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671.
蒸散发是地表陆气水分交换的纽带,准确量化蒸散发的时空演变格局对于水资源规划与管理至关重要。本文基于GLEAM模型的蒸散发及其组分数据集,借助7个通量观测站数据、120个流域的流域水量平衡及PML_V2蒸散发产品,在中国九大流域系统评估了GLEAM-ET产品,分析了植被恢复背景下,蒸散发(ET)及其组分(植被蒸腾Ec,截留蒸发Ei,土壤蒸发Es)在1980—2020年的时空演变格局。本文主要得到以下结论:① GLEAM-ET产品在中国九大流域具有较好的适用性,其性能与气候类型有关,干旱区效果优于湿润区。此外,GLEAM与PML_V2模型在九大流域相关性较好(R>0.7),分布格局与变化趋势整体保持一致。② 全国尺度上,ET均值为416.88 mm,增长速率为1.21 mm/a。Ec与ET均呈自东南向西北递减的分布格局,而Es与其相反。Ec、ET在九大流域均呈显著增加趋势(p<0.001)。Ei、Es在季风区流域分别呈显著增加和显著减小趋势;在内陆区流域呈不显著减小(p>0.05)和显著增加趋势。③在植被恢复背景下,ET组分比例发生了变化。Ec占比变化存在南北差异,南方流域Ec占比均减小,北方流域均增加。Ei占比在各流域均增加,Es占比均减小。黄河流域ET组分对植被恢复的响应最为明显,Ec占比增加了5.21%,Es占比减小了5.56%。 相似文献
672.
蒙阴盆地是在库拉板块向亚洲大陆下俯冲,中国东部隆升伸展板块裂解阶段发育起来的。在中生代,盆地的成生演化经历了侏罗纪拗陷盆地发育阶段和早白垩世拗陷—裂陷阶段。在相应沉积演化过程中,形成侏罗纪湖相红色碎屑岩建造,早白垩世早期滨浅湖—半深湖相灰绿色细粒陆屑岩沉积,早白垩世中期河湖相凝灰质复陆屑岩类夹火山碎屑岩类沉积,早白垩世晚期中基性火山熔岩、火山碎屑岩组合。沉积中心在侏罗纪和早白墨世早期皆偏于西北部,此后,向东南部迁移。晚白垩世,盆地处于风化剥蚀阶段。古近纪,受新生太平洋板块向亚洲大陆下俯冲影响,盆地又处于拗陷—裂陷阶段,相应形成山间河湖相—山麓堆积相类磨拉石建造。古近纪末期,该盆地整体隆起处于长期风化剥蚀状态。 相似文献
673.
We investigated trends in future seasonal runoff components in the Willamette River Basin (WRB) of Oregon for the twenty‐first century. Statistically downscaled climate projections by Climate Impacts Group (CIG), eight different global climate model (GCM) simulations with two different greenhouse gas (GHG) emission scenarios, (A1B and B1), were used as inputs for the US Geological Survey's Precipitation Runoff Modelling System. Ensemble mean results show negative trends in spring (March, April and May) and summer (June, July and August) runoff and positive trends in fall (September, October and November) and winter (December, January and February) runoff for 2000–2099. This is a result of temperature controls on the snowpack and declining summer and increasing winter precipitation. With temperature increases throughout the basin, snow water equivalent (SWE) is projected to decline consistently for all seasons. The decreases in the centre of timing and 7‐day low flows and increases in the top 5% flow are caused by the earlier snowmelt in spring, decreases in summer runoff and increases in fall and winter runoff, respectively. Winter runoff changes are more pronounced in higher elevations than in low elevations in winter. Seasonal runoff trends are associated with the complex interactions of climatic and topographic variables. While SWE is the most important explanatory variable for spring and winter runoff trends, precipitation has the strongest influence on fall runoff. Spatial error regression models that incorporate spatial dependence better explain the variations of runoff trends than ordinary least‐squares (OLS) multiple regression models. Our results show that long‐term trends of water balance components in the WRB could be highly affected by anthropogenic climate change, but the direction and magnitude of such changes are highly dependent on the interactions between climate change and land surface hydrology. This suggests a need for spatially explicit adaptive water resource management within the WRB under climate change. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
674.
In a small island country like Taiwan, where the coastal zones have been heavily utilized, it is critical for the government to protect the health of near shore aquatic environment by enforcing the Marine Pollution Control Act (MPCA). However, the implementation of an effective plan based on MPCA is challenging local area. This is particular the case in the local level when the cross linkage among all related agencies is generally lacking. In 2004, the Kaohsiung city was aware of the shortfalls and then implemented an integrated marine pollution management system. The new system was adopted an action plan, that integrates all agencies with a strong communication mechanism. The encouraging results have shown substantial resource savings and a great improvement in water quality in the Kaohsiung marine environment. The success of this case reflects the needs for the concept of the integrated coastal zone management when dealing with marine affairs. 相似文献
675.
