The Sustainable Global Energy Economy: Hydrogen or Silicon?

A sustainable global silicon energy economy is proposed as a potential alternative to the hydrogen economy. This first visualization of a silicon energy economy is based on large-scale and carbon-neutral metallic silicon production from major smelters in North Africa and elsewhere, supplied by desert silica sand and electricity from extensive solar generating systems. The resulting “fuel silicon” is shipped around the world to emission-free silicon power stations for either immediate electricity generation or stockpiling. The high energy density of silicon and its stable storage make it an ideal material for maintaining national economic functioning through security of base load power supply from a renewable source. This contrasts with the present situation of fossil fuel usage with its associated global warming and geopolitical supply uncertainties. Critical technological requirements for the silicon economy are carbon-neutral silicon production and the development of efficient silicon-fired power stations capable of high-temperature rapid oxidation of fuel silicon. A call is made for the development of research effort into these specific engineering issues, and also with respect to large-scale economical solar power generation.     

A New Model for the Lifetime of Fossil Fuel Resources

A critical examination of Hubbert’s model proves that it does not account for several factors that have significantly influenced the production of petroleum and other fossil fuels. The effect of these factors comes into the price of the fossil fuels, and the latter has a significant influence on the demand and rate of production of energy resources as well as on the long-term rate of production growth at both the regional and global levels. Based on several observations of historical production data, a simple mathematical model is constructed and presented in this paper for the lifetime of a fossil fuel resource. The recent data of global petroleum and natural gas production show that a very important period in the life of energy resources is a period when the demand of these resources increases almost linearly. The linear part of the production curve makes the entire lifetime production of the resource asymmetric. Information on the total available quantity of a resource at any time and of the average slope during this linear period yields an estimate of the timescale, T ₂, when peak production is reached and depletion follows. The total available quantity of the energy resource is laden with significant uncertainty, which propagates in the estimates of the timescale of the peak production in any resource model. The time asymmetry of the current model leads to a delay of the timescale, when the onset of the resource production commences (e.g., peak oil). However, the rate of the resource production decline is significantly higher than that predicted by other models that use a symmetrical curve-fitting method.     

Establishing natural sediment reference conditions for metals and the legacy of long-range and local pollution on lakes in Europe

The intention of the European Water Framework Directive (WFD) and the national guidelines that implement the WFD is that present-day conditions and future management strategies are to be based on an understanding of reference conditions for the particular water body of interest. In the context of non-synthetic pollutants such as lead, mercury and cadmium, the criteria for a high ecological status are that “concentrations [are] within the range normally associated with undisturbed conditions”. How this normal range is to be defined is open to interpretation; for example, in Sweden reference conditions based on sediment records are defined as the conditions prior to modern industrialization, i.e. prior to the mid-1800’s. These pre-industrial reference conditions would correspond to sediments 15–30 cm depth. However, ‘reference conditions’ are not always synonymous with ‘natural background conditions’. Analyses of long sediment profiles from Swedish lakes and from a few other areas, however, have shown that pre-industrial pollution—at least with regard to lead—was extensive. Atmospheric lead pollution has its origin in antiquity, with a small, well-defined peak already during the Greek-Roman period 2,000 years ago. Sediments deposited 300–500 years in Sweden and Scotland, for example, show a dominance of pollution lead, and in some sediment records also cadmium and copper pollution was extensive. Thus, in order to characterize natural background concentrations of metals, long sediment profiles are needed to reach sediments unaffected by pollution (>3,000 years BP); this can correspond to sediments below 50 cm in some lakes, but in others sediments below 300 cm or more.     

