Recent perspectives on temporary river ecology   总被引：1，自引：0，他引：1  

Thibault Datry  David B. Arscott  Sergi Sabater 《Aquatic Sciences - Research Across Boundaries》2011,73(4):453-457

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Catchments of German surface water bodies     

Andreas Gericke  Judith Mahnkopf  Markus Venohr 《水文研究》2021,35(7):e14272

The European Water Framework Directive demands to assess and report the chemical and ecological status of water bodies (WB). Linking their status to drivers and pressures and deriving suitable mitigation measures require knowledge of the shape and area of WB catchments. We derived a network of 26 570 WB catchments in Germany using the hydrologically-defined drainage basins of the German federal states. We established a network of 338 149 drainage basins. This network underwent plausibility checks and a validation with the catchment areas of 348 monitoring stations across Germany. To this network, we assigned the longest intersecting or the next downstream WB code. To account for geometric inaccuracies we revised spurious intersections resulting in splittings and cycles in the WB network. As WB may be ecologically but not hydrologically well defined, we split them at confluences and intersections. The network of drainage basins matched the monitoring stations with a Nash-Sutcliffe efficiency of 1.00. The final WB network contained 11 005 out of the 11 586 original WBs longer than 1 m. The corresponding local catchment areas range from <<0.0001 to 446 km², with a median of 10 km². The dataset combines the requirements of hydrological and ecological modelling applications at basin or national scales with the needs of the EU reporting which can foster their acceptance by state authorities and river-basin management.  相似文献   

The impacts of climate change in Europe (the PESETA research project)   总被引：1，自引：1，他引：0  

Juan-Carlos Ciscar 《Climatic change》2012,112(1):1-6

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Long-term variability of UV radiation in the spectral range of 300–380 nm in Moscow     

E. I. Nezval’  N. E. Chubarova 《Russian Meteorology and Hydrology》2017,42(11):693-699

The seasonal and interannual variability of global ultraviolet (UV) radiation in the spectral range of 300-380 nm (0380) in Moscow in 1968-2014 is analyzed. The effect of cloudiness on the magnitude of 0380 is assessed. The smallest (-22...-26%) losses due to cloudiness are registered in May-August, and the highest ones (to -45%) are observed in October-November. According to the UV radiation reconstruction model and measurement data, the long-term deviations of 0380 from the average (for 1968-1997) due to clouds can reach + (11-12)%. The statistically significant positive linear trend in total annual 0380 is revealed from the data of both the reconstruction model and observations (about 1.5% per decade for 1968-2014 and 3% per decade for 1979-2014).  相似文献   

Geoprotective properties of hydrate-bearing solid phases     

L. B. Svatovskaya  M. V. Shershneva  Yu. E. Puzanova 《Geochemistry International》2010,48(6):621-623

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The effect of the atmosphere on the propagation of high-power ultrabroadband microwave emission pulses     

V. N. Balakin  E. L. Stupitsky 《Geomagnetism and Aeronomy》2010,50(3):369-374

The effect of the atmosphere on the propagation of single successive pulses of the ultrabroadband microwave emission has been calculated in detail. It has been indicated that nonlinear effects mainly influence the propagation of the LF pulse part in the absence of divergence, which substantially affects the propagation of the following pulses.  相似文献   

Floods and livelihoods: The impact of changing water resources on wetland agro-ecological production systems in the Tana River Delta,Kenya     

Crystele Leauthaud  Stéphanie Duvail  Olivier Hamerlynck  Jean-Luc Paul  Hubert Cochet  Judith Nyunja  Jean Albergel  Olivier Grünberger 《Global Environmental Change》2013,23(1):252-263