Acoustic reflection signatures of four hydro-carbon seeps were classified using near-bottom 25-kHz echosounder profiles. Echo patterns were compared with ground-truth data obtained by submersible observations and shallow coring. Six echo types were distinguished: strong reflections from (1)?exposed or (2)?buried hard substrates, such as authigenic carbonate or gas hydrate; acoustic scattering in (3)?unlayered or (4)?layered sediments owing to gas, shells, or disseminated carbonates; (5)?attenuation caused by gas; and (6)?undisturbed sediments. Echo type distributions suggest that high spatial variability indicates a younger, vigorous seep, whereas extensive hard substrate implies an older, encrusted seep. 相似文献
676.
Three methods, Shuffled Complex Evolution (SCE), Simple Genetic Algorithm (SGA) and Micro‐Genetic Algorithm (µGA), are applied in parameter calibration of a grid‐based distributed rainfall–runoff model (GBDM) and compared by their performances. Ten and four historical storm events in the Yan‐Shui Creek catchment, Taiwan, provide the database for model calibration and verification, respectively. The study reveals that the SCE, SGA and µGA have close calibration results, and none of them are superior with respect to all the performance measures, i.e. the errors of time to peak, peak discharge and the total runoff volume, etc. The performances of the GBDM for the verification events are slightly worse than those in the calibration events, but still quite satisfactory. Among the three methods, the SCE seems to be more robust than the other two approaches because of the smallest influence of different initial random number seeds on calibrated model parameters, and has the best performance of verification with a relatively small number of calibration events. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
677.
Evolution of scouring process downstream of grade‐control structures under steady and unsteady flows
For many incised channels, one of the most common strategies is to install some hard structures, such as grade‐control structures (GCSs), in the riverbed to resist further incision. In this study, a series of experiments, including both steady and unsteady flow conditions, were conducted to investigate the scouring process downstream of a GCS. Three distinct phases, including the initial, developing and equilibrium phases, during the evolution of scour holes were identified. In addition, a semi‐empirical method was proposed to predict the equilibrium scour‐hole profile for the scour countermeasure design. In general, the comparisons between the experimental and simulated results are reasonably consistent. As the studies on temporal variation of the scour depth at GCSs caused by floods are limited, the effect of flood hydrograph shapes on the scour downstream of GCSs without upstream sediment supply was also investigated experimentally in this study. Based on the dimensional analysis and the concept of superposition, a methodology is proposed to simulate the time evolution of the maximum scour depth downstream of a GCS for steady flows. Moreover, the proposed scheme predicts reasonably well the temporal variations of the maximum scour depth for unsteady flows with both single and multiple peak. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
678.
The deformation of the solid matrix affects the fluid pore pressure and flow by altering the pore volume. Such interaction in turn affects the storage of groundwater in the void space. Obviously, this subject is of interest in groundwater hydrology. This paper describes an investigation of the effect of aquifer heterogeneity on the variability of the fluid pressure head and solid's volume strain, where the assumption of a constant vertical total stress leads to a relatively simple relationship between changes in solid's volume strain and fluid pressure head. To solve the problem analytically, focus is placed on the one‐dimensional models. It is found from our closed‐form solutions that the variance and correlation length of the log hydraulic conductivity are important in increasing the variability of pressure head and solid's volume strain. It is hoped that our findings will provide a basic framework for understanding and quantifying field‐scale volume strain processes and be useful in stimulating further research in this area. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
679.
本文通过对五大连池地区矿泉水采样分析,进行同位素测年研究,提出该区矿泉水主要来于大气降水。原生冷矿水和次生冷矿水中的放射性碳都已经历了万年以上的蜕变,说明该区矿泉水地下迳流条件极差,其冷矿水形成时间长,资源有限,因此应有计划地合理开采利用,防止过量滥采而导致矿水资源枯竭。 相似文献
680.
Douglas S. Hall Gregory W. Henry Dietmar Böhme Peter A. Brooks Sandy Chang Ales Dolzan George L. Fortier Robert E. Fried Russell M. Genet Bruce S. Grim James Hannon Darrel B. Hoff Kevin Krisciunas Howard J. Landis Howard P. Louth Larry P. Lovell Paul Nielsen Bobby E. Powell Harry D. Powell Don Pray Thomas R. Renner Charles W. Rogers Stephen Shervais Douglas M. Slauson Samuel Slote Harold J. Stelzer Arthur J. Stokes Jack C. Troeger Louis C. Turner Norman F. Wasson Kenneth W. Zeigler 《Journal of Astrophysics and Astronomy》1991,12(4):281-287
We present photoelectric photometry of λ And never before published, obtained between February 1982 and December 1990 at 29
different observatories. Then we combine it with all other photometry available to us (previously published, contained in
the I.A.U. Commission 27 Archives, and obtained with the Vanderbilt 16-inch automatic telescope but not yet published), to
yield a 14.8-year data base. Analysis reveals a long-term cycle in mean brightness, with a full range of 0m.15 and a period of 11.4 ± 0.4 years. Because most of our new photometry was concentrated in the 1983-84 observing season,
we analyze that one well-defined light curve with a two-spot model. Spot A keeps a 0m.04 amplitude throughout four rotation cycles whereas the amplitude of spot B diminishes from 0m.09 down almost to 0m.03. The spot rotation periods were 55d.9 ± 0d.6 and 520d.8 ± 1d.0, respectively. 相似文献