Impacts of human activity and natural change on the wetland landscape pattern along the Yellow River in Henan Province

By using GIS and remote sensing techniques, the paper discusses how human activities have changed along the Yellow River in Henan province, China and how these altered activities have influenced the wetland landscape pattern change from 1987 to 2002. Results show that the total area of the wetland reduces dramatically compared to 1987, the total area of wetland reduces by 19.18%, the number of the patches in 2002 increases by 21.17%, the density increases by 50%, and the total perimeter increases by 1,290,491 m. Disturbed by human activities, landscape diversity index decreases from 1.1740 in 1987 to 0.9803 in 2002. During the last 20 years, the total area of the rice wetland increases, while the others decrease. Among those, the area of the bulrush wetland decreases most. In 1987, it takes 0.5% of the total area, but in 2002, it only takes 0.11%. The interpenetration of human influences on the wetland natural system has been long and close. The impacts of human activities on the spatial pattern of the wetland landscape along the Yellow River in Henan from 1987 to 2002 are great.     

河南沿黄湿地景观格局及其动态

By using GIS and remote sensing techniques, the paper discusses how human activities have changed along the Yellow River in Henan province, China and how these altered activities have influenced the wetland landscape pattern change from 1987 to 2002. Results show that the total area of the wetland reduces dramatically compared to 1987, the total area of wetland reduces by 19.18%, the number of the patches in 2002 increases by 21.17%, the density increases by 50%, and the total perimeter increases by 1,290,491 m. Disturbed by human activities, landscape diversity index decreases from 1.1740 in 1987 to 0.9803 in 2002. During the last 20 years, the total area of the rice wetland increases, while the others decrease. Among those, the area of the bulrush wetland decreases most. In 1987, it takes 0.5% of the total area, but in 2002, it only takes 0.11%. The interpenetration of human influences on the wetland natural system has been long and close. The impacts of human activities on the spatial pattern of the wetland landscape along the Yellow River in Henan from 1987 to 2002 are great.     

QUANTIFYING SEDIMENT TRANSPORT PROCESSES IN PERIGLACIAL MOUNTAIN ENVIRONMENTS AT A CATCHMENT SCALE USING GEOMORPHIC PROCESS UNITS

The research record on the quantification of sediment transport processes in periglacial mountain environments in Scandinavia dates back to the 1950s. A wide range of measurements is available, especially from the Kärkevagge region of northern Sweden. Within this paper satellite image analysis and tools provided by geographic information systems (GIS) are exploited in order to extend and improve this research and to complement geophysical methods. The processes of interest include mass movements such as solifluction, slope wash, dirty avalanches and rock- and boulder falls. Geomorphic process units have been derived in order to allow quantification via GIS techniques at a catchment scale. Mass movement rates based on existing field measurements are employed in the budget calculations. In the Kärkevagge catchment, 80% of the area can be identified either as a source area for sediments or as a zone where sediments are deposited. The overall budget for the slopes beneath the rockwalls in the Kärkevagge is approximately 680 t a⁻¹ whilst about 150 t a⁻¹ are transported into the fluvial system.     

土地覆盖与气候变化对黄河源区径流的影响

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory.Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2℃ and precipitation increases by 20%,catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.     

Impact of land-cover and climate changes on runoff of the source regions of the Yellow River

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory. Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2oC and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.     

沟道流域坡面与沟谷侵蚀演化关系——以晋西王家沟小流域为例

以往坡、沟侵蚀关系研究主要限于水沙关系的探讨 ,有关原型尺度小流域坡、沟地貌侵蚀演化关系的定量研究甚少 ,尤其是坡、沟地貌特征对流域切割程度的综合影响与交互作用的定量研究尚属空白。本文在 3S技术支持下 ,根据晋西王家沟小流域 196 7年 1∶5 0 0 0正摄影像图 (DOM )、高程数字化模型 (DEM )和同期、同比例尺地形图 ,利用正交多项式回归分析方法 ,定量分析了坡、沟地貌特征对流域切割程度的影响与交互作用。研究表明 ,沟谷地在流域地貌演化及地表切割程度中起主导作用 ,在沟间地面积相同时 ,沟谷地面积约为0 1km2 是影响流域切割裂度侵蚀演化强度最大的区域 ,流域面积愈小影响流域地表破碎的程度最大。其沟道流域坡、沟地貌演化机制可用坡、沟水流动能的地貌指标的综合影响与交互作用来解释     

