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Title: Interannual Variation in Hydrologic Budgets in an Amazonian Watershed with a Coupled Subsurface–Land Surface Process Model

The central Amazon forest is projected to experience larger interannual precipitation variability, with uncertain impacts on terrestrial hydrologic fluxes. How surface runoff, groundwater, and evapotranspiration (ET) change as a function of annual precipitation (AP) has large climate and biogeochemical implications. A process-based hydrological model is used to examine the sensitivity of hydrologic budgets and stream discharge Qsgeneration to AP in an upland Amazon catchment. The authors find that AP strongly controls infiltration, base flow, and surface runoff, but not ET. Hence, AP alone can predict interannual changes in these fluxes except ET. Experiments with perturbed rainfall show the strong control derives from the predominant groundwater component that varies linearly with AP but is insensitive to seasonal rainfall fluctuations. Most rainfall from large storms infiltrates and becomes base flow rather than runoff or ET. Annual baseflow index (BFI; the fraction of stream discharge from base flow) is nearly constant (~0.8) when AP is below ~2500 mmyr-1and decreases with AP above this value, which represents an inflection point for increased storage-dependent saturation excess. These results indicate that the system is energy limited and groundwater dominated in dry seasons, which implies some resilience of ET to moderate droughts. The results suggest AP ismore » a good predictor for interannual changes in infiltration. Both the seasonal near-surface soil moisture and surface runoff are correlated more strongly to the subsurface fluxes than to precipitation over monthly and annual time scales. Finally, the results confirm the importance of central Amazon groundwater flow and its buffering effect on storms and droughts, implying needed model development in regional to global models.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3]
  1. Jinan Univ., Guangzhou, Guangdong (China). Inst. of Groundwater and Earth Science; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Santa Barbara, CA (United States). Earth Research Inst.
  2. Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division
  4. Univ. of California, Santa Barbara, CA (United States). Earth Research Inst.
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Published Article
Journal Name:
Journal of Hydrometeorology
Additional Journal Information:
Journal Volume: 18; Journal Issue: 9; Journal ID: ISSN 1525-755X
Publisher:
American Meteorological Society
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1395202
Alternate Identifier(s):
OSTI ID: 1476532

Niu, Jie, Shen, Chaopeng, Chambers, Jeffrey Q., Melack, John M., and Riley, William J.. Interannual Variation in Hydrologic Budgets in an Amazonian Watershed with a Coupled Subsurface–Land Surface Process Model. United States: N. p., Web. doi:10.1175/JHM-D-17-0108.1.
Niu, Jie, Shen, Chaopeng, Chambers, Jeffrey Q., Melack, John M., & Riley, William J.. Interannual Variation in Hydrologic Budgets in an Amazonian Watershed with a Coupled Subsurface–Land Surface Process Model. United States. doi:10.1175/JHM-D-17-0108.1.
Niu, Jie, Shen, Chaopeng, Chambers, Jeffrey Q., Melack, John M., and Riley, William J.. 2017. "Interannual Variation in Hydrologic Budgets in an Amazonian Watershed with a Coupled Subsurface–Land Surface Process Model". United States. doi:10.1175/JHM-D-17-0108.1.
@article{osti_1395202,
title = {Interannual Variation in Hydrologic Budgets in an Amazonian Watershed with a Coupled Subsurface–Land Surface Process Model},
author = {Niu, Jie and Shen, Chaopeng and Chambers, Jeffrey Q. and Melack, John M. and Riley, William J.},
abstractNote = {The central Amazon forest is projected to experience larger interannual precipitation variability, with uncertain impacts on terrestrial hydrologic fluxes. How surface runoff, groundwater, and evapotranspiration (ET) change as a function of annual precipitation (AP) has large climate and biogeochemical implications. A process-based hydrological model is used to examine the sensitivity of hydrologic budgets and stream discharge Qsgeneration to AP in an upland Amazon catchment. The authors find that AP strongly controls infiltration, base flow, and surface runoff, but not ET. Hence, AP alone can predict interannual changes in these fluxes except ET. Experiments with perturbed rainfall show the strong control derives from the predominant groundwater component that varies linearly with AP but is insensitive to seasonal rainfall fluctuations. Most rainfall from large storms infiltrates and becomes base flow rather than runoff or ET. Annual baseflow index (BFI; the fraction of stream discharge from base flow) is nearly constant (~0.8) when AP is below ~2500 mmyr-1and decreases with AP above this value, which represents an inflection point for increased storage-dependent saturation excess. These results indicate that the system is energy limited and groundwater dominated in dry seasons, which implies some resilience of ET to moderate droughts. The results suggest AP is a good predictor for interannual changes in infiltration. Both the seasonal near-surface soil moisture and surface runoff are correlated more strongly to the subsurface fluxes than to precipitation over monthly and annual time scales. Finally, the results confirm the importance of central Amazon groundwater flow and its buffering effect on storms and droughts, implying needed model development in regional to global models.},
doi = {10.1175/JHM-D-17-0108.1},
journal = {Journal of Hydrometeorology},
number = 9,
volume = 18,
place = {United States},
year = {2017},
month = {9}
}