Exploratory modeling for analyzing coupled human-natural systems under uncertainty

Modeling is a crucial approach for understanding the past and exploring the future of coupled human-natural systems. However, uncertainty in various forms challenges inferences from modeling results. Model-based support for decision-making has increasingly adopted an emerging exploratory approach. This approach addresses uncertainty explicitly through systematically exploring the implications of modeling assumptions, aiming to enhance the robustness of inferences from models. Despite a variety of applications, the extent and the way(s) that exploratory modeling can deal with the challenges that arise from the uncertainty and complexity of decision-making with stakeholders has not yet been systematically framed. We address this gap in two ways. First, we present a taxonomy of the ways that exploratory modeling can be used to inform robust inferences in coupled human-natural systems by mapping the technical capabilities of this approach in relation to the diversity of past applications. This subsequently guides an investigation of the practical benefits and challenges of these capabilities in handling uncertainty and complexity. Second, we discuss different ways for integrating genuine stakeholder engagement into exploratory modeling through transdisciplinary research. Finally we outline some priorities for future expansion of this research area.     

Drought and the future of rural communities: Opportunities and challenges for climate change adaptation in regional Victoria,Australia

Australia's vulnerability to climate variability and change has been highlighted by the recent drought (i.e. the Big Dry or Millennium Drought), and also recent flooding across much of eastern Australia during 2011 and 2012. There is also the possibility that the frequency, intensity and duration of droughts may increase due to anthropogenic climate change, stressing the need for robust drought adaptation strategies. This study investigates the socio-economic impacts of drought, past and present drought adaptation measures, and the future adaptation strategies required to deal with projected impacts of climate change. The qualitative analysis presented records the actual experiences of drought and other climatic extremes and helps advance knowledge of how best to respond and adapt to such conditions, and how this might vary between different locations, sectors and communities. It was found that more effort is needed to address the changing environment and climate, by shifting from notions of ‘drought-as-crisis’ towards acknowledging the variable availability of water and that multi-year droughts should not be unexpected, and may even become more frequent. Action should also be taken to revalue the farming enterprise as critical to our environmental, economic and cultural well-being and there was also strong consensus that the value of water should be recognised in a more meaningful way (i.e. not just in economic terms). Finally, across the diverse stakeholders involved in the research, one point was consistently reiterated: that ‘it's not just drought’. Exacerbating the issues of climate impacts on water security and supply is the complexity of the agriculture industry, global economics (in particular global markets and the recent/ongoing global financial crisis), and demographic changes (decreasing and ageing populations) which are currently occurring across most rural communities. The social and economic issues facing rural communities are not just a product of drought or climate change – to understand them as such would underestimate the extent of the problems and inhibit the ability to coordinate the holistic, cross-agency approach needed for successful climate change adaptation in rural communities.     

Agricultural risk management policies under climate uncertainty

Climate change is forecasted to increase the variability of weather conditions and the frequency of extreme events. Due to potential adverse impacts on crop yields it will have implications for demand of agricultural risk management instruments and farmers’ adaptation strategies. Evidence on climate change impacts on crop yield variability and estimates of production risk from farm surveys in Australia, Canada and Spain, are used to analyse the policy choice between three different types of insurance (individual, area-yield and weather index) and ex post payments. The results are found to be subject to strong uncertainties and depend on the risk profile of different farmers and locations; the paper provides several insights on how to analyse these complexities. In general, area yield performs best more often across our countries and scenarios, in particular for the baseline and marginal climate change (without increases in extreme events). However, area yield can be very expensive if farmers have limited information on how climate change affects yields (misalignment in expectations), and particularly so under extreme climate change scenarios. In these more challenging cases, ex post payments perform well to increase low incomes when the risk is systemic like in Australia; Weather index performs well to reduce the welfare costs of risks when the correlation between yields and index is increased by the extreme events. The paper also analyses the robustness of different instruments in the face of limited knowledge of the probabilities of different climate change scenarios; highlighting that this added layer of uncertainty could be overcome to provide sound policy advice under uncertainties introduced by climate change. The role of providing information to farmers on impacts of climate change emerges as a crucial result of this paper as indicated by the significantly higher budgetary expenditures occurring across all instruments when farmers’ expectations are misaligned relative to actual impacts of climate change.     

Geometry,spatial arrangement and origin of carbonate grain‐dominated,scour‐fill and event‐bed deposits: Late Jurassic Jubaila Formation and Arab‐D Member,Saudi Arabia

Outcrop analogues of the Late Jurassic lower Arab‐D reservoir zone in Saudi Arabia expose a succession of fining‐upward cycles deposited on a distal middle‐ramp to outer‐ramp setting. These cycles are interrupted by erosional scours that incise up to 1·8 m into underlying deposits and are infilled with intraclasts up to boulder size (1 m diameter). Scours of similar size and infill are not commonly observed on low‐angle carbonate ramps. Outcrops have been used to characterize and quantify facies‐body geometries and spatial relationships. The coarse grain size of scour‐fills indicates scouring and boulder transport by debris or hyperconcentrated density flows strengthened by offshore‐directed currents. Longitudinal and lateral flow transformation is invoked to produce the ‘pit and wing’ geometry of the scours. Scour pits and wings erode up to 1·8 m and 0·7 m deep, respectively, and are on average 50 m wide between wing tips. The flat bases of the scours and their lack of consistent aspect ratio indicate that erosion depth was limited by the presence of cemented firmgrounds in underlying cycles. Scours define slightly sinuous channels that are consistently oriented north–south, sub‐parallel to the inferred regional depositional strike of the ramp, suggesting that local palaeobathymetry was more complex than commonly assumed. Weak lateral clustering of some scours indicates that they were underfilled and reoccupied by later scour incision and infill. Rudstone scour‐fills required reworking of material from inner ramp by high‐energy, offshore‐directed flows, associated with storm action and the hydraulic gradient produced by coastal storm setup, to generate erosion and sustain transport of clasts that are generally associated with steeper slopes. Quantitative analysis indicates that these coarse‐grained units have limited potential for correlation between wells as laterally continuous, highly permeable reservoir flow units, but their erosional and locally clustered character may increase effective vertical permeability of the Arab‐D reservoir zone as a whole.     

