MODELING THE LONG TERM IMPACTS OF USING RIGID STRUCTURES IN STREAM CHANNEL RESTORATION1

Abstract: Natural channel designs often incorporate rigid instream structures to protect channel banks, provide grade control, promote flow deflection, or otherwise improve channel stability. The long term impact of rigid structures on natural stream processes is relatively unknown. The objective of this study was to use long term alluvial channel modeling to evaluate the effect of rigid structures on channel processes and assess current and future stream channel stability. The study was conducted on Oliver Run, a small stream in Pennsylvania relocated due to highway construction. Field data were collected for one year along the 107 m reach to characterize the stream and provide model input, calibration, and verification data. FLUVIAL-12 was used to evaluate the long term impacts of rigid structures on natural channel adjustment, overall channel stability, and changing form and processes. Based on a consideration of model limitations and results, it was concluded that the presence of rigid structures reduced channel width-to-depth ratios, minimized bed elevation changes due to long term aggradation and degradation, limited lateral channel migration, and increased the mean bed material particle size throughout the reach. Results also showed how alluvial channel modeling can be used to improve the stream restoration design effort.     

Monitoring Ecosystems in the Sierra Nevada: The Conceptual Model Foundation

Monitoring at large geographic scales requires a framework for understanding relationships between components and processes of an ecosystem and the human activities that affect them. We created a conceptual model that is centered on ecosystem processes, considers humans as part of ecosystems, and serves as a framework for selecting attributes for monitoring ecosystems in the Sierra Nevada. The model has three levels: 1) an ecosystem model that identifies five spheres (Atmosphere, Biosphere, Hydrosphere, Lithosphere, Sociocultural), 2) sphere models that identify key ecosystem processes (e.g., photosynthesis), and 3) key process models that identify the "essential elements"that are required for the process to operate (e.g., solar radiation), the human activities ("affectors") that have negative and positive effects on the elements (e.g., air pollution), and the "consequences"of affectors acting on essential elements (e.g., change in primary productivity). We discuss use of the model to select attributes that best reflect the operation and integrity of the ecosystem processes. Model details can be viewed on the web at http://www.r5.fs.fed.us/sncf/spam_report/index.htm(Appendix section).     

基于典型线路地质灾害调查成果进行地质灾害区划评价的研究

根据影响区域地质灾害发生的地质因素、地形因素、诱发因素和人为因素,在工作区上选取典型线路开展地质灾害发生发育状况调查,根据调查成果总结规律,提取影响因子,建立区域地质灾害评价指标体系,对典型线路穿越的评价试验区进行地质灾害区域评价,验证线路成果应用于区域地质灾害评价的可行性,对于调查人员无法涉足、遥感技术难以应用的地区的地质灾害的评价工作有重要价值。     

倒置A^2／O工艺出水指标预测和评价方法的研究

研究了用一种简单的静态物理模型取代复杂的数学动态模型,实现对实际污水处理效果的实时预测及评价的方法。应用国际水协（IWA）GPS-X模拟软件中的ASM2d模型,建立了不同进水水质和不同运行参数条件下倒置A^2／O工艺出水TSS、COD、TN、NH4^＋-N、TP和溶解性磷酸盐浓度的数据库,结果表明,该数据库可以对倒置A^2／O工艺出水指标进行预测。以预测的出水指标和实际出水指标之间的差值为指标因素,采用专家打分法确定指标权重,通过对指标的分级界定建立因素指标的隶属函数,最后运用模糊综合评判的方法实现了对倒置A^2／O工艺处理效果的评价,建立了倒置A^2／O工艺处理效果的数学模型。     

Quantification of net primary production of Chinese forest ecosystems with spatial statistical approaches

Net primary production (NPP) of terrestrial ecosystems provides food, fiber, construction materials, and energy to humans. Its demand is likely to increase substantially in this century due to rising population and biofuel uses. Assessing national forest NPP is of importance to best use forest resources in China. To date, most estimates of NPP are based on process-based ecosystem modeling, forestry inventory, and satellite observations. There are little efforts in using spatial statistical approaches while large datasets of in-situ observed NPP are available for Chinese forest ecosystems. Here we use the surveyed forest NPP and ecological data at 1,266 sites, the data of satellite forest coverage, and the information of climate and topography to estimate Chinese forest NPP and their associated uncertainties with two geospatial statistical approaches. We estimate that the Chinese forest and woodland ecosystems have total NPP of 1,325 ± 102 and 1,258 ± 186 Tg C year⁻¹ in 1.57 million km² forests with a regression method and a kriging method, respectively. These estimates are higher than the satellite-based estimate of 1,034 Tg C year⁻¹ and almost double the estimate of 778 Tg C year⁻¹ using a process-based terrestrial ecosystem model. Cross-validation suggests that the estimates with the kriging method are more accurate. Our developed geospatial statistical models could be alternative tools to provide national-level NPP estimates to better use Chinese forest resources.     

Climate change and financial adaptation in Africa. Investigating the impact of climate change on the robustness of index-based microinsurance in Malawi

This paper discusses the applicability of crop insurance for the case of Malawi and explores the potential impact of climate change on the viability of the Malawi weather insurance program making use of scenarios of climate change-induced variations in rainfall patterns. The analysis is important from a methodological and policy perspective. By combining catastrophe insurance modeling with climate modeling, the methodology demonstrates the feasibility, albeit with large uncertainties, of estimating the effects of climate variability and climate change on the near- and long-term future of microinsurance schemes serving the poor. By providing a model-based estimate of insurance back-up capital necessary to avoid ruin under climate variability and climate change, along with the associated uncertainties and data limitations, this methodology can quantitatively demonstrate the need for financial assistance to protect micro-insurance pools against climate-induced insolvency. This is of major concern to donors, NGOs and others supporting these innovative systems, those actually at-risk and insurers providing insurance. A quantitative estimate of the additional burden that climate change imposes on weather insurance for poor regions is of interest to organizations funding adaptation. Further, by linking catastrophe modeling to regionalized climate modeling, the analysis identifies key modeling inputs necessary as well as important constraints. We end with a discussion of the opportunities and limits to similar modeling and weather predictability for Sub-Saharan Africa beyond the case of Malawi.

高级气候建模与环境仿真系统研究

结合大气环境建模与仿真基础技术及其仿真应用的发展现状,概述了高级气候建模与环境仿真（ACMES）系统的研究背景、核心技术、主要功能和实际运用效果。ACMES系统是大气环境仿真应用方面效费比优良的计算机仿真系统,可为建模与仿真用户提供高分辨率的气候统计产品。     

地质灾害危险性区划评价中隶属度函数构造方法的探讨

运用模糊综合评判方法进行地质灾害危险性区划评价的过程中,隶属函数的构造是一项复杂而重要的工作。在总结前人经验的基础上,对参与区划评价的定量因子的隶属度计算采用了一个简化的"二值模型"的方法构造隶属函数,计算隶属度,收到较好的效果。     

不同季节中水回用于景观水体的藻类增长模拟

文章基于wASP的富营养化模型,模拟了在各季节中水回用于城市景观水体时,不同水质和换水周期条件下叶绿素a峰值和平衡浓度的变化情况.模拟结果表明:(1)在中水水质和换水周期一定时,水华风险在夏季最大,春秋季次之,冬季最小;(2)在夏季和春秋季节,叶绿素a平衡浓度随着换水周期的减小先升高后降低;并且当换水周期小于3天时,减...     

Sewage sludge composting simulation as carbon/nitrogen concentration change

Model in composting play a very promising challenge to many scholars, this article adds on the improving ways for model the compost and composting