Phytoplankton dynamics in Lake Biwa during the 20th century: complex responses to climate variation and changes in nutrient status

We examined algal remains and fossil pigments in ²¹⁰Pb-dated sediment cores from Lake Biwa to explore historical changes in the phytoplankton community of the lake over the past 100 years and to identify environmental factors that caused those changes. Fluxes of fossil pigments and algal remains were very low before the 1960s, but increased through the 1960s and 1970s, indicating that the lake had eutrophied in the 20 years since 1960. After 1980, however, fluxes of all fossil pigments and algal remains decreased or stabilized. Redundancy analysis with meteorological and limnological variables explained more than 70% of the variation of these fluxes and showed that the decrease in fluxes of most algal taxa that occurred in the 1980s was related to changes in meteorological variables such as wind velocity, rather than changes in the lake’s trophic state. Sedimentary records of algal remains also revealed that Aulacoseira nipponica, an endemic diatom species that grows in winter, decreased dramatically after 1980, while Fragilaria crotonensis, a cosmopolitan spring diatom species, became dominant. Replacement of one dominant diatom species by another could not be explained simply by changes in the lake trophic state, but was reasonably strongly related with an increase in winter water temperature. These results suggest that the phytoplankton community in Lake Biwa was influenced by changes in local environmental conditions (nutrient loading) through the 1960s and 1970s, but more so by regional (meteorological) and global (climate warming) factors since 1980.     

Issues in Energy Economics Led by Emerging Linkages between the Natural Gas and Power Sectors

Fuel prices in 2006 continued at record levels, with uranium continuing upward unabated and coal, SO₂ emission allowances, and natural gas all softening. This softening did not continue for natural gas, however, whose prices rose, fell and rose again, first following weather influences and, by the second quarter of 2007, continuing at high levels without any support from fundamentals. This article reviews these trends and describes the remarkable increases in fuel expenses for power generation. By the end of 2005, natural gas claimed 55% of annual power sector fuel expenses, even though it was used for only 19% of electric generation. Although natural gas is enormously important to the power sector, the sector also is an important driver of the natural gas market—growing to over 28% of the market even as total use has declined. The article proceeds to discuss globalization, natural gas price risk, and technology developments. Forces of globalization are poised to affect the energy markets in new ways—new in not being only about oil. Of particular interest in the growth of intermodal traffic and its a little-understood impacts on rail traffic patterns and transportation costs, and expected rapidly expanding LNG imports toward the end of the decade. Two aspects of natural gas price risk are discussed: how understanding the use of gas in the power sector helps define price ceilings and floors for natural gas, and how the recent increase in the natural gas production after years of record drilling could alter the supply–demand balance for the better. The article cautions, however, that escalation in natural gas finding and development costs is countering the more positive developments that emerged during 2006. Regarding technology, the exploitation of unconventional natural gas was one highlight. So too was the queuing up of coal-fired power plants for the post-2010 period, a phenomenon that has come under great pressure with many consequences including increased pressures in the natural gas market. The most significant illustration of these forces was the early 2007 suspension of development plans by a large power company, well before the Supreme Court’s ruling on CO₂ as a tailpipe pollutant and President Bush’s call for global goals on CO₂ emissions.

A Depletion Protocol for Non-Renewable Natural Resources: Australia as an Example

This paper examines the implications of statements by Australia’s Minister of… Resources that Australia’s exports of coal are growing rapidly and that Australia’s coal will last “110 years at current rates of production.” If one assumes that coal production P(t), follows a Gaussian curve (similar to a Hubbert curve) one can construct a family of Gaussian curves showing possible future paths of P(t) which are consistent with the cited “110 years.” Each curve reaches a maximum after which P(t) declines toward zero. Knowledge of the present value of dP/dt allows one member of the family to be identified as the most probable future path of P(t). Families of curves and tabular data are presented for resource quantities that would last 50, 100 and 200 years “at current rates of production.” If, instead, Australia’s P(t) follows a declining exponential curve (exp(−kt)) with k = (1/110) per year, the stated quantity of coal will allow production to continue forever, with P(t) declining with a half life of 76 y. This and more rapidly declining exponential paths are the only paths that can be said to be sustainable. The envelope of the family of Gaussian curves divides the (P, t) plane into “allowed” and “forbidden” areas. The declining exponential curve divides the “allowed” area into an upper area that is “terminal” and a lower area that is “sustainable.” These facts, coupled with Australia’s expectations of rapid growth of its population, suggest that Australia’s present resource policies are “anti-sustainable” and that the people of Australia need to rethink their present policy of rapidly exporting their fossil fuels.     

