New technologies and systems for high quality citrus fruit production,labor-saving and orchard construction in mountain areas of Japan

Novel technologies have been necessary for improving fruit quality and productivity of citrus,labor-saving and orchard conservation on steep slope lands since aging of growers and decrease in the number of successors is remarkable in mountain areas of southwestern Japan. The purpose of this paper is to introduce new technologies for improving citrus production that have been developed in recent years. A new fruit quality control system using drip irrigation and liquid fertilization technique combined with year-round plastic mulching was developed, and it enables high quality and stable citrus fruit production. Water and/or nutrient solution is automatically supplied through drip tubes that are laid under the mulching sheets to give adequate water stress, so as to improve sugar and acid content of fruit. A new transportation system for steep sloping citrus orchards, which is a combination of the monorail system and contour narrow paths, was suggested. A small walking cultivator was developed to explain the procedure of narrow path excavation. After introducing the narrow path, working hours for fertilizer and chemicalherbicide application were reduced. Disasterpr evention mapping of citrus orchards on slope landswas developed based on computer-aided seepage estimation and topographic data. The mapping can show zones of both ascending flow and descendingflow of underground water during heavy rains incitrus orchards. The mapping is considered to be effective for the management of orchards andprevention of erosion on slope lands.     

Managing Soil Erosion Potential by Integrating Digital Elevation Models with the Southern China＇s Revised Universal Soil Loss Equation——A Case Study for the West Lake Scenic Spots Area of Hangzhou, China

In China, many scenic and tourism areas are suffering from the urbanization that results from physical development of tourism projects, leading to the removal of the vegetative cover, the creation of areas impermeable to water, in-stream modifications, and other problems. In this paper, the risk of soil erosion and its ecological risks in the West Lake Scenic Spots （WLSS） area were quantitatively evaluated by integrating the revised universal soil loss equation （RUSLE） with a digital elevation model （DEM） and geographical information system （GIS） software. The standard RUSLE factors were modified to account for local climatic and topographic characteristics reflected in the DEM maps, and for the soil types and vegetation cover types. An interface was created between the Areinfo software and RUSLE so that the level of soil erosion and its ecological risk in the WLSS area could be mapped immediately once the model factors were defined for the area. The results from an analysis using the Areinfo-RUSLE interface showed that the risk value in 93 % of the expanding western part of the WLSS area was moderate or more severe and the soil erosion risk in this area was thus large compared with that in the rest of the area. This paper mainly aimed to increase the awareness of the soil erosion risk in urbanizing areas and suggest that the local governments should consider the probable ecological risk resulting from soil erosion when enlarging and developing tourism areas.     

土壤侵蚀危险度的计算与影响因子分析——以福建安溪红壤水土流失区为例

随着国家对生态环境的重视和水土保持科学的发展,有关土壤侵蚀危险性评价的研究越来越重要。本文对土壤侵蚀危险度评价的一般方法进行了改进。首先,分析了安溪县各强度等级的土壤侵蚀在高程、坡度、土地利用类型和土壤类型的面积分布情况,计算了不同高程带、不同坡度、不同土地利用类型和土壤类型的土壤侵蚀综合指数然后,以各影响因子的土壤侵蚀综合指数为权重,计算了不同侵蚀影响因子在安溪县各子流域的土壤侵蚀危险度,既避免了权重确定的主观性,又保证了土壤侵蚀危险度的计算适合当地的实际情况,从而明确了各子流域土壤侵蚀发生的可能程度最后,依据土壤侵蚀危险度和土壤侵蚀强度的分布规律,对整个研究区进行了水土保持分区,提出了治理方向。     

Natural and artificial connections between atoll islets in the pacific,their process and environmental impact

Three types of natural connection between atoll islets are described. Causeway, as an artificial way of connecting islets, makes a connection to be completed in a few months. In this case shore adjustment becomes more vigorous than that in natural conditions, resulting in lagoon shore erosion. A causeway without short bridges or culverts should be built close to the lagoon shore to reduce lagoon shore erosion. A causeway-crossing channel assemblage is the worst type among all of the connection engineering constructions because the crossing channel traps sediment and further transports it out of the channel, resulting in long period coastal erosion. Reforming Nippon Causeway in Tarawa Atoll, Kiribati by simple means will stop sand loss, reduce shore erosion and greatly upgrade its stability.     

����������״ͼ���ۺϵĹ���Ӧ�÷����о�

????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????о????????÷???????????????????Ч?????????????     

沉积盆地异常低压(负压)与油气分布

在沉积盆地油气勘探过程中,异常压力与油气聚集的关系愈显密切,而异常压力不仅仅是指异常高压,国内外在发现许多异常高压油气藏的同时,也发现了相当数量的异常低压油气藏,而且异常低压在世界许多盆地中均有分布.因此,深入研究异常低压的形成机理及与油气分布的关系,同样重要和不容忽视.本文介绍了异常低压的概念、特征和分类,详细分析了异常低压的形成机制:地层剥蚀卸载后的弹性回返(反弹)作用、流体的供排不平衡、轻烃的扩散作用、断裂和不整合面的压力释放作用、渗透作用和温度变化等;最后论述了异常低压与油气分布的关系.     

