榆阳区明长城典型遗址的雨蚀破坏模式分析

现有的夯土遗址雨蚀病害分类方式关注的是多次降雨后遗址破坏的静态结果,以识别病害、辨明病因为主要目的。为进一步研究水土作用方式在夯土雨蚀病害发育过程中的作用,明确雨蚀病害的动态发育过程,在现场调查的基础上对榆阳区明代夯土长城的雨蚀病害进行分类、统计、分析,综合考虑侵蚀模式、雨蚀动态响应过程和劣化程度三个方面提出雨蚀破坏模式,分别为干湿破坏、冲刷破坏和降雨导致的重力侵蚀三种,三种破坏模式的提出为研究夯土遗址雨蚀和降雨间的响应关系提供新思路。     

降雨对榆阳区明长城单体建筑破坏模式的试验研究

前期调查分析可知,降雨对榆阳区明长城单体建筑的破坏形式包括水力侵蚀和重力侵蚀两大类,主要影响因素为降雨特征、遗址保存形态和遗址土的性质。为了进一步了解降雨对该类土遗址的破坏方式及主要影响因素作用特点,按照相似理论要求设计模型试验,研究了降雨对榆阳区明长城单体建筑的破坏模式。试验结果表明,降雨对遗址模型的破坏方式与前期调查分析结果基本一致,水力侵蚀方式有冲沟侵蚀、片流面蚀、流水淘蚀和流水冲蚀,重力侵蚀方式有坍塌和滑塌。一般A型暴雨条件下,各种水力侵蚀方式均有发生,重力侵蚀发生次数相对较少;B型暴雨条件下,主要发生片流面蚀,重力侵蚀破坏发生次数较多。通过模型试验得出的降雨对遗址模型的破坏方式及发生特点方面的结论,可以在一定程度上为降雨对该类遗址破坏的评估和防治提供参考。     

陕北明长城夯土密度与雨蚀破坏的量化研究

为量化研究夯土性质对陕北明长城遗址雨蚀破坏模式的影响作用,采用室内模拟降雨试验的方法对夯土密度和雨蚀量间的关系进行定量化分析。研究结果显示,大到暴雨条件下,干湿作用产生的破坏是低强度夯土(密度1.5 g·cm^-3、1.6 g·cm^-3)最主要的雨蚀破坏模式,冲刷破坏造成的雨蚀量较小;水力侵蚀产生的冲刷破坏和重力侵蚀引起的小范围掉块是高强度夯土(密度1.7~1.9 g·cm^-3)最主要的破坏模式,冲刷破坏造成的雨蚀量较大;当土体含水率在3%~7%区间时,夯土的雨蚀量和密度呈指数函数关系,二者呈现正相关性。研究结果为探索多因素作用下夯土雨蚀的破坏机制提供方法借鉴,是土遗址病害研究的重要组成部分。     

Land Use and Soil Erosion in Prehistoric and Historical Greece

Abstract

Soil erosion resulting from human exploitation of the land has attracted much public and scientific interest. Being regarded mainly as a modern phenomenon, however, its prehistoric and historical extent remain largely unexplored. Here we summarize three regional studies of Holocene erosion and alluviation in Greece, together with information derived from the literature, and conclude that most recorded Holocene soil erosion events are spatially and temporally related to human interference in the landscape. Wherever adequate evidence exists, a major phase of soil erosion appears to follow by 500–1000 years the introduction of farming in Greece, its age depending on when agriculture was introduced and ranging from the later Neolithic to the late Early Bronze Age. Later Bronze Age and historical soil erosion events are more scattered in time and space, but especially the thousand years after the middle of the 1st millennium B.C. saw serious, intermittent soil erosion in many places. With the exception of the earliest Holocene erosion phase, the evidence is compatible with a model of control of the timing and intensity of landscape destabilization by local economic and political conditions. On the whole, however, periods of landscape stability have lasted much longer than the mostly brief episodes of soil erosion and stream aggradation.     

Local Knowledge and Economic Realities Affecting Soil Erosion in the Rach Rat Catchment,Vietnam

Several parts of Binh Phuóc Province, southern Vietnam, suffer from degraded soils and vegetation as a result of both natural erosion of weak mud rocks and sandstones and intensive human activity, especially through land clearing for agriculture on unstable slopes, deforestation, and abandonment of poor farmland. The underlying cause of this land degradation has been the farming habits of migrants of varying ethnic groups who have settled in the area since 1980. The indigenous farming knowledge of these people and the role of that knowledge in soil erosion were examined by a series of household surveys. They enabled farming practices to be related to ground cover established from a 2002 Landsat 7 ETM (Enhanced Thematic Mapper), and erosion data from a series of erosion bridge measurements. A GIS (Geographical Information System) approach was piloted as a means of identifying areas vulnerable to erosion. This could then be combined with the understanding of farming practices to reveal the relative roles of farmer behaviour, crop cover, and slope and soil characteristics in the erosion process. Land use, local people's knowledge and economic realities are the main factors, as well as natural conditions, that drive this land degradation.     