Wetlands are highly dynamic and productive systems that have been under increased pressure from changes in land use and water management strategies. In Eastern Africa, wetlands provide resources at multiple spatial and temporal levels through farming, fishing, livestock ownership and a host of other ecosystem services that sustain the local economy and individual livelihoods. As part of a broader effort to describe future development scenarios for East African coastal wetlands, this qualitative study focuses on understanding the processes by which river water depletion has affected local food production systems in Kenya's Tana River Delta over the past 50 years, and how this situation has impacted residents’ livelihoods and well-being. Interviews performed in six villages among various ethnic groups, geographical locations and resource profiles indicated that the agro-ecological production systems formerly in place were adapted to the river's dynamic flooding patterns. As these flooding patterns changed, the local population diversified and abandoned or adopted various farming, fishing and livestock-rearing techniques. Despite these efforts, the decrease in water availability affected each subcomponent of the production systems under study, which led to their collapse in the 1990s. Water depletion negatively impacted local human well-being through the loss of food security. The current study provides a detailed account of the dynamics of agro-ecological production systems facing the effects of river water depletion in a wetland-associated environment in Sub-Saharan Africa.  相似文献   

Soil‐pile interaction in the pile vertical vibration considering true three‐dimensional wave effect of soil     

W.B. Wu  K.H. Wang  Z.Q. Zhang  Chin Jian Leo 《国际地质力学数值与分析法杂志》2013,37(17):2860-2876

The dynamic response of an end bearing pile embedded in a linear visco‐elastic soil layer with hysteretic type damping is theoretically investigated when the pile is subjected to a time‐harmonic vertical loading at the pile top. The soil is modeled as a three‐dimensional axisymmetric continuum in which both its radial and vertical displacements are taken into account. The pile is assumed to be vertical, elastic and of uniform circular cross section. By using two potential functions to decompose the displacements of the soil layer and utilizing the separation of variables technique, the dynamic equilibrium equation is uncoupled and solved. At the interface of soil‐pile system, the boundary conditions of displacement continuity and force equilibrium are invoked to derive a closed‐form solution of the vertical dynamic response of the pile in frequency domain. The corresponding inverted solutions in time domain for the velocity response of a pile subjected to a semi‐sine excitation force applied at the pile top are obtained by means of inverse Fourier transform and the convolution theorem. A comparison with two other simplified solutions has been performed to verify the more rigorous solutions presented in this paper. Using the developed solutions, a parametric study has also been conducted to investigate the influence of the major parameters of the soil‐pile system on the vertical vibration characteristics of the pile. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Roughness Lengths at Four Stations Within the Micrometeorological Network over the Indian Monsoon Region     

N. Narendra Reddy  Kusuma G. Rao 《Boundary-Layer Meteorology》2016,158(1):151-164

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A global assessment of the impact of climate change on water scarcity     

Simon N. Gosling  Nigel W. Arnell 《Climatic change》2016,134(3):371-385

This paper presents a global scale assessment of the impact of climate change on water scarcity. Patterns of climate change from 21 Global Climate Models (GCMs) under four SRES scenarios are applied to a global hydrological model to estimate water resources across 1339 watersheds. The Water Crowding Index (WCI) and the Water Stress Index (WSI) are used to calculate exposure to increases and decreases in global water scarcity due to climate change. 1.6 (WCI) and 2.4 (WSI) billion people are estimated to be currently living within watersheds exposed to water scarcity. Using the WCI, by 2050 under the A1B scenario, 0.5 to 3.1 billion people are exposed to an increase in water scarcity due to climate change (range across 21 GCMs). This represents a higher upper-estimate than previous assessments because scenarios are constructed from a wider range of GCMs. A substantial proportion of the uncertainty in the global-scale effect of climate change on water scarcity is due to uncertainty in the estimates for South Asia and East Asia. Sensitivity to the WCI and WSI thresholds that define water scarcity can be comparable to the sensitivity to climate change pattern. More of the world will see an increase in exposure to water scarcity than a decrease due to climate change but this is not consistent across all climate change patterns. Additionally, investigation of the effects of a set of prescribed global mean temperature change scenarios show rapid increases in water scarcity due to climate change across many regions of the globe, up to 2 °C, followed by stabilisation to 4 °C.  相似文献