U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Lateral Processes Dominate Control of Water Available to Tropical Forests
Published: August 18, 2017
Posted: January 23, 2018

Comparing models of different complexities provides important insights for improving drought response simulations.

The Science
The Amazon basin has experienced periodic droughts in the past, and intense, more frequent droughts are predicted. Comparing hydrologic models of different complexities and parameters in a catchment in central Amazonia, a research team led by scientists at the U.S. Department of Energy’s (DOE) Pacific Northwest National Laboratory found that variations in terrain have a dominant influence on groundwater table and streamflow through lateral transport of soil water. Hence, different models produce significantly different water available to plants. Despite the difference, however, plants were not under water stress in any simulation, even during a drought year. The team identified another important process—the efficiency of water transport through the plants—which must be better represented in models to more realistically simulate drought response.

The Impact
Tropical forests are an important carbon sink, but a large fraction of the carbon sequestered during normal and wet years can be released during drought years because of tree mortality and reduced ecosystem productivity. This research shed light on key processes that influence water available for plant use, and provided insights for improving modeling of tropical forest drought response.

To better understand how tropical forests respond to drought requires improved capabilities to predict the spatial variability of water and soil moisture available for plant use. Researchers in the United States and Brazil identified spatial variabilities in soil and topography as the dominant influences on soil hydrology in an Amazonian catchment. Scientists performed a series of numerical experiments using the one-dimensional DOE Accelerated Climate Modeling for Energy (ACME) Land Model (ALM) and the three-dimensional ParFlow hydrology model. Researchers found large differences in groundwater table depth between the models. By varying the model soil parameters, the team found that ALM can reproduce the long-term mean groundwater table depth simulated by ParFlow, but it cannot capture features such as delayed groundwater recharge at the plateau. This study showed that developing approaches to represent lateral processes that are missing in one-dimensional models is critical for modeling water available to plants in tropical forests. In addition, plant hydraulics (the efficiency of water transport through plants) and preferential flow (water movement through macropore soils) are key processes that should be represented in Earth system models for simulating tropical forest response to drought and the future of the land carbon sink. The results could apply to other catchments in the Amazon basin with similar seasonal variability and hydrologic regimes.

Contacts (BER PMs)
Daniel Stover
Terrestrial Ecosystem Science

Dorothy Koch
Earth System Modeling

PI Contact
L. Ruby Leung
Pacific Northwest National Laboratory

The U.S. Department of Energy Office of Science, Biological and Environmental Research supported this research as part of the Terrestrial Ecosystem Science program through the Next Generation Ecosystem Experiment (NGEE)-Tropics project.

Y. Fang, L.R. Leung, Z. Duan, M.S. Wigmosta, R.M. Maxwell, J.Q. Chambers, and J. Tomasella. “Influence of Landscape Heterogeneity on Water Available to Tropical Forests in an Amazonian Catchment and Implications for Modeling Drought Response.” Journal of Geophysical Research: Atmospheres, (2017). [DOI: 10.1002/2017JD027066]

Related Links
Reference link

Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling
  • Research Area: Terrestrial Ecosystem Science
  • Research Area: Next-Generation Ecosystem Experiments (NGEE)

Division: SC-23.1 Climate and Environmental Sciences Division, BER


BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]

May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]

May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]

May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]

Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]

List all highlights (possible long download time)