Parametric uncertainty and sensitivity analysis of hydrodynamic processes for a large shallow freshwater lake

Abstract

A parametric uncertainty and sensitivity analysis of hydrodynamic processes was conducted for a large shallow freshwater lake, Lake Taihu, China. Ten commonly used parameters in five groups were considered including: air–water interface factor, water–sediment interface factor, surrounding terrain factor, turbulent diffusion parameters and turbulent intensity parameters. Latin hypercube sampling (LHS) was used for sampling the parametric combinations, which gave predictive uncertainty results directly without using surrogate models, and the impacts of different parametric distribution functions on the results were investigated. The results showed that the different parametric distribution functions (e.g. uniform, normal, lognormal and triangular) for sampling had very little impact on the uncertainty and sensitivity analysis of the lake hydrodynamic model. The air–water interface factor (wind drag coefficient) and surrounding terrain factor (wind shelter coefficient) had the greatest influence on the spatial distribution of lake hydrodynamic processes, especially in semi-closed bays and lake regions with complex topography, accounting for about 60–70% and 20%, respectively, of the uncertainty on the results. Vertically, velocity in the surface layer was also largely influenced by the two factors, followed by velocity in the bottom layer; the middle velocity had minimal impact. Likewise, the water–sediment interface factor (i.e. bottom roughness height) ranked third, contributing about 10% to the uncertainty of the hydrodynamic processes of the lake. In contrast, turbulent diffusion parameters and turbulent intensity parameters in the lake hydrodynamic model had little effect on the uncertainty of simulated results (less than 1% contribution). The findings were sufficiently significant to reduce the parameter uncertainties and calibration workload of the hydrodynamic model in large shallow lakes.

Editor Z. W. Kundzewicz; Associate editor S. Grimaldi     

POPs and their ecological risk in sewage sludge of waste water treatment plants in Beijing, China

The concentrations of three classes of persistent organic compounds (POPs) in the sewage sludge from 12 Beijing wastewater treatment plants (WWTPs) were investigated and their ecological risks were assessed. The concentrations of 15 polycyclic aromatic hydrocarbons (PAHs), 27 polychlorinated biphenyl congeners (PCBs) and 15 organochlorine pesticides (OCPs) in sewage sludge were measured using gas chromatography–tandem mass spectrometry (GC–MS/MS) technique. Total PAHs concentrations ranged from 445.1 to 3,586.4 ng g^?1 dry weight (dw), and the sum of the phenanthrene (Phe), anthracene (Ant), naphthalene (Nap), fluoranthene and chrysene accounted for 69.3–97.0 % of the total PAHs. The most abundant compounds present were 2-ring and 3-ring Ant, Phe and Nap, indicating a possible petrogenic source. Total PCBs concentrations were ranged between 3.2 and 21.8 ng g^?1 dw. Total OCPs concentrations ranged from 38.0 to 143.3 ng g^?1 dw, and the sum of total DDT, HCB and HCHs accounted for 69.6–97.7 % of the total OCPs. The levels of PAHs, PCBs and OCPs in this study were comparable to or lower than those reported in relatively WWTPs from other regions. In addition, they were also shown to have various distribution patterns, possibly due to their different wastewater sources. The 12 WWTPs may be classified into 4 groups because of their different sources of waste water based on cluster analysis. The ecological risk assessment shows that the concentrations of Ant or Fla at two sites, p,p′-DDE and ∑DDT at 83 % of the 12 sites may cause adverse ecological effects.     

