Incorporation of Total Stress Changes into the Ground Water Model SUTRA   总被引：3，自引：0，他引：3  

Howard W. Reeves  Peter M. Thibodeau  Robert G. Underwood  Leonard R. Gardner 《Ground water》2000,38(1):89-98

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A high-resolution Holocene ostracod record from the Sahel zone of Northeastern Nigeria     

Jonathan A. Holmes  Patrick A. Fothergill  F. Alayne Street-Perrott  R. Alan Perrott 《Journal of Paleolimnology》1998,20(4):369-380

The ostracod record from Kajemarum Oasis in the Sahel zone of Northeastern Nigeria covers the last c. 4000 cal. years of a 5500 cal. year lake-sediment sequence. The first appearance of ostracods, around 4000 cal. yr BP, reflects the switch from a very dilute lake during the mid-Holocene, to slightly oligosaline conditions that favoured the occurrence and preservation of ostracods. Between 3800 and 3100 cal. yr BP, the lake remained permanent and fresh or slightly oligosaline, with a Ca-Mg-HCO3 composition. A rise in salinity c. 3100 cal. yr BP, accompanied by a change to more variable conditions on a seasonal to interannual timescale, led to the influx of more-euryhaline taxa. Oligosaline conditions continued between 3100 and 1500 cal. yr BP. Around 1500 cal. yr BP, there was a sharp rise in salinity, probably accompanied by a shift to Na-CO3-type water, with marked seasonal and interannual variability. Salinity decreased after 900 cal. yr BP, although short-term variations were marked between 900 cal. yr BP and the top of the sequence, 95 cal. yr BP. Changes in the species assemblages and ostracod abundance were a response to climate-driven variations in the seasonal and interannual stability of the lake, together with changes in its salinity and solute composition, but there is no simple relationship between ostracod faunas and salinity. Within Kajemarum, there is no evidence of ostracod assemblages typical of deep, fresh water, nor of hypersaline Na-Cl waters. The sediments associated with the freshest waters at Kajemarum did not favour ostracod preservation, and the driest climatic conditions were associated with oligosaline to mesosaline water of Na-CO3-type. The species-poor assemblages reflect the short-term instability of the lake, coupled with the limited opportunities for the colonisation of this isolated basin.  相似文献   

Meeting review: The nice symposium on the origin of the solar system     

Hubert Reeves 《Icarus》1973,19(4):604-606

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Evidence of a decline in beluga, Delphinapterus leucas, abundance off West Greenland     

Heide-Jorgensen  M. P.; Reeves  Randall R. 《ICES Journal of Marine Science》1996,53(1):61-72

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A simulation study of the implications of age-reading errors for stock assessment and management advice   总被引：2，自引：2，他引：2  

Reeves  Stuart A. 《ICES Journal of Marine Science》2003,60(2):314-328

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Reply to Discussion on []     

C. V. Reeves 《Journal of African Earth Sciences》2003,36(4):389-390

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XMM–Newton observations of high-luminosity radio-quiet quasi-stellar objects     

K. L. Page  J. N. Reeves  P. T. O'Brien  M. J. L. Turner  D. M. Worrall 《Monthly notices of the Royal Astronomical Society》2004,353(1):133-142

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XMM–Newton observations of 3C 273     

K. L. Page  M. J. L. Turner  C. Done  P. T. O'Brien  J. N. Reeves  S. Sembay  M. Stuhlinger 《Monthly notices of the Royal Astronomical Society》2004,349(1):57-67

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Estimating climate change effects on net primary production of rangelands in the United States     

Matthew C. Reeves  Adam L. Moreno  Karen E. Bagne  Steven W. Running 《Climatic change》2014,126(3-4):429-442

The potential effects of climate change on net primary productivity (NPP) of U.S. rangelands were evaluated using estimated climate regimes from the A1B, A2 and B2 global change scenarios imposed on the biogeochemical cycling model, Biome-BGC from 2001 to 2100. Temperature, precipitation, vapor pressure deficit, day length, solar radiation, CO₂ enrichment and nitrogen deposition were evaluated as drivers of NPP. Across all three scenarios, rangeland NPP increased by 0.26 % year^?1 (7 kg C ha^?1 year^?1) but increases were not apparent until after 2030 and significant regional variation in NPP was revealed. The Desert Southwest and Southwest assessment regions exhibited declines in NPP of about 7 % by 2100, while the Northern and Southern Great Plains, Interior West and Eastern Prairies all experienced increases over 25 %. Grasslands dominated by warm season (C4 photosynthetic pathway) species showed the greatest response to temperature while cool season (C3 photosynthetic pathway) dominated regions responded most strongly to CO₂ enrichment. Modeled NPP responses compared favorably with experimental results from CO₂ manipulation experiments and to NPP estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS). Collectively, these results indicate significant and asymmetric changes in NPP for U.S. rangelands may be expected.  相似文献   

Cubic law with aperture-length correlation: implications for network scale fluid flow   总被引：2，自引：2，他引：0  

Christian Klimczak  Richard A. Schultz  Rishi Parashar  Donald M. Reeves 《Hydrogeology Journal》2010,18(4):851-862

Previous studies have computed and modeled fluid flow through fractured rock with the parallel plate approach where the volumetric flow per unit width normal to the direction of flow is proportional to the cubed aperture between the plates, referred to as the traditional cubic law. When combined with the square root relationship of displacement to length scaling of opening-mode fractures, total flow rates through natural opening-mode fractures are found to be proportional to apertures to the fifth power. This new relationship was explored by examining a suite of flow simulations through fracture networks using the discrete fracture network model (DFN). Flow was modeled through fracture networks with the same spatial distribution of fractures for both correlated and uncorrelated fracture length-to-aperture relationships. Results indicate that flow rates are significantly higher for correlated DFNs. Furthermore, the length-to-aperture relations lead to power-law distributions of network hydraulic conductivity which greatly influence equivalent permeability tensor values. These results confirm the importance of the correlated square root relationship of displacement to length scaling for total flow through natural opening-mode fractures and, hence, emphasize the role of these correlations for flow modeling.  相似文献