分布式水文模型全局敏感性高效分析方法研究(英文)

Sensitivity analysis of hydrological model is the key for model uncertainty quantification. However, how to effectively validate model and identify the dominant parameters for distributed hydrological models is a bottle-neck to achieve parameters optimization. For this reason, a new approach was proposed in this paper, in which the support vector machine was used to construct the response surface at first. Then it integrates the SVM-based response surface with the Sobol’ method, i.e. the RSMSobol’ method, to quantify the parameter sensitivities. In this work, the distributed time-variant gain model (DTVGM) was applied to the Huaihe River Basin, which was used as a case to verify its validity and feasibility. We selected three objective functions (i.e. water balance coefficient WB, Nash-Sutcliffe efficiency coefficient NS, and correlation coefficient RC) to assess the model performance as the output responses for sensitivity analysis. The results show that the parameters g1 and g2 are most important for all the objective functions, and they are almost the same to that of the classical approach. Furthermore, the RSMSobol method can not only achieve the quantification of the sensitivity, and also reduce the computational cost, with good accuracy compared to the classical approach. And this approach will be effective and reliable in the global sensitivity analysis for a complex modelling system.     

Geopolitics of the energy transition

Geopolitics of energy transition has increasingly become the frontier and hot research area of world energy geography and global political science. Different historical periods are characterised by obvious differences in energy connotations, attributes, and geopolitical characteristics. In the new energy era, energy geopolitics becomes more diversified, complex, and comprehensive. In this paper, we compare the geopolitical characteristics of energy in the fossil fuel and renewable energy periods...     

国际能源贸易依赖网络特征及替代关系研究：化石能源与可再生能源

随着可再生能源成为国际能源贸易重要增长点,国家和地区间的能源贸易依赖关系也随之变化。基于2011—2020年世界能源、经济及创新指数等数据,通过社会网络分析法阐释化石能源和可再生能源的贸易情况,探讨化石能源和可再生能源贸易依赖网络的演化过程,使用 QAP回归方法定量分析化石能源贸易依赖网络和可再生能源贸易依赖网络之间的关系。结果表明：在2011—2020年,化石能源贸易的稳定性较高,而可再生能源贸易发展迅速。可再生能源贸易依赖网络展现出更高的整体依赖程度,其对化石能源贸易的依赖关系产生了替代作用。中国既要大力推进可再生能源产业发展,也要加强与能源大国的贸易合作,从而与世界建立更加稳固的双向能源贸易合作的网络关系。     

Ethanol Production: Energy and Economic Issues Related to U.S. and Brazilian Sugarcane

For a thorough and up-to-date evaluation of all the fossil energy costs of ethanol production from sugarcane in both the U.S. and Brazil, every energy input in the biomass production and ultimate conversion process must be included. In this study, more than 12 energy inputs in average U.S. and Brazilian sugarcane production are evaluated. Then in the fermentation/distillation operation, nine more fossil fuel inputs are identified and included. Some energy and economic credits are given for the bagasse to reduce the energy inputs required for steam and electricity. Based on all the fossil energy inputs in U.S. sugarcane conversion process, a total of 1.12 kcal of ethanol is produced per 1 kcal of fossil energy expended. In Brazil a total of 1.38 kcal of ethanol is produced per 1 kcal of fossil energy expended. Some pro-ethanol investigators have overlooked various energy inputs in U.S. and Brazilian sugarcane production, including farm labor, farm machinery, processing machinery, and others. In other studies, unrealistic low energy costs were attributed to such energy inputs, as nitrogen fertilizer, insecticides, and herbicides. Both the U.S. and Brazil heavily subsidize ethanol production. Thus billions of dollars are invested in subsidies and this significantly increases the costs to the consumers. The environmental costs associated with producing ethanol in the U.S. and Brazil are significant but have been generally overlooked. The negative environmental impacts on the availability of cropland and freshwater, as well as on air pollution and public health, have yet to be carefully assessed. These environmental costs in terms of energy and economics should be calculated and included in future ethanol analyses so that sound assessments can be made. In addition, the production of ethanol in the U.S. and Brazil further confirms that the mission of converting biomass into ethanol will not replace oil. This mission is impossible. General concern has been expressed about taking food crops to produce ethanol for burning in automobiles instead of using these crops as food for the many malnourished people in the world. The World Health Organization reports that more than 3.7 billion humans are currently malnourished in the world—the largest number of malnourished ever in history.     