A Comparison of Past and Present Episodes of Gully Erosion at Wangrah Creek,Southern Tablelands,New South Wales

Erosion gullies at Wangrah Creek expose walls of at least two previous episodes of gully erosion. Past gullies were of a similar size to those of today but were not as widespread across the region at any particular time. The causes of past and present erosion are examined by mapping points of gully initiation and comparing the geomorphic history with an independent palaeo-environmental history. Past gullies were the result of intrinsically unstable conditions, possibly caused by the expansion of swampy deposits increasing runoff. In contrast, the present gully erosion is the result of major environmental change caused by European settlement, which had a greater effect on gully erosion than any other environmental change over the last 10,000 years. At Wangrah Creek, sites of gully initiation indicate that the present erosion was caused by localised disturbances to the valley floor.     

降雨对陕西省榆林市榆阳区明长城破坏的初步分析

降雨是陕西省榆林市榆阳区明长城的主要破坏因素之一。调查中发现,降雨对遗址破坏严重。为了研究降雨对遗址的破坏,在对遗址详细调查的基础上,结合遗址特征与遗址区降雨特点,并参考土壤侵蚀学等方面理论,分析了降雨对遗址的破坏形式及影响因素。结果表明,降雨对遗址的破坏形式可分为直接破坏和间接破坏两大类。其中,主要破坏形式为冲沟侵蚀、片流面蚀和雨蚀剥离。影响因素包括降雨特点、遗址形态、土的性质、植物生长状况和地幔层等,不同破坏形式的主要影响因素各有不同。本结果不仅丰富了降雨对土遗址破坏方面的研究,还为后续陕西榆阳区明长城保护加固措施的选择提供了依据。     

A Geomorphological Study of the Giza Necropolis,with Implications for the Development of the Site

There are a number of features of weathering and erosion within the enclosure surrounding the Great Sphinx of Giza that suggest the action of flowing water. That this erosion is not uniformly distributed is consistent not with erosion by rainfall per se but by rainfall run‐off—an erosive agent that is known to have been experienced at Giza until the late Fifth Dynasty. When the spatial relationship of various features within the Giza necropolis is considered, the extant erosion indicates that the Sphinx may pre‐date the reign of Khufu, the builder of the first Giza pyramid. The existence of pre‐Fourth Dynasty development at Giza can be inferred from this—support for which is provided by a number of archaeological finds excavated from the site.     

元代以来洛川塬区沟谷发育速度和土壤侵蚀强度研究

文章用史料考证和实地考察相结合的方法 ,以陕西洛川旧县古城的兴废为地面解译标志 ,以旧县南沟为研究小流域 ,恢复了元代以来洛川黄土塬区沟谷发育与土壤侵蚀过程。计算出了不同时段南沟的沟谷发育速度、土壤侵蚀强度。通过分析得出元代以来洛川塬区沟谷发育速度、土壤侵蚀强度有加剧的趋势 ,其变化与气候变迁、人类活动关系密切 ;降水量较丰富时沟谷发育、土壤侵蚀较强 ;人为加速侵蚀与自然侵蚀相叠加是近现代洛川塬区沟谷发育、土壤侵蚀剧烈的主要原因。建国后黄土高原水土保持效果显著     

Quantifying the effects of erosion on the archaeology of intertidal environments: A new approach and its implications for their management

Abstract

While the high archaeological and palaeoecological value of intertidal deposits has become well known, approaches to their management remain extremely restricted. Despite the often high levels of erosion experienced by some sites there has been very little development in methods aimed at understanding or quantifying the threats. This paper presents an approach aimed at monitoring erosion within the Humber estuary, UK, where previous finds including Bronze Age boat remains and trackways have made it an area of international importance. Two sites have been investigated and the results from these demonstrate both the high rate of sediment removal and also the highly variable nature of intertidal erosion. It is argued that global figures relating to rates of erosion are wholly inappropriate when attempting to manage archaeological deposits that have survived in intertidal environments. Rather, management of such archaeologically rich but threatened landscapes is only possible through regular quantitative monitoring. Such an approach offers coastal protection authorities a valuable opportunity to assess the long-term progress of erosion and coastal change. This methodology could be employed alongside management agreements within those particular coastal cells or process units that have been identified in a Shoreline Management Plan.     

