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
Stable hydrogen and oxygen isotopic compositions of precipitation samples from selected Colorado and Utah National Atmospheric Deposition Program (NADP) sites
The stable hydrogen (delta 2H) and oxygen (delta 18O) isotopic compositions of more than 4,300 weekly composite samples of precipitation from thirteen National Atmospheric Deposition Program (NADP) sites (CO02, CO08, CO09, CO10, CO21, CO89, CO91, CO92, CO93, CO96, CO97, CO98, and UT09) in Colorado and Utah were analyzed on archived samples obtained from NADP over various time periods between Janua
Stable hydrogen and oxygen isotopic compositions of precipitation samples from selected Delaware, Maryland, New Jersey, New York, and Pennsylvania National Atmospheric Deposition Program (NADP) sites
The stable hydrogen (delta 2H) and oxygen (delta 18O) isotopic compositions of more than 6,400 daily or weekly composite samples of precipitation from nine National Atmospheric Deposition Program (NADP) sites (DE02, MD07, NJ99, NY67, NY68, PA00, PA15, PA72, and PA98) in New York, New Jersey, Delaware, Maryland and Pennsylvania were analyzed on archived samples obtained from NADP over various time
Temperature, relative humidity and cloud immersion data for Luquillo Mountains, eastern Puerto Rico, 2014-2019
Supplementary data for studies conducted in the Luquillo Experimental Forest (LEF), eastern Puerto Rico include measurements of temperature, relative humidity and cloud immersion at 30-minute resolution. Temperature and relative humidity were measured at five sites; two primary sites have records from March 2014 to June 2019; other sites have shorter records within that period. From these data,
Geospatial data for Luquillo Mountains, Puerto Rico: Mean annual precipitation, elevation, watershed outlines, and rain gage locations
These geospatial data sets were developed as part of a new analysis of all known current and historical rain gages in the Luquillo Mountains, Puerto Rico published in the journal article Murphy, S.F., Stallard, R.F., Scholl, M.A., Gonzalez, G., and Torres-Sanchez, A.J., 2017, Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications: PLOS One 12(7):
Supplementary Data for Method for Quantifying Cloud Immersion in a Tropical Mountain Forest Using Time-Lapse Photography
These data are mean temperature, relative humidity, dew point and cloud immersion with hour of day for sites in El Yunque National Forest, Puerto Rico.
These data support the following publication:
Bassiouni, M., Scholl, M.A., Torres-Sanchez, A.J., Murphy, S.F., in review, A Method for Quantifying Cloud Immersion in a Tropical Mountain Forest Using Time-Lapse Photography, Agricultural and
Filter Total Items: 27
Extreme rainstorms drive exceptional organic carbon export from forested humid-tropical rivers in Puerto Rico
Extreme rainfall events in the humid-tropical Luquillo Mountains, Puerto Rico export the bulk of suspended sediment and particulate organic carbon. Using 25 years of river carbon and suspended sediment data, which targeted hurricanes and other large rainstorms, we estimated biogenic particulate organic carbon yields of 65 ± 16 tC km−2 yr−1 for the Icacos and 17.7 ± 5.1 tC km−2 yr−1 for the Mameyes
Authors
Kasey E. Clark, Robert Stallard, Sheila F. Murphy, Martha A. Scholl, Grizelle González, Alain F. Plante, William H. McDowell
Forest cover lessens the impact of drought on streamflow in Puerto Rico
Tropical regions are experiencing high rates of forest cover loss coupled with changes in the volume and timing of rainfall. These shifts can compromise streamflow and water provision, highlighting the need to identify how forest cover influences streamflow generation under variable rainfall conditions. Although rainfall is the key driver of streamflow regimes, the role of forests is less clear, p
Authors
Jazlynn S. Hall, Martha A. Scholl, Yuri Gorokhovich, Maria Uriarte
Anomalous noble gas solubility in liquid cloud water: Possible implications for noble gas temperatures and cloud physics
The noble gas temperature climate proxy is an established tool that has previously been applied to determine the source of groundwater recharge, however, unanswered questions remain. In fractured media (e.g., volcanic islands) recharge can be so rapid that groundwater is significantly depleted in heavy noble gases, indicating that the water has retained noble gas concentrations from higher elevati
Authors
