Earth Sciences Commons^™

Relating Groundwater To Seasonal Wetlands In Southeastern Wisconsin, Usa, John D. Skalbeck, Donald M. Reed, Randall J. Hunt, Jamie D. Lambert

United States Geological Survey: Staff Publications

Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) …

Mitochondrial Dna Evolution In The Anaxyrus Boreas Species Group, Anna M. Goebel, Tom A. Ranker, Paul Stephen Corn, Richard G. Olmstead

United States Geological Survey: Staff Publications

The Anaxyrus boreas species group currently comprises four species in western North America including the broadly distributed A. boreas, and three localized species, Anaxyrus nelsoni, Anaxyrus exsul and Anaxyrus canorus. Phylogenetic analyses of the mtDNA 12S rDNA, cytochrome oxidase I, control region, and restriction sites data, identified three major haplotype clades. The Northwest clade (NW) includes both subspecies of A. boreas and divergent minor clades in the middle Rocky Mountains, coastal, and central regions of the west and Pacific Northwest. The Southwest (SW) clade includes A. exsul, A. nelsoni, and minor clades in southern California. …

Occurrence And Fate Of Pesticides In Four Contrasting Agricultural Settings In The United States, Gregory V. Steele, Henry M. Johnson, Mark W. Sandstrom, Paul D. Capel, Jack E. Barbash

United States Geological Survey: Staff Publications

Occurrence and fate of 45 pesticides and 40 pesticide degradates were investigated in four contrasting agricultural settings—in Maryland, Nebraska, California, and Washington. Primary crops included corn at all sites, soybeans in Maryland, orchards in California and Washington, and vineyards in Washington. Pesticides and pesticide degradates detected in water samples from all four areas were predominantly from two classes of herbicides—triazines and chloroacetanilides; insecticides and fungicides were not present in the shallow ground water. In most samples, pesticide degradates greatly exceeded the concentrations of parent pesticide. In samples from Nebraska, the parent pesticide atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4- diamine] was about the same concentration …

Pesticides In Rain In Four Agricultural Watersheds In The United States, Jason R. Vogel, Michael S. Majewski, Paul D. Capel

United States Geological Survey: Staff Publications

Rainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with atrazine (70%) and metolachlor (83%) detected at every site. Dacthal, acetochlor, simazine, alachlor, and pendimethalin were detected in more than 50% of the samples. Chlorpyrifos, carbaryl, and diazinon were the only insecticides among the 10 most frequently detected compounds. Of the remaining pesticide …

Using Heat To Characterize Streambed Water Flux Variability In Four Stream Reaches, Hedeff Essaid, Celia M. Zamora, Kathleen A. Mccarthy, Jason R. Vogel, John T. Wilson

United States Geological Survey: Staff Publications

Estimates of streambed water fl ux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to study the temporal and spatial variability of fluxes through the streambed. Synoptic methods (seepage meter and differential discharge measurements) were compared with estimates obtained by using heat as a tracer. Water flux was estimated by modeling one-dimensional vertical flow of water and heat using the model VS2DH. Flux was …

Transport And Fate Of Nitrate At The Ground-Water/Surface-Water Interface, Larry J. Puckett, Celia Zamora, Hedeff Essaid, John T. Wilson, Henry M. Johnson, Michael Brayton, Jason R. Vogel

United States Geological Survey: Staff Publications

Although numerous studies of hyporheic exchange and denitrification have been conducted in pristine, high-gradient streams, few studies of this type have been conducted in nutrient-rich, low-gradient streams. This is a particularly important subject given the interest in nitrogen (N) inputs to the Gulf of Mexico and other eutrophic aquatic systems. A combination of hydrologic, mineralogical, chemical, dissolved gas, and isotopic data were used to determine the processes controlling transport and fate of ₃− in streambeds at five sites across the USA. Water samples were collected from streambeds at depths ranging from 0.3 to 3 m at three to five …

California Drought, An Update April 2008, Baryohay Davidoff, Fawzi Karajeh, Dean Reynolds, Eric Senter, John Woodling

United States Geological Survey: Staff Publications

TABLE OF CONTENTS

CHAPTER 1. RECENT HYDROLOGIC CONDITIONS AND IMPACTS

Introduction....................................................... 1

Water Year 2007 .................................................. 1

Drought in the Colorado River Basin ..................................................... 5

Drought and Dry Conditions in the Early 2000s .................................... 7

