Geology topics

Laura K. Lautz

Publications and source records attributed to Laura K. Lautz.

10 recordsLinked to original sources

USGS2025

Second Integrated Hydro-Terrestrial Modeling (IHTM 2.0) workshop: USGCRP federal agency perspectives

U.S. federal leadership, mobilizing close interagency coordination across sectors, is key to tackling compound climate and human impacts on our nation’s water resources. Recognizing this need, federal agencies and academic collaborators conducted a series of workshops to advance Integrated Hydro-Terrestrial Modeling (IHTM). IHTM is focused on supporting a multiscale framework to accelerate research insights, better integrate operational and planning perspectives, and bridge national-to-regional capabilities to address major interdependent societal water challenges. This framework leverages the capabilities of different agencies and institutional partners across sectors to advance a shared vision for use-inspired modeling and open science. The IHTM conceptual framework has developed over several community workshops in recent years: ● In September 2019, a community coordinating group on IHTM hosted an interagency workshop (“IHTM 1.0”) with support from NSF, DOE, and USGS. The resulting report identified the need for agencies to invest resources in designing pilot use cases, setting the stage for an integrated national IHTM capability. ● In November 2020, the U.S. Global Change Research Program (USGCRP) held a virtual Coastal-IHTM (C-IHTM) workshop in collaboration with the MultiSector Dynamics Community of Practice, which engages researchers across universities and national labs. Building on IHTM 1.0, this workshop aimed to identify coastal modeling capabilities and appropriate coastal applications of the IHTM framework. The workshop report detailed needs for open science, geographical or topical use cases, integrated modeling frameworks, and linking communities of practice. ● From October 31 to November 2, 2023, USGCRP hosted a hybrid IHTM 2.0 community workshop that brought together 160 scientists and managers from nine federal departments/agencies (DHS-FEMA, DOC-NOAA, DoD-USACE, DOE, DOI [U.S. Bureau of Reclamation (USBR), USGS], EPA, NASA, NSF, USDA [ARS, FS, NRCS]) and 32 non-federal academic, non-profit, and private institutions and consortiums. The workshop was organized by a federal Interagency Steering Committee with representatives from DOE, USGS, NSF, NASA, and NOAA, as well as a Scientific Organizing Committee comprising experts from academia and additional federal agency technical experts. The IHTM 2.0 workshop focused on moving the IHTM 1.0 concepts to action by making advances in designing national and regional integrated modeling experiments in five geographic testbeds. These modeling testbeds seek to facilitate collaborative water resources research and assessment that responds to societal needs, extending from basic research to resource management operations, including the assessment of water quantity, quality, and use at national and regional scales. Ultimately, we envision that the IHTM testbeds will improve our ability to provide water resources assessment scenarios to decision-makers and the public. This document summarizes USGCRP and member agencies’ perspectives of the IHTM 2.0 workshop. Sections 2 and 3 build on the work of the IHTM 2.0 workshop Scientific Organizing Committee to outline the importance of IHTM, summarize the workshop, and propose near- and medium-term IHTM priorities. Section 4 presents select ongoing and potential interagency activities that could help realize the IHTM 2.0 vision and align with three of USGCRP’s strategic goals for this decade: Advancing Science, Informing Decisions, and Engaging the Nation. Finally, Section 5 summarizes this report and offers information about how to connect with USGCRP’s IHTM activities. USGCRP and its member agencies are well-positioned to coordinate federal efforts to enhance IHTM capabilities in the coming years.

Conference Paper↗

USGS2020

Integrated hydro-terrestrial modeling: Development of a national capability

Water is one of our most important natural resources and is essential to our national economy and security. Multiple federal government agencies have mission elements that address national needs related to water. Each water-related agency champions a unique science and/or operational mission focused on advancing a portion of the nation’s ability to meet our water-related challenges, often in close collaboration with scientists from the academic community. These diverse mission needs have engendered a rich and extensive base of water-related data and modeling capabilities. While useful for their intended purposes, these capabilities are not well integrated to address complex regional problems and overarching national problems. These major investments by several federal agencies and their scientific partners, however, lay the foundation for an integrated hydro-terrestrial modeling and data infrastructure that will enhance knowledge, understanding, prediction, and management of the nation’s diverse water challenges.

