2022
LaFollette, PT; Hahm, WJ; Rempe, DM; Dietrich, WE; Brauer, CC; Weerts, AH; Dralle, DN
Multicriteria analysis on rock moisture and streamflow in a rainfall-runoff model improves accuracy of model results Journal Article
In: Hydrological Processes, vol. 36, iss. 3, 2022.
Links | BibTeX | Tags: ERCZO, hydrologic modeling, rainfall, rock moisture, Stream Flow
@article{LaFollette2022,
title = {Multicriteria analysis on rock moisture and streamflow in a rainfall-runoff model improves accuracy of model results},
author = {PT LaFollette and WJ Hahm and DM Rempe and WE Dietrich and CC Brauer and AH Weerts and DN Dralle},
url = {https://angelo.berkeley.edu/lafollette_rockmoisture_streamflow_model/},
doi = {https://doi.org/10.1002/hyp.14536},
year = {2022},
date = {2022-03-09},
journal = {Hydrological Processes},
volume = {36},
issue = {3},
keywords = {ERCZO, hydrologic modeling, rainfall, rock moisture, Stream Flow},
pubstate = {published},
tppubtype = {article}
}
2018
Rempe, Daniella; Dietrich, William
Direct observations of rock moisture, a hidden component of the hydrologic cycle Journal Article
In: Proceedings of the National Academy of Science of the United States of America, vol. 115, no. 11, pp. 2664-2669, 2018.
Abstract | Links | BibTeX | Tags: Critical Zone, deep vadose zone, ERCZO, evapotranspiration, rock moisture, water budget
@article{daniellaRempe2018,
title = {Direct observations of rock moisture, a hidden component of the hydrologic cycle},
author = {Daniella Rempe and William Dietrich},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Proceedings-of-the-National-Academy-of-Sciences-2018-Rempe.pdf},
doi = {https://doi.org/10.1073/pnas.1800141115},
year = {2018},
date = {2018-03-13},
journal = {Proceedings of the National Academy of Science of the United States of America},
volume = {115},
number = {11},
pages = {2664-2669},
abstract = {Recent theory and field observations suggest that a systematically varying weathering zone, that can be tens of meters thick, commonly develops in the bedrock underlying hillslopes. Weathering turns otherwise poorly conductive bedrock into a dynamic water storage reservoir. Infiltrating precipitation typically will pass through unsaturated weathered bedrock before reaching groundwater and running off to streams. This invisible and difficult to access unsaturated zone is virtually unexplored compared with the surface soil mantle. We have proposed the term “rock moisture” to describe the exchangeable water stored in the unsaturated zone in weathered bedrock, purposely choosing a term parallel to, but distinct from, soil moisture, because weathered bedrock is a distinctly different material that is distributed across landscapes independently of soil thickness. Here, we report a multiyear intensive campaign of quantifying rock moisture across a hillslope underlain by a thick weathered bedrock zone using repeat neutron probe measurements in a suite of boreholes. Rock moisture storage accumulates in the wet season, reaches a characteristic upper value, and rapidly passes any additional rainfall downward to groundwater. Hence, rock moisture storage mediates the initiation and magnitude of recharge and runoff. In the dry season, rock moisture storage is gradually depleted by trees for transpiration, leading to a common lower value at the end of the dry season. Up to 27% of the annual rainfall is seasonally stored as rock moisture. Significant rock moisture storage is likely common, and yet it is missing from hydrologic and land-surface models used to predict regional and global climate.},
keywords = {Critical Zone, deep vadose zone, ERCZO, evapotranspiration, rock moisture, water budget},
pubstate = {published},
tppubtype = {article}
}
Recent theory and field observations suggest that a systematically varying weathering zone, that can be tens of meters thick, commonly develops in the bedrock underlying hillslopes. Weathering turns otherwise poorly conductive bedrock into a dynamic water storage reservoir. Infiltrating precipitation typically will pass through unsaturated weathered bedrock before reaching groundwater and running off to streams. This invisible and difficult to access unsaturated zone is virtually unexplored compared with the surface soil mantle. We have proposed the term “rock moisture” to describe the exchangeable water stored in the unsaturated zone in weathered bedrock, purposely choosing a term parallel to, but distinct from, soil moisture, because weathered bedrock is a distinctly different material that is distributed across landscapes independently of soil thickness. Here, we report a multiyear intensive campaign of quantifying rock moisture across a hillslope underlain by a thick weathered bedrock zone using repeat neutron probe measurements in a suite of boreholes. Rock moisture storage accumulates in the wet season, reaches a characteristic upper value, and rapidly passes any additional rainfall downward to groundwater. Hence, rock moisture storage mediates the initiation and magnitude of recharge and runoff. In the dry season, rock moisture storage is gradually depleted by trees for transpiration, leading to a common lower value at the end of the dry season. Up to 27% of the annual rainfall is seasonally stored as rock moisture. Significant rock moisture storage is likely common, and yet it is missing from hydrologic and land-surface models used to predict regional and global climate.
