8.0 ka B.P.以来三江平原北部沼泽发育和古环境演变研究

8.0 ka B.P.以来,三江平原北部气候变化序列划分为5个阶段,温暖湿润(8000~5590 a B.P.)→较温暖湿润(5590~1851 a B.P.)→温冷稍湿(1851~1110 a B.P.)→寒冷偏湿(1110~649 a B.P.)→冷凉略湿(649 a B.P.~至今)。气候的变化模式依次为:高温期→温暖适宜期→缓慢降温期→急剧降温期→低温渐暖期。在5590 a B.P.和1317 a B.P.,发生强烈降温事件。沼泽发育也依次划分为5个时期,沼泽化过程发展期→沼泽大发展期→沼泽发育缓慢期→沼泽发育波动期→沼泽发育萎缩期。植被演替相应为:温性阔叶林→针、阔叶混交林和草原→以落叶阔叶树稍多的针、阔叶混交林和草原→以桦为主的阔叶林→针阔混交林、以松占优势的针、阔叶混交林和草原。在1851~1317 a B.P.、649~309 a B.P.和309~0 a B.P.期间,受频繁的农业生产、砍伐森林、开垦沼泽为农田等人类活动的影响,沼泽发育呈现退化的趋势。     

京北浑善达克沙地荒漠化现状、成因与对策

位于首都圈北部内蒙古高原的浑善达克沙地是威胁京津地区的一个主要风沙源区,近几十年来荒漠化发展十分迅速,但相应的荒漠化研究却很薄弱。目前对该区一些局部地区的研究已经揭示了荒漠化快速发展的趋势,但仍缺乏整个沙地荒漠化状况全面和细致的了解。虽然过度放牧等不合理的人类活动被看作是该区荒漠化的主要驱动力,但只有揭示人类生产系统与土地系统之间的反馈作用机制,才能深刻认识荒漠化的成因,才有望对防治荒漠化提供有效的理论依据。最后,提出了围绕浑善达克沙地荒漠化问题需要开展的4个方面的研究工作,即潜在生态系统空间格局、荒漠化动态与监测、荒漠化机理、土地质量评价与土地承载力确定。     

潮白河径流分布规律及人类活动对径流的影响分析

利用潮白河五个水文站1956年以来的径流资料,应用多种数值分析方法,详细分析了潮白河径流的年际、年内分配规律,计算了人类活动对径流的影响。结果表明,潮白河径流的年际变化剧烈,丰水时段历时很短,而枯水时段历时很长。应用累积滤波器和肯德尔秩次相关法,对年径流变化趋势所作的定性和定量的结果表明,潮白河年径流总体呈减少趋势,且减少趋势显著。根据年径流累积曲线和回归分析,人类活动是引起潮白河径流减少的主要因素。     

长江大通-河口段枯季的径流量变化

Based on hydrometric data and extensive investigations on water-extracting projects, this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during dry season. The natural hydrological processes and human factors that influence the water discharge are analyzed with the help of GIS method. The investigations indicate that the water-extracting projects downstream from Datong to Xuliujing had amounted to 64 in number by the end of 2000,with a water-extracting capacity up to 4,626 m3/s averaged in a tidal cycle. The water extraction from the Changjiang River has become the most important factor influencing the water discharge downstream Datong during dry season. The potential magnitude in water discharge changes are estimated based on historical records of water extraction and a water balance model. The computational results were calibrated with the actual data. The future trend in changes of water discharge into the sea during dry season was discussed by taking into consideration of newly built hydro-engineering projects. The water extraction downstream Datong in dry season before 2000 had a great influence on discharges into the sea in the extremely dry year like 1978-1979. It produced a net decrease of more than 490 m^3/s in monthly mean discharges from the Changjiang into the sea. It is expected that the water extraction will continually increase in the coming decades, especially in dry years, when the net decrease in monthly mean water discharge will increase to more than 1000 m^3/s and will give a far-reaching effect on the changes of water discharge from the Changjiang into the sea.     

