Multiple historical geographies: responses and resistance to colonial conservation schemes in East Africa

Examining four colonial soil conservation schemes in East Africa that were part of the modernising project of colonialism, this article considers multiple historical geographies of the colonised world. There were multiple modernities: while information and ideas flowed in many directions between (and within) the metropole and colonies, the particular ‘modernity’ that was put into practice was shaped by its context. The article highlights therefore that – despite playing to the same tune of modernity – colonialism was highly differentiated in the way that its policies played out on the ground. Furthermore, the ‘colonised’ acted and reacted to the policies in highly differentiated ways that depended on their particular context in time and space. All but one of the soil conservation schemes examined were rejected and there was significant resistance to them. Much of the existing literature on such schemes examines them in the context of essentially political processes, and in particular their influence on rising nationalism. Whilst these processes are important, this paper shows that there were other, non-political, factors that influenced the reception they were given, which need to be considered too. These ‘everyday’ details were about the practical and technical nature of the schemes, and by exploring these aspects of the schemes, and comparing them, the article highlights why most were rejected. It suggests that different aspects of conservation schemes need to be explored for a firm understanding of the reasons behind resistance to such schemes.     

Re‐sampling for Soil‐caesium‐137 to Assess Soil Losses after a 19‐year Interval in a Hunter Valley Vineyard,New South Wales,Australia

Soils in a lower Hunter valley vineyard, New South Wales, Australia, were sampled and analysed for caesium‐137, an indicator of soil erosion status, in 1984–1985 and 2004. From the time of the vineyard's first establishment in 1971 to 1985, estimated soil losses were 250 tonnes (equivalent to 64.2 t ha^?1 yr^?1). Re‐sampling in 2004 showed that soil losses were 48 tonnes in the 19 years since 1985, equivalent to 9.7 t ha^?1 yr^?1. The decline in erosion rates may be explained by a change in land and soil management from intensive cultivation to one of no cultivation (sod culture) in 1998, and a lower annual rainfall and fewer rain‐days per year in the period from 1986 to 2004.     

西晋以来彭原古城附近沟谷的演变与复原

根据历史文献和考古调查,确定出甘肃省庆阳市西峰区彭原乡的两座古城遗址分别是后汉富平县城(GC1)和唐宋彭原县城(GC2),唐宋彭原县是北魏永和元年(434年)以后从今庙头嘴村搬迁到南庄村。据此推断泾河四级支流、马莲河三级支流彭原沟(当地称湫沟)流域的现代侵蚀沟,是在此年以后开始发育的。利用黄土高原现代侵蚀沟地貌年龄计算公式,计算出彭原沟主干沟道现代侵蚀沟的地貌年龄为1669±819年,沟口附近的现代侵蚀沟发育于西晋成帝咸康五年(339年)前后,其主要分支沟谷现代侵蚀沟的地貌年龄介于900±442～1300±638年之间。沟头平均延伸速度为3.367m/a,沟谷平均下切速度为0.063m/a,平均加宽速度0.19m/a。公式计算结果与考古结果基本相符,研究结果具有较高的信度。依此结果,将彭原沟及其支流地貌复原至西晋时期。     

Three-dimensional (3D) visualisation: the application of terrestrial laser scanning in the investigation of historical Scottish farming townships

Recent developments in digital technologies are heralding significant changes in the way we acquire, visualise and analyse archaeological data. Terrestrial laser scanners can be used to create photo-realistic virtual copies of landscapes, and archaeological features, and offer the potential to improve our understanding of three-dimensional (3D) spatial relationships at study sites. Here we present a methodology for the integration of a high-resolution 3D site model with soil chemical data obtained from an abandoned settlement site located in the Central Highlands of Scotland. At this site, the multi-element concentration in soil, co-visualised within a topographic setting, has an important role to play in elucidating settlement layout and activity. The methods described here are also of significance in archiving sites of archaeological/historical importance where development activities and/or environmental processes may destroy remains, or where access to field sites is restricted.     

