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USGS2014

A mechanistic modeling and data assimilation framework for Mojave Desert ecohydrology

This study demonstrates and addresses challenges in coupled ecohydrological modeling in deserts, which arise due to unique plant adaptations, marginal growing conditions, slow net primary production rates, and highly variable rainfall. We consider model uncertainty from both structural and parameter errors and present a mechanistic model for the shrub Larrea tridentata (creosote bush) under conditions found in the Mojave National Preserve in southeastern California (USA). Desert-specific plant and soil features are incorporated into the CLM-CN model by Oleson et al. (2010). We then develop a data assimilation framework using the ensemble Kalman filter (EnKF) to estimate model parameters based on soil moisture and leaf-area index observations. A new implementation procedure, the “multisite loop EnKF,” tackles parameter estimation difficulties found to affect desert ecohydrological applications. Specifically, the procedure iterates through data from various observation sites to alleviate adverse filter impacts from non-Gaussianity in small desert vegetation state values. It also readjusts inconsistent parameters and states through a model spin-up step that accounts for longer dynamical time scales due to infrequent rainfall in deserts. Observation error variance inflation may also be needed to help prevent divergence of estimates from true values. Synthetic test results highlight the importance of adequate observations for reducing model uncertainty, which can be achieved through data quality or quantity.

California↗

USGS2017

Late Quaternary stratigraphy and geochronology of the western Killpecker Dunes, Wyoming, USA

New stratigraphic and geochronologic data from the Killpecker Dunes in southwestern Wyoming facilitate a more precise understanding of the dune field's history. Prior investigations suggested that evidence for late Pleistocene eolian activity in the dune field was lacking. However, luminescence ages from eolian sand of ???15,000 yr, as well as Folsom (12,950-11,950 cal yr B.P.) and Agate Basin (12,600-10,700 cal yr) artifacts overlying eolian sand, indicate the dune field existed at least during the latest Pleistocene, with initial eolian sedimentation probably occurring under a dry periglacial climate. The period between ???13,000 and 8900 cal yr B.P. was characterized by relatively slow eolian sedimentation concomitant with soil formation. Erosion occurred between ???8182 and 6600 cal yr B.P. on the upwind region of the dune field, followed by relative stability and soil formation between ???5900 and 2700 cal yr B.P. The first of at least two latest Holocene episodes of eolian sedimentation occurred between ???2000 and 1500 yr, followed by a brief (???500 yr) episode of soil formation; a second episode of sedimentation, occurring by at least ???700 yr, may coincide with a hypothesized Medieval warm period. Recent stabilization of the western Killpecker Dunes likely occurred during the Little Ice Age (???350-100 yr B.P.). The eolian chronology of the western Killpecker Dunes correlates reasonably well with those of other major dune fields in the Wyoming Basin, suggesting that dune field reactivation resulted primarily due to departures toward aridity during the late Quaternary. Similar to dune fields on the central Great Plains, dune fields in the Wyoming Basin have been active under a periglacial climate during the late Pleistocene, as well as under near-modern conditions during the latest Holocene. ?? 2003 University of Washington. All rights reserved.

Quaternary Research↗

USGS2021

Implications of model selection: A comparison of publicly available, conterminous US-extent hydrologic component estimates

