Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

Effective EU and Member State policies for stimulating CCS

Although CO₂ capture and storage (CCS) is widely recognised as an option to mitigate climate change, consistent and effective EU policies to advance CCS are still absent. This paper discusses policy instruments for advancing large-scale deployment of CCS in the European Union, and evaluates them in a multi-criteria analysis. The EU Emissions Trading Scheme (EU-ETS) is a cost-effective instrument for limiting greenhouse gas emissions, but it is questionable whether its currently limited time horizon and short-trading periods will lead to substantial CCS diffusion. Complementary policies at the EU and the Member State level may repair this and provide sufficient incentives for CCS. Potential policies include financial instruments such as investment subsidies, a feed-in scheme, or a CO₂ price guarantee, as well as a CCS mandate or a low-carbon portfolio. These policy options differ with respect to their environmental effectiveness, possible interaction with the EU-ETS, costs and financial risk involved, and their competition with other mitigation options. Interactions between Member State policies and the EU-ETS are smaller in scope than those of EU-wide policies, but they are more likely to lead to displacement of financial resources from other low-carbon technologies. In addition, national policies may pose a significant part of the financial risk of CCS operations with Member States, reducing the operator's incentive to innovate. Overall, structural policies at the EU level, such as a mandate or a low-carbon portfolio standard would be more conducive for realising large-scale deployment of CCS across the EU as well as more acceptable to environmental organisations.     

Impacts on industry of Europe's emerging chemicals policy REACh

For Europe, a new regime in chemicals regulation is about to start. After the proposal of the European Commission concerning the Registration, Evaluation and Authorization of Chemicals (REACh) passed its readings in the European Parliament and some differences with the European Council of Ministers were resolved, the regulation will come into force in June 2007. This paper is focused on the question how serious the cost burdens for industry induced by REACh will be, and whether the New European Member States (NMS) which joined the European Union in May 2004 will be able to cope with the regulation. This evaluation has been done by assessing the legislative, administrative and economic framework in New Member States and by analysing real business cases in companies. The empirical showcase business impact studies are at the same time of interest for companies of EU-15 states, other European countries who may implement the regulation, and even for exporters of raw materials and chemicals outside Europe, who will also have to comply with REACh if they market in the European Community. The results give no indications that REACh adoption will bring significant drawbacks to companies in the NMS. The emerging regulation will bring challenges for individual companies, especially for small and medium-sized ones, but for the European chemical industry as a whole, there is no question that it will be able to cope with REACh burdens without losing its global competitiveness.     

Ecological scenarios analyzed and evaluated by a shallow lake model

We applied the complex ecosystem model EMMO, which was adopted to the shallow lake Müggelsee (Germany), in order to evaluate a large set of ecological scenarios. By means of EMMO, 33 scenarios and 17 indicators were defined to characterize their effects on the lake ecosystem. The indicators were based on model outputs of EMMO and can be separated into biological indicators, such as chlorophyll-a and cyanobacteria, and hydro-chemical indicators, such as phosphorus. The question to be solved was, what is the ranking of the scenarios based on their characterization by these 17 indicators? And how can we handle high quantities of complex data within evaluation procedures? The scenario evaluation was performed by partial order theory which, however, did not provide a clear result. By subsequently applying the hierarchical cluster analysis (complete linkage) it was possible to reduce the data matrix to indicator and scenario representatives. Even though this step implies losses of information, it simplifies the application of partial order theory and the post processing by METEOR. METEOR is derived from partial order theory and allows the stepwise aggregation of indicators, which subsequently leads to a distinct and clear decision. In the final evaluation result the best scenario was the one which defines a minimum nutrient input and no phosphorus release from the sediment while the worst scenario is characterized by a maximum nutrient input and extensive phosphorus release from the sediment. The reasonable and comprehensive results show that the combination of partial order, cluster analysis and METEOR can handle big amounts of data in a very clear and transparent way, and therefore is ideal in the context of complex ecosystem models, like that we applied.     

