Infiltration on mountain slopes: a comparison of three environments     

Carol P. Harden  P. Delmas Scruggs 《Geomorphology》2003,55(1-4):5

Water is well established as a major driver of the geomorphic change that eventually reduces mountains to lower relief landscapes. Nonetheless, within the altitudinal limits of continuous vegetation in humid climates, water is also an essential factor in slope stability. In this paper, we present results from field experiments to determine infiltration rates at forested sites in the Andes Mountains (Ecuador), the southern Appalachian Mountains (USA), and the Luquillo Mountains (Puerto Rico). Using a portable rainfall simulator–infiltrometer (all three areas), and a single ring infiltrometer (Andes), we determined infiltration rates, even on steep slopes. Based on these results, we examine the spatial variability of infiltration, the relationship of rainfall runoff and infiltration to landscape position, the influence of vegetation on infiltration rates on slopes, and the implications of this research for better understanding erosional processes and landscape change.Infiltration rates ranged from 6 to 206 mm/h on lower slopes of the Andes, 16 to 117 mm/h in the southern Appalachians, and 0 to 106 mm/h in the Luquillo Mountains. These rates exceed those of most natural rain events, confirming that surface runoff is rare in montane forests with deep soil/regolith mantles. On well-drained forested slopes and ridges, apparent steady-state infiltration may be controlled by the near-surface downslope movement of infiltrated water rather than by characteristics of the full vertical soil profile. With only two exceptions, the local variability of infiltration rates at the scale of 10° m overpowered other expected spatial relationships between infiltration, vegetation type, slope position, and soil factors. One exception was the significant difference between infiltration rates on alluvial versus upland soils in the Andean study area. The other exception was the significant difference between infiltration rates in topographic coves compared to other slope positions in the tabonuco forest of one watershed in the Luquillo Mountains. Our research provides additional evidence of the ability of forests and forest soils to preserve geomorphic features from denudation by surface erosion, documents the importance of subsurface flow in mountain forests, and supports the need for caution in extrapolating infiltration rates.  相似文献   

Self-Organizing Systems in Geography: A Response to Peterman     

Lyle Courtney  Walter G. Hardwick 《The Professional geographer》1995,47(2):218-220

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The relative performance of various cup anemometers in a gusty wind     

Lyle H. Horn 《Theoretical and Applied Climatology》1958,9(2):231-237

Summary Wind data collected during the Great Plains Turbulence Field Experiment of 1953 are used to study the relative performances of various types of cup anemometers subjected to air flow of known gustiness. Scatter diagrams which relate differences in the indicated mean speeds of two anemometers to gustiness are prepared. Although the instruments compared represent a wide range of moments of inertia, no relationship between gustiness and anemometer performance is noted. This result is examined in light of Schrenk's parameter which describes anemometer performance.

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Zusammenfassung Windbeobachtungen, welche während des Great Plains Turbulence Field Program im Jahre 1953 gewonnen wurden, werden zu einem Vergleich verschiedener Typen von Schalenkreuzanemometern in einem Windfeld von bekannter Böigkeit verwendet. Die Ergebnisse werden in Form von Streubildern veranschaulicht, in denen die Geschwindigkeits-unterschiede von verschiedenen Anemometern als Funktion des Böigkeitsgrades aufgetragen sind. Obgleich die verglichenen Anemometer erheblich verschiedene Trägheitsmomente besitzen, ergibt sich keine Abhängigkeit der Anzeigedifferenzen von der Böigkeit des Windes. Dieser Befund wird mit Hilfe des Schrenkschen Parameters näher beleuchtet.

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Résumé Les observations anémométriques effectuées dans le cadre du Great Plains Turbulence Field Program en 1953 sont utilisées ici dans le but de comparer différents types d'anémomètres à cupules placés dans un champ de mouvement de turbulence connue. Les résultats sont donnés sous forme d'essaims de points dans un système de référence: écarts individuels de l'indication et degré de turbulence. Bien que les instruments comparés présentent des moments d'inertie notablement différents, les écarts observés ne dépendent pas de la turbulence du vent. Ce résultat est encore examiné à l'aide du paramètre de Schrenk.

