Ecohydrologic Process Modeling of Mountain Block Groundwater Recharge

Regional mountain block recharge (MBR) is a key component of alluvial basin aquifer systems typical of the western United States. Yet neither water scientists nor resource managers have a commonly available and reasonably invoked quantitative method to constrain MBR rates. Recent advances in landscape-scale ecohydrologic process modeling offer the possibility that meteorological data and land surface physical and vegetative conditions can be used to generate estimates of MBR. A water balance was generated for a temperate 24,600-ha mountain watershed, elevation 1565 to 3207 m, using the ecosystem process model Biome-BGC (BioGeochemical Cycles) ( Running and Hunt 1993 ). Input data included remotely sensed landscape information and climate data generated with the Mountain Climate Simulator (MT-CLIM) ( Running et al. 1987 ). Estimated mean annual MBR flux into the crystalline bedrock terrain is 99,000 m³/d, or approximately 19% of annual precipitation for the 2003 water year. Controls on MBR predictions include evapotranspiration (radiation limited in wet years and moisture limited in dry years), soil properties, vegetative ecotones (significant at lower elevations), and snowmelt (dominant recharge process). The ecohydrologic model is also used to investigate how climatic and vegetative controls influence recharge dynamics within three elevation zones. The ecohydrologic model proves useful for investigating controls on recharge to mountain blocks as a function of climate and vegetation. Future efforts will need to investigate the uncertainty in the modeled water balance by incorporating an advanced understanding of mountain recharge processes, an ability to simulate those processes at varying scales, and independent approaches to calibrating MBR estimates.     

全面禁止核试验条约（CTBT）科学技术大会（SnT）的科学议程和地震事件性质识别研究进展

全面禁止核试验条约组织（Comprehensive Nuclear-Test-Ban Treaty Organization,CTBTO）科学技术大会（Science and Technology Conference,SnT）致力于推进禁核试的科技进步,依靠科技创新来加强《全面禁止核试验条约》（Comprehensive Nuclear-Test-Ban Treaty,CTBT）的条约核查制度能力,加快条约生效进程。鉴于地震学是禁核试监测的重要手段以及SnT大会的科学进展有助于检视地震科技的发展,本文系统分析了SnT大会的科学议题设置以及SnT大会中地震事件性质识别等研究进展。分析表明,SnT大会主题中的 “地球复杂系统” 和 “传感器与网络技术” ,以及禁核试监测手段中的地震学手段更受关注。事件性质识别研究始终是与CTBT相关的地震学的核心问题,其在朝鲜系列核试验事件的应用研究也同样是关注的焦点问题,而深度学习和机器学习等新技术在事件性质识别研究中展示了较快的发展趋势。      

湖泊富营养化响应与流域优化调控决策的模型研究进展

湖泊富营养化是全球水环境领域面临的长期挑战,富营养化响应与流域优化决策模型是制定经济和高效调控方案的关键.然而已有的模型研究综述主要集中于模型开发、案例应用、敏感性分析、不确定性分析等单一方面,而缺少针对非线性响应、生态系统长期演变等最新湖泊治理挑战的研究总结.本文对数据驱动的统计模型、因果驱动的机理模型和决策导向的优化模型进行了综述.其中,统计模型包含经典统计、贝叶斯统计和机器学习模型,常用于建立响应关系、时间序列特征分析以及预报预警;机理模型包含流域的水文与污染物输移模拟以及湖泊的水文、水动力、水质、水生态等过程的模拟,用于不同时空尺度的变化过程模拟,其中复杂机理模型的敏感性分析、参数校验、模型不确定性等需要较高的计算成本;优化模型结合机理模型形成“模拟优化”体系,在不确定性条件下衍生出随机、区间优化等多种方法,通过并行计算、简化与替代模型可一定程度上解决计算时间成本的瓶颈.本文识别了湖泊治理面临的挑战,包括:①如何定量表征外源输入的非线性叠加和湖泊氮、磷、藻变化的非均匀性?②如何提高优化调控决策和水质目标的关联与精准性?③如何揭示湖泊生态系统的长期变化轨迹与驱动因素?最后,本文针对这些挑战提出研究展望,主要包括:①基于多源数据融合与机器学习算法以提升湖泊的短期水质预测精度;②以生物量为基础的机理模型与行为驱动的个体模型的升尺度或降尺度耦合以表达多种尺度的物质交互过程;③机器学习算法与机理模型的直接耦合或数据同化以降低模拟误差;④时空尺度各异的多介质模拟模型融合以实现精准和动态的优化调控.     