The 2001 Klamath Basin Drought Emergency ............................... 11

CHAPTER 2. PROGRAMMATIC AND INSTITUTIONAL UPDATES

The San Francisco Bay-Sacramento/San Joaquin River Delta.................................................................. 15

The Colorado River .................................................................... 16

State Financial Assistance to Local Agencies.................................... 17

Urban Water Management Planning ................................................... 20

Water Transfers .............................................................................. 20

Small Water Systems and Drought Preparedness ................................. 21

Range-Wide Patterns Of Greater Sage-Grouse Persistence, Cameron L. Aldridge, Scott E. Nielsen, Hawthorne L. Beyer, Mark S. Boyce, John W. Connelly, Steven T. Knick, Michael A. Schroeder

United States Geological Survey: Staff Publications

Aim
Greater sage-grouse (Centrocercus urophasianus), a shrub-steppe obligate species of western North America, currently occupies only half its historical range. Here we examine how broad-scale, long-term trends in landscape condition have affected range contraction.

Location
Sagebrush biome of the western USA.

Methods
Logistic regression was used to assess persistence and extirpation of greater sage-grouse range based on landscape conditions measured by human population (density and population change), vegetation (percentage of sagebrush habitat), roads (density of and distance to roads), agriculture (cropland, farmland and cattle density), climate (number of severe and extreme droughts) and range periphery. Model predictions were …

Distribution And Environmental Limitations Of An Amphibian Pathogen In The Rocky Mountains, Usa, Erin Muths, David S. Pilliod, Lauren J. Livo

United States Geological Survey: Staff Publications

Amphibian populations continue to be imperiled by the chytrid fungus (Batrachochytrium dendrobatidis). Understanding where B. dendrobatidis (Bd) occurs and how it may be limited by environmental factors is critical to our ability to effectively conserve the amphibians affected by Bd. We sampled 1247 amphibians (boreal toads and surrogates) at 261 boreal toad (Bufo boreas) breeding sites (97 clusters) along an 11° latitudinal gradient in the Rocky Mountains to determine the distribution of B. dendrobatidis and examine environmental factors, such as temperature and elevation, that might affect its distribution. The fungus was detected at …

Corrigendum To ‘‘Distribution And Environmental Limitations Of An Amphibian Pathogen In The Rocky Mountains, Usa’’ [Biological Conservation 141 (2008) 1484–1492], Erin Muths, David S. Pilliod, Lauren J. Livo

United States Geological Survey: Staff Publications

The author regrets that in the above published paper the following error occurred:
In our recently published paper, ‘‘Distribution and environmental limitations of an amphibian pathogen in the Rocky Mountains, USA’’, we erroneously included the paper by J. Bosch et al. (2006), ‘‘Climate change and outbreaks of amphibian chytridiomycosis in a montane area of Central Spain: is there a link?’’ in a list of studies from the tropics. Clearly Dr. Bosch and colleagues worked in the temperate zone at a latitude very similar to that in our study suggesting that further investigation of additional similarities between the two sites might …

Paleoclimatic Significance Of Chemical Weathering In Loess-Derived Paleosols Of Subarctic Central Alaska, Daniel R. Muhs, Thomas A. Ager, Gary Skipp, Jossh Beann, James Budahn, John P. Mcgeehin

United States Geological Survey: Staff Publications

Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid- Wisconsin interstadials. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na₂O/TiO₂ is lower in modern soils and most …

Pesticide Fate And Transport Throughout Unsaturated Zones In Five Agricultural Settings, Usa, Tracy C. Hancock, Mark W. Sandstrom, Jason R. Vogel, Richard M.T. Webb, E. Randall Bayless, Jack E. Barbash

United States Geological Survey: Staff Publications

Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and atrazine were applied at a Nebraska site the same year as sampling, and focused recharge coupled with the short time since application resulted in their movement in …

Developing Conceptual Hydrogeological Model For Potsdam Sandstones In Southwestern Quebec, Canada, M. Nastev, Roger H. Morin, R. Godin, A. Rouleau

United States Geological Survey: Staff Publications

A hydrogeological study was conducted in Potsdam sandstones on the international border between Canada (Quebec) and the USA (New York). Two sandstone formations, arkose and conglomerate (base) and well-cemented quartz arenite (upper), underlie the study area and form the major regional aquifer unit. Glacial till, littoral sand and gravel, and marine silt and clay discontinuously overlie the aquifer. In both sandstone formations, sub-horizontal bedding planes are ubiquitous and display significant hydraulic conductivities that are orders of magnitude more permeable than the intact rock matrix. Aquifer tests demonstrate that the two formations have similar bulk hydrologic properties, with average hydraulic conductivities …