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With 4 Figures  相似文献   

Under the surface: Pressure-induced planetary-scale waves,volcanic lightning,and gaseous clouds caused by the submarine eruption of Hunga Tonga-Hunga Ha'apai volcano     

David A. Yuen  Melissa A. Scruggs  Frank J. Spera  Yingcai Zheng  Hao Hu  Stephen R. McNutt  Glenn Thompson  Kyle Mandli  Barry R. Keller  Songqiao Shawn Wei  Zhigang Peng  Zili Zhou  Francesco Mulargia  Yuichiro Tanioka 《地震研究进展（英文）》2022,2(3):100134

We present a narrative of the eruptive events culminating in the cataclysmic January 15, 2022 eruption of Hunga Tonga-Hunga Ha'apai Volcano by synthesizing diverse preliminary seismic, volcanological, sound wave, and lightning data available within the first few weeks after the eruption occurred. The first hour of eruptive activity produced fast-propagating tsunami waves, long-period seismic waves, loud audible sound waves, infrasonic waves, exceptionally intense volcanic lightning and an unsteady volcanic plume that transiently reached—at 58 ?km—the Earth's mesosphere. Energetic seismic signals were recorded worldwide and the globally stacked seismogram showed episodic seismic events within the most intense periods of phreatoplinian activity, and they correlated well with the infrasound pressure waveform recorded in Fiji. Gravity wave signals were strong enough to be observed over the entire planet in just the first few hours, with some circling the Earth multiple times subsequently. These large-amplitude, long-wavelength atmospheric disturbances come from the Earth's atmosphere being forced by the magmatic mixture of tephra, melt and gasses emitted by the unsteady but quasi-continuous eruption from 0402±1–1800 UTC on January 15, 2022. Atmospheric forcing lasted much longer than rupturing from large earthquakes recorded on modern instruments, producing a type of shock wave that originated from the interaction between compressed air and ambient (wavy) sea surface. This scenario differs from conventional ideas of earthquake slip, landslides, or caldera collapse-generated tsunami waves because of the enormous (～1000x) volumetric change due to the supercritical nature of volatiles associated with the hot, volatile-rich phreatoplinian plume. The time series of plume altitude can be translated to volumetric discharge and mass flow rate. For an eruption duration of ～12 ?h, the eruptive volume and mass are estimated at 1.9 ?km³ and ～2 900 ?Tg, respectively, corresponding to a VEI of 5–6 for this event. The high frequency and intensity of lightning was enhanced by the production of fine ash due to magma—seawater interaction with concomitant high charge per unit mass and the high pre-eruptive concentration of dissolved volatiles. Analysis of lightning flash frequencies provides a rapid metric for plume activity and eruption magnitude. Many aspects of this eruption await further investigation by multidisciplinary teams. It represents a unique opportunity for fundamental research regarding the complex, non-linear behavior of high energetic volcanic eruptions and attendant phenomena, with critical implications for hazard mitigation, volcano forecasting, and first-response efforts in future disasters.  相似文献   

The Huygens scientific data archive: Technical overview     

Olivier Witasse  Lyle Huber  Jean-Pierre Lebreton  David Heather  John Zarnecki  Roland Trautner  Piero Leon Stoppato  Chuck See  Cyril Pennanech  Lisa McFarlane  Bobby Kazeminejad  Brijen Hathi  John Haberman  Francesca Ferri  Lyn Doose  Giacomo Colombatti  Michael Bird  Alessio Aboudan 《Planetary and Space Science》2008,56(5):770-777

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The Dual-Domain Porosity Apparatus: Characterizing Dual Porosity at the Sediment/Water Interface     