Backbone curves with physical parameters for passive lateral response of homogeneous abutment backfills

Recent advances in performance-based seismic assessment and design of bridges call for the development of computationally efficient models with high fidelity for nonlinear static pushover and transient dynamic analyses. Response models of bridge abutment systems are significant ingredients of such analyses. Herein, we present closed-form relationships for lateral response of abutment backwalls with uniform backfills. These relationships are obtained by performing extensive parametric studies with a previously validated limit-equilibrium model coupled with hyperbolic soil stress–strain relations. The resulting “Generalized Hyperbolic Force–Displacement (GHFD)” backbone curve has explicit dependencies on the physical properties of the abutment system, including the backwall height. All input parameters to the GHFD relationships are measurable via standard geotechnical laboratory tests. We also perform a validation study using published measurements from several field and laboratory experiments. The GHFD equations are in closed form and can easily be implemented in a structural analysis package as a nonlinear spring that accounts for the bridge abutment–backfill interaction.     

地震预测模型优化方法研究

在分析现有基于观测指标“异常-正常”的“二态”地震前兆模式不足的基础上, 提出了异常可表现为多种状态的“多态”前兆模式, 给出“多态”前兆模式下预测效能判定指标, 进一步提出了基于预测效能最优的单项预测模型参数的选择方法。 在广义(时间、 空间、 时-空联合的预测指标)“多态”前兆模式下, 将所建立的模型应用于我国华北和南北带地区, 分别确定了两地区活断层预测地震(M_S≥6)空间分布的最优模型(分别为断层周围20 km、 30 km)及其预测效能(分别为0.42、 0.34)。     

The topical problems of identifying the results of the observations in recent geodynamics

The paper addresses the problems of identifying the results of deformational observations on the Earth, which arise from the new measurement technologies and lead to the ambiguity relationships such as the “spatial size of the anomaly—density of the observation sites” and the “duration of the anomalies—degree of temporal detail of the measurements.” It is found that many “paradoxical” conclusions concerning the rates and scales of the recent geodynamical processes are removed if the parameters of the measurement system match the properties of the studied object and if the relative character of the observational means is taken into account. It is shown that the time variation in the uniaxial deviatoric stress leads to the variation in the volumetric strain and, consequently, to the variation in gravity. The ambiguity in determining the ground displacement vectors by SAR interferometry is demonstrated. It is concluded that the autonomous use of the interferometry data leads to the significant distortions of the results, and these data should be necessarily used in combination with the ground-based geodetic observations.     

Evolution of seismic risk management for insurance over the past 30 years

During the past 30 years, there has been spectacular growth in the use of risk analysis and risk management tools developed by engineers in the financial and insurance sectors. The insurance, the reinsurance, and the investment banking sectors have enthusiastically adopted loss estimation tools developed by engineers in developing their business strategies and for managing their financial risks. As a result, insurance/reinsurance strategy has evolved as a major risk mitigation tool in managing catastrophe risk at the individual, corporate, and government level. This is particularly true in developed countries such as US, Western Europe, and Japan. Unfortunately, it has not received the needed attention in developing countries, where such a strategy for risk management is most needed. Fortunately, in the last five years, there has been excellent focus in developing "Insur Tech" tools to address the much needed "Insurance for the Masses", especially for the Asian Markets. In the earlier years of catastrophe model development, risk analysts were mainly concerned with risk reduction options through engineering strategies, and relatively little attention was given to financial and economic strategies. Such state-of-affairs still exists in many developing countries. The new developments in the science and technologies of loss estimation due to natural catastrophes have made it possible for financial sectors to model their business strategies such as peril and geographic diversification, premium calculations, reserve strategies, reinsurance contracts, and other underwriting tools. These developments have not only changed the way in which financial sectors assess and manage their risks, but have also changed the domain of opportunities for engineers and scientists.This paper will address the issues related to developing insurance/reinsurance strategies to mitigate catastrophe risks and describe the role catastrophe risk insurance and reinsurance has played in managing financial risk due to natural catastrophes. Historical losses and the share of those losses covered by insurance will be presented. How such risk sharing can help the nation share the burden of losses between tax paying public, the "at risk" property owners, the insurers and the reinsurers will be discussed. The paper will summarize the tools that are used by the insurance and reinsurance companies for estimating their future losses due to catastrophic natural events. The paper will also show how the results of loss estimation technologies developed by engineers are communicated to the business flow of insurance/reinsurance companies. Finally, to make it possible to grow "Insurance for the Masses – IFM", the role played by parametric insurance products and Insur Tech tools will be discussed.     