Spatiotemporally continuous estimates of the hydrologic cycle are often generated through hydrologic modeling, reanalysis, or remote sensing (RS) methods and are commonly applied as a supplement to, or a substitute for, in situ measurements when observational data are sparse or unavailable. This study compares estimates of precipitation ( P ), actual evapotranspiration (ET), runoff ( R ), snow water equivalent (SWE), and soil moisture (SM) from 87 unique data sets generated by 47 hydrologic models, reanalysis data sets, and remote sensing products across the conterminous United States (CONUS). Uncertainty between hydrologic component estimates was shown to be high in the western CONUS, with median uncertainty (measured as the coefficient of variation) ranging from 11 % to 21 % for P , 14 % to 26 % for ET, 28 % to 82 % for R , 76 % to 84 % for SWE, and 36 % to 96 % for SM. Uncertainty between estimates was lower in the eastern CONUS, with medians ranging from 5 % to 14 % for P, 13 % to 22 % for ET, 28 % to 82 % for R , 53 % to 63 % for SWE, and 42 % to 83 % for SM. Interannual trends in estimates from 1982 to 2010 show common disagreement in R, SWE, and SM. Correlating fluxes and stores against remote-sensing-derived products show poor overall correlation in the western CONUS for ET and SM estimates. Study results show that disagreement between estimates can be substantial, sometimes exceeding the magnitude of the measurements themselves. The authors conclude that multimodel ensembles are not only useful but are in fact a necessity for accurately representing uncertainty in research results. Spatial biases of model disagreement values in the western United States show that targeted research efforts in arid and semiarid water-limited regions are warranted, with the greatest emphasis on storage and runoff components, to better describe complexities of the terrestrial hydrologic system and reconcile model disagreement.

Hydrology and Earth System Sciences↗

USGS2017

Is Obsidian Hydration Dating Affected by Relative Humidity?

Experiments carried out under temperatures and relative humidities that approximate ambient conditions show that the rate of hydration of obsidian is a function of the relative humidity, as well as of previously established variables of temperature and obsidian chemical composition. Measurements of the relative humidity of soil at 25 sites and at depths of between 0.01 and 2 m below ground show that in most soil environments, at depths below about 0.25 m, the relative humidity is constant at 100%. We have found that the thickness of the hydrated layer developed on obsidian outcrops exposed to the sun and to relative humidities of 30-90% is similar to that formed on other portions of the outcrop that were shielded from the sun and exposed to a relative humidity of approximately 100%. Surface samples of obsidian exposed to solar heating should hydrate more rapidly than samples buried in the ground. However, the effect of the lower mean relative humidity experiences by surface samples tends to compensate for the elevated temperature, which may explain why obsidian hydration ages of surface samples usually approximate those derived from buried samples.

Quaternary Research↗

USGS2008

Sensitivity of June near‐surface temperatures and precipitation in the eastern United States to historical land cover changes since European settlement

Land cover changes alter the near surface weather and climate. Changes in land surface properties such as albedo, roughness length, stomatal resistance, and leaf area index alter the surface energy balance, leading to differences in near surface temperatures. This study utilized a newly developed land cover data set for the eastern United States to examine the influence of historical land cover change on June temperatures and precipitation. The new data set contains representations of the land cover and associated biophysical parameters for 1650, 1850, 1920, and 1992, capturing the clearing of the forest and the expansion of agriculture over the eastern United States from 1650 to the early twentieth century and the subsequent forest regrowth. The data set also includes the inferred distribution of potentially water‐saturated soils at each time slice for use in the sensitivity tests. The Regional Atmospheric Modeling System, equipped with the Land Ecosystem‐Atmosphere Feedback (LEAF‐2) land surface parameterization, was used to simulate the weather of June 1996 using the 1992, 1920, 1850, and 1650 land cover representations. The results suggest that changes in surface roughness and stomatal resistance have caused present‐day maximum and minimum temperatures in the eastern United States to warm by about 0.3°C and 0.4°C, respectively, when compared to values in 1650. In contrast, the maximum temperatures have remained about the same, while the minimums have cooled by about 0.1°C when compared to 1920. Little change in precipitation was found.

Water Resources Research↗

USGS2012

Field information links permafrost carbon to physical vulnerabilities of thawing

Deep soil profiles containing permafrost (Gelisols) were characterized for organic carbon (C) and total nitrogen (N) stocks to 3m depths. Using the Community Climate System Model (CCSM4) we calculate cumulative probability functions (PDFs) for active layer depths under current and future climates. The difference in PDFs over time was multiplied by C and N contents of soil horizons in Gelisol suborders to calculate newly thawed C and N, Thawing ranged from 147 PgC with 10 PgN by 2050 (representative concentration pathway RCP scenario 4.5) to 436 PgC with 29 PgN by 2100 (RCP 8.5). Organic horizons that thaw are vulnerable to combustion, and all horizon types are vulnerable to shifts in hydrology and decomposition. The rates and extent of such losses are unknown and can be further constrained by linking field and modelling approaches. These changes have the potential for strong additional loading to our atmosphere, water resources, and ecosystems.

