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121.
Impacts of environmental stressors on the water resources of intensively managed hydrologic systems 下载免费PDF全文
Watersheds are complex systems due to their surface and subsurface spatially connected water fluxes and biochemical processes that shape Earth's critical zone. In intensively managed landscapes, the implementation of watershed management practices (WMPs) regulate their short‐term responses, whereas climate variability controls the long‐term processes. Understanding their responses to anthropogenic and natural stressors requires a holistic approach that takes into account their multiscale spatio‐temporal linkages. The objective of this study was to simulate the impacts of spatially and temporally varying WMPs and projected climate changes on the surface and groundwater resources in the Upper Sangamon River Basin (USRB), a watershed in central Illinois greatly impacted by agricultural and industrial operations. The physically based hydrologic model MIKE‐SHE was used to simulate the hydrologic responses of the basin to different WMPs and climatic conditions. The simulation of a WMP was varied spatially across the basin to determine the spectrum of responses and critical conditions. In general, the wetlands and forested riparian buffer scenarios were found to cause a reduction in the average streamflow, whereas crop rotation had varied responses depending on the location of implementation and the climate condition assumed. Reductions of up to 30% in the average streamflow were found for the forested riparian buffer under the ESM 2M climate projections, whereas an increase of up to 13% with the crop rotation schemes under CM3 climate was predicted. The model results showed that the installation of tile drains across the USRB increased the water table depth (from ground level) by up to 56%, making crop production possible. Groundwater level in USRB appeared to be more sensitive to future climatic conditions than to WMP implementation. The impacts of WMPs are determined to depend on the climate conditions under which they are applied. Investigating individual and combined stressors' effects over the critical zone at a watershed scale can lead to a more comprehensive analysis of the risk and trade‐offs in every managerial decision that will enable an efficient use of resources. 相似文献
122.
于洪波 《地震地磁观测与研究》2012,33(3):214-217
应用倒谱对终止相识别的理论依据,根据厦门地震遥测中心记录的9·21集集地震进行实例分析,认为倒谱分析可以辅助识别终止相,结合传统的终止相走时特征和动力学特征识别方法,进而提高终止相识别的准确度。 相似文献
123.
宇宙成因核素~(21)Ne测年原理和应用 总被引:1,自引:1,他引:0
宇宙成因核素测年方法在地表暴露测年和沉积物埋藏测年方面均具有重要应用价值,还可用于定量计算地表侵蚀、地形抬升和河流下切等反映气候及构造运动影响的地表过程速率,对研究地球各圈层之间的相互作用关系具有重要意义,是第四纪年代学领域中一种重要的测年方法。与放射性宇宙成因核素10Be、26Al相比,稳定核素21Ne在地表暴露定年方面具有测年范围宽、测年材料选择范围广、测试所需样品量少、前处理过程简单等优点。通过与放射性核素的结合使用,稳定核素21Ne还可用于沉积物的埋藏测年,并具有比10Be-26Al埋藏测年法更高的测年上限和测年精度。稳定核素21Ne测年方法的应用在国内尚处于起步阶段,但可以预见,这一方法将以其独特的优势在第四纪地质学、地貌演化及活动构造等诸多研究领域得到广泛的应用。 相似文献
124.
晋县凹陷赵芯2井(2459m,Ezk)低熟蒸发岩样品中检出了异常分布的C22-C27甾烯和C24-C30四环萜烷(17,21-断藿烷),但在同井更深、成熟度相对更高的沉积物中并未检出。实测镜质组反射率R^0=0.43%以及芳烃馏分中有高丰度的苯并噻吩和多烷基化的二苯并噻吩,说明热催化作用成因是不可能的,微生物参与成为最可能的生成途经。沉积抽提物未显示出常规生物降解的痕迹,因此这些化合物很可能是在早期成岩阶段特定微生物作用的结果。该区油样中检出的C21-C29甾烷的特征与同时检出的C22-C27甾烯特征一致,进一步表明微生物作用的可能性;高丰度的C24-C30四环萜烷(17,21-断藿烷)和常规藿烷、甲基藿烷相匹配,以及高丰度的C22-C27甾烯和规则甾烷缺失相匹配,特别是芳烃馏分中多取代二苯并噻吩类有机含硫化合物的检出,均表明异常分布的C22-C27甾烯与C24-C30四环萜烷类似,很可能是早期成岩阶段微生物改造作用下的产物。 相似文献
125.