2012
Salve, Rohit; Rempe, Daniella M.; Dietrich, William E.
Rain, rock moisture dynamics, and the rapid response of perched groundwater in weathered, fractured argillite underlying a steep hillslope Journal Article
In: Water Resources Research, vol. 48, no. 11, 2012.
Abstract | Links | BibTeX | Tags: fractured argillite, groundwater, rain, rock moisture
@article{Salve2012,
title = {Rain, rock moisture dynamics, and the rapid response of perched groundwater in weathered, fractured argillite underlying a steep hillslope},
author = {Rohit Salve and Daniella M. Rempe and William E. Dietrich},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Salve_2012_WatResoRese.pdf},
doi = {10.1029/2012WR012583},
year = {2012},
date = {2012-11-28},
journal = {Water Resources Research},
volume = {48},
number = {11},
abstract = {Various field studies have concluded that shallow groundwater in weathered bedrock underlying hillslopes can contribute to both base and stormflow and thus dominate runoff. The processes associated with recharge from the ground surface, through this unsaturated zone, have received little study, yet they influence runoff dynamics, the chemical evolution of water, and moisture availability. Here we use five measurement systems to document soil and rock moisture dynamics within a 4000 m2zero-order basin in which all runoff occurs through weathered argillite. At this site, the weathered bedrock zone (in which the groundwater fluctuates by 8 m seasonally) varies in depth from ∼4 m at the base of the hillslope to nearly 19 m near the hill top. An aggregate-rich, porous, 0.5 m thick soil overlies the weathered bedrock. We find that during the first rains of the wet season, water rapidly travels meters into the weathered bedrock zone. Consistently, however, groundwater at some places responds quickly to the first major storm, well before the wetting front has been detected much beyond about 1 m. Furthermore, throughout the wet season, the lower portion of the unsaturated weathered bedrock shows little or no moisture change. These observations suggest a fracture-dominated flow path, leading to a highly variably groundwater response across the hillslope for a given storm. Seasonal changes in rock moisture content are greatest in the first 5 to 10 m depth and may exceed the magnitude of moisture changes in the soil, suggesting that it could constitute a significant unmapped moisture reservoir.},
keywords = {fractured argillite, groundwater, rain, rock moisture},
pubstate = {published},
tppubtype = {article}
}
Various field studies have concluded that shallow groundwater in weathered bedrock underlying hillslopes can contribute to both base and stormflow and thus dominate runoff. The processes associated with recharge from the ground surface, through this unsaturated zone, have received little study, yet they influence runoff dynamics, the chemical evolution of water, and moisture availability. Here we use five measurement systems to document soil and rock moisture dynamics within a 4000 m2zero-order basin in which all runoff occurs through weathered argillite. At this site, the weathered bedrock zone (in which the groundwater fluctuates by 8 m seasonally) varies in depth from ∼4 m at the base of the hillslope to nearly 19 m near the hill top. An aggregate-rich, porous, 0.5 m thick soil overlies the weathered bedrock. We find that during the first rains of the wet season, water rapidly travels meters into the weathered bedrock zone. Consistently, however, groundwater at some places responds quickly to the first major storm, well before the wetting front has been detected much beyond about 1 m. Furthermore, throughout the wet season, the lower portion of the unsaturated weathered bedrock shows little or no moisture change. These observations suggest a fracture-dominated flow path, leading to a highly variably groundwater response across the hillslope for a given storm. Seasonal changes in rock moisture content are greatest in the first 5 to 10 m depth and may exceed the magnitude of moisture changes in the soil, suggesting that it could constitute a significant unmapped moisture reservoir.