Geophysical Research Letters↗

USGS2006

Arsenic speciation in arsenic-rich Brazilian soils from gold mining sites under anaerobic incubation

Background. Arsenic speciation in environmental samples is essential for studying toxicity, mobility and bio-transformation of As in aquatic and terrestrial environments. Although the inorganic species As(III) and As(V) have been considered dominant in soils and sediments, organisms are able to metabolize inorganic forms of arsenic into organo-arsenic compounds. Arsenosugars and methylated As compounds can be found in terrestrial organisms, but they generally occur only as minor constituents. We investigated the dynamics of arsenic species under anaerobic conditions in soils surrounding gold mining areas from Minas Gerais State, Brazil to elucidate the arsenic biogeochemical cycle and water contamination mechanisms. Methods. Surface soil samples were collected at those sites, namely Paracatu Formation, Banded Iron Formation and Riacho dos Machados Sequence, and incubated in CaCl2 2.5 mmol L-1 suspensions under anaerobic conditions for 1, 28, 56 and 112 days. After that, suspensions were centrifuged and supernatants analyzed for soluble As species by IC-ICPMS and HPLC-ICPMS. Results. Easily exchangeable As was mainly arsenite, except when reducible manganese was present. Arsenate was mainly responsible for the increase in soluble arsenic due to the reductive dissolution of either iron or manganese in samples from the Paracatu Formation and Riacho dos Machados Sequence. On the other hand, organic species of As dominated in samples from the Banded Iron Formation during anaerobic incubation. Discussion. Results are contrary to the expectation that, in anaerobic environments, As release due to the reductive dissolution of Fe is followed by As(V) reduction to As(III). The occurrence of organo-arsenic species was also found to be significant to the dynamics of soluble arsenic, mainly in soils from the Banded Iron Formation (BIF), under our experimental conditions. Conclusions. In general, As(V) and organic As were the dominant species in solution, which is surprising under anaerobic conditions in terrestrial environments. The unexpected occurrence of organic species of As was attributed to enrollment of ternary organic complexes or living organisms such as algae or cyanobacteria. Perspectives. These findings are believed to be useful for remediation strategies in mine-affected regions, as the organic As species are in general considered to be less toxic than inorganic ones and even As(V) is considered less mobile and toxic than As(III). ?? 2007 ecomed publishers (Verlagsgruppe Hu??thig Jehle Rehm GmbH).

Environmental Science and Pollution Research↗

USGS2013

Channel unit use by Smallmouth Bass: Do land-use constraints or quantity of habitat matter?

I examined how land use influenced the distribution of Smallmouth Bass Micropterus dolomieu in channel units (discrete morphological features—e.g., pools) of streams in the Midwestern USA. Stream segments ( n = 36), from four clusters of different soil and runoff conditions, were identified that had the highest percent of forest ( n = 12), pasture ( n = 12), and urban land use ( n = 12) within each cluster. Channel units within each stream were delineated and independently sampled once using multiple gears in summer 2006. Data were analyzed using a generalized linear mixed model procedure with a binomial distribution and odds ratio statistics. Land use and channel unit were strong predictors of age-0, age-1, and age->1 Smallmouth Bass presence. Each age-class was more likely to be present in streams within watersheds dominated by forest land use than in those with pasture or urban land uses. The interaction between land use and channel unit was not significant in any of the models, indicating channel unit use by Smallmouth Bass did not depend on watershed land use. Each of the three age-classes was more likely to use pools than other channel units. However, streams with high densities of Smallmouth Bass age >1 had lower proportions of pools suggesting a variety of channel units is important even though habitat needs exist at the channel-unit scale. Management may benefit from future research addressing the significance of channel-unit quality as a possible mechanism for how land use impacts Smallmouth Bass populations. Further, management efforts aimed at improving stream habitat would likely be more beneficial if focused at the stream segment or landscape scale, where a variety of quality habitats might be supported.

