北京市永定河河滩流动沙地风沙活动分析

风蚀是塑造地貌景观格局的基本过程之一,也是土地荒漠化的一个过程。在永定河河滩流动沙地风沙活动季节进行试验观测,选择河滩流动沙地以及周边稀疏草地为研究材料,通过对试验样地的风沙流活动、粗糙度、沙丘运移等进行了定位与半定位试验观测,并对流动沙地以及周边稀疏荒草地的风沙流活动特点和影响因子进行了分析。     

近35年松嫩沙地风沙-植被动态演变及模拟预测

在全球气候变化与人类活动影响下,松嫩沙地风沙—植被发生了明显变化。基于Landsat系列影像与该区气象、社会经济数据,分析了1980—2015年松嫩沙地风沙—植被动态演变过程及驱动因素,并对其未来发展变化进行了模拟预测。结果表明:近35 a该区风沙地貌面积呈波动增加趋势,净增355.00 km²,变幅21.43%,其中2000年达最大值,而后持续减少;植被覆盖面积总体减少了812.29 km²,其中,高、低植被覆盖区面积呈波动减少趋势,分别减少了7 919.35,15 479.84 km²,而中植被覆盖区面积呈增加趋势,净增22 587.90 km²;风沙覆盖面积与低植被覆盖区面积呈显著负相关。根据预测,到2020年松嫩沙地风沙地貌面积仍呈减少趋势,植被覆盖面积有所增加,尤其低植被覆盖区面积增长明显,达4 292.95 km²。松嫩沙地风沙—植被动态演变受控于区域气候变化和社会经济发展,且与社会经济因素相关性较强。研究为松嫩沙地风沙治理及区域持续发展提供科学依据。     

人类活动与土壤侵蚀

综述了人类活动通过影响坡面流水过程、坡地重力过程、河流过程、风沙过程、海岸过程而引起的土壤侵蚀现象,指出人类活动是造成水土流失的重要原因之一。     

土地利用地域分区方法研究——以桂林市为例

本文采用遥感解译地域分类和聚类分析归类方法，对桂林市土地利用地域分区进行了研究。结果表明：１）地貌是明显区域，两种方法分区结果基本一致；２）区内地貌类型基本一致区域，应以聚类分析地域归类为主；３）地貌类型过渡区域，应采取遥感解译地域分类和聚类分析地域归类相结合方法，并考虑土地利用本来发展方向等。     

拉萨河下游河谷区风沙灾害现状、成因及发展趋势探讨

通过对拉萨河下游河谷实地调查和IKONOS、QuickBird的影像解译结果,查明了该区沙尘源地具有沿河谷及河谷两侧分布、分布地貌部位多样且呈小面积零星分布的特征,并对城市环境和工农业生产造成了严重的风沙危害。通过分析表明高原气候条件下脆弱的生态环境、沙源特征和植被条件,以及近年来强烈人类活动的干扰是风沙灾害的主要原因。从气候和人类活动变化趋势分析表明,未来15年内气候变化不利于削弱风沙灾害强度;人类活动尽管对风沙灾害强度的加强作用会逐渐降低,但总体上仍起强化作用,如果不采取人工治理,拉萨河谷风沙灾害就趋于加强的态势。     

扇形地的类型辨析及区分方法探讨

[目的]总结国内外对扇形地的研究成果及存在的问题,为扇形地合理分类和地貌实体的区分提供方法和建议。[方法]通过文献梳理,总结了各类扇形地的概念、命名、地貌、地表环境和利用方式等方面的不同特征,并对各类型扇形地进行辨析。[结果]现有研究对扇形地的概念和类型尚未形成共识,且部分研究对冲积扇、洪积扇和泥石流堆积扇的概念和命名有混淆。冲积扇和洪积扇地貌实体之间的主要区别为:冲积扇扇面一般具有常流水,且流道多固定,但洪积扇则与此相反。区分各类扇形地地貌实体主要包括地理分布、地貌特征、遥感影像和实地勘察等方法。[结论]明确扇形地的类型、地表环境特征和区域背景环境,将有利于扇形地合理开发、利用和保护。     