The Evolution of Giant Oil Field Production Behavior

The giant oil fields of the world are only a small fraction of the total number of fields, but their importance is huge. Over 50% of the world’s oil production came from giants by 2005 and more than half of the world’s ultimate reserves are found in giants. Based on this, it is reasonable to assume that the future development of the giant oil fields will have a significant impact on the world oil supply. In order to better understand the giant fields and their future behavior, one must first understand their history. This study has used a comprehensive database on giant oil fields in order to determine their typical parameters, such as the average decline rate and life-times of giants. The evolution of giant oil field behavior has been investigated to better understand future behavior. One conclusion is that new technology and production methods have generally led to high depletion rates and rapid decline. The historical trend points towards high decline rates of fields currently on plateau production. The peak production generally occurs before half the ultimate reserves have been produced in giant oil fields. A strong correlation between depletion-at-peak and average decline rate is also found, verifying that high depletion rate leads to rapid decline. Our result also implies that depletion analysis can be used to rule out unrealistic production expectations from a known reserve, or to connect an estimated production level to a needed reserve base.     

The palaeolimnological record from lake Cullulleraine,lower Murray River (south-east Australia): implications for understanding riverine histories

Australia’s largest river system, the Murray-Darling Basin, is the focus of scientific and political attention, due mainly to the competing issues of economic productivity versus environmental flows. Central to this dialogue is the need to know about the Basin’s natural condition and the degree to which the system has deviated from this pre-disturbance, baseline status. This study examines the patterns of ecological change in Lake Cullulleraine, a permanently connected artificial wetland adjacent to Lock Nine on the Murray River, south-east Australia. A 43-cm sediment core was collected in January 1998 and diatoms were analysed at 1-cm intervals for use as aquatic ecological indicators. The sediment core was dated using ²¹⁰Pb. Changes in the diatom community have occurred since the time of lake formation in 1926, particularly shifts between Aulacoseira subborealis, Staurosira construens var. venter, Aulacoseira granulata, Staurosirella pinnata and Pseudostaurosira brevistriata. An electrical conductivity (EC) transfer function was applied to the fossil diatom assemblages and inferred EC values were compared to long-term, historical EC data from the River. Despite the presence of good analogues between fossil and modern diatom assemblages, inferred EC did not reflect measured EC accurately. In recent decades, patterns in the two data sets were reversed. Despite clear changes in the fossil record, quantitative palaeo-environmental interpretation was limited because the dominant taxa occupy broad ecological niches. Despite these limitations, changes in the Lake Cullulleraine record, particularly in the planktonic taxa, can be interpreted in terms of landscape change. Furthermore, because of the good chronology from the site, the record may be useful for dating changes observed in sites with poor chronological control.     

