Influence of rainfall spatial variability on flood prediction   总被引：9，自引：0，他引：9  

Patrick Arnaud  Christophe Bouvier  Leonardo Cisneros  Ramon Dominguez 《Journal of Hydrology》2002,260(1-4):216-230

This paper deals with the sensitivity of distributed hydrological models to different patterns that account for the spatial distribution of rainfall: spatially averaged rainfall or rainfall field. The rainfall data come from a dense network of recording rain gauges that cover approximately 2000 km² around Mexico City. The reference rain sample accounts for the 50 most significant events, whose mean duration is about 10 h and maximal point depth 170 mm. Three models were tested using different runoff production models: storm-runoff coefficient, complete or partial interception. These models were then applied to four fictitious homogeneous basins, whose sizes range from 20 to 1500 km². For each test, the sensitivity of the model is expressed as the relative differences between the empirical distribution of the peak flows (and runoff volumes), calculated according to the two patterns of rainfall input: uniform or non-uniform. Differences in flows range from 10 to 80%, depending on the type of runoff production model used, the size of the basin and the return period of the event. The differences are generally moderate for extreme events. In the local context, this means that uniform design rainfall combining point rainfall distribution and the probabilistic concept of the areal reduction factor could be sufficient to estimate major flood probability. Differences are more significant for more frequent events. This can generate problems in calibrating the hydrological model when spatial rainfall localization is not taken into account: a bias in the estimation of parameters makes their physical interpretation difficult and leads to overestimation of extreme flows.  相似文献   

Synergistic Application of Four Remedial Techniques at an Industrial Site     

Jean. M. Dasch  Abdul S. Abdul  Devi N. Rai  Thomas L. Gibson  Noel Grosvenor 《Ground Water Monitoring & Remediation》1997,17(3):194-209

The soil and ground water at a General Motors plant site were contaminated with petroleum products from leaking underground storage tanks. Based on the initial assessment, the site was complex from the standpoint of geology (clay layers), hydrology (a recharge zone with a perched water table), and contaminant (approximately 4800 gallons of mixed gasoline and oil). After a thorough study of remedial alternatives, a synergistic remedial approach was adopted including pump and treat, product removal, vapor extraction, and bioventing. The system was designed and implemented at the site through 22 dual-extraction wells. Over a 21-month period, 4400 gallons of gasoline and oil were removed from the system, including 59 percent by vapor extraction, 28 percent by bioventing, and 13 percent by pump and treat. Synergism between the various remedial methods was demonstrated clearly. Ground water pump and treat lowered the water table, allowing air to flow for vapor extraction. The vacuum applied for vapor extraction increased the ground water removal rate and the efficiency of pump and treat. The vapor extraction system also added oxygen to the soil to stimulate aerobic biodegradation.  相似文献   

Genetic variability of rock glaciers     

Douglas H. Clark  Eric J. Steig  Noel Potter  Jr.  Alan R. Gillespie 《Geografiska Annaler: Series A, Physical Geography》1998,80(3-4):175-182

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Multimillion year thermal history of a porphyry copper deposit: application of U–Pb, 40Ar/39Ar and (U–Th)/He chronometers, Bajo de la Alumbrera copper–gold deposit, Argentina     

Anthony C. Harris  W. James Dunlap  Peter W. Reiners  Charlotte M. Allen  David R. Cooke  Noel C. White  Ian H. Campbell  Suzanne D. Golding 《Mineralium Deposita》2008,43(3):295-314

Application of multiple chronometers (including U–Pb and ⁴⁰Ar/³⁹Ar geochronology and zircon and apatite (U–Th)/He thermochronology) to porphyry intrusions at the Bajo de la Alumbrera porphyry copper–gold deposit, Argentina, reveals a complex history of reheating that spans millions of years. Previous U–Pb geochronology, combined with our new ⁴⁰Ar/³⁹Ar data, shows that the multiple porphyritic intrusions at Bajo de la Alumbrera were emplaced during two episodes, the first at about 8.0 Ma (P2 and associated porphyries) and the second about a million years later (Early and Late P3 porphyries). Complex overprinting alteration events have obscured the earliest hydrothermal history of the deposit. By contrast, ⁴⁰Ar/³⁹Ar data reveal the close temporal relationship of ore-bearing potassic alteration assemblages (7.12 ± 0.13 Ma; biotite) to the emplacement of the P3 intrusions. Consistent with low closure temperatures, younger ages have been determined for associated hydrothermal alkali feldspar (6.82 ± 0.05 Ma and 6.64 ± 0.09 Ma). The temperature-sensitive Ar data also record an unexpected prolonged cooling history (to below 200°C) extending to 5.9 Ma. Our data suggest that the Bajo de la Alumbrera system underwent protracted cooling, after the collapse of the main hydrothermal system, or that one or more low-temperature (~100–200°C) reheating events occurred after emplacement of the porphyritic intrusions at Bajo de la Alumbrera. These have been constrained in part by our new ⁴⁰Ar/³⁹Ar data (including multidomain diffusion modeling) and (U–Th)/He ages. Single-grain (U–Th)/He ages (n = 5) for phenocrystic zircon from P2 and P3 intrusive phases bracket these thermal events to between 6.9 (youngest crystallization of intrusion) and 5.1 Ma. Multidomain modeling of alkali feldspar data (from both igneous and hydrothermal crystals) is consistent with the deposit cooling rapidly from magmatic temperatures to below about 300°C, with a more protracted history down to 150°C. We conclude that the late-stage low-temperature (150 to 200°C) thermal anomaly localized at Bajo de la Alumbrera resulted from radiation of heat and/or fluids sourced from deeper-seated magma bodies, emplaced beneath the deposit. To produce the observed thermal longevity of the porphyry system, magma bodies underlying the Bajo de la Alumbrera deposit must have been repeatedly replenished by new magma batches. Without replenishment, crystallization of the source magma will occur, and heat release will stop, leading to rapid cooling (in less than ten thousand years). The influx of deep-seated magma may have caused the development of late low-temperature hydrothermal alteration assemblages at Bajo de la Alumbrera, at the same time that mineralization formed at Agua Rica, some 25 km away. All available chronologic data for the Bajo de la Alumbrera deposit suggest that the hydrothermal system was active episodically over at least a three-million and possibly up to a four-million-year period. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Diurnal variations of winds over an upwelling region off Oregon     