Erosion and Errors: Testing the Use of Repeated LIDAR Analyses and Erosion Modelling for the Assessment and Prediction of Erosion of Archaeological Sites?

Slope soil erosion is one of the main threats to archaeological sites. Several methods were applied to establish the erosion rates at archaeological sites. Digital elevation models (DEMs) from three different dates were used. We compared the elevations from these three models to estimate erosion. We also applied the landscape evolution model LAPSUS with the available DEMs as basis. Spatial processing errors and effects of tillage and harvesting practices explain most of the DEM elevation differences between the recordings. Increased DEM resolution does not result in more precise or reliable erosion. The present technological level of landscape evolution modelling makes it possible to indicate areas most vulnerable to soil displacement by surface runoff erosion and tillage. Future research, using sediment and surface dating techniques such as deposit of radionuclides, heavy metals and OSL dating will provide a more accurate estimation of erosion rates and the subsequent impact on archaeological sites.     

Bank Erosion in the Bellinger Valley,New South Wales: Definition and Management

Lateral channel migration is normal or autogenic, with bank erosion often on concave and accretion on convex banks. Where bank erosion occurs, particularly at an accelerated rate through land abuse and an increase in flood magnitude and frequency or allogenic, it threatens human use of the flood plain. There is a demand for protection, often with very little understanding of the erosion hazard. Measurements based on photogrammetry were used to define bank erosion and accretion, as well as width changes, in eight meander arcs (11 sections in each) over 41 years. It was concluded that, if this rate continued over the next century, 82 ha of alluvial land, 6.2 km of roads, two bridges, 9 homes and 51 home sites could be lost. Various management options, costs and benefits are given in order to show how future planning and protection can be more rational.     

Exploring the Relations Between Riverbank Erosion and Geomorphological Controls Using Geographically Weighted Logistic Regression

The relations between riverbank erosion and geomorphological variables that are thought to control or influence erosion are commonly modelled using regression. For a given river, a single regression model might befitted to data on erosion and its geomorphological controls obtained along the river's length. However, it is likely that the influence of some variables may vary with geographical location (i.e., distance upstream). For this reason, the spatially stationary regression model should be replaced with a non‐stationary equivalent. Geographically weighted regression (GWR) is a suitable choice. In this paper, GWR is extended to predict the binary presence or absence of erosion via the logistic model. This extended model was applied to data obtained from historical archives and a spatially intensive field survey of a length of 42 km of the Afon Dyfi in West Wales. The model parameters and the residual deviance of the model varied greatly with distance upstream. The practical implication of the result is that different management practices should be implemented at different locations along the river. Thus, the approach presented allowed inference of spatially varying management practice as a consequence of spatially varying geomorphological process.     

唐代铁佛残块及汉代铁剑的科学分析及有机硅在其保护中的应用

章介绍了两件铁质物的科学分析及其用有机硅进行保护的过程,通过金属腐蚀速率的实验说明了有机硅可以有效减缓铁器的腐蚀速率,并结合相关资料证实了有机硅在铁质物何护中应用的可行性。     

浅析近世误读进化论所产生之负面效应

本文分别从个人主义的泛滥与新道德和民主政治构建的难产、理想主义的滥觞与激进主义者实践道路的迷惘、唯科学主义思潮的横行与国人人生观的困惑等视角发掘出误读进化论所产生的近代社会转型问题,希望唤起学界对进化论展开深刻反思,审视它在近代所带来的负面效应.     

Fire,Humans and Denudation at Wangrah Creek,Southern Tablelands,N.S.W.

The influence of altered fire regimes on the denudation of a catchment is determined from alluvial deposits of the last 10,000 yrs and by monitoring runoff and erosion before and after a wildfire. An increase in fire frequency beginning at 3,000–4,000 yrs BP, as a result of intensified Aboriginal burning, did not change the mechanisms or rates of denudation nor did it cause widespread alluviation as suggested by others. The results of monitoring show that before and after mild fires there is insufficient runoff on most slopes to entrain sediment. Only after intense fires are runoff and erodibility increased enough to significantly accelerate erosion. Conditions are then identified which are most likely to lead to accelerated erosion from altered fire regimes in other catchments.     

