In:
Hydrology and Earth System Sciences, Copernicus GmbH, Vol. 26, No. 18 ( 2022-09-28), p. 4721-4740
Abstract:
Abstract. In inland settings, groundwater discharge thermally modulates receiving
surface water bodies and provides localized thermal refuges; however, the
thermal influence of intertidal springs on coastal waters and their thermal
sensitivity to climate change are not well studied. We addressed this
knowledge gap with a field- and model-based study of a threatened coastal
lagoon ecosystem in southeastern Canada. We paired analyses of drone-based
thermal imagery with in situ thermal and hydrologic monitoring to estimate
discharge to the lagoon from intertidal springs and groundwater-dominated
streams in summer 2020. Results, which were generally supported by
independent radon-based groundwater discharge estimates, revealed that
combined summertime spring inflows (0.047 m3 s−1) were comparable
to combined stream inflows (0.050 m3 s−1). Net advection values for the
streams and springs were also comparable to each other but were 2 orders
of magnitude less than the downwelling shortwave radiation across the
lagoon. Although lagoon-scale thermal effects of groundwater inflows were
small compared to atmospheric forcing, spring discharge dominated heat
transfer at a local scale, creating pronounced cold-water plumes along the
shoreline. A numerical model was used to interpret measured groundwater temperature
data and investigate seasonal and multi-decadal groundwater temperature
patterns. Modelled seasonal temperatures were used to relate measured spring
temperatures to their respective aquifer source depths, while multi-decadal
simulations forced by historic and projected climate data were used to
assess long-term groundwater warming. Based on the 2020–2100 climate
scenarios (for which 5-year-averaged air temperature increased up to
4.32∘), modelled 5-year-averaged subsurface temperatures increased
0.08–2.23∘ in shallow groundwater (4.2 m depth) and
0.32–1.42∘ in the deeper portion of the aquifer (13.9 m),
indicating the depth dependency of warming. This study presents the first
analysis of the thermal sensitivity of groundwater-dependent coastal
ecosystems to climate change and indicates that coastal ecosystem management
should consider potential impacts of groundwater warming.
Type of Medium:
Online Resource
ISSN:
1607-7938
DOI:
10.5194/hess-26-4721-2022
DOI:
10.5194/hess-26-4721-2022-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2100610-6
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