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Thermal effect of climate change on groundwater‐fed ecosystems
Author(s) -
Burns Erick R.,
Zhu Yonghui,
Zhan Hongbin,
Manga Michael,
Williams Colin F.,
Ingebritsen Steven E.,
Dunham Jason B.
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2016wr020007
Subject(s) - groundwater recharge , groundwater , vadose zone , hydrology (agriculture) , environmental science , climate change , depression focused recharge , geology , aquifer , geotechnical engineering , oceanography
Groundwater temperature changes will lag surface temperature changes from a changing climate. Steady state solutions of the heat‐transport equations are used to identify key processes that control the long‐term thermal response of springs and other groundwater discharge to climate change, in particular changes in (1) groundwater recharge rate and temperature and (2) land‐surface temperature transmitted through the vadose zone. Transient solutions are developed to estimate the time required for new thermal signals to arrive at ecosystems. The solution is applied to the volcanic Medicine Lake highlands, California, USA, and associated springs complexes that host groundwater‐dependent ecosystems. In this system, upper basin groundwater temperatures are strongly affected only by recharge conditions. However, as the vadose zone thins away from the highlands, changes in the average annual land‐surface temperature also influence groundwater temperatures. Transient response to temperature change depends on both the conductive time scale and the rate at which recharge delivers heat. Most of the thermal response of groundwater at high elevations will occur within 20 years of a shift in recharge temperatures, but the large lower elevation springs will respond more slowly, with about half of the conductive response occurring within the first 20 years and about half of the advective response to higher recharge temperatures occurring in approximately 60 years.