The impacts of human activities on the water–land environment of the Shiyang River basin,an arid region in northwest China / Les impacts des activités humaines sur l’environnement pédo-hydrologique du bassin de la Rivière Shiyang,une région aride du nord-ouest de la Chine

Abstract

Abstract The Shiyang River basin is a typical interior river basin that faces water shortage and environmental deterioration in the arid northwest of China. Due to its arid climate, limited water resources and some inappropriate water-related human activities, the area has developed serious loss of vegetation, and gradual soil salinization and desertification, which have greatly impeded the sustainable development of agriculture and life in this region. In this paper, the impacts of human activities on the water–soil environment in Shiyang River basin are analysed in terms of precipitation, runoff in branches of the river, inflow into lower reaches, water conveyance efficiency of the canal system and irrigation water use efficiency in the field, replenishment and exploitation of groundwater resources, soil salinization, vegetation cover and the speed of desertification. The results show that human activities and global climate change have no significant influence on the precipitation, but the total annual runoff in eight branch rivers showed a significant decrease over the years. The proportion of water use in the upper and middle reaches compared to the lower reach was increased from 1:0.57 in the 1960s, to 1:0.27 in the 1970s and 1:0.09 in the 1990s. A reduction of about 74% in the river inflow to the lower reaches and a 15-m drop in the groundwater table have occurred during the last four decades. Strategies for improving the water–soil environment of the basin, such as the protection of the water resources of the Qilian Mountains, sustainable use of water resources, maintenance of the balance between land and water resources, development of water-saving agriculture, diverting of water from other rivers and control of soil desertification, are proposed. The objective of this paper is to provide guidelines for reconstruction of the sustainable water management and development of agriculture in this region.     

Impact of human activities on stream flow in the Biliu River basin,China

The obvious decline in stream flow to the Biliu River reservoir over the period 1990–2005 has raised increasing concerns. Climate change and human activities, which mainly include land use changes, hydraulic constructions and artificial water consumption, are considered to be the most likely reasons for the decline in stream flow. This study centres on a detailed analysis of the runoff response to changes in human activities. Using a distributed hydrological model, (Soil and Water Assessment Tool), we simulated runoffs under different human activity and climate scenarios to understand how each scenario impacts stream flow. The results show that artificial water consumption correlates with the precipitation (wet, normal and dry) of the year in question and is responsible for most of the decrease in runoff during each period and for each different wetness year. A Fuzzy Inference Model is also used to find the relationship between the precipitation and artificial water consumption for different years, as well as to make inferences regarding the future average impact on runoff. Land use changes in the past have increased the runoff by only a small amount, while another middle reservoir (Yunshi) has been responsible for a decrease in runoff since operation began in 2001. We generalized the characteristics of the human activities to predict future runoff using climate change scenarios. The future annual flow will increase by approximately 10% from 2011 to 2030 under normal human activities and future climate change scenarios, as indicated by climate scenarios with a particularly wet year in the next 20 years. This study could serve as a framework to analyse and predict the potential impacts of changes both in the climate and human activities on runoff, which can be used to inform the decision making on the river basin planning and management. Copyright © 2012 John Wiley & Sons, Ltd.     

How did the suspended sediment load change in the North Caucasus during the Anthropocene?

Quantifying and understanding catchment sediment fluxes is crucial both from a scientific and environmental management perspective. To deepen the understanding of landuse impacts and climate change on sediment load, we explore factors controlling the suspended sediment load formation in the Northern Caucasus during the Anthropocene. We examine how sediment flux of various river basins with different land-use/landcover and glacier cover changes during the 1925–2018 period. Our analysis is based on observed mean annual suspended sediment discharges (SSD, kg s⁻¹) and annual fluxes (SSL, t year⁻¹) from 33 gauging stations of The Federal Service for Hydrometeorology and Environmental Monitoring (Russia). SSL series have been analysed to detect statistically significant changes during the 1925–2018 period. The occurrence of abrupt change points in SSD was investigated using cumulative sum (CUSUM) charts. We found that SSL has decreased by −1.17% per year on average at most gauges. However, the decline was not linear. Several transition years are expected in the region increasing trends from the 1950s and decreasing trends from 1988 to 1994. Correlation analyses showed that variation in SSL trend values is mainly explained by gauging station altitude, differences in landuse (i.e. the fraction of cropland), and catchment area. Nonetheless, more accurate quantifications of SSL trend values and more refined characterizations of the catchments regarding (historical) landuse, soil types/lithology, weather conditions, and topography may reveal other tendencies.     

Early to mid‐Holocene climate change at Lago dell'Accesa (central Italy): climate signal or anthropogenic bias?

