Historical background

Historical background

The CZO Multiscale TROPIcal CatchmentS (M-TROPICS) consists in the merging, in 2016, of two previously-existing CZOs: BVET (India and Cameroon) and MSEC (Laos and Vietnam).

Historical background of MSEC

In 1998, the International Board for Soil Research and Management (IBSRAM) and the Asian Development Bank (ADB) formed the Management of Soil Erosion Consortium (MSEC) to assess the causes and the extent of soil erosion in South-East Asia. During this first phase (1998-2002), MSEC sought (i) to quantify erosion in small catchments cultivated according to local agricultural practices that were representative of those areas, excluding modern industrial farming, and (ii) to test alternative farming practices that would decrease land degradation and improve household livelihoods for communities inhabiting sloping lands and mountainous regions.

Houay Pano catchment: very high soil erosion by splash in teak tree plantations (photo. C. Valentin).

A second phase (2003-2010) of MSEC, supported by the International Water Management Institute (IWMI) and the Institut de Recherche pour le Développement (IRD), was operated in Indonesia (until 2005), Lao PDR, the Philippines (until 2005), Thailand (until 2019) and Vietnam (until 2021) with national partners. The ultimate goal of this phase was to achieve the sustainable development of watersheds by addressing the twin objectives of conserving resources and underpinning food security. The IWMI, due to new rules of funding had to leave the consortium late 2010. The IRD and its partners have then initiated a third phase (2011-2015): the Management of Soil Erosion Consortium was renamed Multi-Scale Environmental Changes in order to underline the multiscale environmental approach of processes impacted by global changes.

In 2011, the Laotian site became more broadly dedicated to the study of land use and land-use change, water and sediment fluxes, along with the dissemination of microbiological contaminants, following a multiple-scale monitoring approach (0.6-272,155 km²). The basic variables (hydro-meteorology, land use, and suspended and bedload sediment fluxes) have been certified by both the IRD and the Institut National des Sciences de l’Univers (INSU) in 2016. Water quality variables, including the fecal indicator bacterium Escherichia coli, has been certified in 2021.

Historical background of BVET

The first site was implemented in 1993 in Southern Cameroon, within the humid tropical forested ecosystem constituted by the Nyong River basin, with the small experimental watershed (0.6 km² SEW) of the Mengong stream, near the Nsimi village in partnership with the University of Yaoundé I and the Institut de Recherches Géologiques et Minières (Geological survey of Cameroon). The objective was to study the response of water and biogeochemical budgets – including chemical weathering – to global changes in the context of a humid tropical forest. In 1998 the hydro-biogeochemical monitoring was extended to several next orders basins: the Awout (206 km²), the So’o (3 000 km²), and the Nyong at M’balmayo (13 500 km²) up to the Nyong station at Olama (18 500 km²). These nested watersheds are characterized by remarkable homogeneous pedoclimatic conditions.

In 2002, a second phase was initiated, in collaboration with the Indian Institute of Science (Bangalore, India) with the monitoring of the sub-humid tropical watersheds of Mule Hole (4.3 km², pristine deciduous forest) and Maddur (7.1 km²), half pristine deciduous forest, half cultivated) which belong to the Kabini River basin (Southern India), in order to monitor the effects of land use (agriculture) and climate change on water and biogeochemical budgets in dry tropical conditions. Since 2012 (third phase) the monitoring of Maddur SEW has been extended to the next order, the Berambadi watershed (84 km2), a more suitable scale to combine land use practices/changes with remote sensed data, and to involve social sciences.