The Plynlimon catchments are located in the headwaters of the rivers Wye and Severn in mid-Wales UK about 24 km from the Irish Sea coast. The catchments have an upland character at 300-700 m above sea level, are located on base-poor Lower Palaeozoic shales overlain by a mosaic of acid soils with some locally derived drift. The experiment was orginally conceived in 1968 to compare water yields from plantation forestry (Upper Severn)and grassland (Upper Wye)catchments. Three instrumented subcatchments are nested within each of the main instrumented catchments, each with its own flow gauging structure supported by automatic weather stations and a raingauge network. The site now has nearly 40 years of high temporal resolution river flow and meterological data, supplemented by hydrological process studies on flow pathways, forest intereception and evaporation. Hydrochemical measurements commenced in the Upper Wye sub- catchments at Plynlimon in 1979 and in the Upper Severn sub-catchments in 1983. Subsequently, the measurements have generated a 30 year uninterupted record of weekly to monthly measurements of wet deposition and stream water chemistry for a wide range of determinands including pH, alkalinity, nutrients, major cations, anions, trace metals, dissolved organic carbon and dissolved organic nitrogen. At various times throughout the last 30 years, "routine" monitoring has been supplemented by more detailed plot and small catchment-scale studies of flow generation, weathering and element cycling in grassland and forest systems, biogeochemical responses to forest harvesting, acid rain and atmospheric nitrogen deposition. The data from the site have been used to report on the hydrochemical responses of upland catchments to declining acid deposition, forest harvesting, agricultural management and climate change. More recently, high temporal resolution sampling has been used to develop new mathematical and statistical methods for the interpretation of short and long-term chemical trends. Data from the site have been used extensively to inform the development and calibration of biogeochemical models of acidifcation, weathering and carbon and nitrogen dynamics.

Plynlimon data, which include spatial data, time series hydrology and time series stream water chemistry, are publicly available for download at the CEH Information Gateway. From the Gateway homepage, click on "Start searching" to bring up a simple search engine, enter Plynlimon in the box and hit start search.

Contact: Professor Brian Reynolds br@ceh.ac.uk

The Kindla catchment is included in a larger nature reserve and located at N 59o45' and E 14o54' in the central south Sweden, in the region of "Bergslagen". It is a coniferous forest ecosystem with over 100 years old trees. The catchment area is c. 20 ha and with a sloping topography from 312m to 415m above mean sea level. The bedrock consists of granite and the quarterny deposits is sandy-silty till. The soils are Leptosols, Podzols and Gleysols with smaller areas of peatlands hosting Histosols. It is located locally remote from municipalities to avoid direct influences. Mean annual temperature is +4.2 oC with c. 900 mm precipitation and 450 mm runoff leaving another 450 mm for evapotranspiration. The monitoring programme started 1996. http://info1.ma.slu.se/IM/station/Kind.html
Contact: Professor Lars Lundin Lars.Lundin@mark.slu.se

The Strengbach catchment is an experimental forest monitored since 1986 for hydrological, geochemical and meteorological data. This 80ha surface area catchment is located in the Vosges massif with a temperate oceanic mountainous climate, on granitic bedrock. All reservoirs involved in the biogeochemical cycling are studied. Wet atmospheric depositions (rain, snow), dry atmospheric particles (aerosols), all stream and spring waters, groundwaters (piezometer), soil profiles, saprolite and bedrock, vegetation (roots, wood, bark, leaves, litter). The Strengbach experimental catchment represents a natural laboratory to study and understand the weathering processes and the biogeochemical cycles at the scale of a forested ecosystem.
Contact: Marie-Claire Pierret, pierret@illite.u-strasbg.fr

The study area is located near the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences, Yingtan, Jiangxi Province. The climate is representative for subtropical SE China. Typical monsoonal rainfall peaks in April, May and June, exceeding 250 mm per month, mean monthly temperature between June and September range between 25 and 30° C. Potential evapotranspiration exceeds rainfall from August to November causing seasonal drought. Sun Jia catchment was selected in the research due to its representatives in topography and land use of red basins. It covers an area of 46 ha of gently sloping terrain and exhibits an altitudinal range of 15 m. Slope inclination is up to 8.5%. The land use in Sun Jia catchment include paddy fields (double cropping of rice) and three ponds on the valley bottom and lower slopes and upland fields on the slopes (Fig. 1). The upland fields are used for rain-fed agriculture with small vegetable fields, large peanut (Archis hypogaea) fields and orchards where chestnut (Castanus sativa) and citrus (Citrus unshiu) fruits are grown. Paddy fields account for 20.2 % of the total area, whereas peanut fields make up 49.5 % and orchards 17.0 %.
Full pdf Document

Clear Creek River Basin used a as a testbed for Digital Watershed is a tributary of the Iowa River draining 270 km area subjected to considerable anthropogenic influence. The watershed is scientific "hotspot" because it is located in a region with the highest erosion rate in the nation. In addition, the watershed includes wetlands, agricultural and urbanized catchments that allow inference on the different effects of human intervention on the natural landscape.
http://www.czen.org/content/clear-creek-observatory
Contact: Thanos Papanicolaou, athanasios-papanicolaou@uiowa.edu

The Shale Hills Critical Zone Observatory (CZO) is a forested, small, temperate-climate catchment in central Pennsylvania in which the regolith is developing upon homogeneous shale. The purpose of the observatory and associated interdisciplinary research is to quantitatively predict the creation, evolution, and structure of regolith as a function of the geochemical, hydrologic, biologic, and geomorphologic processes operating in a temperate, forested landscape.
http://www.czo.psu.edu/
Contact: Professor Chris Duffy, cxd11@psu.edu

The Southern Sierra CZO is a community platform for research on critical-zone processes across the rain-snow transition in the mixed-conifer forest of the Southern Sierra Nevada. While this elevation range has characteristically rapid seasonal changes, going from snow cover to wet soil to dry soil over a 1-2 month period, climate warming will shift this transition period earlier or eliminate it entirely at the current transitional elevation. The characteristic spatial differences along gradients offer the opportunity to substitute space for time, making the CZO an excellent natural laboratory for studying how critical zone processes respond to perturbations, and particularly how the water cycle drives critical zone processes.
https://snri.ucmerced.edu/CZO
Contact: Dr Roger Bales, rbales@ucmerced.edu

Boulder Creek CZO is a research enterprise to develop understanding of how erosion and weathering control the architecture and function of the Critical Zone, the weathered, hydrologically active near surface environment. The headwaters of Boulder Creek encompass widely varying erosion histories; glacial scouring, slow post-Laramide denudation, and recent base level lowering—so that the effects of these on weathering can be explored. The field sites also span climate and ecological gradients from lower montane to alpine tundra.
http://czo.colorado.edu/
Contact: Dr Suzanne Anderson, Suzanne.Anderson@Colorado.EDU