沿海地区用于防浪抗风固沙的水土保持植物资源

<正>我国背依亚欧大陆,面向太平洋,东南部沿海地区有一个巨大的弧形并向东南突出,形成了一条漫长蜿蜒的海岸线。这条海岸线北起中朝两国交界的鸭绿江,经辽宁、河北、天津、山东、江苏、上海、浙江、福建、广东、海南、广西等11个省(市、区),南至中越边界上的北仓河口,全长1.8万km,横跨22个纬度带,全国40%的人口和60%的GDP都集中在这一区域。按其成因,我国海岸可分为侵蚀型海岸、堆积型海岸和平衡型海岸;按陆地地貌,可分为平原海岸、山地丘陵海岸;按其物质组成,可分为基岩海岸、砂质海岸、泥质海岸和生物海岸。一般来说,基岩海岸都是上升型海岸和侵蚀型海岸,砂质海岸和泥质海岸则视具体情况分别属于堆积型海岸或平衡型海岸。     

基于GEE的广西北部湾沿海水产养殖池塘遥感提取

沿海水产养殖池塘带来经济效益的同时,也会引起诸多环境问题,了解其空间分布对于海岸带的科学管理和渔业可持续发展具有重要意义。广西北部湾海岸带地形错综复杂,养殖池塘沿岸线散乱分布,导致传统遥感识别方法难以实现高精度提取。针对此问题,该研究提出一种基于Google Earth Engine（GEE）平台和全年Sentinel-1和Sentinel-2时序遥感数据的水产养殖池塘识别方法,结合多阈值分割和面向对象分类提取2019年广西北部湾海岸带的水产养殖池塘。结果表明：1）广西北部湾海岸带养殖池塘面积总计199.3 km2,遍布整个沿岸地区;识别结果总体精度达到0.921,Kappa系数为0.842;2）选取4个典型区域,对比该研究方法提取结果与Google高清影像目视解译结果,在规模化集聚型养殖区域中,识别结果占目视解译的面积比例达到90%以上,在排布密集的小型池塘区域面积占比也能达到80%以上;3）以时序遥感数据作为分类特征值,能够有效排除废弃池塘、水稻田和季节性水域。该方法在大范围复杂环境中仍具有良好性能,显著提高了水产养殖池塘遥感识别的精度,能够为海岸带生态环境的智能监控、养殖区域空间优化提供技术支持。     

陕西省土地资源开发利用的战略思考

根据区域地貌特征,陕西省土地被分为5个开发利用区,即:风沙旱滩区,黄土丘陵沟壑区,黄土高原沟壑区,渭河平原区,秦巴山区,并对每区的开发利用战略进行了讨论。最后提出,人类必须遵循生态学原理,把现代农业技术和传统经验相结合,因地制宜,分区建立良好的区域经济生态系统。     

河南省多级地貌特征及与土壤多样性的关系

从土壤多样性向地多样性发展符合土壤地理学的研究趋势,选择河南省作为研究区,将地貌这一主要的地学要素加入到土壤多样性的研究中,并用改进的仙农熵公式对多级地貌空间分布多样性及其与土壤多样性的相关性进行探讨。首先,对河南省1︰175万地貌类型图进行矢量化得到地貌类型等级系统;然后,对地貌和土壤的构成组分多样性和2种不同分类体系的分支率进行计算并分析其特征;最后,在3 km×3 km网格尺度下分析地貌和土壤多样性间的相关性。研究表明:河南省共有3个一级地貌,12个二级地貌和37个三级地貌;随着土壤和地貌分类的等级细化,其分类个数和构成组分多样性值均呈上升趋势,即土壤和地貌所有分类单元在数量构成上的均匀程度越来越高;两种分类系统中,土壤分类较地貌分类有更详细的分类体系,且分支率有较大范围的变化;河南省一级地貌、二级地貌和三级地貌的空间分布多样性值和面积值均最大的类型分别是流水地貌、冲积平原和泛滥平坦地,是不同级别的优势地貌类型;一级地貌类型与土类、亚类和土属多样性间存在紧密的相关关系,且以流水地貌与土壤多样性间的相关性最强。     

