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191.
Morgan N. Hardwick-Witman Arthur C. Mathieson 《Estuarine, Coastal and Shelf Science》1983,16(2):113-129
Quantitative sampling of the dominant intertidal epibiota was conducted seasonally along an estuarine gradient within the Great Bay Estuary System, New Hampshire, U.S.A. The abundance and zonation of the dominant macroorganisms varied with distance into the estuary. Replacement of marine by estuarine species occurred, and overall abundance and species richness decreased along the estuarine gradient. Zonation patterns within the inner estuary were primarily allied with substrata. Maximum abundance of invertebrates occurred in the mid-intertidal zone where a dense fucoid canopy provided habitat heterogeneity. Densities of epibiotic organisms decreased toward low water, especially in the inner estuary where hard substratum was limiting. Settlement blocks, introduced into the low intertidal zone, were dominated by barnacles and fucoid algae; after 16 months, the species composition on the settlement blocks resembled the adjacent community. Semibalanus balanoides settled in the spring, while Fucus vesiculosus var. spiralis exhibited low but constant settlement. Despite the physical rigors of the estuarine environment, only Semibalanus balanoides, Ilyanassa obsoleta and Spartina alterniflora showed significant seasonal changes in density. Thus, there are predictable and persistent epibiotic species assemblages within the intertidal zone of the Great Bay Estuary System. 相似文献
192.
Thomas W. Cronin 《Estuarine, Coastal and Shelf Science》1982,15(2):207-220
Larvae of estuarine organisms continually face possible export from the parent estuary. Retention of larvae of the estuarine crab Rhithropanopeus harrisii was investigated in the upper Newport River estuary, North Carolina. All of the developmental stages occurred in the same area of the estuary with similar horizontal distributions, and the concentrations of intermediate and late stages were not greatly reduced from those of the first larval stage. This was strong evidence for the continuous retention of larvae in the upper estuary.To determine mechanisms by which retention might be effected, field studies of the vertical distributions and migrations of these larvae were made. The four zoeal stages had similar but complex vertical migration patterns, which varied from study to study. These migrations centered on the depth of no net flow, reducing longitudinal transport during development. Cross-spectral analysis of the larval migrations and the environmental cycles of light, salinity and current speed revealed that each of these external cycles affected larval depth. Megalopae of R. harrisii also migrated vertically, but they were present in much lower concentrations than the zoeal stages, an indication of a change to benthic existence in this final larval form. 相似文献
193.
194.
A geostatistically based approach is developed for the identification of aquifer transmissivities in Yolo Basin, California. The approach combines weighted least-squares with universal kriging and cokriging techniques in an overall scheme that (1)considers a prioriknown information on aquifer transmissivity and specific capacities of wells, (2)considers uncertainties in water level and transmissivity data, and (3)estimates the reliability of the generated transmissivity values. Minimization of a global least-squares function that incorporates calibration and plausibility criteria leads to a transmissivity map that shows a good agreement with pumping-test results. 相似文献
195.
196.
Hannu Marttila Annalea Lohila Pertti Ala-Aho Kashif Noor Jeffrey M. Welker Danny Croghan Kaisa Mustonen Leo-Juhani Meriö Anna Autio Filip Muhic Hannah Bailey Mika Aurela Jussi Vuorenmaa Timo Penttilä Valtteri Hyöky Eric Klein Anton Kuzmin Pasi Korpelainen Timo Kumpula Anssi Rauhala Bjørn Kløve 《水文研究》2021,35(9):e14350
Subarctic ecohydrological processes are changing rapidly, but detailed and integrated ecohydrological investigations are not as widespread as necessary. We introduce an integrated research catchment site (Pallas) for atmosphere, ecosystems, and ecohydrology studies in subarctic conditions in Finland that can be used for a new set of comparative catchment investigations. The Pallas site provides unique observational data and high-intensity field measurement datasets over long periods. The infrastructure for atmosphere- to landscape-scale research in ecosystem processes in a subarctic landscape has recently been complemented with detailed ecohydrological measurements. We identify three dominant processes in subarctic ecohydrology: (a) strong seasonality drives ecohydrological regimes, (b) limited dynamic storage causes rapid stream response to water inputs (snowmelt and intensive storms), and (c) hydrological state of the system regulates catchment-scale dissolved carbon dynamics and greenhouse (GHG) fluxes. Surface water and groundwater interactions play an important role in regulating catchment-scale carbon balances and ecosystem respiration within subarctic peatlands, particularly their spatial variability in the landscape. Based on our observations from Pallas, we highlight key research gaps in subarctic ecohydrology and propose several ways forward. We also demonstrate that the Pallas catchment meets the need for sustaining and pushing the boundaries of critical long-term integrated ecohydrological research in high-latitude environments. 相似文献
197.