关于“胡焕庸线能否突破”的学术争鸣

著名地理学家胡焕庸先生于1935年提出中国人口地理的重要分界线（简称“胡焕庸线”）,被广泛认可和引用,是中国地理学发展的重要成果。2014年底,李克强总理参观人居科学研究展时,高度关注胡焕庸线,并提出了胡焕庸线能否突破的问题。胡焕庸线因而再度引起争论和热议。据此,组织了一些地理学者围绕该问题进行学术讨论,力图从不同层面展现学者们对胡焕庸线的理解与反思,从而深化胡焕庸线的科学价值和现实意义,进而指导中国新型城镇化战略的实施和区域实践。     

滇东北早石炭世无烟煤理化特性及应用方向

经过10余年的资源勘查和多学科的综合研究,已基本查明滇东北(昭通市)早石炭世无烟煤的分布、煤质特征及主要利用方向。与国内外其他地区、其他时代的无烟煤比较,本区无烟煤内在矿物质含量极低、有机组分中主要成分为无结构镜质体,有机质中C、H元素高达97%,H/C原子比为0.5。结合X衍射分析(XRD)和高分辨透射电镜(HRTEM)研究结果,该区无烟煤有机质的化学组成与分子构型与沥青中间相炭微球(MCMB)类似。一系列实验表明,经选别制备的超低灰无烟煤是多种中、高端新型炭材料和炭素的优质原料。有序而保护性地开发利用该区资源,对我国经济建设和社会发展具有重要意义。      

四川丘陵区经济发展的核心要素及其驱动能力

以四川68个丘陵县(市、区)为研究区域和对象,采用Pearson相关分析法,选择农业总产值、规模以上工业总产值、规模以上工业增加值、全社会固定资产投资等要素与GDP、地方财政收入、人均GDP、人均地方财政收入等经济发展水平重点指标进行相关性分析,定量分析得出了工业发展水平、社会固定资产投入水平对丘陵区经济发展具有明显的驱动作用,并就驱动能力进行了定量测度,并选择传统农业县、工业较发达县、旅游和第三产业较发达县作为典型案例进行具体分析,最后,提出了丘陵区发展的主要思路和建议.     

福建地区中小地震加速度反应谱衰减规律

本文基于收集福建省地震监测台网7个基岩台站从1999年至2007年获得的94个地震(ML=2.8～4.9,△=13～462 km) 的1974条宽频带速度记录,利用实时仿真方法得到了相应的加速度记录,进而得到了福建地区基岩场地中小地震绝对加速度反应谱的衰减关系.对基岩反应谱有影响的因素主要有震源、传播途径,本文简要分析这两个因素对地震动的影响.此项工作对于福建省抗震设防具有重要的意义.     

Hydrological effects of the increased CO2 and climate change in the Upper Mississippi River Basin using a modified SWAT

Increased atmospheric CO₂ concentration and climate change may significantly impact the hydrological and meteorological processes of a watershed system. Quantifying and understanding hydrological responses to elevated ambient CO₂ and climate change is, therefore, critical for formulating adaptive strategies for an appropriate management of water resources. In this study, the Soil and Water Assessment Tool (SWAT) model was applied to assess the effects of increased CO₂ concentration and climate change in the Upper Mississippi River Basin (UMRB). The standard SWAT model was modified to represent more mechanistic vegetation type specific responses of stomatal conductance reduction and leaf area increase to elevated CO₂ based on physiological studies. For estimating the historical impacts of increased CO₂ in the recent past decades, the incremental (i.e., dynamic) rises of CO₂ concentration at a monthly time-scale were also introduced into the model. Our study results indicated that about 1–4% of the streamflow in the UMRB during 1986 through 2008 could be attributed to the elevated CO₂ concentration. In addition to evaluating a range of future climate sensitivity scenarios, the climate projections by four General Circulation Models (GCMs) under different greenhouse gas emission scenarios were used to predict the hydrological effects in the late twenty-first century (2071–2100). Our simulations demonstrated that the water yield would increase in spring and substantially decrease in summer, while soil moisture would rise in spring and decline in summer. Such an uneven distribution of water with higher variability compared to the baseline level (1961–1990) may cause an increased risk of both flooding and drought events in the basin.     