黄河流域沙漠化空间格局与成因

黄河流域地势西高东低,自西向东有青藏高原、内蒙古高原、黄土高原和黄淮海平原4个地貌单元,总面积为79.6万km²。黄河流域是中国重要的生态屏障和重要经济带,黄河流域生态保护和高质量发展已上升为国家战略。沙漠化是中国北方干旱、半干旱以及部分半湿润地区主要的土地退化形式,沙漠化对黄河流域,尤其是流域中、上游地区的影响较大。为了全面掌握黄河流域的沙漠化土地空间分布特征,本研究以Landsat遥感影像为数据源,通过地理信息系统（GIS）技术,获得了黄河流域2010年的沙漠化土地分布数据。结果表明：黄河流域内沙漠化土地面积为128 667 km²,占流域总面积的16.2%;黄河上游的沙漠化土地面积最大,然后依次是黄河中游、黄河源区、黄河下游,沙漠化土地面积分别为89 341、21 426、17 894、7 km²,分别占全流域沙漠化土地总面积的69.4%、16.7%、13.9%、0.01%。黄河流域的沙漠化土地绝大部分分布于内蒙古,其沙漠化土地面积为91 398 km²,占全流域沙漠化土地面积的71.0%;其次是青海,沙漠化土地面积为17 432 km²,占全流域沙漠化土地面积的13.5%;陕西和宁夏的沙漠化土地面积分别占全流域沙漠化土地面积的8.3%和6.5%。黄河流域的沙漠化空间格局主要是降水量与沙源空间耦合的结果,流域92.6%（119 114 km²）的沙漠化土地分布于干旱、半干旱地区。从20世纪70年代以来,黄河流域的沙漠化总体上经历了快速发展—发展放缓—明显逆转的过程,沙漠化大幅度的变化主要受人类活动影响所致,在过去几十年间风速持续减小对沙漠化逆转的积极作用也应引起重视。     

Factors affecting landslides occurrence in agro-ecological zones in the Merek catchment, Iran

Part of the mountainous semi-arid areas of Iran is geologically and topographically susceptible to landslides. A study was conducted at the Merek catchment, Iran which is geologically characterized by limestone, sandstone, shale and marls so as to determine the factors responsible for the occurrence of landslides. In this study, geomorphological units within the catchment were mapped by overlapping geological, topographical, land use and erosion data, using satellite image and GIS. Rocks and soils were sampled within each unit to determine their physico-chemical and mineralogical properties. It was found that landslides have affected about 15% of the Merek catchment and that their occurrence were promoted by unstable soils, being eroded at the rate of 18.57 t ha⁻¹ yr⁻¹. These landslides were initiated by crack formation in areas having smectite, a mineral which can swell and contract, depending on the availability of water. Smectite is the dominant mineral in about 80% of the area affected by landslides. Low aggregate stability in the topsoil further promotes the occurrence of landslides. Field verification showed that landslides occur mainly in the forest where the canopy cover is less than 15% with slope of 10-40%. Deforestation, overgrazing and improper tillage practices were found to accelerate landslides in this catchment.     

