whereas the two stations retrieved hourly measurements of temperature, turbidity, NO3−, Cl− and pH to capture transient rainstorm responses. It was found through the Piper diagram that water type was mainly calcium-chloride, whereas the Gibbs diagram identified that the dominant geochemical process was rock weathering. On the other hand, during transient rainstorms responses, we found that concentrations of HCO3−, NO3− and Cl− changed from bicarbonate type to no dominant type. Furthermore, hysteretic effects of rainstorms were influenced by the soil moisture of the catchment area. Additionally, HCO3− and NO3− had different hysteretic loop directions between Q1 and Q2. This approach proved that river water chemistry adjustments caused by rainstorms were successfully identified by relying on grab water samples and continuous measurements.