Courtney R. Scruggs  Martin Briggs  Frederick D. Day-Lewis  Dale Werkema  John W. Lane Jr 《Ground water》2019,57(4):640-646

The characterization of pore-space connectivity in porous media at the sediment/water interface is critical in understanding contaminant transport and reactive biogeochemical processes in zones of groundwater and surface-water exchange. Previous in situ studies of dual-domain (i.e., mobile/less-mobile porosity) systems have been limited to solute tracer injections at scales of meters to hundreds of meters and subsequent numerical model parameterization using fluid concentration histories. Pairing fine-scale (e.g., sub-meter) geoelectrical measurements with fluid tracer data over time alleviates dependence on flowpath-scale experiments, enabling spatially targeted characterization of shallow sediment/water interface media where biogeochemical reactivity is often high. The Dual-Domain Porosity Apparatus is a field-tested device capable of variable rate-controlled downward flow experiments. The Dual-Domain Porosity Apparatus facilitates inference of dual-domain parameters, i.e., mobile/less-mobile exchange rate coefficient and the ratio of less mobile to mobile porosity. The Dual-Domain Porosity Apparatus experimental procedure uses water electrical conductivity as a conservative tracer of differential loading and flushing of pore spaces within the region of measurement. Variable injection rates permit the direct quantification of the flow-dependence of dual-domain parameters, which has been theorized for decades but remains challenging to assess using existing experimental methodologies.  相似文献   

Is irrigated agriculture in the Murray Darling Basin well prepared to deal with reductions in water availability?   总被引：1，自引：0，他引：1  

Yongping WeiJohn Langford  Ian R. WillettSnow Barlow  Clive Lyle 《Global Environmental Change》2011,21(3):906-916

The “Big Dry”, a prolonged dry period in Australia from 1997 to 2009, dried out much of the Murray-Darling Basin (MDB) and resulted in large agricultural losses and degraded river ecosystems. Climate projections are that dry conditions in the MDB are likely to be more regular and severe than ever before, and recent policy initiatives are likely to reduce consumptive water use and redirect water to ecosystem management. This paper aims to develop an understanding of the interactions between water policy and irrigation practices by deriving lessons from drought management in irrigated agriculture of the MDB during the Big Dry, and furthermore, to draw out lessons to enhance the preparedness of irrigated agriculture for a future drier climate and reduced water availability. Reviews of irrigation farmers’ practices, attitudes and capacity to manage during prolonged droughts in the MDB, and the evolution of agricultural water policy in Australia since 1990 were made. It is clear that farmers could be better prepared to deal with a drier climate if their water management practices, e.g. irrigation methods and soil moisture measuring tools are improved, if the impediments to the uncertainty of water allocation and low water availability could be overcome, and if well-targeted research and extension could assist farmers to use water more wisely. It is also clear that Australian water policy could be better prepared in terms of assisting irrigated agriculture to deal with a drier climate. Key areas are reduction of barriers and distortions to water trading, optimizing the environmental water allocation, and seeking mutual benefits between environmental water allocation and irrigated agriculture, improvement of the cost-effectiveness of investments in water supply infrastructure, facilitating carryover and capacity sharing at larger scales, and provision of accurate, accessible and useful water information at different scales. An approach to irrigation practice and water policy is proposed based on past experience and potential opportunities. The approach is a set of linked strategies for more robust agricultural production and a more sustainable environment under a drier climate and reduced water availability.  相似文献   

A Basin Study of Ground-Water Discharge from Bedrock into Glacial Drift Part I—Definition of Ground-Water System     

Douglas C. Kent  Lyle V. A. Sendlein 《Ground water》1972,10(4):24-34

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Comparison of AnnAGNPS and SWAT model simulation results in USDA‐CEAP agricultural watersheds in south‐central Kansas     

Prem B. Parajuli  Nathan O. Nelson  Lyle D. Frees  Kyle R. Mankin 《水文研究》2009,23(5):748-763