Chris M. Hall, M. Clara Castro, Martha A. Scholl, Julien Amalberti, Stephen B. Gingerich
Drought stress and hurricane defoliation influence mountain clouds and moisture recycling in a tropical forest
Mountain ranges generate clouds, precipitation, and perennial streamflow for water supplies, but the role of forest cover in mountain hydrometeorology and cloud formation is not well understood. In the Luquillo Experimental Forest of Puerto Rico, mountains are immersed in clouds nightly, providing a steady precipitation source to support the tropical forest ecosystems and human uses. A severe drou
Authors
Martha A. Scholl, Maoya Bassiouni, Angel J. Torres-Sanchez
Groundwater dynamics at Kīlauea Volcano and vicinity, Hawaiʻi
Kīlauea Volcano, on the Island of Hawaiʻi, is surrounded and permeated by active groundwater systems that interact dynamically with the volcanic system. A generalized conceptual model of Hawaiian hydrogeology includes high-level dike-impounded groundwater, very permeable perched and basal aquifers, and a transition (mixing) zone between freshwater and saltwater. Most high-level groundwater is asso
Authors
Shaul Hurwitz, Sara E. Peek, Martha A. Scholl, Deborah Bergfeld, William C. Evans, James P. Kauahikaua, Stephen B. Gingerich, Paul A. Hsieh, R. Lopaka Lee, Edward F. Younger, Steven E. Ingebritsen
A 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico
The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest
managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 yr, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although the CBH in the area was not quantified until recently. The
Authors
Paul W. Miller, Thomas L. Mote, C.A. Ramseyer, Ashley E. Van Beusekom, Martha A. Scholl, Grizelle Gonzalez
Seasonality of stable isotope composition of atmospheric water input at the southern slopes of Mt. Kilimanjaro, Tanzania
To understand the moisture regime at the southern slopes of Mt. Kilimanjaro, we analysed the isotopic variability of oxygen (δ18O) and hydrogen (δD) of rainfall, throughfall, and fog from a total of 2,140 samples collected weekly over 2 years at 9 study sites along an elevation transect ranging from 950 to 3,880 m above sea level. Precipitation in the Kilimanjaro tropical rainforests consists of a
Authors
Insa Otte, Florian Detsch, Adrian Gutlein, Martha A. Scholl, Ralf Kiese, Tim Appelhans, Thomas Nauss
A method for quantifying cloud immersion in a tropical mountain forest using time-lapse photography
Quantifying the frequency, duration, and elevation range of fog or cloud immersion is essential to estimate cloud water deposition in water budgets and to understand the ecohydrology of cloud forests. The goal of this study was to develop a low-cost and high spatial-coverage method to detect occurrence of cloud immersion within a mountain cloud forest by using time-lapse photography. Trail cameras
Authors
Maoya Bassiouni, Martha A. Scholl, Angel J. Torres-Sanchez, Sheila F. Murphy
Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications
Mountains receive a greater proportion of precipitation than other environments, and thus make a disproportionate contribution to the world’s water supply. The Luquillo Mountains receive the highest rainfall on the island of Puerto Rico and serve as a critical source of water to surrounding communities. The area’s role as a long-term research site has generated numerous hydrological, ecological, a
Authors
Sheila F. Murphy, Robert F. Stallard, Martha A. Scholl, Grizelle Gonzalez, Angel J. Torres-Sanchez
Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change
The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes
Authors
Ashley E. Van Beusekom, Grizelle González, Martha A. Scholl
Noble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems
Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observe
Authors
Yi Niu, M. Clara Castro, Chris M. Hall, Stephen B. Gingerich, Martha A. Scholl, Rohit B. Warrier
Tropical river suspended sediment and solute dynamics in storms during an extreme drought
Droughts, which can strongly affect both hydrologic and biogeochemical systems, are projected to become more prevalent in the tropics in the future. We assessed the effects of an extreme drought during 2015 on stream water composition in the Luquillo Mountains of Puerto Rico. We demonstrated that drought base flow in the months leading up to the study was sourced from trade-wind orographic rainfal
Authors
Kathryn E. Clark, James B. Shanley, Martha A. Scholl, Nicolas Perdrial, Julia N. Perdrial, Alain F. Plante, William H. McDowell