Late-Seasonal A Ctivity And Diet Of The Eveninc Bat (Nycticeius Humeralis) In Nebraska, Keith Geluso, Jason P. Damm, Ernest W. Valdez

United States Geological Survey: Staff Publications

In North America, Nebraska represents part of the northwestern edge of the distribution for the evening bat (Nycticeius humeralis). To date, little information on this bat’s natural history has been published from the state or from other parts of the Great Plains. Here we report on aspects of its natural history in Nebraska from 2 localities. In late summer and early autumn of 2006, we documented individuals farther west in Nebraska (Harlan County) than previously reported and determined that individuals fed mainly on Coleoptera and Hymenoptera. In 2006, evening bats appeared to migrate from Nebraska during late September–early …

Sacramento-San Joaquin Delta Regional Ecosystem Restoration Implementation Plan, Charles N. Alpers, Collin Eagles-Smith, Chris Foe, Susan Klasing, Mark C. Marvin-Dipasquale, Darell G. Slotton, Lisamarie Windham-Myers

United States Geological Survey: Staff Publications

Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the …

Development And Evaluation Of Geochemical Methods For The Sourcing Of Archaeological Maize, L.V. Benson, H. E. Taylor, K.A. Peterson, B.D. Shattuck, C.A. Ramotnik, J.R. Stein

United States Geological Survey: Staff Publications

Strontium (Sr)-isotope values on bone from deer mice pairs from 12 field sites in the Chaco Canyon area, New Mexico, were compared with isotope values of synthetic soil waters from the same fields. The data indicate that mice obtain Sr from near-surface sources and that soil samples collected at depths ranging from 25 to 95 cm contain Sr that is more accessible to the deep roots of maize; thus, synthetic soil solutions provide better data for the sourcing of archaeological maize. However, the Sr-isotope composition of mice may be more valuable in sourcing archaeological remains of animals such as rabbit, …

Tools And Technology Article: Estimation And Correction Of Visibility Bias In Aerial Surveys Of Wintering Ducks, Aaron T. Pearse, Patrick D. Gerard, Stephen J. Dinsmore, Richard M. Kaminski, Kenneth J. Reinecke

United States Geological Survey: Staff Publications

Incomplete detection of all individuals leading to negative bias in abundance estimates is a pervasive source of error in aerial surveys of wildlife, and correcting that bias is a critical step in improving surveys. We conducted experiments using duck decoys as surrogates for live ducks to estimate bias associated with surveys of wintering ducks in Mississippi, USA. We found detection of decoy groups was related to wedand cover type (open vs. forested), group size (1-100 decoys), and interaction of these variables. Observers who detected decoy groups reported counts that averaged 78% of the decoys actually present, and this counting bias …

Relations Between And Among Contaminant Concentrations And Biomarkers In Black Bass (Micropterus Spp.) And Common Carp (Cyprinus Carpio) From Large U.S. Rivers, 1995–2004, Jo Ellen Hinck, Christopher J. Schmitt, Mark R. Ellersieck, Donald E. Tillitt

United States Geological Survey: Staff Publications

Environmental contaminant and biomarker monitoring data from major U.S. river basins were summarized for black bass (Micropterus spp.) and common carp (Cyprinus carpio) sampled over a nine year period. Cumulative frequency distributions revealed taxon differences for many organochlorine residue concentrations, elemental contaminant concentrations, and biomarkers, but few gender differences were evident for chemical concentrations. Concentrations of dacthal, pentachloroanisole, p,p'-DDE, endosulfan sulfate, barium, cadmium, copper, manganese, lead, selenium, vanadium, and zinc were greater in carp than bass, but concentrations of mercury and magnesium were greater in bass. Gender differences were evident in bass for mercury and in carp …

Downflow Limestone Beds For Treatment Of Net-Acidic, Oxic, Iron-Laden Drainage From A Flooded Anthracite Mine, Pennsylvania, Usa: 2. Laboratory Evaluation, Charles A. Cravotta Iii, Suzanne J. Ward, Jane M. Hammarstrom

United States Geological Survey: Staff Publications

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO₃ and MgCO₃ contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO₃ and MgCO₃ contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to …

Impact Of Drought On Prehistoric Western Native Americans, Larry Benson

United States Geological Survey: Staff Publications

Some droughts that occurred during the so-called Medieval Climate Anomaly (approximately AD 800-1300) appear to have been catalysts for major changes in settlement patterns of two western Native American groups - the Lovelock culture in Nevada’s Great Basin and the Anasazi people of the Four Corners area. Both groups’ subsistence bases were impacted by diminished water supplies associated with prolonged drought, leading to the dispersal of these Native Americans from their former territories.