MIssouri↗

USGS2016

Effects of microhabitat and large-scale land use on stream salamander occupancy in the coalfields of Central Appalachia

Large-scale coal mining practices, particularly surface coal extraction and associated valley fills as well as residential wastewater discharge, are of ecological concern for aquatic systems in central Appalachia. Identifying and quantifying alterations to ecosystems along a gradient of spatial scales is a necessary first-step to aid in mitigation of negative consequences to aquatic biota. In central Appalachian headwater streams, apart from fish, salamanders are the most abundant vertebrate predator that provide a significant intermediate trophic role linking aquatic and terrestrial food webs. Stream salamander species are considered to be sensitive to aquatic stressors and environmental alterations, as past research has shown linkages among microhabitat parameters, large-scale land use such as urbanization and logging, and salamander abundances. However, there is little information examining these relationships between environmental conditions and salamander occupancy in the coalfields of central Appalachia. In the summer of 2013, 70 sites (sampled two to three times each) in the southwest Virginia coalfields were visited to collect salamanders and quantify stream and riparian microhabitat parameters. Using an information-theoretic framework, effects of microhabitat and large-scale land use on stream salamander occupancy were compared. The findings indicate that Desmognathus spp. occupancy rates are more correlated to microhabitat parameters such as canopy cover than to large-scale land uses. However, Eurycea spp . occupancy rates had a strong association with large-scale land uses, particularly recent mining and forest cover within the watershed. These findings suggest that protection of riparian habitats is an important consideration for maintaining aquatic systems in central Appalachia. If this is not possible, restoration riparian areas should follow guidelines using quick-growing tree species that are native to Appalachian riparian areas. These types of trees would rapidly establish a canopy cover, stabilize the soil, and impede invasive plant species which would, in turn, provide high-quality refuges for stream salamanders.

Journal of Ecology and the Natural Environment↗

USGS2016

Nutrients in the nexus

Synthetic nitrogen (N) fertilizer has enabled modern agriculture to greatly improve human nutrition during the twentieth century, but it has also created unintended human health and environmental pollution challenges for the twenty-first century. Averaged globally, about half of the fertilizer-N applied to farms is removed with the crops, while the other half remains in the soil or is lost from farmers’ fields, resulting in water and air pollution. As human population continues to grow and food security improves in the developing world, the dual development goals of producing more nutritious food with low pollution will require both technological and socio-economic innovations in agriculture. Two case studies presented here, one in sub-Saharan Africa and the other in Midwestern United States, demonstrate how management of nutrients, water, and energy is inextricably linked in both small-scale and large-scale food production, and that science-based solutions to improve the efficiency of nutrient use can optimize food production while minimizing pollution. To achieve the needed large increases in nutrient use efficiency, however, technological developments must be accompanied by policies that recognize the complex economic and social factors affecting farmer decision-making and national policy priorities. Farmers need access to affordable nutrient supplies and support information, and the costs of improving efficiencies and avoiding pollution may need to be shared by society through innovative policies. Success will require interdisciplinary partnerships across public and private sectors, including farmers, private sector crop advisors, commodity supply chains, government agencies, university research and extension, and consumers.

Journal of Environmental Studies and Sciences↗

USGS2020

Comparing native bee communities on reconstructed and remnant prairie in Missouri

The tallgrass prairie of North America is an imperiled ecosystem that has been the subject of considerable restoration effort and research in the past two decades. While native prairie plant species are purposely introduced during restoration, prairie invertebrates, including native bees (Anthophila), are not, and must colonize from surrounding remnants. Prairie restorations may not support the same bee communities as remnant prairies because of habitat differences and dispersal limitations. We sampled native bees on reconstructed and remnant prairies in Missouri in the summers of 2016 and 2017 and compared the communities by evaluating species richness, diversity, and community composition. We detected no differences in bee species richness or diversity between reconstructions and remnants; remnants and reconstructions shared all but three of the 57 taxa observed. Community composition of bees on reconstructions was different from that of remnants because of differences in the relative abundance of taxa. Several species were associated with either reconstructed or remnant prairies. At a functional level, stem nesters were more common on reconstructed than remnant prairie. We also examined whether bee communities on reconstructions converged with those observed on remnants over time by comparing bee communities across restorations of different ages and found that reconstruction communities did not appear to be converging with remnants. Reconstructing prairie bee communities may depend on restoring soil conditions and disturbance regimes that influence bee nesting habitat.