Report↗

USGS2019

Hydrogeology of an alpine talus aquifer: Cordillera Blanca, Peru

The dramatic loss of glacial mass in low latitudes is causing shifts in downstream water availability and use during the driest months of the year. The world’s largest concentration of tropical glaciers lies in the Cordillera Blanca range of Peru, where glacial runoff is declining and regional stresses are emerging over water resources. Throughout the Cordillera Blanca, groundwater inputs from alpine meadow–talus complexes, locally known as pampas, supply proglacial streams with up to 80% of their flow during the region’s dry season. Structural knowledge of the pampa aquifers is needed to estimate their drainable groundwater storage capacity and residence time, to elucidate the role and importance of alpine groundwater storage in the regional water budget of the Cordillera Blanca. To understand the structure of these proglacial aquifers, multiple near-surface geophysical methods were implemented in a proglacial valley near dense networks of spring-fed tributaries. Geophysical results and borehole logs suggest groundwater is stored in a confined aquifer composed of buried talus deposits overlain by lacustrine clay, while deeper portions of the unit, 10–15 m in depth, are relatively clay-free and more hydraulically conductive. Based on these findings and assumptions of aquifer porosity, the pampas of the Callejon de Huaylas may store from 0.006 to 0.02 km 3 of groundwater. Furthermore, these findings suggest that the talus aquifers of the Cordillera Blanca were formed in proglacial lakes, followed by infilling with fine lacustrine sediments that confine lower units and allow for groundwater discharge to springs via macropores and preferential flow.

Hydrogeology Journal↗

USGS2019

Historical changes in New York State streamflow: Attribution of temporal shifts and spatial patterns from 1961 to 2016

To better understand the effects of climate change on streamflow, the hydrologic response to both temperature and precipitation needs to be examined at the mesoscale. New York State provides a hydrologically diverse mesoscale region, where sub-regional clusters of watersheds may respond differently to changes in temperature and in seasonal precipitation rates. Connections between streamflow and climate were examined for 97 gaging stations across the state and surrounding areas, for a historical period of 56 years of daily average streamflow. Gages were grouped into clusters if their mean annual discharge rates were strongly correlated to one another. Within each cluster, sharp temporal changes in discharge, or change points, were identified. These change points clustered both spatially and by flow regime, with low, medium, and high flows increasing around 1970 for much of the state consistent with other studies in the region. A step increase in Catskill low flows in 2003 coincides with increases in summer precipitation, and is consistent with a positive correlation between summer precipitation and annual low flows. Our results support previous studies that have shown that streamflow at this mesoscale is strongly tied to precipitation, and the strength of that connection is modulated by land cover, geographic position, and seasonal moisture conditions. Across the state, the winter-spring center of volume date has moved earlier along with increasing January streamflow rates, the result of warmer winter temperatures and an increased proportion of precipitation as rain. The transition to a post-1970s pluvial period also coincided with more frequent peak over threshold flows statewide, and this wetter period has continued to the present day.

New York↗

USGS2018

Using halogens (Cl, Br, I) to understand the hydrogeochemical evolution of drought-derived saline porewater beneath a prairie wetland