Wayne Burt  Henry Crew  Noel Plutchak  Jozef Dumon 《Boundary-Layer Meteorology》1974,6(1-2):35-45

The diurnal variation of surface winds off the coast of Oregon is described and compared with a recent analysis of winds off the coast of Peru. The Oregon wind speeds have a distinct 24-h periodicity, while the Peru wind speeds were reported to have an irregular 12-h variation. The long-and trans-shore components of both winds exhibit 24-h periodicities; the ratio of the long-shore to trans-shore diurnal amplitudes off Oregon is 2.8, twice the ratio found off Peru. Although meteorological conditions off Oregon were quasi-stationary during the period investigated, there were considerable day-to-day variations in diurnal amplitudes and phases. Diurnal amplitudes were found to be correlated with the daily mean long-shore winds.  相似文献   

The Relationship Between Fracture Traces and Joints in a Tertiary Basin, Southwest Montana     

Noel C. Krothe  Marcel P. Bergeron 《Ground water》1981,19(2):138-143

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Effect of tidal flooding on mortality of juvenile muskrats     

Quin J. Kinler  Robert H. Chabreck  Noel W. Kinler  R. G. Linscombe 《Estuaries and Coasts》1990,13(3):337-340

The effect of tidal flooding on survival of juvenile muskrats (Ondatra zibethicus) was investigated in a brackish marsh in Louisiana by examining 50 muskrat lodges each month from July 1984 to June 1985 and tidal data over a 19-yr period. Tide levels increased at a rate of 1.58 cm yr^?1 during the 19-yr period prior to the study, and during the study nest chambers in muskrat lodges were flooded on 43 d. Seventy-seven captured litters averaged 2.2±0.3 young per litter. older litters were less common than younger litters, but the number of young per litter did not differ among 5-d age classes, suggesting that mortality factors usually affected entire litters. The frequency of tidal flooding prior to opening of lodges each month was associated negatively with the number of litters and number of young per litter. If marsh subsidence and sea level rise continue, tidal flooding will become more prevalent and litter mortality will likely increase.  相似文献   

Southern Kurile Islands/ Northern territories resource potential     

Mark J. Valencia  Noel Ludwig 《GeoJournal》1991,24(2):227-231

The islands of the Habomai group, Shikotan, Kunashir and Iturup are claimed by both the Soviet Union and Japan. These islands are each entitled to an Exclusive Economic Zone. This paper examines the mineral and energy potential on these islands and in their maritime zones and the implications for resource allocation and management of different solutions to the islands question. Return of all four islands would mean the transfer of substantial titanium sand, sulfur and sulfide deposits, as well as extensive fishing grounds. Return of only the southern two would still entail a major transfer of fishing grounds but not known mineral deposits. Return of the southern two and joint development of the other two would give Japan significant fishing grounds and access to several economic mineral deposits.  相似文献   

On the stability of the geostatistical method     

Noel Cressie  Dale L. Zimmerman 《Mathematical Geology》1992,24(1):45-59

A thorough geostatistical analysis of spatial data, observed at given spatial locations, includes exploratory data analysis, spatial-model building, diagnosing the model fit, and inference on unknown model parameters or unobserved values (at known locations). Using results from mathematical analysis, exact and asymptotic distribution theory, and simulation studies, we argue that, when used sensibly, the geostatistical method is reassuringly stable.  相似文献   

Spatial prediction and ordinary kriging   总被引：11，自引：0，他引：11  

Noel Cressie 《Mathematical Geology》1988,20(4):405-421

Suppose data {Z(s _i ):i=1, ..., n} are observed at spatial locations {s _i :i=1, ..., n}. From these data, an unknownZ(s ₀) is to be predicted at a known locations ₀c, or, ifZ(s₀) has a component of measurement error, then a smooth versionS(s ₀) should be predicted. This article considers the assumptions needed to carry out the spatial prediction using ordinary kriging, and looks at how nugget effect, range, and sill of the variogram affect the predictor. It is concluded that certain commonly held interpretations of these variogram parameters should be modified.This paper was presented at MGUS 87 Conference, Redwood City, California, 14 April 1987.  相似文献