非均质含水层中渗流与溶质运移研究进展简

Natural aquifer heterogeneity controls the groundwater flow and solute transport, and how to accurately quantify the flow and solute transport in heterogeneous aquifers has received wide attention by many scholars, and has become a hot research topic in earth science. Theoretically, a systematic review is given by the following aspect: flow and solute transport model, moment analysis, multi scale analysis. The resolved and remained issues for scale conversion in hydrogeology research are pointed out. Secondly, recent advances of heterogeneous field test, uncertainty and velocity connectivity are analyzed. Finally, the geophysical inversion of aquifer heterogeneity, stochastic theory and development of stochastic simulation software, scale conversion and uncertainty of velocity connectivity, and the relationship between heterogeneity and hydrogeological condition on the major four aspects of the future research direction is pointed out.     

ICP-MS测定矿泉水中锂和锶含量的不确定度分析

采用电感耦合等离子体质谱法（ICP-MS）对饮用天然矿泉水中的锂和锶进行测定,分析了测定过程中不确定度的主要来源,按JJF 1059-1999《测量不确定度评定与表示》对各个不确定度来源进行分析评定,给出了此法测定过程中的扩展不确定度,使得测定结果的表达更加客观和真实.     

Coupled hydro-mechanical fault reactivation analysis incorporating evidence theory for uncertainty quantification

The injection of water (or CO₂) at high pressure is a common practice to enhance oil production. A crucial component of this activity is the estimation of the maximum pressure at which the fluids can be injected without inducing the reactivation of pre-existing faults that may exist in the formation. The damage zones typically formed around the geological faults are highly heterogeneous. The materials involved in the damage zones are characterized by the huge variation of their properties and high uncertainties associated with them. To estimate the maximum allowable injection pressure this paper presents a novel approach based on: a coupled hydro-mechanical formulation (for the numerical analyses); a criterion based on the total plastic work (for the fault reactivation); and the evidence theory (for uncertainty quantification). A case study based on information gathered from an actual field is presented to illustrate the capabilities of the proposed framework.     

Calibrating cross-site variability for reliability-based design of pile foundations

The cross-site variability (i.e., variability from site to site) makes the statistics of the bias factor of a design model vary from site to site. How to characterize the cross-site variability of the model bias factor is important for design of pile foundations based on site-specific load test data. In this study, a probabilistic model that allows for explicit modeling of the cross-site variability is suggested. An equation is derived based on Bayes’ theorem to calibrate the suggested model with load test data from different sites, which is applicable even when the number of load tests at each site is small. A procedure based on hybrid Markov Chain Monte Carlo simulation is employed to solve the Bayesian equation. How to update the statistics of the model bias factor, when applied to a future site, with site-specific load test data is also described. As an illustration, the probabilistic model is applied to the design of bored piles in Shanghai, China. It is found that, given a certain number of site-specific pile load tests, the effect of updating depends on the mean and the COV of the measured model bias factor. With the assistance of regional experience, a small number of load tests can significantly reduce the uncertainty associated with the design model, and further increase in the number of load tests may not change the site-specific statistics of the bias factor and hence the resistance factor substantially.     

我国现代气候业务现状及未来发展趋势

从气候监测诊断、气候预测、气候系统模式、气候评价与灾害风险管理、气候变化业务和气候业务平台等角度,系统概述了我国现代气候业务现状。提出了以气候监测和动力学诊断为基础,以提升气候服务、气候风险管理和应对气候变化能力为目标,以发展客观化气候预测技术和定量化气候评估方法为核心的现代气候业务概念。分析了国际气候业务发展趋势及我国气候业务的差距,明确了加强气候系统基本变量监测、提高气候系统模式分辨率和改进物理过程、发展第2代短期气候预测系统、研发气象灾害风险评估方法并建立中国气候服务系统 (CFCS) 等发展任务。     

Replacing carbon lost from forests: an assessment of insurance,reserves, and expiring credits

Abstract

Concern over the “non-permanence” or reversibility of carbon sequestration projects has been prominent in discussions over how to develop guidelines for forest project investments under the Clean Development Mechanism (CDM) of the UNFCCC Kyoto Protocol. Accordingly, a number of approaches have been proposed that aim to help ensure that parties do not receive credit for carbon that is lost before project obligations are fulfilled. These approaches include forest carbon insurance, land reserves, and issuance of expiring credits. The potential costs of each of these different approaches are evaluated using a range of assumptions about project length, risk and discount rate, and a comparison of costs is ventured based on the estimated reduction in value of these credits compared with uninsured, and permanent credits. Obstacles to participation in the different approaches are discussed related to problems of long-term commitments, project scale, rising replacement costs, and low credit value. It is concluded that a system of expiring credits, which could be coupled with insurance or reserves, could guarantee obligations that span time-scales longer than that of conventional insurance policies while maintaining incentives for long-term sequestration.