Observed groundwater temperature response to recent climate change

Abstract

Abstract. Climate change is known to have a considerable influence on many components of the hydrological cycle. Yet, the implications for groundwater temperature, as an important driver for groundwater quality, thermal use and storage, are not yet comprehensively understood. Furthermore, few studies have examined the implications of climate-change-induced groundwater temperature rise for groundwater-dependent ecosystems. Here, we examine the coupling of atmospheric and groundwater warming by employing stochastic and deterministic models. Firstly, several decades of temperature time series are statistically analyzed with regard to climate regime shifts (CRSs) in the long-term mean. The observed increases in shallow groundwater temperatures can be associated with preceding positive shifts in regional surface air temperatures, which are in turn linked to global air temperature changes. The temperature data are also analyzed with an analytical solution to the conductionadvection heat transfer equation to investigate how subsurface heat transfer processes control the propagation of the surface temperature signals into the subsurface. In three of the four monitoring wells, the predicted groundwater temperature increases driven by the regime shifts at the surface boundary condition generally concur with the observed groundwater temperature trends. Due to complex interactions at the ground surface and the heat capacity of the unsaturated zone, the thermal signals from distinct changes in air temperature are damped and delayed in the subsurface, causing a more gradual increase in groundwater temperatures. These signals can have a significant impact on largescale groundwater temperatures in shallow and economically important aquifers. These findings demonstrate that shallow groundwater temperatures have responded rapidly to recent climate change and thus provide insight into the vulnerability of aquifers and groundwater-dependent ecosystems to future climate change.

Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

“…This observation could indicate shallow aquifer groundwater discharge, which is more influenced by atmospheric temperatures than deeper regional flow (Kurylyk et al, 2014a;Menberg et al, 2014). However, consistent temperatures in the site's shallow groundwater wells and 1-D temperature profiles indicate that these seepage temperatures are controlled by a lower flux rather than distinct atmospherically influenced shallow flow paths.…”

“…Local, shallow flow paths can be more sensitive to climatic and seasonal changes in evaporation and precipitation (Fraser et al, 2001;Kurylyk et al, 2014b;Menberg et al, 2014;Reeve et al, 2006) and may not contribute to the thermal stability of aquatic systems to the same extent as deep (> 10 m) regional aquifers. This noted, during the thermal study periods, groundwater temperatures range from 10-11 • C in on-site wells below the peat.…”

Analytical simulation of groundwater flow and land surface effects on thermal plumes of borehole heat exchangers

“…According to [58], the air temperature in northern Switzerland had a trend of only 0.38°C/decade for the period 1984-2013. However, at small scales, like the single house we are considering here, site-specific GST conditions apparently play a substantial role and a coupled relation between ground surface and air temperatures is hard to establish [59,60]. It is also worth mentioning that T s is valid only for the period of calibration.…”

Effect of Temperature Rising on the Stygobitic Crustacean Species Diacyclops belgicus: Does Global Warming Affect Groundwater Populations?

“…In the extreme cases, groundwater temperatures in shallow porous aquifers (depth < 15 m below ground level) are expected to increase by up to 4-5 • C in some temperate climate regions in the 45 • northern latitude, depending on the degree of urbanization [8]. Climate warming will affect the aquifers that are recharged by surface water through riverbank infiltration [9] as well as those that are directly recharged by precipitation and those affected by ground surface heating [8]. In shallow porous aquifers temperatures are not constant.…”