Numerous closed-basin prairie wetlands throughout the Prairie Pothole Region (PPR) of North America maintain moderate surface pond salinities (total dissolved solids [TDS] from 1 to 10 g L − 1 ) under semiarid climate by accumulation of gypsum and saline lenses of sulfate-rich porewater (TDS > 10 g L − 1 ) in wetland sediments during droughts. In order to understand the hydrogeochemical origin and composition of these saline porewaters, we made a detailed geochemical survey of Cl − , SO 4 2 − , Br, and I in the porewater, pondwater, and upland groundwater of a typical closed-basin prairie wetland (P1 in the Cottonwood Lake study area, North Dakota). Concentrations of Cl − ranged up to 5.9 mM in the saline porewaters, and was strongly correlated with SO 4 2 − and Br (Pearson's r > 0.7, p < 0.05; concentrations ranging up to 131 mM and 39 μM, respectively) due to the conservative effects of surface water evaporation. In contrast, total dissolved I was not significantly correlated with Cl − (Pearson's r = 0.18, p = 0.273) and was concentrated in porewaters located above the saline lenses with a peak concentration of 4.1 μM beneath the center of the wetland— the highest value for dissolved I ever measured in a terrestrial aquatic system and an order of magnitude above that of seawater. We hypothesize that chromatographic separation between more mobile anions (Cl − , SO 4 2 − , Br − ) and I occurs during droughts when wetland ponds dry and sedimentary iodide (I − ) oxidizes to its less-mobile form, iodate (IO 3 − ). Understanding the origin and geochemical composition of porewater salinity that develops beneath prairie wetlands during drought can help to fingerprint sources of salinity to wetland ponds during wet climate and elucidate halogen systematics in saline and organic-rich subsurface environments associated with hydrocarbon generation.

North Dakota↗

USGS2018

Inferring watershed hydraulics and cold-water habitat persistence using multi-year air and stream temperature signals

Streams strongly influenced by groundwater discharge may serve as “climate refugia” for sensitive species in regions of increasingly marginal thermal conditions. The main goal of this study is to develop paired air and stream water annual temperature signal analysis techniques to elucidate the relative groundwater contribution to stream water and the effective groundwater flowpath depth. Groundwater discharge to streams attenuates surface water temperature signals, and this attenuation can be diagnostic of groundwater gaining systems. Additionally, discharge from shallow groundwater flowpaths can theoretically transfer lagged annual temperature signals from aquifer to stream water. Here we explore this concept using multi-year temperature records from 120 stream sites located across 18 mountain watersheds of Shenandoah National Park, VA, USA and a coastal watershed in Massachusetts, USA. Both areas constitute important cold-water habitat for native brook trout ( Salvelinus fontinalis ). Observed annual temperature signals indicate a dominance of shallow groundwater discharge to streams in the National Park, in contrast to the coastal watershed that has strong, apparently deeper, groundwater influence. The average phase lag from air to stream signals in Shenandoah National Park is 11 d; however, extended lags of approximately 1 month were observed in a subset of streams. In contrast, the coastal stream has pronounced attenuation of annual temperature signals without notable phase lag. To better understand these observed differences in signal characteristics, analytical and numerical models are used to quantify mixing of the annual temperature signals of surface and groundwater. Simulations using a total heat budget numerical model indicate groundwater-induced annual temperature signal phase lags are likely to show greater downstream propagation than the related signal amplitude attenuation. The measurement of multi-seasonal paired air and water temperatures offers great promise toward understanding catchment processes and informing current cold-water habitat management at ecologically-relevant scales.

Virginia↗

USGS2016

Using diurnal temperature signals to infer vertical groundwater-surface water exchange

Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan-view flux maps. Key advantages of heat tracing include cost-effective sensors and ease of data collection and interpretation, without the need for expensive and time-consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.

Groundwater↗

USGS2016

Improved vertical streambed flux estimation using multiple diurnal temperature methods in series

Analytical solutions that use diurnal temperature signals to estimate vertical fluxes between groundwater and surface water based on either amplitude ratios ( A r ) or phase shifts (Δ ϕ ) produce results that rarely agree. Analytical solutions that simultaneously utilize A r and Δ ϕ within a single solution have more recently been derived, decreasing uncertainty in flux estimates in some applications. Benefits of combined ( A r Δ ϕ ) methods also include that thermal diffusivity and sensor spacing can be calculated. However, poor identification of either A r or Δ ϕ from raw temperature signals can lead to erratic parameter estimates from A r Δ ϕ methods. An add-on program for VFLUX 2 is presented to address this issue. Using thermal diffusivity selected from an A r Δ ϕ method during a reliable time period, fluxes are recalculated using an A r method. This approach maximizes the benefits of the A r and A r Δ ϕ methods. Additionally, sensor spacing calculations can be used to identify periods with unreliable flux estimates, or to assess streambed scour. Using synthetic and field examples, the use of these solutions in series was particularly useful for gaining conditions where fluxes exceeded 1 m/d.