A neural network based general reservoir operation scheme

Construction of dams and the resulting water impoundments are one of the most common engineering procedures implemented on river systems globally; yet simulating reservoir operation at the regional and global scales remains a challenge in human–earth system interactions studies. Developing a general reservoir operating scheme suitable for use in large-scale hydrological models can improve our understanding of the broad impacts of dams operation. Here we present a novel use of artificial neural networks to map the general input/output relationships in actual operating rules of real world dams. We developed a new general reservoir operation scheme (GROS) which may be added to daily hydrologic routing models for simulating the releases from dams, in regional and global-scale studies. We show the advantage of our model in distinguishing between dams with various storage capacities by demonstrating how it modifies the reservoir operation in respond to changes in capacity of dams. Embedding GROS in a water balance model, we analyze the hydrological impact of dam size as well as their distribution pattern within a drainage basin and conclude that for large-scale studies it is generally acceptable to aggregate the capacity of smaller dams and instead model a hypothetical larger dam with the same total storage capacity; however we suggest limiting the aggregation area to HUC 8 sub-basins (approximately equal to the area of a 60 km or a 30 arc minute grid cell) to avoid exaggerated results.     

Intraseasonal predictability of the duration of flooding above National Weather Service flood warning levels across the U.S. Midwest

Unpreparedness is often the main cause of the economic and social damages caused by floods. To mitigate these impacts, short-term forecasting has been the focus of several studies during the past decades; however, less effort has been paid to flood predictions at longer lead times. Here, we use forecasts by six models from the North American Multi-Model Ensemble project with a lead time from 0.5 to 9.5 months to predict the seasonal duration of floods above four National Weather Service flood categories (“action,” “flood,” “moderate” and “major”). We focus on 202 U.S. Geological Survey gage stations across the U.S. Midwest and use a statistical framework which considers precipitation, temperature, and antecedent wetness conditions as predictors. We find that the prediction skill of the duration of floods for the “action” and “flood” categories is overall low, largely because of the low accuracy of the climate forecasts rather than of the errors introduced by the statistical models. The prediction skill slightly improves when considering the shortest lead times (i.e., from 0.5 to 2.5 months) during spring in the Northern Great Plains, where antecedent wetness conditions play an important role in influencing the generation of floods. It is very difficult to draw strong conclusions with respect to the “moderate” and “major” flood categories because of the limited number of available events.     

再论地震大小的度量

本文是针对迄今为止中国在地震大小的度量方面存在的主要问题撰写的。在阐明地震大小物理含义的基础上,首先指出由震源辐射能量E_R出发所定义的传统震级标度M_L,m_b(m_B),M_S都存在着"以偏概全","震级饱和"和M_L震级标度的"局限性",以及不同标度的震级之间不可相互换算等问题。而由在地震破裂的整个过程中震源区"等效力"所做的功出发导出的地震矩M₀是对地震大小最科学的度量。为继续应用"震级"这一术语来描述地震的大小,由M₀所定义的矩震级标度M_W不仅克服了传统震级标度存在的各种问题,而且适用对不同大小、不同震中距、不同震源深度地震大小的度量。因此近20年已被国际地震学界普遍采用。最后强调推进地震大小的度量与国际接轨是推进中国地震科技现代化必须解决的重要基础性工作,不仅有利于国际地震科技交流合作,而且有助于增强防震减灾工作的科学性。     

关于环境地球物理学的思考

分析了环境科学的研究领域，世界及我国的环境状况，世界范围的环境问题对地球科学提出了的和带来的机会。以此为基础提出了环境地球物理学的对象及研究方向。提出水资源的污染监测及水源保护应例为环境地球物理学的优先领域。     

Extending the Capture Map Concept to Estimate Discrete and Risk-Based Streamflow Depletion Potential

A popular and contemporary use of numerical groundwater models is to estimate the discrete relation between groundwater extraction and surface-water/groundwater exchange. Previously, the concept of a “capture map” has been put forward as a means to effectively summarize this relation for decision-making consumption. While capture maps have enjoyed success in the environmental simulation industry, they are deterministic, ignoring uncertainty in the underlying model. Furthermore, capture maps are not typically calculated in a manner that facilitates analysis of varying combinations of extraction locations and/or reaches. That is, they are typically constructed with focus on a single reach or group of reaches. The former of these limitations is important for conveying risk to decision makers and stakeholders, while the latter is important for decision-making support related to surface-water management, where future foci may include reaches that were not the focus of the original capture analysis. Herein, we use the concept of a response matrix to generalize the theory of the capture-map approach to estimate spatially discrete streamflow depletion potential. We also use first-order, second-moment uncertainty estimation techniques with the concept of “risk shifting” to place capture maps and streamflow depletion potential in a stochastic, risk-based framework. Our approach is demonstrated for an integrated groundwater/surface-water model of the lower San Antonio River, Texas, USA.     