Coastal dynamics and impact of coastal protection works on the Spurn Head spit (UK)

The erosion of the glacial tills along the Holderness Coast (eastern England) has released material which has led to the formation of a 4.5 km sand and gravel spit, Spurn Head, across the mouth of the Humber estuary. This paper examines the sedimentology and geomorphology of the spit and of the tidal flat behind it (Spurn Bight), and assesses the effects of coastal defences on the nearshore dynamics. A study of the coastal dynamics was carried out by analysing wind data and modelling wave shoaling and refraction at the estuary mouth, and on the tidal flat. The geomorphology and sedimentology of the beaches and the tidal flat were studied to assess the response of the spit system to different weather conditions.The results show that only 6% of the longshore drift produced by cliff erosion in Holderness is transported along Spurn Head, mainly by waves from the north and the north-east. This drift is stored in an area of sand and gravel banks at the tip. Medium-size sand is carried around the tip by south-easterly waves, leading to the formation of a small area of tidal sand waves. Waves from the southwest, which originate within the estuary, spread the sand over the tidal flat, but are not able to carry it towards the most northern inner part of the spit. Coastal defences built along the spit have slowed its rate of landward migration and prevented overwash processes. The defences have not been maintained for the last 30 years so that the spit is now likely to be breached in the winter months whenever surge conditions exist.     

Long‐term Human Impacts on the Coast of La Graciosa,Canary Islands

Global change is affecting coastal areas and leading them to degradation. This is severe in sand dunes and sand plains, because they are very fragile ecosystems. The objective of this paper is to characterize the relationship between the historical land uses and the aeolian sedimentary dynamics in an arid coastal system, the island of La Graciosa (Canary Islands) since the second half of the 18th century. The methodology is based on the interpretation of historical documents, aerial photographs and oral testimonies to characterize the changes in the island, in terms of both land use and aeolian geomorphology. The results suggest the existence of six stages during which the intensity of human pressure on the environment changed. Copyright © 2015 John Wiley & Sons, Ltd.     

陕北毛乌素沙地生物结皮发育特征的初步研究

通过野外采样和室内分析相结合,掌握了陕北毛乌素沙地不同采样点生物结皮层的理化性质以及该地区生物结皮的发育特征,为以后进一步研究毛乌素沙地生物结皮的防风固沙效应奠定了理论基础.结果表明:随着生物结皮的发育,结皮层厚度增加.最大值为11.82 mm;土壤颗粒细化,0.02～0.05 mm之间的颗粒含量为7.3%～27.7%,高于流沙中的颗粒含量;由于颗粒的细化,结皮层容重增加,其抗剪强度明显提高,且抗剪强度与厚度和容重之间存在一定的相关性.生物结皮层pH值为7.23～7.81,低于流动沙地的pH值;有机质、N和K含量明显高于流沙的含量;P含量有所增加但不明显.研究表明,各个样点的生物结皮效应表现有所不同,原因有多方面.主要是结皮的发育程度、植被盖度以及采样点地形地貌之间的差异所引起.     

近地层沙尘水平通量与集沙效率野外观测分析

沙漠是沙尘物质的重要源区,沙漠近地层沙尘水平通量的测量与研究是认识沙尘输送过程、评估风沙活动强度的基础。集沙仪是测量沙尘水平通量的最重要手段之一,被广泛应用于各种观测试验中。集沙效率是集沙仪最重要的参数,是校正沙尘水平通量测量数据的依据。选择塔克拉玛干沙漠腹地塔中地区的典型平沙面为观测点,利用全自动高精度集沙仪,H-11B型Sensit风蚀传感器、10 m气象塔,于2010.7-2010.8月开展了野外观测试验,基于观测数据对全自动集沙仪的集沙效率、近地层沙尘水平通量进行了分析研究。结果表明:相同时段内,集沙总量与Sensit风蚀传感器所记录的跃移颗粒数具有较好的线性关系,R~2值平均为0.6053;全自动集沙仪在5 cm高度上的平均集沙效率为94.3%;观测期间,不同沙尘天气过程的沙尘输送量存在显著差异,通过宽2 cm×高5 cm截面的最大沙尘水平通量为190.335 kg,最小为1.2 kg;5 cm高度上的跃移输沙率总体上随着风速的增加而增大,但其中有部分天气时段输沙率随风速的变化不一致,而此情况下对应时段的地表温度明显更大。     