This study was conducted under the USDA‐Conservation Effects Assessment Project (CEAP) in the Cheney Lake watershed in south‐central Kansas. The Cheney Lake watershed has been identified as ‘impaired waters’ under Section 303(d) of the Federal Clean Water Act for sediments and total phosphorus. The USDA‐CEAP seeks to quantify environmental benefits of conservation programmes on water quality by monitoring and modelling. Two of the most widely used USDA watershed‐scale models are Annualized AGricultural Non‐Point Source (AnnAGNPS) and Soil and Water Assessment Tool (SWAT). The objectives of this study were to compare hydrology, sediment, and total phosphorus simulation results from AnnAGNPS and SWAT in separate calibration and validation watersheds. Models were calibrated in Red Rock Creek watershed and validated in Goose Creek watershed, both sub‐watersheds of the Cheney Lake watershed. Forty‐five months (January 1997 to September 2000) of monthly measured flow and water quality data were used to evaluate the two models. Both models generally provided from fair to very good correlation and model efficiency for simulating surface runoff and sediment yield during calibration and validation (correlation coefficient; R², from 0·50 to 0·89, Nash Sutcliffe efficiency index, E, from 0·47 to 0·73, root mean square error, RMSE, from 0·25 to 0·45 m³ s^?1 for flow, from 158 to 312 Mg for sediment yield). Total phosphorus predictions from calibration and validation of SWAT indicated good correlation and model efficiency (R² from 0·60 to 0·70, E from 0·63 to 0·68) while total phosphorus predictions from validation of AnnAGNPS were from unsatisfactory to very good (R² from 0·60 to 0·77, E from ? 2·38 to 0·32). The root mean square error–observations standard deviation ratio (RSR) was estimated as excellent (from 0·08 to 0·25) for the all model simulated parameters during the calibration and validation study. The percentage bias (PBIAS) of the model simulated parameters varied from unsatisfactory to excellent (from 128 to 3). This study determined SWAT to be the most appropriate model for this watershed based on calibration and validation results. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Fluxes of metals to a manganese nodule radiochemical,chemical, structural,and mineralogical studies     

Willard S. Moore  Teh-Lung Ku  J. Douglas Macdougall  Virginia Mee Burns  Roger Burns  Jack Dymond  Mitchel W. Lyle  David Z. Piper 《Earth and Planetary Science Letters》1981,52(1):151-171

Fluxes of metals to the top and bottom surfaces of a manganese nodule were determined by combining radiochemical (²³⁰Th,²³¹Pa,²³²Th,²³⁸U,²³⁴U) and detailed chemical data. The top of the nodule had been growing in its collected orientation at 4.7 mm Myr^?1 for at least 0.5 Myr and accreting Mn at 200 μg cm^?2 kyr^?1. The bottom of the nodule had been growing in its collected orientation at about 12 mm Myr^?1 for at least 0.3 Myr and accreting Mn at about 700 μg cm^?2 yr^?1. Although the top of the nodule was enriched in iron relative to the bottom, the nodule had been accreting Fe 50% faster on the bottom.²³²Th was also accumulating more rapidly in the bottom despite a 20-fold enrichment of²³⁰Th on the top.The distribution of alpha-emitting nuclides calculated from detailed radiochemical measurements matched closely the pattern revealed by 109-day exposures of alpha-sensitive film to the nodule. However, the shape and slope of the total alpha profile with depth into the nodule was affected strongly by²²⁶Ra and²²²Rn migrations making the alpha-track technique alone an inadequate method of measuring nodule growth rates.Diffusion of radium in the nodule may have been affected by diagenetic reactions which produce barite, phillipsite and todorokite within 1 mm of the nodule surface; however, our sampling interval was too broad to document the effect. We have not been able to resolve the importance of nodule diagenesis on the gross chemistry of the nodule.  相似文献