Ecohydrologic separation alters interpreted hydrologic stores and fluxes in a headwater mountain catchment

Recent studies have demonstrated that compartmentalized pools of water preferentially supply either plant transpiration (poorly mobile water) or streamflow and groundwater (highly mobile water) in some catchments, a phenomenon referred to as ecohydrologic separation. The omission of processes accounting for ecohydrologic separation in standard applications of hydrological models is expected to influence estimates of water residence times and plant water availability. However, few studies have tested this expectation or investigated how ecohydrologic separation alters interpretations of stores and fluxes of water within a catchment. In this study, we compare two rainfall‐runoff models that integrate catchment‐scale representations of transport, one that incorporates ecohydrologic separation and one that does not. The models were developed for a second‐order watershed at the H.J. Andrews Experimental Forest (Oregon, USA), the site where ecohydrologic separation was first observed, and calibrated against multiple years of stream discharge and chloride concentration. Model structural variations caused mixed results for differences in calibrated parameters and differences in storage between reservoirs. However, large differences in catchment storage volumes and fluxes arise when considering only mobile water. These changes influence interpreted residence times for streamflow‐generating water, demonstrating the importance of ecohydrologic separation in catchment‐scale water and solute transport.     

Robust Data Worth Analysis with Surrogate Models

Highly detailed physically based groundwater models are often applied to make predictions of system states under unknown forcing. The required analysis of uncertainty is often unfeasible due to the high computational demand. We combine two possible solution strategies: (1) the use of faster surrogate models; and (2) a robust data worth analysis combining quick first-order second-moment uncertainty quantification with null-space Monte Carlo techniques to account for parametric uncertainty. A structurally and parametrically simplified model and a proper orthogonal decomposition (POD) surrogate are investigated. Data worth estimations by both surrogates are compared against estimates by a complex MODFLOW benchmark model of an aquifer in New Zealand. Data worth is defined as the change in post-calibration predictive uncertainty of groundwater head, river-groundwater exchange flux, and drain flux data, compared to the calibrated model. It incorporates existing observations, potential new measurements of system states (“additional” data) as well as knowledge of model parameters (“parametric” data). The data worth analysis is extended to account for non-uniqueness of model parameters by null-space Monte Carlo sampling. Data worth estimates of the surrogates and the benchmark suggest good agreement for both surrogates in estimating worth of existing data. The structural simplification surrogate only partially reproduces the worth of “additional” data and is unable to estimate “parametric” data, while the POD model is in agreement with the complex benchmark for both “additional” and “parametric” data. The variance of the POD data worth estimates suggests the need to account for parameter non-uniqueness, like presented here, for robust results.     

Regional calibration of a watershed model

Abstract

As watershed models become increasingly sophisticated and useful, there is a need to extend their applicability to locations where they cannot be calibrated or validated. A new methodology for the regionalization of a watershed model is introduced and evaluated. The approach involves calibration of a watershed model to many sites in a region, concurrently. Previous research that has sought to relate the parameters of monthly water balance models to physical drainage basin characteristics in a region has met with limited success. Previous studies have taken the two-step approach: (a) estimation of watershed model parameters at each site, followed by (b) attempts to relate model parameters to drainage basin characteristics. Instead of treating these two steps as independent, both steps are implemented concurrently. All watershed models in a region are calibrated simultaneously, with the dual objective of reproducing the behaviour of observed monthly streamflows and, additionally, to obtain good relationships between watershed model parameters and basin characteristics. The approach is evaluated using 33 basins in the southeastern region of the United States by comparing simulations using the regional models for three catchments which were not used to develop the regional regression equations. Although the regional calibration approach led to nearly perfect regional relationships between watershed model parameters and basin characteristics, these “improved” regional relationships did not result in improvements in the ability to model streamflow at ungauged sites. This experiment reveals that improvements in regional relationships between watershed model parameters and basin characteristics will not necessarily lead to improvements in the ability to calibrate a watershed model at an ungauged site.     