Missouri↗

USGS2023

An examination of soil crusts on the floor of Jezero crater, Mars

Martian soils are critically important for understanding the history of Mars, past potentially habitable environments, returned samples, and future human exploration. This paper examines soil crusts on the floor of Jezero crater encountered during initial phases of the Mars 2020 mission. Soil surface crusts have been observed on Mars at other locations, starting with the two Viking Lander missions. Rover observations show that soil crusts are also common across the floor of Jezero crater, revealed in 45 of 101 locations where rover wheels disturbed the soil surface, 2 out of 7 helicopter flights that crossed the wheel tracks, and 4 of 8 abrasion/drilling sites. Most soils measured by the SuperCam laser-induced breakdown spectroscopy (LIBS) instrument show high hydrogen content at the surface, and fine-grained soils also show a visible/near infrared (VISIR) 1.9 µm H 2 O absorption feature. The Planetary Instrument for X-ray Lithochemistry (PIXL) and SuperCam observations suggest the presence of salts at the surface of rocks and soils. The correlation of S and Cl contents with H contents in SuperCam LIBS measurements suggests that the salts present are likely hydrated. On the “Naltsos” target, magnesium and sulfur are correlated in PIXL measurements, and Mg is tightly correlated with H at the SuperCam points, suggesting hydrated Mg-sulfates. Mars Environmental Dynamics Analyzer (MEDA) observations indicate possible frost events and potential changes in the hydration of Mg-sulfate salts. Jezero crater soil crusts may therefore form by salts that are hydrated by changes in relative humidity and frost events, cementing the soil surface together.

Journal of Geophysical Research: Planets↗

USGS2025

Late Quaternary pollen record from southwest Seward Peninsula, western Alaska, and the vegetation history of central Beringia

Pollen analysis of samples from a coastal exposure near Teller, southwestern Seward Peninsula, Alaska, provides a record of vegetation and climate spanning the Last Glacial Maximum (LGM) through the Holocene. The site is near the center of the former Bering Land Bridge (BLB). The oldest pollen-bearing sediment unit is a loess deposit of LGM age, with pollen assemblages that closely resemble LGM assemblages from other key sites in central Beringia spanning 16° of latitude. These fossil assemblages represent vegetation composed primarily of grasses, sedges, Artemisia , willows, and forbs and are interpreted to represent steppe–tundra, associated with dry climates and summer temperatures cooler than at present. LGM mosses did not accumulate insulating layers of peat; the summer active soil layer was deeper than at present. Permafrost with ice wedges and loess deposition were widespread. A regional transition from steppe–tundra vegetation to a dwarf shrub–sedge–moss mesic-to-wetland vegetation began in central Beringia with the onset of Bølling–Allerød (B-A) warming at 14,700 cal yr BP. Warming events of the B-A and early Holocene resulted in widespread development of thermokarst terrain on the BLB and on ice-rich terrain in Western Alaska. Mesic climates and vegetation developed on the BLB during the marine transgression and because of B-A and early Holocene warming. Early Holocene warming allowed some boreal forest species such as alders to begin colonizing Western Alaska from the interior.

Alaska↗

USGS2023

Seed banks of rare Physostegia correllii (Lamiaceae) in Lady Bird Lake, Austin, Texas, U.S.A.

Rare species threatened by climate and land-use change may harbor seeds in soil seed banks for periods of time even if adults have disappeared from the site. Soil samples were collected from sites with current Phyostegia correllii populations and from sites with former populations in Lady Bird Lake (a reservoir of the Colorado River, Austin, Texas. A seedling emergence study was conducted under greenhouse conditions, and the presence/absence of seedling emergence was recorded for two years. Seeds germinated from the seed banks of all current and former colonies tested. The presence of seed banks in a historical site (Blunn Creek) of Physostegia correllii suggests that management to encourage the germination of seeds might help to encourage the establishment of populations of this species. The re-establishment of disturbance fugitives might be facilitated by removing overhanging ground vegetation or imposing water management regimes that mimic natural floodplain dynamics.