内蒙古河套平原耕地盐碱化时空演变及其对产能的影响

以内蒙古自治区巴彦淖尔市河套平原为研究区,利用RS和GIS技术在野外样本采集的基础上,以第一次地理国情普查数据和LandsatTM/OLI、GF-1卫星影像为数据源,通过计算盐碱度与波段的相关性构建出反演模型,以专家决策树进行分类,对2006~2014年耕地盐碱化进行动态监测,并分析了不同盐碱化程度农田植被净初级生产力（NPP）时空变化特征。结论表明：2006~2014年研究区域非盐碱耕地和轻度盐碱耕地面积呈现持续减少的趋势,减少幅度为6.23%,占耕地总面积的3.55%,NPP先增后降,减少了2.06%;中度盐碱耕地面积呈先降后增的趋势,净增加幅度为22.40%,占耕地总面积的5.10%,NPP先不变后增加,增加了6.73%;而重度盐碱耕地面积呈现先增后降的趋势,净减少7.68%,占耕地总面积的1.55%,NPP则持续增加,增加了3.81%。总体上看,9 a间虽然因为自然、人为因素的影响,中度盐碱耕地面积增长,但可利用土地面积和有效耕地面积不断增加,且改良区域的NPP处于持续增长的趋势,在一定程度上说明盐碱地治理取得了成效。     

广佛区域土地利用结构对非点源污染的影响

在野外布点采样的基础上分析了非点源污染评价指标,同时,利用GIS技术研究广佛区域内不同土地利用结构与非点源污染之间的关系.结果表明,在以单一土地利用类型为主控制的单元中,由林地和基水地控制的地表水水质明显优于以耕地或城镇、农村居民点为主的单元;在不同的土地利用类型的组合结构中,各项污染物浓度往往介于林地、基水地或耕地为主控制的研究单元之间;在其他条件相似时,随着研究单元内林地和基水地的增加,非点源污染降低,而随着耕地或城镇、农村居民点比例的升高,非点源污染有逐渐增大的趋势.此外,土地利用结构对非点源污染的     

中国高速铁路网络的发展过程、格局及空间效应评价

高速铁路作为现代交通基础设施的重要组成部分,其建设产生时空收敛效果,并进一步对生产要素流动、城市空间扩张、区域空间结构重构产生重要影响。文章在分析中国高速铁路发展过程、模式的基础上,剖析了其空间格局特征及与区域人口和经济的耦合关系;同时,借助ArcGIS方法从空间服务水平、时空收敛效应和中心城市交通圈等角度,探讨高速铁路网络的空间效应。结果显示：高速铁路的空间扩展过程表现出独特的“核心―核心”至“核心―网络”模式,与城市群的空间分布具有较好的耦合性;高速铁路的空间格局与中国城市人口、工业分布表现基本一致,站点1 h范围内可覆盖全国50.07%的城镇人口、73.47%的GDP和98.17%的第二产业产值;中国高速铁路建设导致的时空收敛效果呈现出明显的廊道效应,中心城市枢纽地位得以强化,服务范围的拓展和生产要素的便捷流动为城市群的空间扩张和重构提供了条件。     

高斯两步移动搜索法的模型研究——以上海市绿地可达性为例

合理的配置公共服务设施对城市的现代化建设至关重要。空间可达性是度量公共服务设施配置是否合理的方法之一。在诸多的研究方法中,高斯两步移动搜索法由于直观且运算简便,因而得到广泛应用。但该方法也有不足之处,本文运用格网GIS方法,以上海市的绿地空间可达性为例,对两步移动搜索法进行模型方法的改进研究,并对高斯两步移动搜索法和格网化的高斯两步移动搜索法进行对比分析,结果表明：后者可降低空间可达性的误差,提高可达性精度,对上海市绿地空间可达性反映更加真实、客观。如果选择合理的数据将其格网化,该方法也可以用于其他公共服务设施的空间可达性研究。     

基于遥感和GIS的干旱区绿洲景观破碎化分析--以金塔绿洲为例

以2个时期的遥感图像所解译的土地利用数据为基本信息源，基于GIS工具，选用斑块密度、廊道密度、斑块破碎度、分离度和斑块面积变异系数5个指标对金塔绿洲的破碎化程度进行了分析。结果表明：(1)1990～2000年，金塔绿洲总体的景观破碎化程度轻微地降低。(2)从景观类型上看，基质的破碎化程度增强；水浇地面积增大，趋于集中分布，破碎化程度降低；城镇用地破碎度增加，分离度减小。这些变化与人类开发利用活动的程度和方式有关，体现了荒漠基质受人类影响而逐步形成的典型农业型绿洲的特点。     