Tree-ring-based Palmer Drought Severity Index (PDSI) reconstructions by Cook et al. (2004) indicate that over 50% of the western U.S. experienced drought conditions during the middle-12th and …

Grenetic Evidence Of Intercontinental Movement Of Avian Influenza In A Migratory Bird: The Northern Pintail (Anas Acuta), Anson V. Koehler, John M. Pearce, Paul L. Flint, J. Christian Franson, Hon S. Ip

United States Geological Survey: Staff Publications

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses …

Downflow Limestone Beds For Treatment Of Net-Acidic, Oxic, Iron-Laden Drainage From A Flooded Anthracite Mine, Pennsylvania, Usa: 1. Field Evaluation, Charles A. Cravotta Iii, Suzanne J. Ward

United States Geological Survey: Staff Publications

Passive-treatment systems that route acidic mine drainage (AMD) through crushed limestone and/or organic-rich substrates have been used to remove the acidity and metals from various AMD sources, with a wide range of effects. This study evaluates treatment of net-acidic, oxic, iron-laden AMD with limestone alone, and with organic-rich compost layered with the limestone. In the fall of 2003, a treatment system consisting of two parallel, 500-m² downflow cells followed by a 400-m² aerobic settling pond and wetland was installed to neutralize the AMD from the Bell Mine, a large source of AMD and baseflow to the Schuylkill River …

Geochemical Evidence For Hydroclimatic Variability Over The Last 2460 Years From Crevice Lake In Yellowstone National Park, Usa, Lora R. Stevens, Walter E. Dean

United States Geological Survey: Staff Publications

A 2460-year-long hydroclimatic record for Crevice Lake, Yellowstone National Park, Montana was constructed from the δ¹⁸O values of endogenic carbonates. The δ¹⁸O record is compared to the Palmer Hydrologic Drought Index (PHDI) and Pacific Decadal Oscillation (PDO) indices, as well as inferred discharge of the Yellowstone River. During the last century, high δ¹⁸O values coincide with drought conditions and the warm phase of the PDO index. Low δ¹⁸O values coincide with wet years and a negative PDO index. Comparison of tree-ring inferred discharge of the Yellowstone River with the δ¹⁸O …

Environmental Contaminant Hazards To Wildlife At National Capital Region And Mid-Atlantic National Park Service Units, Barnett A. Rattner, Betty K. Ackerson

United States Geological Survey: Staff Publications

Part of the mission of the National Park Service (NPS) entails preservation of natural resources, processes, systems, and associated values of its units in an unimpaired condition. Environmental contamination and pollution processes are well recognized stressors that can adversely affect park units and are addressed by NPS management policies and plans. Nonetheless, biota remain at risk to contaminants at many NPS units. One U.S. Department of the Interior activity that addresses pollution hazards is the Biomonitoring of Environmental Status and Trends project (Zylstra 1994). Its does so through active field monitoring and by use of decision support tools, including the …

Intelligent Environmental Decision Support Systems, M. Sànchez-Marrè, K. Gibert, R. S. Sojda, J. P. Steyer, P. Struss, I. Rodríguez-Roda, J. Comas, V. Brilhante, E. A. Roehl

United States Geological Survey: Staff Publications

Introduction
Complexity of environmental systems
New tools for a new paradigm
Intelligent Environmental Decision Support Systems (IEDSS)
IEDSS development
About Uncertainty Management
Temporal Reasoning
Featuring the problem
Approaches to temporal reasoning
Case-based reasoning for temporal reasoning
Geographic Information and Spatial Reasoning
Understanding spatial reasoning
Kriging and variants
Representing change/time steps/feedback loops
Middleware. blackboards and communication protocols
Multiagent systems
Evaluation of IEDSS and Benchmarking
Benchmarking
Conclusions and Future Trends