Groundwater↗

USGS2014

Practical limitations on the use of diurnal temperature signals to quantify groundwater upwelling

Groundwater upwelling to streams creates unique habitat by influencing stream water quality and temperature; upwelling zones also serve as vectors for contamination when groundwater is degraded. Temperature time series data acquired along vertical profiles in the streambed have been applied to simple analytical models to determine rates of vertical fluid flux. These models are based on the downward propagation characteristics (amplitude attenuation and phase-lag) of the surface diurnal signal. Despite the popularity of these models, there are few published characterizations of moderate-to-strong upwelling. We attribute this limitation to the thermodynamics of upwelling, under which the downward conductive signal transport from the streambed interface occurs opposite the upward advective fluid flux. Governing equations describing the advection–diffusion of heat within the streambed predict that under upwelling conditions, signal amplitude attenuation will increase, but, counterintuitively, phase-lag will decrease. Therefore the extinction (measurable) depth of the diurnal signal is very shallow, but phase lag is also short, yielding low signal to noise ratio and poor model sensitivity. Conversely, amplitude attenuation over similar sensor spacing is strong, yielding greater potential model sensitivity. Here we present streambed thermal time series over a range of moderate to strong upwelling sites in the Quashnet River, Cape Cod, Massachusetts. The predicted inverse relationship between phase-lag and rate of upwelling was observed in the field data over a range of conditions, but the observed phase-lags were consistently shorter than predicted. Analytical solutions for fluid flux based on signal amplitude attenuation return results consistent with numerical models and physical seepage meters, but the phase-lag analytical model results are generally unreasonable. Through numerical modeling we explore reasons why phase-lag may have been over-predicted by the analytical models, and develop guiding relations of diurnal temperature signal extinction depth based on stream diurnal signal amplitude, upwelling magnitude, and streambed thermal properties that will be useful in designing future experiments.

Journal of Hydrology↗

USGS2013

Residence time control on hot moments of net nitrate production and uptake in the hyporheic zone

The retention capacity for biologically available nitrogen within streams can be influenced by dynamic hyporheic zone exchange, a process that may act as either a net source or net sink of dissolved nitrogen. Over 5 weeks, nine vertical profiles of streambed chemistry (NO 3 - and NH 4 + ) were collected above two beaver dams along with continuous high-resolution vertical hyporheic flux data. The results indicate a non-linear relation of net NO 3 - production followed by net uptake in the hyporheic zone as a function of residence time. This Lagrangian-based relation is consistent through time and across varied morphology (bars, pools, glides) above the dams, even though biogeochemical and environmental factors varied. The empirical continuum between net NO 3 - production and uptake and residence time is useful for identifying two crucial residence time thresholds: the transition to anaerobic respiration, which corresponds to the time of peak net nitrate production, and the net sink threshold, which is defined by a net uptake in NO 3 - relative to streamwater. Short-term hyporheic residence time variability at specific locations creates hot moments of net production and uptake, enhancing NO 3 - production as residence times approach the anaerobic threshold, and changing zones of net NO 3 - production to uptake as residence times increase past the net sink threshold. The anaerobic and net sink thresholds for beaver-influenced streambed morphology occur at much shorter residence times (1.3 h and 2.3 h, respectively) compared to other documented hyporheic systems, and the net sink threshold compares favorably to the lower boundary of the anaerobic threshold determined for this system with the new oxygen Damkohler number. The consistency of the residence time threshold values of NO 3 - cycling in this study, despite environmental variability and disparate morphology, indicates that NO 3 - hot moment dynamics are primarily driven by changes in physical hydrology and associated residence times.

Hydrological Processes↗