Texas↗

USGS1996

Loess studies in central United States: Evolution of concepts

Few words in the realm of earth science have caused more debate than "loess". It is a common term that was first used as a name of a silt deposit before it was defined in a scientific sense. Because this "loose" deposit is easily distinguished from other more coherent deposits, it was recognized as a matter of practical concern and later became the object of much scientific scrutiny. Loess was first recognized along the Rhine Valley in Germany in the 1830s and was first noted in the United States in 1846 along the lower Mississippi River where it later became the center of attention. The use of the name eventually spread around the world, but its use has not been consistently applied. Over the years some interpretations and stratigraphic correlations have been validated, but others have been hotly contested on conceptual grounds and semantic issues. The concept of loess evolved into a complex issue as loess and loess-like deposits were discovered in different parts of the US. The evolution of concepts in the central US developed in four indefinite stages: the eras of (1) discovery and development of hypotheses, (2) conditional acceptance of the eolian origin of loess, (3) "bandwagon" popularity of loess research, and (4) analytical inquiry on the nature of loess. Toward the end of the first era around 1900, the popular opinion on the meaning of the term loess shifted from a lithological sense of loose silt to a lithogenetic sense of eolian silt. However, the dual use of the term fostered a lingering skepticism during the second era that ended in 1944 with an explosion of interest that lasted for more than a decade. In 1944, R.J. Russell proposed and H.N. Fisk defended a new non-eolian, property-based, concept of loess. The eolian advocates reacted with surprise and enthusiasm. Each side used constrained arguments to show their view of the problem, but did not examine the fundamental problem, which was not in the proofs of their hypothesis, but in the definition of the term. Between 1944 and about 1950, the debates about loess reached a maximum level of complexity. The main semantic problem was submersed in peripheral arguments about physical properties and genetic interpretations. The scholarly treatment of the subject by Fisk and Russell stimulated quality responses from a diversity of earth scientists interested in academic and applied studies, particularly geo-history, pedology, soil mechanics and stratigraphy. The long-lasting popularity of loess studies during the bandwagon era lasted to about 1970. By that time, the analytical and technical interests had attracted the mainstream into the fourth era with a focus beyond the old arguments. Although Fisk and Russell found themselves defending an unpopular theory, they stimulated a scientific interest in the late Quaternary history of the Mississippi Valley that may never be exceeded.

Engineering Geology↗

USGS2011

Beaver assisted river valley formation

We examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in‐channel beaver dams. Our data show a 1.7‐m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient‐rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de‐watered following the dam breach by high stream flows, protecting the deposited sediment from future re‐mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re‐occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938.

Colorado↗

USGS2017

Pyrolysis-combustion 14C dating of soil organic matter

Radiocarbon (14C) dating of total soil organic matter (SOM) often yields results inconsistent with the stratigraphic sequence. The onerous chemical extractions for SOM fractions do not always produce satisfactory 14C dates. In an effort to develop an alternative method, the pyrolysis-combustion technique was investigated to partition SOM into pyrolysis volatile (Py-V) and pyrolysis residue (Py-R) fractions. The Py-V fractions obtained from a thick glacigenic loess succession in Illinois yielded 14C dates much younger but more reasonable than the counterpart Py-R fractions for the soil residence time. Carbon isotopic composition (??13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and ??13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of 14C dates and ??13C values indicates that the Py-V fractions are less biodegradation resistant and the Py-R fractions are more biodegradation resistant. The pyrolysis-combustion method provides a less cumbersome approach for 14C dating of SOM fractions. With further study, this method may become a useful tool for analyzing unlithified terrestrial sediments when macrofossils are absent. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

Quaternary Research↗

USGS2015

On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS–NIR, 350–2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400–700 nm) and the short-wavelength infrared (SWIR) area (1100–2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

Aeolian Research↗