The Forest of Meerdaal is situated on the Belgian loess belt about 25 km south-east of Brussels. It is an ancient woodland site, previously managed as coppice with standards, well known history (up to the middle ages). It is managed as multifunctional forest containing strict forest reserves with dense sampling grid (measured every decade). its proximity to the university make it an ideal research subject. Over the years many different studies have been conducted and documented.

The Bassée floodplain is a large area in the Seine river basin (~ 50 km long and 5-10 km wide). Series of hydrological installations (dikes, channelization, damming, drainage, sand and gravel pits) have considerably reduced the flooding in the plain which nervertheless remains an important resource in the Seine river basin for freshwater and biodiversity. The level of anthropization increases from upstream to downstream. Projects for new hydrological installation (damming, channelization) still exist, which supports a high monitoring activity in this area.

The Wüstebach catchment is located in the Eifel National Park and covers an area of 38.5 ha, with mean altitude of about 610 m. The geology is dominated by Devonian shale, which is covered by a periglacial solifluction layer of about 1–2 m thickness. Cambisols and Planosols have developed on the hillslopes, whereas Gleysols and Histosols have formed in the valley. The main soil texture is silty clay loam and the litter layer has a thickness between 0.5 and 14 cm. The mean annual precipitation is about 1200 mm. Norway Spruce planted in 1946 is the prevailing vegetation type. During late summer/early autumn of 2013, trees were almost completely removed in an area of 9 ha by the national park forest management in order to promote the natural regeneration of near-natural deciduous forest from spruce monoculture forest.

Dong Cao is a small agricultural catchment (47 ha) of northern Vietnam, located at 70 km from Hanoi, in a sloping land environment. The objective is to monitor the impacts of land use changes (from cassava to fodder and tree plantations) and possible climate changes upon hydrological and sedimentary fluxes and budgets. The catchment has an elevation of 125 m to 485 m and slopes range from 15 to 120%. Monitoring devices include an automatic meteorological station, and weirs to monitor discharge, suspended sediment and bedload. More information is available on https://mtropics.obs-mip.fr/ and in the following paper: Valentin, C., et al., 2008. Runoff and sediment losses from 27 upland catchments in Southeast Asia: Impact of rapid land use changes and conservation practices. Agric. Ecosyst. Environ. 128, 225–238. https://doi.org/10.1016/j.agee.2008.06.004

Quercus robur and Pinus silvestris forests on glacio-fluvial sediments

Ensemble of agricultural and forestry systems in a catchment area of five consecutively connected lakes

The HOBE experimental catchment is located in the western part of Denmark. The topography of the catchment is relatively flat. The surface elevations in the eastern part of the catchment are about 125 m above sea level at the Jutland ridge and gently decreasing to sea level elevations towards the coast. Alluvial outwash deposits in the form of sand and gravel dominate the central part of the catchment. Towards east, glacial deposits of moraine till are present with a higher content of clay. Also the remnants from the Saale glaciation have higher clay content and the dominant sediment type at these locations is clayey sand. Overall the top sediments are highly permeable with little water retention capability and the stream flow is therefore dominated by groundwater inflow. Based on a classification of the topsoil four soil classes can be identified in the catchment. The by far most dominating soil type is fine/coarse sandy soil. The Quaternary deposits have a thickness less than 50 m in the eastern and central part of the area increasing up to 250 m towards west. The Quaternary deposits are underlain by Miocene sediments in the form of alternating layers of marine, lacustrine and fluvial deposits forming layers of clay, silt, sand and gravel. Further below thick layers of Paleogene clay are found with little permeability and thus acting as a lower impermeable boundary for the aquifer systems. The sand and gravel layers from the Quaternary and Miocene periods form interconnected aquifer systems. The land surface of the catchment is predominantly agriculture and due to the sandy soil characteristics extensive irrigation of the agricultural crops takes place. Based on satellite data the land-use distribution is estimated as follows: grain and corn (55%), grass (30%), forest (7%), heath (5%), urban (2%) and other (1%). The climate of the observatory is of maritime origin and influenced by weather systems coming from the Atlantic Ocean. The weather conditions are variable with frequent precipitation. The prevailing winds from west lead to relatively mild winters and cool summers. The mean annual precipitation is about 1050 mm/year. It varies over the season with highest amounts in the months of October-December and lowest in the months of April-May. The mean annual temperature is 8.20C. The highest mean monthly temperature is in August (16.50C) and the lowest in January (1.40C). Precipitation in the form of snow is highly variable from year to year; in some years, no snowfall occurs and in others, it may stay on the ground for months.

Intensive Forest Monitoring site with Pinus silvestris - Betula pendula forest

The Ploemeur-Guidel observatory (Britanny, France) is focusing on surface-depth relationships in a fractured crystalline geological context and oceanic climate. It is built on 2 sub-sites, one highly anthropized, the other in natural state. In Ploemeur, groundwater has been pumped since 1991, supplying more than 1 million m3 of clean drinking water annual at a sustainable rate. Such high productivity is explained the specific fractured network in granite and micaschists, draining deep geological layers (~400 m). Extracted water quality is very good, with limited nitrate concentration, in a region that has been strongly affected by widespread pollution. Guidel site is in a similar, but natural context. Deep iron-rich groundwater is upflowing, creating surface and deep groundwater-dependent ecosystems, and feeding a classified coastal wetland. Both sites have a very dense equipment to study rapid to long-term surface-depth exchanges: a flux tower, unsaturated zone monitoring, a network of ~50 shallow (<10m) and deep boreholes (>80m), hydrochemical, temperature and deformation. An well-characterized fractured experimental site offers the possibility to conduct experiments to test innovative instruments and develop new methodologies

Fagus sylvatica forest on limestone plateau