The Strengbach Catchment: A Multidisciplinary Environmental Sentry for 30 Years

Abstract

Research activity associated with various observations at the Strengbach catchment in the Vosges Massif (880-1150 m) addresses many questions in the domains of hydrology and geochemistry. The catchment is the observation and experimental site of the Observatoire Hydro-Géochimique de l'Environnement appointed by the Centre National de la Recherche Scientifique. It also belongs to the research facilities that form the French Network of Critical Zone Observatories (OZCAR), which supports a network of critical zone observatories. The catchment is small (0.8 km 2 ) with steep slopes (20-30%) on granitic bedrock that mainly allow for forestry (spruce and beech stands) as the main land cover. Meteorological, hydrological, and geochemical data have been monitored since 1986. The first studies conducted were dedicated to the elucidation of acid rain effects on forest ecosystems and particularly on forest decline. Multidisciplinary research studies conducted on the Strengbach catchment enable exploration of the following issues: (i) hydrological functioning at the scale of a small catchment and questions regarding the evolution and preservation of the water resources in mountainous environments (stock, recharge, infiltration, and water pathways), (ii) exchange processes observed at the soil-plant-atmosphere continuum and in particular weathering processes and the evolution of soil mineral fertility (Ca, Mg, K, P), (iii) processes responsible for the export of water and for associated fluxes (dissolved chemicals, suspended materials, bed loads) and their dynamic at the outlet, and (iv) responses of the ecosystems to environmental disturbances (acid rain, forest management, and climate change) and their current and future modeling. University of Strasbourg), is well suited for addressing such issues owing to (i) a long-term dataset available for the area (from 1985;Probst et al., 1987), (ii) the availability of field equipment and monitoring devices, and (iii) numerous scientific studies that have been performed on the area. Research performed at this catchment, which is located in the Vosges Mountains in northeastern France, has focused on the evaluation of water and soil resources in relation to climatic changes (i.e., rainfall regimes and atmospheric chemistry trends) and anthropogenic patterns (e.g., forest management and acid precipitation) occurring in this moderate-altitude mountainous region.Usually, in this type of ecosystem, water is scarce and not evenly distributed, and stocks may rapidly vary over time. In addition, although wood production is an economically important activity in these regions, soil degradation (e.g., from acidification and nutrient depletion) modifies soil fertility features and thus affects the development of forests.The scientific objective of the OHGE is to develop a detailed understanding of water transport processes and of related chemical fluxes (including nutrients and contaminants) through the critical zone extending from the near atmosphere to the near subsurface. The main purposes of...

Variability of Water Transit Time Distributions at the Strengbach Catchment (Vosges Mountains, France) Inferred Through Integrated Hydrological Modeling and Particle Tracking Algorithms

“…The Strengbach catchment is a small, forested headwater catchment of 0.8 km 2 surface area located on the upper crests of the Vosges mountains, in Northeast France [40]. The elevation of the area ranges between 880 and 1150 m with heavily incised side slopes, especially in the part of the catchment close to the permanent stream in the bottom of the valley (Figure 1).…”

“…Hydrological, geochemical, and climatic parameters have been monitored at the catchment since 1986 at various scales and with a dense network of sensors (see [40] for details). The location of the equipment necessary to collect the data employed in this study is specified in Figure 1.…”

“…The inversion of the MRS signal allows for estimates of the saprolite thickness, the quantity of water beneath the measurement points, and the permeability of the porous medium (e.g., [42]). MRS measurements were performed once at each station between April and May 2013 [40]. Data were collected using eight-shaped loops 37.5 m in length.…”

“…Although this saturated area represents only a small fraction of the total area of the catchment (3%), the dynamics of the water table close to the stream produce most of the streamflow, with a high contribution of pre-event water to the total instantaneous outflow [44]. Further details on previous studies carried out at the Strengbach catchment are summarized in [40].…”

Twenty-five year record of chemicals in open field precipitation and throughfall from a medium-altitude forest catchment (Strengbach - NE France): An obvious response to atmospheric pollution trends

“…Therefore, it is important to have an accurate evaluation of "true" atmospheric deposition (Pascaud, 2013;Coddeville et al, 2016) and to monitor these inputs over long time periods in "supposed pristine" ecosystems taken as observatories and "sentinels" of these disturbances (i.e., Paces, 1985;Moldan and Schnoor, 1992;Matzner and Meiwes, 1994;Probst et al, 1995a;Kram et al, 1997;Laudon et al, 1999;Pierret et al, 2018).…”