基于DEM的淮河源地貌形态类型划分

[目的]对淮河源地貌形态类型进行划分研究,为该区土地利用、旅游和城市规划以及生物多样性保护提供参考依据。[方法]以淮河源地区为研究对象,基于分辨率为30m的DEM数据,采用地貌形态划分方案中具有代表性的柴宗新方案、徐汉明方案和高玄彧方案,运用空间分析中的邻域分析、重分类、地图代数以及转换工具等,分别对各方案下的淮河源地貌形态类型进行划分并与实际勘察地形进行对比与分析,探寻适合淮河源地貌基本形态划分的最佳方案。[结果]柴宗新方案要素单一,不能确切反映地貌的基本特征;高玄彧方案中的2级分类对研究区并未发挥其作用,该方案比较适合高程高,地貌形态类型多的地区;徐汉明方案采用相对高度和海拔高度2个条件作为地貌基本形态划分的依据,此方案即兼顾了绝对高度的客观作用,又考虑了人们观察山地的真实感受,因此徐汉明方案比较适合淮河源地貌形态的划分。[结论]根据徐汉明方案将淮河源地区地貌形态划分为平原、丘陵、低山和中低山4种类型,主要以平原和丘陵为主,表现为东低西高,北低南高的地势特征。     

Morphological and molecular diversity analysis among the Indian clones of <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> L.

Sesuvium portulacastrum L. (seapurslane) is a halophyte used as pioneer species in sand dune fixation and stabilization of saline soil. Studies on the morphological and molecular diversity were carried out for the 14 clones of Sesuvium collected from the different coastal regions of India. Significant differences were observed for morphological traits viz., length, width, diameter and area of leaf, internodal distance and stem diameter for different clones when compared with the clone from Gujarat state (GJ1). A UPGMA dendrogram for morphological traits based on the Pearson’s similarity coefficient clustered the clones into three groups considering 80% polymorphism as criteria. Molecular diversity among the clones was studied using Randomly Amplified Polymorphic DNA (RAPD), Internal Transcribed Spacer (ITS) and markers specific to Ac homologous region. Of the total 749 RAPD loci amplified with 70 random primers, 294 were polymorphic with 39.25% diversity. A phylogenetic tree constructed with UPGMA and SHAN, grouped the clones into three major clades based on RAPD data. The molecular diversity studied with ITS and markers specific to Ac homologous region revealed 37.50% and 66.66% polymorphism and clustered the clones into three and four clades, respectively. The genetic diversity analysis revealed wide variations among the S. portulacastrum clones, reflecting a high level of diversity within the species which might be due to anthropogenic impact and geographic environmental conditions. Further, the various clones from the different eco-geographic coastal localities might have originated from native places of wild abundance. To the best of our knowledge, this is the first attempt to evaluate both morphological and genetic diversity among the Sesuvium clones collected from the distant habitats of the coastal regions of the India.     

利用地面高光谱和逐步判别法进行滨海盐土开发程度评价

At different times over the past 30 years in Zhejiang Province, China, the coastal tidelands have been successively enclosed and reclaimed for agricultural land use. The purpose of this work was to evaluate whether laboratory hyperspectral data might be used to estimate the physicochemical characteristics of these reclaimed saline soils. A coastal region of Shangyu City （Zhejiang Province）, which was grouped into four subzones according to reclamation history, was used as the study area, and soil samples were collected in each subzone. Physicochemical analyses showed that the soils were characterized by high electrical conductivity and sand content with low organic matter; the longer the saline lands had been reclaimed, the lower were the electrical conductivity and sand content and the higher the organic matter content. These changing trends of soil chemical and physical properties were found in laboratory reflectance spectra of soil samples and their first-order derivative curves. Stepwise discriminant analysis （SDA） identified six salient spectral bands at 488, 530, 670, 880, 1400, and 1900 nm. Using derived discriminant functions for saline lands with different historical years of reclamation, classification revealed an overall accuracy from a self-test of 86.6% and from cross-validation of 89.3%. Therefore, as opposed to time-consuming field investigations, this study suggested that remotely sensed hyperspectral data could serve as a promising measure to assess the reclamation levels of coastal saline lands.     