能源地缘政治与能源权力研究

围绕油气资源的权力博弈仍然是当今世界最主要的能源权力争夺,但不同时代的能源权力的属性有所不同,能源安全与能源战略内涵也有所不同。论文在系统梳理能源地缘政治基础上,提出了能源权力的概念,并从地缘政治格局、能源安全观、能源网络和全球能源治理4个方面进行了具体阐述。研究认为：① 以能源分布、产销空间变化及其规律性总结是传统能源地缘政治研究的核心,油气资源地理分布的不平衡性是能源权力产生的最直接因素。② 从石油危机时代到未来新能源时代,能源安全观的不同是影响国际能源地缘政治权力变化的重要因素。③ 能源的商品属性和地缘属性决定了能源贸易不仅是经济行为,其空间的流动与国际政治关系密切。生产与消费的分离使得油气二次分配过程中的贸易控制和通道控制对能源权力重构产生重要影响。④ 全球能源权力巨变和复杂错综的能源权力网络将引发全球能源治理体系的新秩序。权力的主体从国家、国际组织、跨国公司转变为全球能源网络中利益共同体,能源治理的主题从一国之利益走向了全球能源权力的再分配过程。展望未来,如何在理论上建构新时代的能源权力的理论体系,深化气候变化和新能源等因素影响下的世界能源权力的演变、地理空间与权力的相互依赖关系、权力秩序的重构及其效应、全球能源治理机制及其治理模式等研究,对科学认知和研判世界能源形势与能源战略的演化具有重要的意义,也是能源地缘政治学研究的重要方向性命题。     

21世纪中国历史地理学发展的思考

本文在回顾中国历史与近 5 0年来取得的巨大成就的基础上 ,结合当今地球系统科学、地理科学的发展趋势以及国际全球变化与可持续发展研究的最新动向 ,提出了新世纪中国历史地理学研究应以收集、发掘人类文明演进的地理证据 ,分析历史上人地交互作用的时空特征为核心 ,以探寻当今地理学历史渊源人类适应环境变化模式的历史证据为目标 ,以文献分析、野外调查、考古发掘等传统方法与现代实验技术、空间信息技术的集成为手段 ,以编制5 0 0 0年来华夏故土嬗变与文明演进的历史图谱为主要平台的发展新思路 ,并认为中国历史地理学在国际全球变化与可持续发展研究中可以做出具有重大显示度的贡献     

How We Lose Ground When Earth Scientists Become Territorial: Defining “Soil”

This short review aims to provide some examples where terrestrial earth sciences—including, for this purpose, geology, engineering geology, soil science, pedology, hydrology, hydrogeology, geography, geomorphology and environmental sciences—do not interact sufficiently to ensure optimal results. Apart from different terminologies (for instance, “soil”), different specialist fields claim expertise over certain disciplines or portions of the Earth’s crust without a proper understanding of the influence of other specialist fields. This severely limits interdisciplinary understanding, and it is recommended that a better understanding of interdisciplinary definitions is required to ensure a wider audience. Although this is not a technical article in its own right, this forms part of a study to link vadose zone hydrology for the disciplines as noted earlier, thereby creating hopefully a platform for easier communication.     

Paleolimnological evidence of mining and demographic impacts on Lac Dauriat, Schefferville (subarctic Québec, Canada)

Qualitative and quantitative analysis of fossil diatoms and geochemical signals preserved in the sediments of Lac Dauriat (subarctic Quebec) were performed to evaluate the impacts of nearby mining activity and the expansion of the town of Schefferville on the water quality of the lake, and to reconstruct the changes of its trophic status. The presence of taxa typical of nutrient-enriched environments (e.g., Cyclostephanos invisitatus, Nitzschia gracilis, Nitzschia perminuta) and the low percentages of chrysophytes were indicative of the advanced state of eutrophication of the lake during the peak of mining activity, and were evidence of the negative impacts of municipal waste on the water quality of Lac Dauriat. Sedimentary analysis of metals, notably lead, mercury, cadmium, bismuth, cobalt, copper and zinc, showed maximum concentrations between 1940 and 1960 with mining era to pre-development enrichment factors ranging from 4.5 to 7.9. The changes seen in recent sediments reflected 3 distinct stages in the recent history of this ecosystem: (a) the non-perturbed, pre-mining (1882–1939), (b) the perturbed, mining period (1939–1977) with accelerated eutrophication, and (c) the post-mining period (1977–1999) with indications of natural recovery of the system after the installation of a water treatment plant in 1975, the closing of the mine in 1983, and the subsequent exodus of the town’s population. Despite the trajectory towards a return to the lake’s natural conditions, water resource managers and (paleo-)limnologists should be alarmed that the impacts of past human disturbance are still in evidence more than 20 years after the closure of the mines, and that Lac Dauriat has yet to reach its natural state of the period preceding extreme anthropogenic impact.     