宽甸县水土流失灾害与防治对策

宽甸县处于新构造运动强烈上升区,境内峰峦叠嶂,山势陡峻,沟深谷狭,暴雨频繁,地质环境十分脆弱;加之森林大量砍伐,陡坡开荒严重,垦植指数过高,超载养蚕放牧,滥采乱挖猖獗,使生态环境遭到严重破坏,水土流失程度日益加剧。严重的水土流失,导致水库淤积,河道堵塞,土层变薄,地力下降,洪水泛滥,灾害频繁,给国民经济和社会发展造成巨大损失。本文阐述了宽甸山区水土流失的形成因素和危害现状,并因地制宜提出了水土流失灾害的防治对策     

Quaternary uplift of northern England

Upland flats, attributable to erosion, have long been recognised in the landscape of the Lake District region of NW England, at altitudes of up to ~ 800 m O.D. Extrapolation using uplift rates derived from dated Pleistocene sites (karstic caves and other features) in the adjacent Pennine uplands suggests that if this succession of flats formed close to sea-level they date from the Middle Pliocene onwards, indicating a subsequent time-averaged uplift rate of almost 0.3 mm a^− 1. Numerical modelling indicates that erosion of surrounding areas at a typical rate of 0.2 mm a^− 1 since 3.1 Ma could have caused this uplift, as well as constraining the local effective viscosity of the lower crust as ~ 4 × 10¹⁸ Pa s and the typical local Moho temperature as ~ 650 °C. It is thus feasible that most of the topography of northern England has developed since the Middle Pliocene, as a consequence of coupling between erosion and the resulting induced flow in the lower continental crust. The much faster vertical crustal motions indicated in this part of northern England, compared with SE England, are thus mainly a consequence of much greater mobility of the lower crust in the north, due to its younger thermal age and the heating effect of radioactive Palaeozoic granites. Uplift of this magnitude, which has previously gone unrecognised, may have affected post-Pliocene global climate.     

干旱环境下氯盐和硫酸盐对遗址土体强度的影响

为了探讨氯盐和硫酸盐对遗址土体强度的影响,本文通过室内试验,对洗盐后的素土分别以0.2%的梯度加入NaCl和Na2SO4两种可溶盐,测试特定盐分含量和类别的含盐土在干旱环境下的单轴抗压强度、抗拉强度、弹性波速以及抗风蚀能力的变化。试验结果表明：在室内环境条件下,盐分的存在对土体起着一定的胶结固化作用,使得土体的强度表现出相应程度的增大,并且硫酸盐对土体的胶结固化作用比氯盐显著。随着盐分含量的增加,含盐试样的单轴抗压强度、抗拉强度呈现出指数形式的增大; 垂直于压制方向和平行于压制方向的弹性波速均呈现出增大的趋势; 随着挟沙风速的增大,试样的风蚀损失量增加,同时在18ms-1的挟沙风速作用下,随着盐分含量的增加,试样的风蚀损失量逐渐减小,含盐试样表现出渐进破坏的形式。     

The use of caesium‐137 to estimate agricultural erosion on steep slopes in a tropical watershed

The estimation of erosion and sediment delivery rates in tropical mountain watersheds is difficult and most of the methods widely used for estimating soil erosion over large areas have serious limitations. The ¹³⁷Cs approach has potential for quantifying soil erosion because it can provide retrospective estimates of long‐term (since 1963) net sediment redistribution relatively quickly. Despite its great potential, ¹³⁷Cs has not yet been used in an extensive, reconnaissance level survey of erosion in complex tropical mountain environments. The objective of this study was to examine the applicability of the ¹³⁷Cs method to estimate erosion on steep tropical agricultural lands (23 to 80% slopes) in the Nizao watershed, a humid, tropical mountain area of the Dominican Republic. In this study we (i) examine the variation of ¹³⁷Cs in ten reference sites—eight coffee groves and two forested sites—and (ii) estimate erosion from 14 cultivated fields. The soil pool of ¹³⁷Cs ranged from to 150 to 192 mBq cm⁻² on reference sites with minimal erosion. Variability among reference sites was less than expected for such complex mountain terrain. The variability within coffee and forested reference (average CV=28%) sites was similar to the variability found on grassland and forested reference sites in the temperate zone. The estimated annual soil loss from 14 sampled fields ranged from 6 to 61 t ha⁻¹ year⁻¹ with an overall mean of 26 t ha⁻¹ year⁻¹. Overall, the soil erosion estimates found using the ¹³⁷Cs method were much lower than those often assumed for such steep tropical hillsides. These erosion estimates account for soil loss since 1963 only and it seems likely that soil losses may have been much higher in earlier decades immediately after initial forest clearing earlier in the 20th century. Copyright © 2000 John Wiley & Sons, Ltd.