Investigating the respective impacts of groundwater exploitation and climate change on wetland extension over 150 years

Abstract

processes. Peat soils have a significant impact on water quality, ecosystem productivity and 3 greenhouse gas emissions. However, the extent of peatlands is decreasing across the world, 4 mainly because of anthropogenic activities such as drainage for agriculture or groundwater 5 abstractions in underlying aquifers. Potential changes in precipitation and temperature in the 6 future are likely to apply additional pressure to wetland. In this context, a methodology for 7 assessing and comparing the respective impacts of groundwater abstraction and climate 8 change on a groundwater-fed wetland (135 km²) located in Northwest France, is presented. A 9 groundwater model was developed, using flexible boundary conditions to represent surface-10 subsurface interactions which allowed examination of the extent of the wetland areas. This 11 variable parameter is highly important for land management and is usually not considered in 12 impact studies. The model was coupled with recharge estimation, groundwater abstraction 13 scenarios, and climate change scenarios downscaled from 14 GCMs corresponding to the 14 A1B greenhouse gas (GHG) scenario over the periods 1961-2000 and 2081 -2100 show that climate change is expected to have an important impact and reduce the surface of 16 wetlands by 5.3 % to 13.6 %. In comparison, the impact of groundwater abstraction (100 % 17 increase in the expected scenarios) would lead to a maximum decrease of 3.7 %. Results also 18show that the impacts of climate change and groundwater abstraction could be partially 19 mitigated by decreasing or stopping land drainage in specific parts of the area. Water 20 management will require an appropriate compromise which encompasses ecosystem 21 preservation, economic and public domain activities. 22

Assessing Groundwater Depletion and Dynamics Using GRACE and InSAR: Potential and Limitations

“…For a detailed discussion of capture and groundwater depletion, see Konikow and Leake (). Depending on what is deemed as acceptable consequences (environmental, economic, and social) of the groundwater depletion and the effects of any induced recharge or reduced discharge such as decreased springflow or streamflow or drying lakes and wetlands, the development and use of groundwater may or may not be considered sustainable (Alley et al ; Armandine et al ).…”

Response to Referee #1

“…Printer-friendly version Discussion paper (e.g. Ala-aho et al, 2017;Armandine Les Landes et al, 2014;Haahti et al, 2016;Hammersmark et al, 2008;House et al, 2016;Li et al, 2019). The excellent fit of simulated long-term mean groundwater table depth, groundwater upwelling rate and groundwater seepage rate with observed mire boundaries (including along the narrow valley downstream and in the small sub-basins located upstream of and 30m above the main mire extent where no groundwater table depth data were available for calibration) demonstrates that the model satisfactorily reproduces the dominant hydrological characteristics of the mire and its catchment.…”

“…Calibration and validation periods covering a total duration of 3 years (and often much less) are the norm rather than the exception in physically-based hydrological modelling studies of wetlands (e.g. Ala-aho et al, 2017;Armandine Les Landes et al, 2014;Haahti et al, 2016;House et al, 2016;Levison et al, 2014;Li et al, 2019;Quillet et al, 2017;Thompson et al, 2004). In many cases this is the result of the unfortunate exclusion of wetland environments from formal hydrometric networks (e.g.…”

High-Resolution, Integrated Hydrological Modeling of Climate Change Impacts on a Semi-Arid Urban Watershed in Niamey, Niger

“…Uncertainties are particularly high when it comes to groundwater resources [16]. Most studies [16][17][18][19][20][21] have been focused on the climate change impacts on surface water, often neglecting groundwater, which is more complicated to model and assumed to be less vulnerable to climate change. Moreover, few [22][23][24] have considered large-scale, fully-integrated hydrological models when investigating climate change impacts.…”