Sieve mesh size and quantitative chironomid paleoclimatology

The minimum sieve mesh size for fossil chironomid analysis is usually set at 100 μm, to ensure adequate recovery of small species. Yet taking into account the labor intensity of sorting and identifying fossil chironomid remains, the large numbers of samples requiring processing in paleoclimate studies with high temporal resolution, and the increasing need to engage non-specialist analysts in this work, it seems appealing to sieve samples through a larger mesh size that would mainly retain easier-to-see, easier-to-extract and easier-to-identify fossil specimens. In this study we evaluated the influence of sieve mesh size on chironomid-based quantitative paleoenvironmental reconstructions in African lakes. We developed two chironomid-salinity calibration data sets based on either the >100 μm or >150 μm size fractions of surface-sediment fossil assemblages, and compared the performance of salinity-inference models derived from them. We find that, despite ∼35% additional fossil loss, restriction to >150 μm data did not appreciably affect individual taxon optima or tolerances, and resulted in only a modest reduction of mean taxon richness per lake. Parameters of statistical model performance were as good, or better than those of models based on the >100 μm data, albeit only after excluding two atypically dilute (<100 μS/cm) lakes from the calibration. Application of inference models based on >150 μm or >100 μm data to a 200-year fossil record from Lake Abiyata, Ethiopia, produced very similar trends, amplitudes and uncertainty ranges of inferred past salinity change. Restriction to >150 μm data reduced the mean fossil yield of core samples by ∼20% on average, i.e. fossil loss was markedly lower than in surface-sediment samples. Using the larger mesh size reduced sample processing time by up to 50%, partly by removing a significant proportion of visually obstructive organic debris, and partly by allowing a greater fraction of chironomid fossils to be identified directly in the sorting tray. The fraction of 1st instar group taxa in surface-sediment samples was reduced from 13% to 3%, increasing the mean taxonomic resolution of fossil assemblages, and thus their ecological specificity.     

Pyrolysis of Municipal Solid Waste for Syngas Production by Microwave Irradiation

In the present study, we discuss the application of microwave-irradiated pyrolysis of municipal solid waste (MSW) for total recovery of useful gases and energy. The MSW pyrolysis under microwave irradiation highly depends on the process parameters, like microwave power, microwave absorbers, and time of irradiation. The thoroughness of pyrolysis and product recovery were studied by changing the abovesaid variables. Pyrolysis of MSW occurs in the power rating range of 450–850 W—outside this power rating range, pyrolysis is not possible. Experiments were carried out using various microwave absorbers (i.e., graphite, charcoal, and iron) to enhance the pyrolysis even at lower power rating. The results show that the pyrolysis of MSW was possible even at low power ratings. The major composition of the pyrolysis gaseous product were analyzed with GC–MS which includes CO₂, CO, CH₄, etc.     

The Use of Fossil Caddisfly Assemblages in the Reconstruction of Flow Environments from Floodplain Paleochannels of the River Trent, England

