Multiscale TROPical CatchmentS (M-TROPICS)

M-TROPICS Critical Zone Observatories

The CZO Multiscale TROPIcal CatchmentS (M-TROPICS) provides the international scientific community with unique decennial time series of meteorological, hydrological, geochemical, and ecological variables in tropical environments. The CZO M-TROPICS involves academic and governmental partners in tropical countries (Cameroun, India, Lao PDR, and Vietnam) and is included in the Research Infrastructure OZCAR, the French contribution to the international CZO initiative.

Objectives

• Long-term monitoring of the variables needed for establishing water, biogeochemical (including particulate matter), and energy budgets: water and inorganic and organic matter in solution (major anions and cations, carbon), in suspension (suspended particulate matter, including organic carbon), and bed particulate matter
• Impact assessment of global change (land-use, climate) on water fluxes, chemical weathering, and physical erosion
• Data and information dissemination to the scientific and stakeholder communities
• Capacity building in the field of catchment hydrology and soil erosion, through on-the-job training, teaching, and student internships, and basic geochemistry through analytical platforms
• Recommendations on land use policy to the national authorities

Strengths

• Multiscale approach, both spatially (from microplot to catchment and larger river basins scales) and temporally (from sub-hourly to multi-decennial time-series)
• Multidisciplinary approach, currently involving hydrology, biogeochemistry, soil science, agronomy, ecology, remote sensing, experimentation, and modelling

Achievements

Besides data collection and dissemination, the achievements of M-TROPICS on November 2022 are:

• 257 scientific publications in international journals
• 33 scientific publications in national journals
• 1 special issue in the Lao Journal of Agriculture and Forestry (2008): Management of soil erosion and water resources in the uplands of Lao P.D.R., by Ribolzi O. (Ed.), Pierret A. (Ed.), Gebbie L. (Ed.), Sengtaheuanghoung O. (Ed.), and Chanphengxay M. (Pref.)
• 57 PhDs, 7 post-docs, 6 HDR, and 281 MSc, BSc and Agric. Eng. degrees

Rationale

The Earth Critical Zone (CZ) is defined as the thin layer between the top of the canopy and the bottom of groundwater aquifer in which complex interactions involving rock, soil water, air and living organisms regulate the natural habitat and determine the availability of life sustaining resources. This concept brings together scientific disciplines in the aim to tackle crucial environmental issues regarding how the various components of the CZ react to global changes, including land use and climate changes:

• What are the water, solute, and particulate fluxes exported from tropical catchments?
• What is the impact of rapid land use changes on hydrology, water quality, soil resources?

The strategies adopted to answer these questions are often integrated approaches on experimental catchments, where hydrological, sedimentary, biogeochemical and ecological studies can be coupled. Acquiring simultaneous time series of meteorological, hydrological, geochemical, and ecological data over decades on river systems (both small experimental watersheds and larger basins) representative of the diversity of ecosystems is pivotal for the understanding of these processes, building integrated modelling and for proposing predictive scenarios.

Among the Critical Zone Observatories (CZOs) that have been implemented by the Earth Science community in the past 30 years, very few were set up in the Tropics despite the huge importance of these regions in terms of population density, fast-changing land use, biodiversity hotspots, biomass stock on continents (humid forests), size of river systems. In addition, rainfall in the Tropics is mostly governed by monsoon systems, which are particularly sensitive to climate change.