Barry Hankin Trevor J. C. Page Nick A. Chappell Keith J. Beven Paul J. Smith Ann Kretzschmar Rob Lamb 《水文研究》2021,35(11):e14418
The Q-natural flood management project has co-developed with the Environment Agency 18 monitored micro-catchments (~1 km2) in Cumbria, UK installing calibrated flumes aimed at quantifying the potential shift in observed flows resulting from a range of nature-based-solutions installed by local organizations. The small-scale reduces the influence of variability characterizing larger catchments that would otherwise mask any such shifts, which we attempt to relate to a shift in model parameters. This paper demonstrates an approach to applying donor-parameter-shifts obtained from modelling two of the paired micro-catchments to a much larger scale, in order to understand the potential for improved distributed modelling of nature-based solutions in the form of additional tree-planting. The models include a rainfall-runoff model, Dynamic Topmodel, and a 2D hydrodynamic model, JFlow, permitting analysis of changes in hillslope processes and channel hydrodynamics resulting from a range of distributed measures designed to emulate natural hydrological processes that evaporate, store or infiltrate flows. We report on attempts to detect shift in hydrological response using one of the paired-micro-catchment moorland versus forestry sites in Lorton using Dynamic Topmodel. A donor-parameter-shift approach is used in a hypothetical experiment to represent new woodland in a much larger catchment, although testing all combinations of spatial planting strategies, responses to multiple-extremes, failure-modes and changes to synchronization becomes intractable to support good decision making. We argue that the problem can be re-framed to use donor-parameter-shifts at multi-local-scale catchments above communities known to be at risk, commensurate with most of the evidence of NbS impacts being effective at the small scale (ca. 10 km2). This might lead to more effective modelling to help catchment managers prioritize those communities-at-risk where there is more evidence that NbS might be effective. 相似文献
198.
1959-2017年天山乌鲁木齐河源1号冰川流域径流及其组分变化 总被引:1,自引:1,他引:0
冰川是气候变化的指示器,气候变化对冰川及其径流的影响研究是目前国内外关注的热点和前沿领域之一,目前的研究以模拟为主,实测资料十分有限且不确定性很大。以新疆天山乌鲁木齐河源1号冰川(简称“1号冰川”)流域为例,基于中国科学院天山冰川观测试验站1959-2017年观测数据,研究了中国西部典型小型冰川流域径流及其组分长期变化以及对气候变化的响应,为冰川径流长期变化过程的认识提供重要参考。结果表明,1号冰川流域径流主要由冰川径流和非冰川区降水径流组成,分别占70%和30%。其中冰川径流又可分为冰川区降水径流和冰川融水径流,分别占44%和26%。59年间,冰川径流整体呈上升趋势,在1992年之后出现了一个阶梯式的上升,与气温升高和降水的增加有关,1997-2007年达到高峰,2008年以后出现波动下降趋势,其原因除了与该时段的降水有所减少有关之外,冰川面积减小的影响也不可忽视。另外,还利用实测径流和冰川物质平衡值,通过水量平衡模型,检验了模型使用的冰川区和非冰川区径流系数。 相似文献
199.
WEI Xiang GUO Ying CHENG Hanlie MENG Xiangdong CHENG Mingqian YANG Ting XU Chunmei 《《地质学报》英文版》2019,93(2):362-372
Geological and hydrological characteristics, joint geometric features, rock physical and mechanical properties and rock mass quality are studied in the Beishan area, preselected for China’s high-level radioactive waste (HLW) disposal engineering. A comprehensive survey method is developed to study joint geometric features in the outcrop and samples from borehole BS06 into the Xinchang rock mass were tested. The optimal joint sets are determined by rose diagrams and equal-area lower hemisphere plots of joint poles. Results show that: 1) the distribution of joint occurrence obeys a normal distribution, while the distribution of joint spacing obeys a negative exponential distribution; 2) concentric circular and tangent circular sampling windows are applied to study the trace length and the trace midpoint density. Results indicate that tangent circular sampling window is more stable and reasonable; 3) Beishan granite shows high density, low porosity and high strength based on many laboratory tests and the physical properties and mechanical properties are closely related; and 4) a synthesis index, Joint Structure Rating (JSR), is applied to evaluate the quality of rock mass. Through the research results of rock mass characteristics, the Xinchang rock mass in the Beishan preselected area has the favorable conditions for China’s HLW disposal repository site. 相似文献
200.