基于景观格局的广州市边缘区生态压力研究——以番禺区为例

基于RS、GIS技术和统计分析方法,选取破碎化指数、斑块结合度指数、分形维数3个景观指数和土地利用脆弱性指数构建生态压力指数,以番禺为例从景观尺度研究城市边缘区在城市化梯度上的生态压力空间分异。结果表明:不同用地类型的景观指数在3个梯度区内依人为干扰的强烈程度出现明显的空间分异,生态压力呈现自北向南依次降低的空间分布格局。景观生态压力强弱的分布与区域内土地利用方式和强度具有较高的相关关系,人为干扰是影响景观生态压力扩散的重要原因。     

风力作用下沙粒蠕移概率的转化特征

建立了沙粒从蠕移状态向静止、跳跃转化以及继续滚动的概率模型.根据滚动沙粒简化的运动方程,结合两个关键随机变量-沙床表面风速和床面位置参数,求出了静止概率、滚动概率、跳跃概率随时间变化的表达式.在此基础上通过对时间求极限得到稳定情况下沙粒处于三种运动状态的概率.利用沙粒蠕移概率除蠕移概率和跃移概率之和,得到沙粒相对蠕移概率,并以此反映蠕移输沙量占总输沙量的比例.计算结果表明,三种转移概率是时间、沙床表面风速和沙粒直径的函数.静止概率随时间增大而增大,但随粒径增大而减小;滚动概率随时间的变化根据粒径的不同表现出不同的特点.粒径较小,滚动概率随时间的增大先增大后减小,存在极大值;粒径较大时,滚动概率随时间的增大逐渐增大,不存在峰值.跳跃概率随时间的增大而增大.三种概率达到稳定状态所需要的时间随粒径的增大而减少.同粒径的沙粒在相同的时间内,三种转移概率会趋于定值.稳定概率和相对蠕移概率由沙床表面风速分布和粒径大小来确定,具有很大的取值范围;静止稳定概率和跳跃稳定概率随粒径的增大分别增大和减小;而滚动稳定概率随粒径的增大逐步先增大后减小.在一定风速条件下,相对蠕移概率随风速和方差的变化都不大,沙粒粒径是最主要的影响因素.     

Comprehensive analysis of changes to catchment slope properties in the high-sediment region of the Loess Plateau, 1978-2010

To control soil erosion and restore the degraded environment in the Loess Plateau, a large number of measures related to soil and water conservation have been employed that have profoundly affected catchment properties. This study constructed three indicators to characterize changes to the catchment slope, proposed both a method for a regression analysis of adjacent images and a sequence model, and applied multisource remotely sensed images and GIS spatial clustering analysis technologies to extract thematic information and comprehensively analyze the catchment change characteristics. The results indicate that the catchment slope properties changed significantly. At catchment scale, the average values of ARC, DVC and ART were 6.43%, 25.57% and 4.30%, respectively. There were six clustering types of catchment slope property changes. The maximum and minimum of the average similarities of the clustering types were 0.992 and 0.935. Each slope control measures had a distinct effect on catchment slope; the dominating factor of each clustering type was identified as: Type 1: D-VC, Type 2: D-VCLU, Type 3: D-LUVC, Type 4: D-TAVC, Type 5: D-TAC and Type 6: D-MFC. Type 5 and Type 1 covered the largest areas, respectively occupying 37.28% and 31.01%. Catchment slope property changes also had distinct types that depended on their geomorphological conditions. These findings provide a useful basis from which to further study catchment slope hydrological and soil erosion processes.     

