Martha A Scholl
Martha Scholl is a research hydrologist in the Earth System Processes Division, Water Cycle Branch of the USGS Water Resources Mission Area. Her work includes synthesizing stable isotope tracer methods with precipitation and land cover characteristics to determine climate patterns that control groundwater recharge and streamflow.
M.S. 1989 University of Virginia, Environmental Sciences (Hydrology)
B.S. 1985 University of Minnesota Duluth, Geology
Research topics:
Water availability in forested mountain watersheds: Mountain forests provide a steady, sustainable supply of high-quality water, and our research aims to improve understanding of the geologic, land cover and atmospheric interactions that affect this important resource.
Ecohydrology of cloud forests and coastal fog systems: Cloud water and fog inputs sustain important coastal and mountain ecosystems on six continents. Our research aims to quantify this unmeasured precipitation source in the water balance, including contributions to soil moisture, transpiration suppression, recharge and streamflow.
Science and Products
Insights into plant water uptake from xylem-water isotope measurements in two tropical catchments with contrasting moisture conditions
High mercury wet deposition at a “clean Air” site in Puerto Rico
Stable-isotope and solute-chemistry approaches to flow characterization in a forested tropical watershed, Luquillo Mountains, Puerto Rico
Stable isotope (δ18O and δ2H) data for precipitation, stream water, and groundwater in Puerto Rico
Precipitation isotopes link regional climate patterns to water supply in a tropical mountain forest, eastern Puerto Rico
USGS48 Puerto Rico precipitation - A new isotopic reference material for δ2H and δ18O measurements of water
Book review: The year without summer: 1816 and the volcano that darkened the world and changed history
Stable-isotope ratios of hydrogen and oxygen in precipitation at Norman, Oklahoma, 1996–2008
Canopy water balance of windward and leeward Hawaiian cloud forests on Haleakalā, Maui, Hawai'i
Understanding the role of fog in forest hydrology: Stable isotopes as tools for determining input and partitioning of cloud water in montane forests
Interpreting canopy water balance and fog screen observations: separating cloud water from wind-blown rainfall at two contrasting forest sites in Hawai'i
The stable isotope amount effect: New insights from NEXRAD echo tops, Luquillo Mountains, Puerto Rico
Science and Products
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Filter Total Items: 27
Insights into plant water uptake from xylem-water isotope measurements in two tropical catchments with contrasting moisture conditions
Water transpired by trees has long been assumed to be sourced from the same subsurface water stocks that contribute to groundwater recharge and streamflow. However, recent investigations using dual water stable isotopes have shown an apparent ecohydrological separation between tree-transpired water and stream water. Here we present evidence for such ecohydrological separation in two tropical envirAuthorsJaivime Evaristo, Jeffrey J. McDonnell, Martha A. Scholl, L. Adrian Bruijnzeel, Kwok P. ChunHigh mercury wet deposition at a “clean Air” site in Puerto Rico
Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μgAuthorsJames B. Shanley, Mark A. Engle, Martha A. Scholl, David P. Krabbenhoft, Robert Brunette, Mark L. Olson, Mary E. ConroyStable-isotope and solute-chemistry approaches to flow characterization in a forested tropical watershed, Luquillo Mountains, Puerto Rico
The prospect of changing climate has led to uncertainty about the resilience of forested mountain watersheds in the tropics. In watersheds where frequent, high rainfall provides ample runoff, we often lack understanding of how the system will respond under conditions of decreased rainfall or drought. Factors that govern water supply, such as recharge rates and groundwater storage capacity, may beAuthorsMartha A. Scholl, James B. Shanley, Sheila F. Murphy, Jane K Willenbring, Marcie Occhi, Grizelle GonzálezStable isotope (δ18O and δ2H) data for precipitation, stream water, and groundwater in Puerto Rico