A Survey of Soil Erosion in Australia using Caesium‐137

A survey of soil erosion was conducted in Australia using the fallout radioisotope caesium‐137 as an indicator of topsoil redistribution. Two hundred and six sites were sampled, 100 within rotational cropping and horticultural use, 52 within uncultivated permanent pasture and forest, and 54 in rangelands. Average net soil losses were approximately equal for cultivated cropping lands and rangelands (ca. 5.5 t ha^?1 yr^?1), and just over 1 t ha^?1 yr^?1 for pasture and forest. The Mann Whitney U Test revealed that losses under cropping and rangeland conditions were significantly higher (p < 0.05) than under uncultivated pasture and forest. Soil loss was negatively correlated with mean annual rainfall and slope gradient, and positively correlated with slope length (Spearman's rank correlation). There was no correlation between rates of soil loss and a rainfall erosi‐vity index. An assessment of erosional events was provided by landholders for 104 sites, with their ranking being weakly but significantly correlated with soil loss estimates (r =+0.35). Sixty percent of sites had net soil losses greater than 1 t ha^?1 yr^?1, and 74% of sites had losses of more than 0.5 t ha^?1 yr^?1. This latter rate may be regarded as a limit for a tolerable level of soil loss. These high rates of soil loss have occurred since the mid‐1950s despite there being significant landholder awareness of the soil erosion hazard.     

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.     

Burning Libraries: A Community Response

ABSTRACT

The first decade of the twenty-first century has seen a growing recognition that widespread impacts of climate change (erosion, sea level rise, wildfires, warming soil temperatures) are rapidly destroying archaeological sites and permanently wiping out millennia of cultural heritage and important scientific data on a global scale. This paper provides a brief overview of the efforts of the international archaeological community and its allies to organise a broad and coordinated response to this widespread and urgent threat to our basic record by mobilising at the local, national and international level. The work of the archaeological professional societies has supplemented a growing host of initiatives on multiple scales by national and local governmental agencies, regional research teams, local and Indigenous heritage groups and the international global change scientific community. This paper provides some reflections on the Society for American Archaeology’s Climate Change Strategies and the Archaeological Record team effort from 2015 to 2018, some links to more contacts and resources and some suggestions for future directions.     

Optimal Control of Structures under Earthquakes Including Soil-Structure Interaction

It is well known that the soil-structure interaction (SSI) changes the dynamic response of a structure supported on flexible soil. The analysis of optimally controlled SSI systems has certain difficulties due to the nature of the SSI and the optimal control problem. In this paper, a two-step iteration-based numerical algorithm is proposed to handle optimally controlled SSI systems under earthquakes. First, the optimal control forces are obtained by using a fixed-base system. Then, the optimal control forces are converted to the frequency domain by the Fourier transform technique to be used in the equations of the SSI system. The lateral displacement and the rocking of the foundation are obtained from the equations of the SSI system containing the optimal control forces in the frequency domain. The lateral displacement and rocking of the foundation are then converted to the time domain by the inverse Fourier transform technique, and the lateral accelerations and the rocking accelerations of the foundation are obtained by the forward finite difference method. During the second step, the optimal control forces are calculated again by using the lateral acceleration and the rocking acceleration of the foundation along with the earthquake ground motion. Using the method explained above, the optimal control forces obtained in the time domain are used in the equations of the soil-structure system from which the behavior of foundation and structure is obtained. In the final section of the paper, a numerical study is conducted for a controlled structure supported on flexible soil.     

Numerical Analyses of the Effectiveness of Soft Barriers into the Soil for the Mitigation of Seismic Risk

An approach to mitigate the seismic risk of existing structures by means of the creation of a continuous thin layer of grouted soil at a convenient depth is presented. A parametric numerical analysis is reported using different constitutive models with reference to two geometrical schemes. It is shown that if the grouted layer has a stiffness significantly lower than that of the surrounding soil, it may be effective in reducing the seismic demand. In the parametric analyses, the positive role of yielding is also observed, which indicates that the barrier is more effective with larger input amplitudes.     

Soil and organic carbon losses from varying land uses: a global meta‐analysis

Soil (SL) and organic carbon losses (SOC_L) have increased with human population and climate change linked extreme events. While SL and SOC_L are clearly associated with surface run‐off, the impact of land use is still not well understood. This article elucidates the effects of land use, surface cover, and other environmental factors on SL and SOC_L using data from 55 published studies. The overall SL (12.34 ± 2.25 Mg ha^?1 year^?1) and SOC_L (21.80 ± 0.91 g C m^?2 year^?1) suggests substantial losses of the fertile topsoil globally. Grasslands (4.19 ± 1.22 Mg ha^?1 year^?1) had 77%, 66%, and 41% lower SL than orchards, croplands, and forests, respectively, which is attributable to higher soil organic matter and surface cover. Croplands had the highest SOC_L at 22.78 ± 2.22 g C m^?2 year^?1. Natural vegetation had 98% and 70% lower run‐off and SL than did plant residue mulched plots, indicating its great potential for surface run‐off and soil erosion control. Rainfall and slope were key drivers of soil erosion, while soil surface cover, SOC, and clay content decreased. These findings improve our knowledge on soil and organic carbon losses, which is useful for fostering sustainable management of soils and natural vegetation to enhance ecosystems functionality.