Catchment-scale (dis)connectivity in sediment flux in the upper Hunter catchment, New South Wales, Australia

(Dis)connectivity within and between landscape compartments affects the extent and rate of transfer of energy and matter through catchments. Various landforms may impede sediment conveyance in a river system, whether laterally to the channel (termed buffers) or longitudinally along the channel itself (termed barriers). A generic approach to analysis of landscape (dis)connectivity using slope threshold analysis in GIS, tied to air photograph interpretation and field mapping of buffers and barriers, is tested in the upper Hunter catchment, Australia. Under simulated conditions, effective catchment area, which is a measure of the proportion of a catchment that has the potential to contribute sediment to the channel network, varies from 73% to just 3% of the total catchment area for differing subcatchments in the upper Hunter. This variability can be explained by the spatial distribution and assemblage of buffers and barriers in each subcatchment. Multiple forms of disconnectivity are evident in some subcatchments, such that when one buffer or barrier is breached, other features still impede sediment transfer within the system. The importance of the position of buffers and barriers within any given subcatchment is emphasised. Spatial variability in valley width exerts a critical control on catchment connectivity, with more efficient sediment conveyance in narrow valleys relative to wider valleys characterised by piedmonts, terraces, fans and extensive floodplains in which conveyance is impeded. This variability reflects the landscape history and geological setting of each subcatchment. The framework developed in this paper can be used to assess the impact of natural or human-induced buffers and barriers on catchment-scale sediment flux in any landscape setting, providing a physical template atop which other biogeochemical fluxes could be examined.     

陕西渭河下游湿地环境风险因素分析

运用统计计算和RS/G IS方法,分析渭河下游湿地环境的水文特性、水污染特征、土地利用/覆被状况及其演变特征等湿地环境风险因素,结论为:①渭河下游水沙量年际变化大、年内水沙量分配不均,且呈现减少趋势;汛期黄河洪水倒灌渭河,降低了由于水沙供给变化而导致的湿地水文环境风险度;②湿地水环境日趋恶化的变化趋势降低了湿地的生态净化功能,增加了湿地水环境风险度;③1989~2000年渭河下游新增湿地12.76km²,年均增长率2.70%;湿地裸地化和盐碱化形势严峻;④以加强湿地保护立法、完善流域水污染治理、重建河岸植被带、强化湿地管理等重点措施确保湿地环境安全和湿地资源的可持续利用。     

黄土高原沟道流域产沙过程的初步分析

黄土高原的主要产沙地区是河口镇至龙门黄河干流两侧和泾、洛、渭河中上游,产沙时间集中7—9月或一、二次暴雨期。流域产沙量与河道断面输沙量基本一致。产沙最与降雨量加径流深组合因子成正比相关,并随坡度增大而增加,坡度超过25—28度水流面蚀强度减弱。砂黄土的可蚀性最大,黄土其次,粘黄土最小。灌木林的防蚀效果最好。近三十年来黄土高原的产沙量进一步增加,其中由人类活动而增加的沙量约占黄河平均输沙量的23～35%。沟道流域的产沙过程具有垂直分带规律。沟间地以细沟侵蚀产沙为主,沟谷地是水力、重力和洞穴侵蚀综合作用的场所。黄土丘陵区沟谷地的产沙量此沟间地大59.0%左右;黄土塬区产生的泥沙绝大部来自沟谷地。     

基于GIS与BP神经网络的采空塌陷易发性预测

以湖北省鄂州程潮铁矿和黄石大冶铁矿为例,利用GIS空间分析功能对研究区数据进行提取分级、赋值统计及归一化等处理,构建了包括高程、坡度、地层、地下开采点的分布密度、相距最近地下开采点的距离、开采厚度与深度比值、蚀变接触带缓冲区、地下水深度以及地表地物类型的矿区采空塌陷易发性评价指标数据集;借助IDL语言调用Matlab神经网络工具箱,将研究区2011和2012年的指标数据集作为输入数据,塌陷易发性作为期望输出,建立基于BP神经网络的矿区采空塌陷易发性预测模型;通过选取并优化训练样本,实现对2013年矿山塌陷易发性的预测。结果表明,高易发区及以上的区域包含89.91%的采空塌陷,随着易发等级的提高,采空塌陷面积占易发等级面积比也随之增大;采空塌陷的分布具有明显的地带性,高易发区基本沿着岩体与围岩的接触带分布。模型解决了塌陷预测中的非线性映射问题,预测结果与实际调查情况基本吻合。BP神经网络模型与GIS技术相结合预测矿区采空塌陷的易发性具有可行性。