Title: Influence of landscape heterogeneity on water available to tropical forests in an Amazonian catchment and implications for modeling drought response

Abstract

The Amazon basin has experienced periodic droughts in the past, and intense and frequent droughts are predicted in the future. Landscape heterogeneity could play an important role in how tropical forests respond to drought by influencing water available to plants. Using the one-dimensional ACME Land Model and the three-dimensional ParFlow variably saturated flow model, numerical experiments were performed for a catchment in central Amazon to elucidate processes that influence water available for plant use and provide insights for improving Earth system models. Results from ParFlow show that topography has a dominant influence on groundwater table and runoff through lateral flow. Without any representations of lateral processes, ALM simulates very different seasonal variations in groundwater table and runoff compared to ParFlow even if it is able to reproduce the long-term spatial average groundwater table of ParFlow through simple parameter calibration. In the ParFlow simulations, even in the plateau with much deeper water table depth during the dry season in the drought year of 2005, plant transpiration is not water stressed as the soil saturation is still sufficient for the stomata to be fully open based on the empirical wilting formulation in the models. This finding is insensitive to uncertainty in atmosphericmore » forcing and soil parameters, but the empirical wilting formulation is an important factor that should be addressed using observations and modeling of coupled plant hydraulics-soil hydrology processes in future studies. Furthermore, the results could be applicable to other catchments in the Amazon basin with similar seasonal variability and hydrologic regimes.« less

Authors:

Fang, Yilin  ^[1];

• Search DOE PAGES for author "Fang, Yilin"
• Search DOE PAGES for ORCID "0000-0003-1969-9889"

Leung, L. Ruby  ^[1];

• Search DOE PAGES for author "Leung, L. Ruby"
• Search DOE PAGES for ORCID "0000-0002-3221-9467"

Duan, Zhuoran ^[1]; Wigmosta, Mark S. ^[1]; Maxwell, Reed M. ^[2]; Chambers, Jeffrey Q. ^[3]; Tomasella, Javier  ^[4]

• Search DOE PAGES for author "Tomasella, Javier"
• Search DOE PAGES for ORCID "0000-0003-2597-8833"

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+ Show Author Affiliations

1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. Colorado School of Mines, Golden, CO (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
4. Centro Nacional de Monitoramento e Alerta de Desastres Naturais, Sao Paulo (Brazil)

Publication Date:

Mon Aug 07 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1479325

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 122; Journal Issue: 16; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; landscape heterogeneity; lateral transport of soil moisture; transpiration; seasonal variability of groundwater dynamics and runoff