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901.
通过科学合理地划分河段实现栖息地分类管理是恢复流域生物完整性的重要内容之一.湖泊流域入湖河流空间尺度小、坡降大、生态学过程差异性显著的特点导致其河段类型复杂多样,与河流流域河段类型的大尺度特征具有明显区别,因此,河流流域河段划分指标及其方法不适用于湖泊流域,亟需发展以栖息地分类管理为目的的湖泊流域河段划分方法.本文通过回顾河流分类的概念、划分依据及划分方法的发展历程,明确了湖泊流域河段划分理论基础,提出了基于保护目标制定的湖泊流域河段划分方法,为恢复湖泊流域生物完整性提供了更为精细的管理单元.同时,以滇池流域为例,通过筛选与大型底栖动物敏感种群和濒危种群显著相关的环境因子,建立了由地貌类型、土地利用方式、河水来源、河道人工化情况及水体营养程度构成的指标划分体系;在实现各划分指标空间化的基础上,利用空间叠加聚类技术手段,将滇池流域入湖河流划分为9个河段类型,为滇池流域水生态系统健康恢复提供了科学依据. 相似文献
902.
Paolo Cocci Francesco Alessandro Palermo Luana Quassinti Massimo Bramucci Antonino Miano Gilberto Mosconi 《环境科学学报(英文版)》2016,28(5):48-53
Environmental estrogen-like compounds (i.e. xenoestrogens) are a variety of pollutants, ranging from synthetic to natural occurring molecules, that are found in surface and waste waters over a wide range of concentrations. In aquatic environment, the overall estrogenic activity is often due to the presence of a mixture of chemicals and their degraded products which can induce synergistic effects. Current strategies for monitoring estrogen-like chemicals are based on the use of a battery of in vivo and in vitro ecotoxicological tests. In this regard, the aim of the present work was to carry out a bio-monitoring study for testing estrogenicity of the Chienti river (Marche Region, Italy) by using both an E-screen and a vitellogenin (Vtg) induction assay in juvenile goldfish. Three sites were used for analysis, localized at the mouth (sampling point 1), in the middle (sampling point 2) and at the origin (sampling point 3) of Chienti river. For most of the water samples (i.e. samples collected at sampling points 2 and 3), clear estrogenic activity was detected in the E-screen assay suggesting different proliferation activities in function of the collecting site. In contrast, the Vtg ELISA demonstrated that water samples collected from each sampling point were estrogenic. Overall, we showed for the first time that the estrogenic activities in water samples from the Chienti river were significant in both in vivo and in vitro; we also observed a different sensitivity between bioassays. 相似文献
903.
目的研究武汉市巡司河底淤泥在不同无机絮凝剂及PAM的助凝作用下淤泥清浑分界面的沉降速率、淤泥浓缩比以及淤泥沉降指数的变化情况。方法采用实验研究的方法,对巡司河底淤泥进行沉降实验,并通过沉降分析找到最佳脱水效果的脱水剂。结果当淤泥质量分数为10%时,Ca(OH)2取得的絮凝脱水效果最好,Ca(OH)2投加比为5 g/L,PAM投加比为0.04 g/L时,淤泥清浑分界面的沉降速率最大可达到3.7 cm/min,淤泥浓缩比为3.94,淤泥沉降指数为24.9%。结论 Ca(OH)2和PAM对巡司河底淤泥的脱水有促进效果,淤泥在Ca(OH)2和PAM共同作用下先后经历了自由沉降、絮凝沉降、区域沉淀和压缩沉降。 相似文献
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907.
Towards Real‐Time Continental Scale Streamflow Simulation in Continuous and Discrete Space
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Fernando R. Salas Marcelo A. Somos‐Valenzuela Aubrey Dugger David R. Maidment David J. Gochis Cédric H. David Wei Yu Deng Ding Edward P. Clark Nawajish Noman 《Journal of the American Water Resources Association》2018,54(1):7-27
The National Weather Service (NWS) forecasts floods at approximately 3,600 locations across the United States (U.S.). However, the river network, as defined by the 1:100,000 scale National Hydrography Dataset‐Plus (NHDPlus) dataset, consists of 2.7 million river segments. Through the National Flood Interoperability Experiment, a continental scale streamflow simulation and forecast system was implemented and continuously operated through the summer of 2015. This system leveraged the WRF‐Hydro framework, initialized on a 3‐km grid, the Routing Application for the Parallel Computation of Discharge river routing model, operating on the NHDPlus, and real‐time atmospheric forcing to continuously forecast streamflow. Although this system produced forecasts, this paper presents a study of the three‐month nowcast to demonstrate the capacity to seamlessly predict reach scale streamflow at the continental scale. In addition, this paper evaluates the impact of reservoirs, through a case study in Texas. Validation of the uncalibrated model using observed hourly streamflow at 5,701 U.S. Geological Survey gages shows 26% demonstrate PBias ≤ |25%|, 11% demonstrate Nash‐Sutcliffe Efficiency (NSE) ≥ 0.25, and 6% demonstrate both PBias ≤ |25%| and NSE ≥ 0.25. When evaluating the impact of reservoirs, the analysis shows when reservoirs are included, NSE ≥ 0.25 for 56% of the gages downstream while NSE ≥ 0.25 for 11% when they are not. The results presented here provide a benchmark for the evolving hydrology program within the NWS and supports their efforts to develop a reach scale flood forecasting system for the country. 相似文献
908.
Historical and Future Stream Temperature Change Predicted by a Lidar‐Based Assessment of Riparian Condition and Channel Width
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Gustav B. Seixas Timothy J. Beechie Caleb Fogel Peter M. Kiffney 《Journal of the American Water Resources Association》2018,54(4):974-991
Riparian forests attenuate solar radiation, thereby mediating an important component of the thermal budget of streams. Here, we investigate the relationship between riparian degradation, stream temperature, and channel width in the Chehalis River Basin, Washington State. We used lidar data to measure canopy opening angle, the angle formed between the channel center and trees on both banks; we assumed historical tree heights and calculated the change in canopy angle relative to historical conditions. We then developed an empirical relationship between canopy angle and water temperature using existing data, and simulated temperatures between 2002 and 2080 by combining a tree growth model with climate change scenarios from the NorWeST regional prediction. The greatest change between historical and current conditions (~7°C) occurred in developed portions of the river network, with the highest values of change predicted at channel widths less than ~40 m. Tree growth lessened climate change increases in maximum temperature and the length of river exceeding biologically critical thresholds by ~50%–60%. Moreover, the maximum temperature of channels with bankfull widths less than ~50 m remained similar to current conditions, despite climate change increases. Our findings are consistent with a possible role for the riparian landscape in explaining the low sensitivity of stream temperatures to air temperatures observed in some small mountain streams. 相似文献
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Christophe Boschet Tina Rambonilaza 《Journal of Environmental Planning and Management》2018,61(1):105-123
Several studies attempt to explain how collaborative environmental governance processes operate, but the question of why collaboration relationships form has received much less attention. Motivated by this need, this paper provides insights to the broad question: why does collaborative river basin management in France depend so heavily on partnerships made up around a few actors? Accordingly, our analytical framework develops a transaction cost explanation for the extent to which participatory procedures help stakeholders to identify partners and initiate collaboration, and for the causal link between the attributes of these stakeholders and their partnerships. The p2 model is implemented to investigate partnership networks of the key actors that govern the management of the Gironde estuary, the study case. The results provide evidence that environmental institutions bring together heterogeneous actors who might not be ready for collaboration, thereby actors’ perceived power similarity; their geographical proximity and co-presence in formal fora limit transaction costs. 相似文献