Jonkershoek: Africa's oldest catchment experiment ‐ 80 years and counting

Abstract

The Jonkershoek Forestry Research Station was established in the Mediterranean climate region of South Africa in 1935 to implement a multiple catchment experiment to determine the effects of afforestation on water yield. The experiment consists of six neighbouring catchments previously supporting indigenous fynbos shrublands, five of which were sequentially afforested with Pinus radiata plantations every 8 years from 1940 to 1980 and one kept as the control. They conclusively demonstrated a significant impact of afforestation on streamflow. The treatment catchments have seen subsequent plantation rotations since 1980 and rainfall and streamflow observations have been continued to date. Here we describe the site, experimental design, rainfall and streamflow records, instrumentation, and how to access the data. We also provide details of recently installed instrumentation, including full weather stations, fog gauges, and an eddy covariance flux tower. The Jonkershoek catchment experiment was the core of a globally significant interdisciplinary research programme that shaped most environmental policies and practices relating to biodiversity, forestry, fire and water in South Africa and beyond. The South African Environmental Observation Network (SAEON) inherited the experiment in 2010 and is maintaining it as a longterm eco-hydrological research platform and global change observatory.

Spatial heterogeneity in rain-bearing winds, seasonality and rainfall variability in southern Africa's winter rainfall zone

“…1). The south-western mountains are very wet (MAR > 1500 mm), but the WRZ also encompasses hyper-arid areas (MAR < 100 mm) in northern coastal Namaqualand and the Tanqua Karoo (Lynch, 2004;Schulze and Maharaj, 2007;Slingsby et al, 2021).…”

Determining Hydrological Variability Using a Multi-Catchment Model Approach for the Western Cape, South Africa

“…Daily totals of precipitation and solar radiation, mean daily relative humidity, temperature, windspeed and maximum and minimum daily temperature were collected for the period 1988-2002 (including a 2-year initialization period). The data were attained from the World Meteorological Organisation (WMO) as global surface summary of the day (GSOD) data [23], as well as the Agricultural Research Council (ARC), the South African Weather Services (SAWS), the Department of Water Affairs and Sanitation, South Africa (DWS), the South African Earth Observation Network [45] and previous JAMS/J2000 model data [18,[46][47][48][49][50]. In total, 97 precipitation, 24 temperature, 12 relative humidity, 15 windspeed and seven solar radiation stations were used (Table 2).…”

Mountain Watch: How LT(S)ER Is Safeguarding Southern Africa’s People and Biodiversity for a Sustainable Mountain Future

“…Jonkershoek Valley LTER ("Jonkershoek"; 1935-1992 and 2010-present; with some rainfall gauging commencing in 1925; South Africa) is Africa's longest running catchment experiment [46]. It is located in a Mediterranean shrubland ("fynbos") catchment of the winter-rainfall Cape Floristic Region near Stellenbosch in the Boland Mountains of the Cape Fold Belt (Figure 1).…”

“…Wider application by scientists and policy makers to inform national catchment management and water policy in South Africa is arguably the finest example of science-driven policy from LTER in the country. These catchment experiments form the core of globally significant interdisciplinary research programmes that have shaped many environmental policies and practices relating to afforestation, biodiversity, fire, and water [46]. These policies were deconstructed from the late 1980s in favour of the National Water Act, which instead governs water-user rights among competitors.…”

“…Fortunately, the LTER platforms at Jonkershoek and Cathedral Peak were resurrected from 2010 and 2012, respectively, under the gamut of the South African Environmental Observation Network (Table A1). They have evolved from longterm eco-hydrological monitoring platforms [62] to global change observatory catchments, encouraging more multi-disciplinary research using high-tech instrumentation [46]. Their value lies in understanding which land uses and management practices best support and optimise water supply in these sensitive and critical water supply areas, together with understanding the potential negative global change impacts.…”