塔里木河中上游土地利用变化的径流响应 总被引:1,自引:0,他引:1
为了定量分析塔里木河中上游土地利用变化对径流的影响程度,基于塔里木河流域1980-2015年土地利用数据及相关水文系列资料,利用MIKE SHE分布式水文模型客观模拟评价了流域中上游土地利用变化下的水文响应过程。结果表明:MIKE SHE模型可以较好的模拟塔里木河流域中上游的日流量过程,在研究区具有良好的适用性;1980-2015年间流域土地利用变化导致流域地表日径流量减少了4.2 m3·s-1。通过仿真模拟分析草地、林地、耕地三种土地利用情景,得到日均流量分别为147.56 m3·s-1、141.80 m3·s-1,144.72 m3·s-1由此可见,该流域径流对不同土地利用类型的响应差异较大,产流量的总体趋势为草地>耕地>林地。研究成果对于流域土地利用格局的合理规划及极端水文事件的控制具有重要意义。 相似文献
126.
以沾化凹陷渤南洼陷罗63井和义21井沙一段取心段为例,依据研究样品的热解、全岩与黏土矿物X射线衍射、有机岩石学、孔隙度、氩离子抛光+扫描电镜以及微孔隙结构等分析结果,开展了沙一段湖相富有机质烃源岩岩石学与孔隙结构特征研究,结果表明:罗63井和义21井沙一段取心段富有机质烃源岩主要由碳酸盐矿物、黏土矿物和石英组成,另含少量长石、黄铁矿和石膏,其中黏土矿物主要由伊/蒙混层、伊利石组成,由取心段顶部至底部,碳酸盐矿物质量分数明显增高,而黏土矿物和石英则显著降低,呈现由钙质或灰质泥岩至演变为泥质灰岩的特征,岩石构造类型包括层状、纹层状和块状3类;罗63井和义21井沙一段取心段富有机质烃源岩平均孔隙度分别为2.09%和4.43%,具纹层状构造的烃源岩具有相对高的孔隙度;主要发育矿物基质孔隙(即粒间孔隙和粒内孔隙)和裂缝型孔隙两大类,而有机质孔隙不发育,孔隙半径从十几微米至几纳米的孔隙均有分布,以发育孔径50 nm以上的宏孔为主。 相似文献
127.
128.
Effect of potential evapotranspiration estimates on effective parameters and performance of the MIKE SHE-code applied to a medium-size catchment 总被引:3,自引:0,他引:3
R. F. Vzquez 《Journal of Hydrology》2003,270(3-4):309-327
The effect of the method of calculating a time series of crop potential evapotranspiration (ETp) on both the model performance and the magnitude of the main effective parameters of a distributed hydrological model was assessed on the basis of an independent multi-calibration. The ETp was estimated as a function of the reference evapotranspiration (ETo) by means of a crop coefficient approach. Three methods for deriving ETo estimates were used in modelling a medium size catchment in Belgium: (A) Food and Agriculture Organisation (FAO) FAO-24 standard approach; (B) FAO-24 approach but used with coefficients, for both the wind and the Stefan-Boltzmann equations, differing from the standard formulation; and (C) FAO-56 standard approach. For assessing the performance of the estimation approaches, the point scale ETo outputs of the generation methods were compared to local point scale ETo guidelines derived from previous research. The outputs of generation method B and of the generation method C showed a close agreement with the local point scale ETo guidelines. Their effect (to a catchment scale) on the performance of the hydrological model also seemed to be comparable. The best model performance was obtained by using the higher ETo data generated by method A. The research also revealed a significant dependency of some of the effective parameters on the different ETp estimates; especially of those parameters related to the computation of the actual evapotranspiration (ETact). 相似文献
129.
Climate Change Projections for the 21st Century by the NCC/IAP T63 Model with SRES Scenarios 总被引:10,自引:1,他引:10 下载免费PDF全文
1. IntroductionFor the latest 15 years, the climate change hasbeen paid more attention by the policy-makers, scien-tists, and the public. The global warming of 0.4-0.8°Cfor the 20th century has been measured by the instru-mental observations. The atmospheric concentrationof CO2 increased from 280 ppm for the period 1000-1750 to 368 ppm in the year 2000 with an increase of27%-35%. In the light of new evidence and taking intoaccount the remaining uncertainties, most of the ob-served warming o… 相似文献
130.
Floods have been the most severe natural disasters in the West Black Sea Region of Turkey for many years; therefore Ulus Basin
is selected as a study area for a thorough hydrologic flood analysis. The lack of embankments around the Ulus River and careless
changes to the riverbed made by villagers, resulted in major flood events in the basin, causing significant damage in the
area. In this study, the hydrodynamic characteristics of the basin and the riverbed are determined by calibrating the hydraulic
module of the MIKE 11 modeling system with the observed 1991 flood. Then, for the 25-, 50- and 100-year floods the highest
water levels in the river are forecasted by integration of the MIKE 11 hydrologic and hydraulic modules. Afterwards, inundation
maps are obtained by using together the hydraulic and GIS modules of the MIKE 11 system. 相似文献