“互联网+”时代发展下的防震减灾宣传工作研究

随着“互联网+”时代的到来,人们接受信息的方式发生了翻天覆地的变化,越来越多的人们尤其是年轻人更愿意通过移动App、门户网站等来获取信息。为了顺应时代的变化,防震减灾宣传平台也需要转变宣传工作形式,更加注重碎片化、即时性、形象化的传播。结合“互联网+”时代信息通讯的实际特点,在分析当前防震减灾宣传工作存在的重要问题基础上,以“互联网+”时代信息传递技术为主要发展特点,提出防震减灾科普知识泛在化宣传新模式,并根据泛在化宣传模式的特征,设计开发基于iOS系统的泛在化宣传资源,为防震减灾宣传工作提供基于移动设备的数字化资源支持。该研究对移动互联网时代地震科普宣传作了新的探讨与尝试,对于当前及未来全民普及防震减灾科学知识有积极的促进作用。      

Advances in interpretation of subsurface processes with time‐lapse electrical imaging

Electrical geophysical methods, including electrical resistivity, time‐domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time‐lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time‐lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest. Copyright © 2014 John Wiley & Sons, Ltd.     

Advances in the use of observed spatial patterns of catchment hydrological response

Over the past two decades there have been repeated calls for the collection of new data for use in developing hydrological science. The last few years have begun to bear fruit from the seeds sown by these calls, through increases in the availability and utility of remote sensing data, as well as the execution of campaigns in research catchments aimed at providing new data for advancing hydrological understanding and predictive capability. In this paper we discuss some philosophical considerations related to model complexity, data availability and predictive performance, highlighting the potential of observed patterns in moving the science and practice of catchment hydrology forward. We then review advances that have arisen from recent work on spatial patterns, including in the characterisation of spatial structure and heterogeneity, and the use of patterns for developing, calibrating and testing distributed hydrological models. We illustrate progress via examples using observed patterns of snow cover, runoff occurrence and soil moisture. Methods for the comparison of patterns are presented, illustrating how they can be used to assess hydrologically important characteristics of model performance. These methods include point-to-point comparisons, spatial relationships between errors and landscape parameters, transects, and optimal local alignment. It is argued that the progress made to date augers well for future developments, but there is scope for improvements in several areas. These include better quantitative methods for pattern comparisons, better use of pattern information in data assimilation and modelling, and a call for improved archiving of data from field studies to assist in comparative studies for generalising results and developing fundamental understanding.     

极低频探地工程数据分析中的窗函数选择

“极低频探地（WEM）工程”是国家发展和改革委员会批准的“十一五”国家重大科学技术基础设施建设项目之一,用于资源探测和地震预测及其他前沿科学研究。文章对工程数据分析中所使用的窗函数进行研究,深入分析不同窗型对频谱泄露的影响,给出相应的 Matlab 仿真结果,提出适用于极低频探地工程项目数据分析的窗型选择。     

Vertical Discretization Impact in Numerical Modeling of Matrix Diffusion in Contaminated Groundwater

Understanding the effects of contaminants that can diffuse into low-permeability (“low-k”) zones is crucial for effective groundwater remedial decision-making. Because low-k zones can serve as low-level sources of contamination to more transmissive zones over time, an accurate evaluation of the impacts of matrix diffusion at contaminated sites is vital. This study compared numerical groundwater flow and transport simulations using MODFLOW/RT3D at a hypothetical site using three cases, each with increasing discretization of the vertical 10-m thick domain: (1) a coarse multilayer heterogeneous grid based on one layer for each of four different hydrogeological units, (2) a “low-resolution” discretization approach where the low-k units were divided into several sublayers giving the model 10 layers, and (3) a “high-resolution” numerical model with 199 layers that are a few centimeters thick. When comparing the results of each case, significant differences were observed between the discretizations used, even though all other model input data were identical. The conventional grid models (Cases 1 and 2) appeared to underestimate groundwater plume concentrations by a factor ranging from 1.1 to 36 when compared to the high-resolution grid model (Case 3), and underestimated predicted cleanup times by more than a factor of 10 for some of the hypothetical sampling points in the modeling domain. These results validate the implication of Chapman et al. (2012), that conventional vertical discretization of numerical groundwater flow and transport models at contaminated sites (with layers that are greater than 1 m thick) can lead to significant errors when compared to more accurate high-resolution vertical discretization schemes (layers that are centimeters thick).