Riparian management and stream bank erosion in New Zealand     

AO Hughes 《新西兰海洋与淡水研究杂志》2016,50(2):277-290

Improvements in riparian management, such as shrub/tree planting and livestock exclusion, are often assumed to result in reduced stream bank erosion and associated catchment sediment yield. Studies that quantify the effectiveness of riparian interventions aimed at reducing bank erosion and river sediment yields are, however, rare. This paper discusses how bank erosion processes can vary throughout catchments (with particular reference to their scale dependence) and hence how the effectiveness of different riparian interventions can be variable. The findings of known published accounts of the effectiveness of riparian management interventions for reducing stream bank erosion in New Zealand are also summarised. Only nine relevant studies were identified and most used qualitative or semi-quantitative analysis methods. Most studies compared stream banks in pasture catchments (with unlimited livestock access) with stream banks where livestock were excluded and riparian shrubs/trees were present. Many studies reported that managed stream banks were in better condition than unmanaged banks. The exclusion of livestock from riparian areas was generally reported as the principal factor in the measured improvements or differences. Only two studies specifically attributed reduced stream bank erosion to the presence of riparian vegetation. The dearth of research identified here highlights the need for further quantitative studies to determine the effectiveness of riparian management measures for reducing bank erosion.  相似文献   

Spatial Variability of the Flow and Turbulence Within a Model Canopy     

Ian N. Harman  Margi Böhm  John J. Finnigan  Dale Hughes 《Boundary-Layer Meteorology》2016,160(3):375-396

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The downside risk of climate change in California’s Central Valley agricultural sector     

Michael Hanemann  Susan Stratton Sayre  Larry Dale 《Climatic change》2016,134(1-2):15-28

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The effect of the atmosphere and ionosphere on long period magnetospheric micropulsations   总被引：1，自引：0，他引：1  

W.J. Hughes 《Planetary and Space Science》1974,22(8):1157-1172

A study is made of the screening effect of the atmosphere and ionosphere which lets only part of a magnetospheric micropulsation signal reach the ground. We obtain analytical expressions relating the magnetic field in the magnetosphere to that on the ground, which are confirmed by computing a full solution. Only the part of the signal with no vertical current will be seen on the ground; this agrees with previous work. Using this result, we find that the reflection condition of a transverse hydromagnetic wave incident on the top of the ionosphere indicates a ‘fixed-end’ boundary condition for the field line. To a first approximation, micropulsation polarisations observed on the ground must be rotated through a right angle to obtain those in the magnetosphere. The strength of the electric field predicted in the ionosphere agrees with radio aurorae observations.  相似文献   

Mid-eclipse brightening of the Galilean satellites     

Dale W. Smith 《Icarus》1975,25(3):447-451

Brinkmann (1973) has suggested that the Galilean satellites might briefly manifest a brightening at mid-eclipse due to a concentration of light refracted into the geometric umbra of Jupiter by the atmosphere around the terminator. Results obtained using two different models of the Jovian atmosphere indicate that such a brightening is unlikely even for Callisto due to the probable aerosol concentration in the Jovian atmosphere at the relevant altitudes.  相似文献   

Anatomy of a granophyre intrusion     

Charles J. Hughes 《Lithos》1971,4(4):403-415

Various structural and textural features of a drusy granophyric ring-dyke intrusion can be explained in terms of the behaviour of magmatic water. Initial crystallization of water-rich magma close to ternary eutectic composition resulted in textures grading from granophyric to microgranitic. Eventual entrapment of water-rich pockets resulted in crystallization from a silicate liquid and a hydrothermal liquid simultaneously, probably at magmatic overpressure, to form isolated bodies of pegmatite containing giant euhedral quartz crystals. Later aplite, rhyolite breccia, and tuffisite veins reflect the escape of magma and magmatic gas through the congealed parts of the intrusion, at first permissively, but later with increasingly explosive effects.  相似文献   

Planets X and Pluto: By William G. Hoyt. Univ. of Arizona Press,Tucson, 1980. 302 pp., $9.50 (paper), $17.50 (cloth)     

Dale P. Cruikshank 《Icarus》1980,44(1):223-224

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New X.R.F. data retrieval techniques and their application to U.S.G.S. standard rocks     

G.C. Brown  D.J. Hughes  J. Esson 《Chemical Geology》1973,11(3):223-229

Accurate and consistent X-ray fluorescence analysis of major and trace elements using a single pressed pellet for each sample has been achieved with a wide variety of rock compositions. Counting techniques for use with data reduction and correction programs in Standard Fortran IV are described; the latter depend throughout on data developed from a wide range of standard rock compositions. A comparison of ten major and fifteen trace element analyses for U.S.G.S. standard rocks with averages taken from the literature testifies to the precision of these techniques.  相似文献   

Geomorphology,acoustic backscatter,and processes in Santa Monica Bay from multibeam mapping   总被引：2，自引：0，他引：2  

Gardner JV  Dartnell P  Mayer LA  Hughes Clarke JE 《Marine environmental research》2003,56(1-2):15-46

Santa Monica Bay was mapped in 1996 using a high-resolution multibeam system, providing the first substantial update of the submarine geomorphology since the initial compilation by Shepard and Emery [(1941) Geol. Soc. Amer. Spec. Paper 31]. The multibeam mapping generated not only high-resolution bathymetry, but also coregistered, calibrated acoustic backscatter at 95 kHz. The geomorphology has been subdivided into six provinces; shelf, marginal plateau, submarine canyon, basin slope, apron, and basin. The dimensions, gradients, and backscatter characteristics of each province is described and related to a combination of tectonics, climate, sea level, and sediment supply. Fluctuations of eustatic sea level have had a profound effect on the area; by periodically eroding the surface of Santa Monica plateau, extending the mouth of the Los Angeles River to various locations along the shelf break, and by connecting submarine canyons to rivers. A wetter glacial climate undoubtedly generated more sediment to the rivers that then transported the increased sediment load to the low-stand coastline and canyon heads. The trends of Santa Monica Canyon and several bathymetric highs suggest a complex tectonic stress field that has controlled the various segments. There is no geomorphic evidence to suggest Redondo Canyon is fault controlled. The San Pedro fault can be extended more than 30 km to the northwest by the alignment of a series of bathymetric highs and abrupt changes in direction of channel thalwegs.  相似文献   

Resource rents from single and multispecies individual transferable quota programs   总被引：1，自引：0，他引：1  

Squires  Dale; Kirkley  James 《ICES Journal of Marine Science》1995,52(2):153-164

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