Puerto Rico is located in the northeastern Caribbean Sea (18.2 °N, 66.3 °W), with the Atlantic Ocean on its northern coast. The U.S. Geological Survey’s Water, Energy, and Biogeochemical Budgets (WEBB) program study area in which most of these data were collected comprises the El Yunque National Forest and surrounding area of eastern Puerto Rico. Samples were collected in two forested watersheds,AuthorsMartha A. Scholl, Angel Torres-Sanchez, Manuel Rosario-TorresPrecipitation isotopes link regional climate patterns to water supply in a tropical mountain forest, eastern Puerto Rico
Like many mountainous areas in the tropics, watersheds in the Luquillo Mountains of eastern Puerto Rico have abundant rainfall and stream discharge and provide much of the water supply for the densely populated metropolitan areas nearby. Projected changes in regional temperature and atmospheric dynamics as a result of global warming suggest that water availability will be affected by changes in raAuthorsMartha A. Scholl, Sheila F. MurphyUSGS48 Puerto Rico precipitation - A new isotopic reference material for δ2H and δ18O measurements of water
A new secondary isotopic reference material has been prepared from Puerto Rico precipitation, which was filtered, homogenised, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material, designated as USGS48, is intended to be one of two isotopic reference waters for daAuthorsHaiping Qi, Tyler B. Coplen, Lauren V. Tarbox, Jennifer M. Lorenz, Martha A. SchollBook review: The year without summer: 1816 and the volcano that darkened the world and changed history
No abstract available.Review info: The year without summer: 1816 and the volcano that darkened the world and changed history. By Klingaman, W.K and Klingaman, N.P., 2013. ISBN: 9781250042750, 338 p.AuthorsMartha A. SchollStable-isotope ratios of hydrogen and oxygen in precipitation at Norman, Oklahoma, 1996–2008
Precipitation samples for measurement of stable-isotope ratios of hydrogen (delta2H) and oxygen (delta18O) were collected at the Norman Landfill Research Site in Norman, Oklahoma, from May 1996 to October 2008. Rainfall amounts also were measured at the site (U.S. Geological Survey gaging station 07229053) during the collection period. The delta2H of precipitation samples ranged from -121.9 to +8.AuthorsJeanne B. Jaeschke, Martha A. Scholl, Isabelle M. Cozzarelli, Jason R. Masoner, Scott Christenson, Haiping QiCanopy water balance of windward and leeward Hawaiian cloud forests on Haleakalā, Maui, Hawai'i
The contribution of intercepted cloud water to precipitation at windward and leeward cloud forest sites on the slopes of Haleakalā, Maui was assessed using two approaches. Canopy water balance estimates based on meteorological monitoring were compared with interpretations of fog screen measurements collected over a 2-year period at each location. The annual incident rainfall was 973 mm at the leewAuthorsThomas W. Giambelluca, John K. DeLay, Michael A. Nullet, Martha A. Scholl, Stephen B. GingerichUnderstanding the role of fog in forest hydrology: Stable isotopes as tools for determining input and partitioning of cloud water in montane forests
Understanding the hydrology of tropical montane cloud forests (TMCF) has become essential as deforestation of mountain areas proceeds at an increased rate worldwide. Passive and active cloud‐water collectors, throughfall and stemflow collectors, visibility or droplet size measurements, and micrometeorological sensors are typically used to measure the fog water inputs to ecosystems. In addition, stAuthorsMartha A. Scholl, W. Eugster, R. BurkardInterpreting canopy water balance and fog screen observations: separating cloud water from wind-blown rainfall at two contrasting forest sites in Hawai'i
No abstract available.AuthorsThomas W. Giambelluca, J. K. DeLay, M.A. Nullet, Martha A. Scholl, Stephen B. GingerichThe stable isotope amount effect: New insights from NEXRAD echo tops, Luquillo Mountains, Puerto Rico
The stable isotope amount effect has often been invoked to explain patterns of isotopic composition of rainfall in the tropics. This paper describes a new approach, correlating the isotopic composition of precipitation with cloud height and atmospheric temperature using NEXRAD radar echo tops, which are a measure of the maximum altitude of rainfall within the clouds. The seasonal differences in ecAuthorsMartha A. Scholl, James B. Shanley, Jan Paul Zegarra, Tyler B. Coplen - News