基于MapGIS建立的中国地质环境图系数据库

中国地质环境图系数据库,是中国首套统一结构、统一格式、统一编码的涵盖地质环境、地质灾害、地下水、矿山地质环境、地质遗迹5个专业领域的全国性数据库。该套数据库是基于1：1 000 000数据源的地理信息库,以分省1：500 000环境地质调查、县市地质灾害调查、重点地区1：50 000地质灾害调查、新一轮地下水资源评价、第二轮全国矿山地质环境摸底调查和矿产资源集中开采区矿山地质环境调查、首轮地质遗迹调查等数据为基础,集成近20年来水工环地质调查监测数据和最新综合研究成果,根据统一的建库技术要求建立而成。该套数据库具有统一的系统库（符号库、颜色库、图案库、线型库）,属性按照统一的编码规则和要求建立,图件按照统一的图饰图例进行了规范化处理,共包含163个专业图层,图元数量共337 833个,容量约8.8 GB。该套数据库为实现成果图件的动态管理与更新、构建数字地质环境奠定了基础,可为地质环境保护管理、国土空间规划、生态修复、地质灾害防治提供详细的基础信息资料。     

The Late Carboniferous–Early Permian Ocean-Continent Transition in the West Junggar, Central Asian Orogenic Belt: Constraints from Columnar Jointed Rhyolite

The West Junggar of the western Central Asian Orogenic Belt is one of the typical regions in the term of ocean subduction, contraction and continental growth in the Late Paleozoic. However, it is still controversial on the exact time of ocean-continent transition so far. This study investigates rhyolites with columnar joint in the West Junggar for the first time.Based on zircon U-Pb dating, we determined that the ages of the newly-discovered rhyolites are between 303.6 and 294.5 Ma, belonging to Late Carboniferous–Early Permian, which is the oldest rhyolite with columnar joint preserved in the world at present. Geochemical results show that the characteristics of the major element compositions include a high content of SiO_2(75.78–79.20 wt%) and a moderate content of Al_2O_3(12.21–13.19 wt%). The total alkali content(K_2O +Na_2O) is 6.14–8.05 wt%, among which K_2O is 2.09–4.72 wt% and the rate of K_2O/Na_2O is 0.38–3.05. Over-based minerals such as Ne, Lc, and Ac do not appear. The contents of TiO_2(0.09–0.24 wt%), CaO(0.15–0.99 wt%) and MgO(0.06–0.18 wt%) are low. A/CNK=0.91–1.68, A/NK=1.06–1.76, and as such, these are associated with the quasi-aluminum-weak peraluminous high potassium calc-alkaline and some calc-alkaline magma series. These rhyolites show a significant negative Eu anomaly with relative enrichment of LREE and LILE(Rb, Ba, Th, U, K) and depletion of Sr, HREE and HFSE(Nb, Ta, Ti, P). These rhyolites also have the characteristics of an A2-type granite, similar to the Miaoergou batholith,which indicates they both were affected by post-orogenic extension. Combining petrological, zircon U-Pb dating and geochemical characteristics of the rhyolites, we conclude that the specific time of ocean-continent transition of the West Junggar is the Late Carboniferous–Early Permian.     

生态模型在渔业管理中的应用

随着人们对于海洋生态的认识逐渐深入,渔业等人类活动的影响受到了更多的关注,"基于生态系统的渔业管理"（EBFM）这一概念被越来越多的研究者和国际组织所接受。生态模型为EBFM的实践提供了科学的评估方法和技术工具。与单鱼种评估模型相比,生态模型更多地考虑了系统内的各种生态过程和作用机制,栖息地等环境条件的变化,以及生态系统整体的结构和功能等,依此来反映生态系统的动态变化。由于生态模型是多样化的,关注和涉及不同的目标对象、机制过程、模型结构和参数,本文按照生态模型所关注的生态层次和组分将其分为多物种模型、群落结构模型和生态系统模型3个类型,分析了各类模型的优劣点。本文进一步阐述了生态模型在渔业管理中的应用领域,以管理策略评估为中心的应用方式,以及实践中模型选择和构建所需要注意的问题,还探讨了生态模型中降低不确定性和提高预测能力的方法。