Science and Products
- Data
Stable hydrogen and oxygen isotopic compositions of precipitation samples from selected Colorado and Utah National Atmospheric Deposition Program (NADP) sites
The stable hydrogen (delta 2H) and oxygen (delta 18O) isotopic compositions of more than 4,300 weekly composite samples of precipitation from thirteen National Atmospheric Deposition Program (NADP) sites (CO02, CO08, CO09, CO10, CO21, CO89, CO91, CO92, CO93, CO96, CO97, CO98, and UT09) in Colorado and Utah were analyzed on archived samples obtained from NADP over various time periods between JanuaStable hydrogen and oxygen isotopic compositions of precipitation samples from selected Delaware, Maryland, New Jersey, New York, and Pennsylvania National Atmospheric Deposition Program (NADP) sites
The stable hydrogen (delta 2H) and oxygen (delta 18O) isotopic compositions of more than 6,400 daily or weekly composite samples of precipitation from nine National Atmospheric Deposition Program (NADP) sites (DE02, MD07, NJ99, NY67, NY68, PA00, PA15, PA72, and PA98) in New York, New Jersey, Delaware, Maryland and Pennsylvania were analyzed on archived samples obtained from NADP over various timeTemperature, relative humidity and cloud immersion data for Luquillo Mountains, eastern Puerto Rico, 2014-2019
Supplementary data for studies conducted in the Luquillo Experimental Forest (LEF), eastern Puerto Rico include measurements of temperature, relative humidity and cloud immersion at 30-minute resolution. Temperature and relative humidity were measured at five sites; two primary sites have records from March 2014 to June 2019; other sites have shorter records within that period. From these data,Geospatial data for Luquillo Mountains, Puerto Rico: Mean annual precipitation, elevation, watershed outlines, and rain gage locations
These geospatial data sets were developed as part of a new analysis of all known current and historical rain gages in the Luquillo Mountains, Puerto Rico published in the journal article Murphy, S.F., Stallard, R.F., Scholl, M.A., Gonzalez, G., and Torres-Sanchez, A.J., 2017, Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications: PLOS One 12(7):Supplementary Data for Method for Quantifying Cloud Immersion in a Tropical Mountain Forest Using Time-Lapse Photography
These data are mean temperature, relative humidity, dew point and cloud immersion with hour of day for sites in El Yunque National Forest, Puerto Rico. These data support the following publication: Bassiouni, M., Scholl, M.A., Torres-Sanchez, A.J., Murphy, S.F., in review, A Method for Quantifying Cloud Immersion in a Tropical Mountain Forest Using Time-Lapse Photography, Agricultural and - Publications
Filter Total Items: 27
Extreme rainstorms drive exceptional organic carbon export from forested humid-tropical rivers in Puerto Rico
Extreme rainfall events in the humid-tropical Luquillo Mountains, Puerto Rico export the bulk of suspended sediment and particulate organic carbon. Using 25 years of river carbon and suspended sediment data, which targeted hurricanes and other large rainstorms, we estimated biogenic particulate organic carbon yields of 65 ± 16 tC km−2 yr−1 for the Icacos and 17.7 ± 5.1 tC km−2 yr−1 for the MameyesAuthorsKasey E. Clark, Robert Stallard, Sheila F. Murphy, Martha A. Scholl, Grizelle González, Alain F. Plante, William H. McDowellForest cover lessens the impact of drought on streamflow in Puerto Rico
Tropical regions are experiencing high rates of forest cover loss coupled with changes in the volume and timing of rainfall. These shifts can compromise streamflow and water provision, highlighting the need to identify how forest cover influences streamflow generation under variable rainfall conditions. Although rainfall is the key driver of streamflow regimes, the role of forests is less clear, pAuthorsJazlynn S. Hall, Martha A. Scholl, Yuri Gorokhovich, Maria UriarteAnomalous noble gas solubility in liquid cloud water: Possible implications for noble gas temperatures and cloud physics
The noble gas temperature climate proxy is an established tool that has previously been applied to determine the source of groundwater recharge, however, unanswered questions remain. In fractured media (e.g., volcanic islands) recharge can be so rapid that groundwater is significantly depleted in heavy noble gases, indicating that the water has retained noble gas concentrations from higher elevatiAuthorsChris M. Hall, M. Clara Castro, Martha A. Scholl, Julien Amalberti, Stephen B. GingerichDrought stress and hurricane defoliation influence mountain clouds and moisture recycling in a tropical forest
