Improved prediction of management-relevant groundwater discharge characteristics throughout river networks

Water Resources Research
By: , and 

Links

Abstract

Groundwater discharge zones connect aquifers to surface water, generating baseflow and serving as ecosystem control points across aquatic ecosystems. The influence of groundwater discharge on surface flow connectivity, fate and transport of contaminants and nutrients, and thermal habitat depends strongly on hydrologic characteristics such as the spatial distribution, age, and depth of source groundwater flow paths. Groundwater models have the potential to predict spatial discharge characteristics within river networks, but models are often not evaluated against these critical characteristics and model equifinality with respect to discharge processes is a known challenge. We quantify discharge characteristics across a suite of groundwater models with commonly used frameworks and calibration data. We developed a base model (MODFLOW‐NWT) for a 1,570‐km2 watershed in the northeastern United States and varied the calibration data, control of river‐aquifer exchange directionality, and resolution. Most models (n = 11 of 12) fit similarly to calibration metrics, but patterns in discharge location, flow path depth, and subsurface travel time varied substantially. We found (1) a 15% difference in the percent of discharge going to first‐order streams, (2) threefold variations in flow path depth, and (3) sevenfold variations in the subsurface travel times among the models. We recalibrated three models using a synthetic discharge location data set. Calibration with discharge location data reduced differences in simulated discharge characteristics, suggesting an approach to improved equifinality based on widespread field‐based mapping of discharge zones. Our work quantifying variation across common modeling approaches is an important step toward characterizing and improving predictions of groundwater discharge characteristics.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Improved prediction of management-relevant groundwater discharge characteristics throughout river networks
Series title Water Resources Research
DOI 10.1029/2020WR028027
Volume 56
Issue 10
Year Published 2020
Language English
Publisher Wiley
Contributing office(s) New England Water Science Center
Description e2020WR028027, 19 p.
Country United States
State Connecticut, Massachusetts
Other Geospatial Farmington River watershed
Google Analytics Metrics Metrics page
Additional publication details