Blowout dynamics on Lake Huron sand dunes: analysis of digital multispectral data from colour air photos

We adapted a digital image analysis procedure to extract multispectral data from sequential colour air photos of a Lake Huron sand dune system and then classify land cover into water, sand, and vegetation. We isolated portions containing individual blowouts from georeferenced land cover maps of the dune system in 1973 and 1998 and overlaid the sequential images using geographic information systems (GIS). This allowed us to quantify changes in blowouts over the 25-year period. Net change in land cover (m²) within each blowout was expressed as the difference between retrogression (bare areas created by erosion or burial of existing vegetation) and colonization (vegetation patches created by plant establishment on bare areas). The analysis procedure produced maps with an overall accuracy of ≥90% for land cover classification within blowouts. The individual blowouts fell along a continuum of activity, varying from significant retrogression (+748 m²) to significant colonization (−1148 m²). Overall, sand movement in all sampled blowouts produced 3991 m² (17.9% of the blowout area in 1998) of bare sand patches that replaced formerly existing patches of vegetation. Colonization of bare areas over the 25-year period was 4127 m² or 18.5% of the 1998 blowout area. Retrogression and colonization are natural cooccurring processes in coastal dune systems, and the technique described here represents a new tool for the study of temporal and spatial vegetation dynamics in blowouts.     

土工格栅沙障防风积沙效应风洞模拟实验

 模型按1∶10比例设计,在71、5和20m/s的实验风速下,对不同规格和孔隙度的土工格栅沙障模型进行风洞模拟实验,测定其防风与积沙效应。结果表明:不同规格格栅沙障的风速流场趋势相同,在障前、障中和障后形成4个减速区和3个加速区。障前、障后风速降低是土工格栅沙障防沙的主要机制;障中的增速区是引起沙障中部不积沙或少积沙的诱因。格栅沙障因障间互相连接而增强了防护功能,使得流沙被有效地控制在体系内部。同一规格的沙障,障内积沙厚度随着风速的增大而增大,随着距沙源距离的增加而减小。不同规格的沙障,障内积沙厚度随着规格的增大而减小,随着孔隙度的增大而减小。不同风速下,不同规格沙障间积沙厚度差异显著。从积沙厚度和防沙目的分析,10cm×10cm规格的沙障积沙效应最好,10cm×20cm次之,20cm×20cm最差。在设计与设置沙障时需要考虑成本、防护目的和沙源等多方面的因素。     

Classifying land cover conversions in coastal wetlands in the Mediterranean: Pairwise comparisons of landsat images

This study classified land cover conversions by using quantitative change detection methods in the eastern Mediterranean coastal wetlands of Turkey. Three Landsat TM scenes acquired in 1984, 1998 and 2007 were analysed using image pairs of consecutive dates. The amounts of change were calculated for the periods from 1984 to 1998 and from 1998 to 2007, using binary change masks and supervised image classifications, in which eleven a priori defined land cover classes were used. Change areas accounted for 14.81 and 15.64 per cent of the total area, in the first and second periods, respectively. Conversions from/to sand dunes, mud flats and afforestation were by far the most extensive changes. Sand dunes and mud flats decreased, while afforestation and agriculture areas increased in the 23‐year period between 1984 and 2007. Five types of qualitative change were identified on the basis of land cover transformations within and between natural and anthropogenic systems. Type I changes, which indicated conversions from (semi)natural to anthropogenic systems, took place as agricultural expansion over coastal sand dunes, while Type II changes mostly occurred within agricultural systems. Type III changes included changes in human uses, leading to conversions from one anthropogenic system to another. Conversions between semi(natural) systems such as salt marshes and mud‐flats were typical Type IV changes. Type V changes were mainly due to conversions from agriculture to wetland categories or other semi(natural) cover types. Implications of these changes were discussed for management of coastal environmental resources. Copyright © 2011 John Wiley & Sons, Ltd.