Quantifying groundwater's contribution to regional environmental flows
in diverse hydrologic landscapes
Abstract
Increasing recognition of the importance of ecosystem services in water
resources management has accelerated the development and applications of
environmental flows requirements for lotic ecosystems which are often
dependent on groundwater. However, most environmental flows management
focuses on water infrastructure, like dams or diversions, without
explicitly taking groundwater into account and ignoring the importance
of groundwaters’ contribution to environmental flows. Here, we introduce
two methods for estimating groundwater contribution to environmental
flows: 1) a groundwater-centric method, which proposes that high levels
of ecological protection are maintained if 90% of groundwater discharge
is preserved and 2) a surface water-centric method, which quantifies
groundwater’s contribution to environmental flows from streamflow using
region-specific streamflow sensitivity metrics and local environmental
flows policies. The two methods are tested in British Columbia, Canada,
which has a diverse, complex, and highly coupled groundwater-surface
water systems. The two methods gave comparable results in different
hydrogeoclimatic settings. Though the two methods are demonstrated using
British Columbia as a case study, this framework can be implemented
across different spatial and temporal scales for different regions and
globally in data-scarce, hydrologically complex landscapes. Application
of these methods can aid in a robust and holistic assessment of
environmental flows, taking into account the often missing groundwater
component.
Keywords: Groundwater, Environmental
flows, British Columbia, Surface water centric method, Groundwater
centric method