Despite the high potential of pollen records for climate reconstruction, pollen–climate relationships may be biased due to past and present human activities on the landscape. We use (i) transfer functions based on modern pollen–climate relationships to infer seasonal temperature and summer precipitation for the period 11 500–4500 cal. a BP and (ii) lake‐level change records based on different sedimentary proxies in multiple cores that are mainly indicative for summer hydrology at Lago dell'Accesa (central Italy). Quantitative reconstructions indicate lowest summer precipitation during two phases (8500–7700 cal. a BP and after 6000 cal. a BP) and a gradual winter temperature increase from 11 500 to ca. 8000 cal. a BP. Lowest summer precipitation was reconstructed during these phases characterised by vegetation shifts from open forests dominated by summergreen oaks (Quercus) to forests dominated by evergreen oaks (Quercus ilex), which are at present most abundant where summer drought is stronger. Similarly, the lake‐level record indicates two long‐lasting low summer precipitation phases (8800–7700 and 6400–4400 cal. a BP) that were interrupted by short‐term high summer precipitation events. Based on the broad agreement between the pollen‐inferred summer precipitation and the low‐frequency lake‐level changes, we suggest that the duration of the high summer precipitation events may have been too short to maintain drought‐sensitive trees, which may have been affected by high mortality rates when summer dry conditions returned. Although past and modern pollen–climate relationships may very likely have been affected by human activities since the Neolithic (i.e. when exploitation of the landscape started), we reject the hypothesis of a significant anthropogenic bias in the pollen‐based climate reconstruction. In addition, we suggest that pollen‐based and lake‐level reconstructions may have different inherent abilities of capturing high‐ and low‐frequency precipitation signals. Copyright © 2010 John Wiley & Sons, Ltd.     

Impacts of climate change and human activities on surface runoff in the Dongjiang River basin of China

Observed rainfall and flow data from the Dongjiang River basin in humid southern China were used to investigate runoff changes during low‐flow and flooding periods and in annual flows over the past 45 years. We first applied the non‐parametric Mann–Kendall rank statistic method to analyze the change trend in precipitation, surface runoff and pan evaporation in those three periods. Findings showed that only the surface runoff in the low‐flow period increased significantly, which was due to a combination of increased precipitation and decreased pan evaporation. The Pettitt–Mann–Whitney statistical test results showed that 1973 and 1978 were the change points for the low‐flow period runoff in the Boluo sub‐catchment and in the Qilinzui sub‐catchment, respectively. Most importantly, we have developed a framework to separate the effects of climate change and human activities on the changes in surface runoff based on the back‐propagation artificial neural network (BP‐ANN) method from this research. Analyses from this study indicated that climate variabilities such as changes in precipitation and evaporation, and human activities such as reservoir operations, each accounted for about 50% of the runoff change in the low‐flow period in the study basin. Copyright © 2010 John Wiley & Sons, Ltd.     

The human impact on natural rock reserves using basalt,anorthosite, and carbonates as raw materials in insulation products

Typical crustal rocks such as basalt, limestone, and anorthosite are used in stone wool insulation products. The raw materials for stone wool production are not specific to any rare mineral source but depend upon the mixture of materials having the correct chemical composition, exemplified by 40 wt% basalt, 20 wt% anorthosite, and 40 wt% cement-bonded renewable materials. This study provides an overview of the natural cycle of these resources, including their abundances in nature, and sets the consumption by the stone wool industry and other human activities in perspective.

Basalt, anorthosite, and carbonates are widespread on all continents. Although basaltic rocks cover most of the ocean floor, these reserves are hidden below several kilometres of water and therefore are regarded as inaccessible. Instead, large igneous provinces on land constitute major basaltic reserves useful for human rock exploration. Globally, anorthositic provinces comprise smaller volumes than do limestone or basalt, but still occur in sufficient amounts to supply for the production of insulation materials indefinitely. An evaluation of the modern consumption rates and reserves shows that the crustal inventories of these rock types are so large that they could supply current human demand for millions of years.

The natural degradation of surface rocks occurs by physical and chemical weathering creating sediment that is transported along rivers and deposited in the ocean. Sediments are either obducted with continental lithosphere or subducted with oceanic crust and recycled through the mantle by plate tectonics. Insulation products have a chemical composition similar to average crustal rocks and participate in the natural rock cycle. However, these products need not accumulate in nature, inasmuch as old insulation materials serve as excellent source materials for new products. Moreover, current production lines exploit more than 30 natural and 20–30 synthetic source materials that circumvent regional depletion and contribute to the recycling of other industrial materials.