Validation of a hybrid life-cycle inventory analysis method

The life-cycle inventory analysis step of a life-cycle assessment (LCA) may currently suffer from several limitations, mainly concerned with the use of incomplete and unreliable data sources and methods of assessment. Many past LCA studies have used traditional inventory analysis methods, namely process analysis and input-output analysis. More recently, hybrid inventory analysis methods have been developed, combining these two traditional methods in an attempt to minimise their limitations. In light of recent improvements, these hybrid methods need to be compared and validated, as these too have been considered to have several limitations. This paper evaluates a recently developed hybrid inventory analysis method which aims to improve the limitations of previous methods. It was found that the truncation associated with process analysis can be up to 87%, reflecting the considerable shortcomings in the quantity of process data currently available. Capital inputs were found to account for up to 22% of the total inputs to a particular product. These findings suggest that current best-practice methods are sufficiently accurate for most typical applications, but this is heavily dependent upon data quality and availability. The use of input-output data assists in improving the system boundary completeness of life-cycle inventories. However, the use of input-output analysis alone does not always provide an accurate model for replacing process data. Further improvements in the quantity of process data currently available are needed to increase the reliability of life-cycle inventories.     

Deficit analysis: service capacity assessment and planning in developing countries – case study in the Philippines

Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example.     

隐伏断裂的地气测量及其意义

传统概念的地气测量是指地下上升到地表并扩散到大气空间的天然状态气体 ,如CO2 、CH4 、Rn、Hg、H2 等。近十多年的研究证实地气还包含着新的内涵 ,即地壳岩石以及地表土壤中还存着痕量的金属与非金属气体 ,通过捕集这些气体 ,可以获得更多的深部地质构造、矿床信息。据报导 ,国内外的研究主要是在已知矿床上做的正演研究。本文是在已知隐伏断层构造上方地表 ,试验金属与非金属地气存在的可能性。     

地铁区间隧道竖井送风有效风量研究

为得到地铁区间隧道竖井送风有效风量的无量纲计算模型,通过推导地铁区间隧道竖井送风有效风量的无量纲公式,并采用数值模拟方法明确竖井送风有效风量与火源功率、火源距离、阻塞比和竖井送风量之间的量化关系.结果表明:火源功率、火源距离与竖井送风有效风量之间不存在函数关系;阻塞比对竖井送风有效风量影响显著,随着阻塞比的增大,有效风...     

拉伸加载下老化复合固体推进剂的损伤演化定量分析

目的 定量分析老化对拉伸加载下复合固体推进剂细观损伤演化的影响规律。方法 开展不同老化时间（0、32、74、98 d）下三组元端羟基聚丁二烯（HTPB）复合固体推进剂的热加速老化试验,以及老化后推进剂的微型哑铃形试验件在不同拉伸应变水平（0、5%、10%、20%、40%、50%）下的微CT扫描观测试验,并对扫描重构图像进行定量分析,获得老化对推进剂细观损伤演化的影响规律。结果 随拉伸应变增加,老化前后推进剂微CT图像的灰度均方差、平均孔隙率和图像的分形维数均呈非线性增加趋势,图像的灰度均值呈非线性减小趋势。在较低应变水平（<10%）下,上述参数受老化时间的影响不显著,但随拉伸应变增加（≥10%）和老化时间增长,灰度均方差、平均孔隙率、孔隙率增量和分形维数的数值整体增高,而灰度均值随老化时间的增长而降低,且不同老化时间下,分形维数与平均孔隙率之间存在正线性关系。结论 重构得到微CT图像的灰度均值、平均孔隙率和分形维数可作为表征参数,用于定量分析老化复合固体推进剂在拉伸载荷下的细观损伤和损伤的动态演化规律,推进剂的初始损伤和小应变下的损伤程度受老化的影响较弱,而老化时间对推进剂细观损...