Modeling conservative contaminant effects on reservoir water quality

Abstract

The Wachusett Reservoir in central Massachusetts was modeled using the two‐dimensional CEQUAL‐W2 hydrodynamic and water quality model to simulate a conservative contaminant spill from a roadway and analyze contaminant behavior at the Cosgrove drinking water intake 12.5 km (7.8 mi) from the spill site. Modeled calendar years 2003–09 were developed using meteorology, bathymetry, inflow quantity and quality, and outflow quantity data. Scenarios investigated included the influence of season, spill density, additional water transferred from Quabbin Reservoir, and wind on contaminant transport. Contaminants arrived at the intake much earlier than the mean hydraulic residence time. Contaminant concentrations were greater and more variable during the summer. Turning the Quabbin transfer off decreased the variability in concentration at the intake, especially during the summer. Model results provide useful information to reservoir operators for how to respond to potential contaminant spills under various scenarios.

Effects of dimensionality on the performance of hydrodynamic models

“…The error in terms of water level similar for all models (~10 cm), and is in the range of errors reported in the literature (e.g. Dai et al, 2013;Jeznach et al, 2014;Chen et al, 2016;Bueche et al, 2020). GLM had a constant water level from Jan to May 2018, corresponding to the maximum level defined by the hypsographic curve due to the spillway crest elevation.…”

“…This information is important for management of reservoirs during spilling accidents (e.g. Jeznach et al, 2014), for GLM it is not possible to estimate time travel, 560 since inflows are directly placed at defined layers. Studies assessing the inflow pathways through modeling demonstrated a good agreement between simulations and observations, for example Marti et al (2011) and (Zamani et al, 2020) with 3D models and Jeznach et al (2014) with CE-QUAL-W2.…”

“…Read et al, 2014;Woolway and Merchant, 2019) 635 2D:  Assist in actions and time response regarding substance transport, e.g. in case of contamination of the principal inflow (Jeznach et al, 2014). However specific determination of layers containing the density currents are uncertain, it will depend on initial mixing of inflow and depths of UML and thermocline, which none of the models could reproduce with precision, although the 3D had better correlation.…”

Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs

“…Regarding the water balance, all models had errors of comparable magnitude: 1D, 2D and 3D models had errors in stored water volume of −4.4 %, −4.9 % and −3.7 %. The error in terms of water level was similar for all models (∼ 10 cm) and is in the range of errors reported in the literature (e.g., Dai et al, 2013;Jeznach et al, 2014;Chen et al, 2016;Bueche et al, 2020). GLM had a constant water level from January to May 2018, corresponding to the maximum level defined by the hypsographic curve due to the spillway crest elevation.…”

Future Climate Effects on Thermal Stratification in the Wachusett Reservoir

“…The model has been used to simulate a combination of rivers, lakes, reservoirs, and estuaries around the world (Cole & Wells, 2008). The CE‐QUAL‐W2 model was a logical choice for the current study because of its extensive calibration, verification, and application in many previous studies of the Wachusett Reservoir (Jeznach et al, 2014; Devonis, 2011; Sojkowski, 2011; Stauber, 2009; Matthews, 2007; Buttrick, 2005; Joaquin, 2001; CDM, 1995).…”