This paper examines the use of fossil larval trichopteran communities to investigate and describe the flow environment of a paleochannel network in the middle reaches of the River Trent floodplain (UK). Previous research utilising fossil insect communities (principally O. Coleoptera, O. Chironomidae) has focussed upon climate reconstruction. However, larval trichopteran communities (O. Trichoptera) also offer an aquatic signal, giving information regarding channel habitat structure and flow environments. The taxonomic diversity of each fossil community and the categorisation of each taxon into a known flow group, using the “LIFE” methodology, facilitates the reconstruction of the river flow conditions at each site based upon known faunal associations with mean flow velocity. A total of 49 trichopteran taxa were recorded from 17 paleochannels (n = 170 samples). Detrended Correspondence Analysis (DCA) identified a environmental gradient on the first DCA axis that reflected variability in flow, from rapid/fast flow to slow flowing and standing water habitats. In addition, two distinct faunal groups were identified on the second DCA axis characteristic of (i) small nutrient rich lentic habitats; and (ii) larger water bodies displaying features of both lentic, lotic and ephemeral habitats where marginal vegetation is abundant on a mineral substratum. The results demonstrate that larval Trichoptera can be used in paleolimnological research to reconstruct a flow signal and provide additional information regarding the aquatic habitat structure. Their wider use in describing the aquatic environment, in association with other proxies (e.g., Chironomidae and Coleoptera), may provide a more holistic understanding of floodplain paleoenvironment succession.     

Floodplain sedimentation in the Upper Mississippi Valley: Natural versus human accelerated

Understanding the time scales and pathways for response and recovery of rivers and floodplains to episodic changes in erosion and sedimentation has been a long standing issue in fluvial geomorphology. Floodplains are an important component of watershed systems because they affect downstream storage and delivery of overbank flood waters, and they also serve as sources and temporary sinks for sediments and toxic substances delivered by river systems. Here, ¹⁴C and ¹³⁷Cs isotopic dating methods are used along with ages of culturally related phenomena associated with mining and agriculture to determine rates of sedimentation and morphologic change for a reach of the upper Mississippi River and adjacent tributaries in southwestern Wisconsin and northwestern Illinois. The most important environmental change that influenced fluvial activity in this region during last 10,000 years involved the conversion of a late Holocene mosaic of prairie and forest to a landscape dominated by cropland and pastureland associated with Euro-American settlement. Results presented herein for the Upper Mississippi Valley (UMV) show that the shift from pre-agriculture, natural land cover to landscape dominance by agricultural land use of the last 175–200 years typically increased rates and magnitudes of floodplain sedimentation by at least an order of magnitude. Accelerated overbank flooding led to increased bank heights on tributary streams and, in turn, contributed to more frequent deep flows of high energy. These high energy flows subsequently promoted bank erosion and lateral channel migration, and the formation of a historical meander belt whose alluvial surface constitutes a new historical floodplain inset against the earlier historical floodplain. The new historical floodplain serves as a “flume-like” channel that provides efficient downstream transport of water and sediment associated with moderate and large magnitude floods. Floodplains on lower tributaries, however, continue to experience rates of overbank sedimentation that are of anomalously high magnitude given improved land cover and land conservation since about 1950. This lower valley anomaly is explained by minimal development of historical (agriculture period) meander belts because of relatively low stream power in these channel and floodplain reaches of relatively low gradient. In general, long-term pre-agriculture rates of vertical accretion between about 10,000 and 200 years ago averaged about 0.2 mm yr^− 1 in tributary watersheds smaller than about 700 km² and about 0.9 mm yr^− 1 on the floodplain of the upper Mississippi River where the contributing watershed area increases to about 170,000 km². On the other hand, rates of historical vertical accretion during the period of agricultural dominance of the last 200 years average between 2 and 20 mm yr^− 1, with short episodes of even higher rates during times of particularly poor land conservation practices. Significant hydrologic effects of mining and agricultural started by the 1820s and became widespread in the study region by the mid-19th century. The hydrologic and geomorphic influences of mining were relatively minor compared to those related to agriculture. High resolution dating of floodplain vertical accretion deposits shows that large floods have frequently provided major increments of sedimentation on floodplains of tributaries and the main valley upper Mississippi River. The relative importance of large floods as contributors to floodplain vertical accretion is noteworthy because global atmospheric circulation models indicate that the main channel upper Mississippi River should experience increased frequencies of extreme hydrologic events, including large floods, with anticipated continued global warming. Instrumental and stratigraphic records show that, coincident with global warming, a shift to more frequent large floods occurred since 1950 on the upper Mississippi River, and these floods generally contributed high magnitudes of floodplain sedimentation.