Geochemical Evidence For Airborne Dust Additions To Soils In Channel Islands National Park, California, Daniel R. Muhs, James R. Budahn, Donald L. Johnson, Marith Reheis, Jossh Beann, Gary Skipp, Eric Fischer, Julia A. Jones

United States Geological Survey: Staff Publications

There is an increasing awareness that dust plays important roles in climate change, biogeochemical cycles, nutrient supply to ecosystems, and soil formation. In Channel Islands National Park, California, soils are clay-rich Vertisols or Alfi sols and Mollisols with vertic properties. The soils are overlain by silt-rich mantles that contrast sharply with the underlying clay-rich horizons. Silt mantles contain minerals that are rare or absent in the volcanic rocks that dominate these islands. Immobile trace elements (Sc-Th-La and Ta-Nd-Cr) and rare-earth elements show that the basalt and andesite on the islands have a composition intermediate between upper-continental crust and oceanic crust. …

Origin And Paleoclimatic Significance Of Late Quaternary Loess In Nebraska: Evidence From Stratigraphy, Chronology, Sedimentology, And Geochemistry, Daniel R. Muhs, E. Arthur Bettis Iii, John N. Aleinikoff, John P. Mcgeehin, Jossh Beann, Gary Skipp, Brian D. Marshall, Helen M. Roberts, William C. Johnson, Rachel Benton

United States Geological Survey: Staff Publications

Loess is one of the most extensive surficial geologic deposits in mid-continental North America, particularly in the central Great Plains region of Nebraska. Last-glacial-age loess (Peoria Loess) reaches its greatest known thickness in the world in this area. New stratigraphic, geochronologic, mineralogic, and geochemical data yield information about the age and provenance of Peoria Loess, as well as evaluation of recent climate models.

The Threat Of The Non-Native Neotropical Rust Puccinia Psidii To Hawaiian Biodiversity And Native Ecosystems: A Case Example Of The Need For Prevention, Lloyd Loope, Janice Uchida, Loyal Mehrhoff

United States Geological Survey: Staff Publications

The threat of invasive species to natural areas presents enormous challenges, but there are opportunities for working toward solutions, often in conjunction with agricultural and forestry perspectives. There is a growing awareness of the danger to botanical biodiversity and conservation from “emerging infectious diseases” that have increased in incidence, geographical distribution, or host range/pathogenicity; have newly evolved characteristics; and/or have been newly discovered (Anderson et al. 2004). There is a heightened concern for forest health due to accelerating worldwide movement of plant pathogens (e.g., with ineffective quarantine measures) that negatively affect both biodiversity and commercial forestry (Wingfield 2003). An important …

Limited Occurrence Of Denitrification In Four Shallow Aquifers In Agricultural Areas Of The United States, Christopher T. Green, Larry J. Puckett, John Karl Böhlke, Barbara A. Bekins, Steven P. Phillips, Leon J. Kauffman, Judith M. Denver, Henry M. Johnson

United States Geological Survey: Staff Publications

The ability of natural attenuation to mitigate agricultural nitrate contamination in recharging aquifers was investigated in four important agricultural settings in the United States. The study used laboratory analyses, field measurements, and flow and transport modeling for monitoring well transects (0.5 to 2.5 km in length) in the San Joaquin watershed, California, the Elkhorn watershed, Nebraska, the Yakima watershed, Washington, and the Chester watershed, Maryland. Ground water analyses included major ion chemistry, dissolved gases, nitrogen and oxygen stable isotopes, and estimates of recharge date. Sediment analyses included potential electron donors and stable nitrogen and carbon isotopes. Within each site and …

Whole-Stream Response To Nitrate Loading In Three Streams Draining Agricultural Landscapes, John H. Duff, Anthony J. Tesoriero, William B. Richardson, Eric A. Strauss, Mark Munn

United States Geological Survey: Staff Publications

Physical, chemical, hydrologic, and biologic factors affecting nitrate (NO₃^-) removal were evaluated in three agricultural streams draining orchard/dairy and row crop settings. Using 3-d “snapshots” during biotically active periods, we estimated reachlevel NO₃^- sources, NO₃^- mass balance, in-stream processing (nitrification, denitrification, and NO₃^- uptake), and NO₃^- retention potential associated with surface water transport and ground water discharge. Ground water contributed 5 to 11% to stream discharge along the study reaches and 8 to 42% of gross NO₃^- input. Streambed processes potentially reduced 45 to 75% of ground …