The use of Caesium–137 to Assess Surface Soil Erosion Status in a Water–Supply Catchment in the Hunter Valley,New South Wales,Australia

In the absence of direct erosion measurements, the soil activity of the fallout radionuclide caesium–137 (¹³⁷Cs) offers an attractive tool for the estimation of long–term (approximately 45 years) net surface and minor rill soil erosion rates for hillslopes. A transect–based soil sampling technique was applied to one woodland and five grazed pasture hillslopes in the Williams River water–supply catchment in the Hunter Valley, New South Wales. An Australian regression model (SOILOSS) relating net soil loss from runoff–erosion plots to ¹³⁷Cs deficit in soils was used to calculate a weighted net surface and minor rill erosion rate for the six hillslopes. The net median surface erosion rates ranged between 0.00 and 0.64 t ha^–1yr^–1with the average median soil erosion rate of 0.19 t ha^–1 yr^–1(std. dev. = 0.23), indicating that these hillslopes were unlikely to be major sources of sediment to the catchment's waterways. Net soil loss rates were also shown to be low in comparison to Australia–wide data and comparable to hillslope data obtained elsewhere in the same region. Minimum and maximum error bounds were provided with each erosion rate to account for radionuclide detector count error. For one hillslope the estimated error due to detection was 1.34 t ha^–1yr^–1, while the remaining five hillslopes exhibited error of up to 0.41 t ha^–1yr^–1. Correlation analyses between the net soil loss rates and physical hillslope characteristics were non–significant.     

Integrating Geomorphological Assessments and Oral Histories in Catchment Management: Implications for the Mulgrave River,Northeastern Australia

The dramatic decline in the integrity of Australian river systems in recent decades has seen the development of landcare and catchment management groups across the continent as the main facilitators of river rehabilitation works. There is growing concern for the need to develop adaptive management frameworks that assist informed decision making through the integration of social and geomorphological knowledge into catchment planning. In the Mulgrave River Catchment of northeastern Queensland, difficult management decisions have to be made with limited access to knowledge of natural processes and baseline geomorphological data. To date management decisions have been based almost exclusively on oral histories that state that point bars are accreting and the river is becoming shallower due to bank erosion. As a result bank stabilisation and removal of sand from within the channel have been recommended in the absence of any geomorphological assessments. This study compares oral histories of river bank erosion in the Mulgrave River with geomorphic evidence to highlight the need for integrated landscape scenario planning. The results of grain size analysis of bank and bed material from 27 locations, involving 47 samples, suggest that bank erosion cannot be delivering sediments to point bars. Furthermore, qualitative analysis of historic parish maps and aerial photographs shows that there has only been moderate bank erosion at three locations along the Mulgrave River since European settlement. The study demonstrates the important role that geomorphological investigations have for catchment management and the need for management frameworks that integrate geomorphological processes and landholder priorities for sustainable river management.     

Soil erosion and flooding on the eastern South Downs, southern England, 1976–2001

The South Downs in southern England have been farmed for 5000 years: the initial loess cover is now a thin, stony remnant as a result of erosion. During the 1980s, field monitoring of erosion events in an area of 36 km² showed that average rates of erosion are low (0.5–5.0 m³ ha⁻¹ yr⁻¹), but that occasional storms result in losses of over 200 m³ ha⁻¹ yr⁻¹ on individual fields. On soils that are only 15 cm thick, such rates pose a threat to future farming. Almost all recent erosion has been on fields of winter cereals, which are bare in the wet autumn period. Of greater significance in the short term are the effects of soil-laden runoff (or muddy floods) on urban areas. Flood damage to property has been a regular event since the conversion of this area to winter cereals in the 1970s. Soil conservation measures have been negligible and flood protection has consisted mainly of engineering works and limited land-use change at sites where property damage has occurred. Conversion to grass under the Set Aside, and an Environmentally Sensitive Area (ESA) scheme, could be an effective soil conservation and flood protection approach. In the longer term, increasing stoniness of soils, the economic incentives for arable farming in marginal areas, and the success of legal proceedings relating to flood damage, will determine the future of erosion on the South Downs. Current farming systems clearly are unsustainable and would become more so under future climates without substantial site-targeted land use change.     

试论地方治理的特殊性——宋人对“蜀乱”的认识与辨析

"蜀人好乱"之说起源于南朝,在宋代尤其是北宋仍是社会各界的主流认识。但随着形势的发展,巴蜀社会稳定、地位不断提升,以蜀人为主的一部分士大夫从乱蜀者、蜀中及全国形势、治蜀政策等多个方面,极力批判蜀人好乱之说,为蜀人辩诬。明清以来,蜀人好乱之说更为流行,宋人的辨析无疑在巴蜀史上成为独特的现象,其深厚的历史及思想文化内涵值得人们反思。