Mountain ranges generate clouds, precipitation, and perennial streamflow for water supplies, but the role of forest cover in mountain hydrometeorology and cloud formation is not well understood. In the Luquillo Experimental Forest of Puerto Rico, mountains are immersed in clouds nightly, providing a steady precipitation source to support the tropical forest ecosystems and human uses. A severe drou
AuthorsMartha A. Scholl, Maoya Bassiouni, Angel J. Torres-SanchezGroundwater dynamics at Kīlauea Volcano and vicinity, Hawaiʻi
Kīlauea Volcano, on the Island of Hawaiʻi, is surrounded and permeated by active groundwater systems that interact dynamically with the volcanic system. A generalized conceptual model of Hawaiian hydrogeology includes high-level dike-impounded groundwater, very permeable perched and basal aquifers, and a transition (mixing) zone between freshwater and saltwater. Most high-level groundwater is assoAuthorsShaul Hurwitz, Sara E. Peek, Martha A. Scholl, Deborah Bergfeld, William C. Evans, James P. Kauahikaua, Stephen B. Gingerich, Paul A. Hsieh, R. Lopaka Lee, Edward F. Younger, Steven E. IngebritsenA 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico
The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 yr, studies of the Luquillo cloud forest have suggested an increase in cloud base heights (CBH), although the CBH in the area was not quantified until recently. TheAuthorsPaul W. Miller, Thomas L. Mote, C.A. Ramseyer, Ashley E. Van Beusekom, Martha A. Scholl, Grizelle GonzalezSeasonality of stable isotope composition of atmospheric water input at the southern slopes of Mt. Kilimanjaro, Tanzania
To understand the moisture regime at the southern slopes of Mt. Kilimanjaro, we analysed the isotopic variability of oxygen (δ18O) and hydrogen (δD) of rainfall, throughfall, and fog from a total of 2,140 samples collected weekly over 2 years at 9 study sites along an elevation transect ranging from 950 to 3,880 m above sea level. Precipitation in the Kilimanjaro tropical rainforests consists of aAuthorsInsa Otte, Florian Detsch, Adrian Gutlein, Martha A. Scholl, Ralf Kiese, Tim Appelhans, Thomas NaussA method for quantifying cloud immersion in a tropical mountain forest using time-lapse photography
Quantifying the frequency, duration, and elevation range of fog or cloud immersion is essential to estimate cloud water deposition in water budgets and to understand the ecohydrology of cloud forests. The goal of this study was to develop a low-cost and high spatial-coverage method to detect occurrence of cloud immersion within a mountain cloud forest by using time-lapse photography. Trail camerasAuthorsMaoya Bassiouni, Martha A. Scholl, Angel J. Torres-Sanchez, Sheila F. MurphyReassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications
Mountains receive a greater proportion of precipitation than other environments, and thus make a disproportionate contribution to the world’s water supply. The Luquillo Mountains receive the highest rainfall on the island of Puerto Rico and serve as a critical source of water to surrounding communities. The area’s role as a long-term research site has generated numerous hydrological, ecological, aAuthorsSheila F. Murphy, Robert F. Stallard, Martha A. Scholl, Grizelle Gonzalez, Angel J. Torres-SanchezAnalyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change
The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changesAuthorsAshley E. Van Beusekom, Grizelle González, Martha A. SchollNoble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems
Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observeAuthorsYi Niu, M. Clara Castro, Chris M. Hall, Stephen B. Gingerich, Martha A. Scholl, Rohit B. WarrierTropical river suspended sediment and solute dynamics in storms during an extreme drought
Droughts, which can strongly affect both hydrologic and biogeochemical systems, are projected to become more prevalent in the tropics in the future. We assessed the effects of an extreme drought during 2015 on stream water composition in the Luquillo Mountains of Puerto Rico. We demonstrated that drought base flow in the months leading up to the study was sourced from trade-wind orographic rainfalAuthorsKathryn E. Clark, James B. Shanley, Martha A. Scholl, Nicolas Perdrial, Julia N. Perdrial, Alain F. Plante, William H. McDowell - News