Extent and Channel Morphology of Unmapped Headwater Stream Segments of the Quabbin Watershed,Massachusetts1

Brooks, Robert T. and Elizabeth A. Colburn, 2011. Extent and Channel Morphology of Unmapped Headwater Stream Segments of the Quabbin Watershed, Massachusetts. Journal of the American Water Resources Association (JAWRA) 47(1):158‐168. DOI: 10.1111/j.1752‐1688.2010.00499.x Abstract: Effective regulatory protection and management of headwater resources depend on consistent and accurate identification and delineation of stream occurrence. Published maps and digital resources fail to represent the true occurrence and extent of headwater streams. This study assessed the accuracy of mapped origins of “blue‐line” streams depicted on U.S. Geological Survey topographic maps, and, if present, the morphological characteristics of unmapped stream segments. We identified 170 mapped stream origins on the Quabbin Reservoir watershed, Massachusetts. Of 30 mapped stream origins, we identified and examined 26 unmapped stream segments above 25, with an average length of 502 m. Twenty unmapped tributaries occurred on 10 of the 26 unmapped segments, with an average length of 127 m. Wetland reaches occurred more frequently and were larger on unmapped than on mapped stream segments. A significant and complex stream network occurs above most mapped stream origins. For the Quabbin watershed, we estimate that there are 85.8 km of unmapped stream upgradient of 314.5 km of mapped streams. Reliance on mapped stream networks for regulatory standards allows for the potential disturbance or even destruction of the unmapped stream resources. Jurisdictional regulations and guidelines should be revised so that the occurrence of streams should require field validation.     

山区县域土地利用格局变化及其地形梯度效应——以井冈山市为例

地形是影响土地利用的重要地理因素,山区土地资源禀赋及其开发利用方式深受地形条件限制。以井冈山市为例,采用1995-2015年多期遥感数据,选取坡度、高程、地形位指数等多项因子,通过定性分析与定量评价相结合的方法,深入探讨地形对土地利用类型分布、土地利用动态变化,以及土地利用景观格局的作用机制。研究表明：井冈山市土地利用空间分布具有明显的地形梯度效应,林地、草地多分布在海拔>400 m、坡度>15°的山地和高丘陵区,耕地、水域、建设用地多分布在海拔<400 m、坡度<15°的平原和低丘陵区。研究期内,井冈山市土地利用动态变化主要表现为林地减少和建设用地增加,其中林地净减少992 km²,建设用地净增加352 km²,土地利用方式的改变主要发生在海拔<800 m、坡度<15°、人类活动密集的平原和低缓丘陵地区。土地利用景观格局亦受地形因素影响,在平原和低缓丘陵区,斑块密集分布,景观多样性指数、散布与并列指数、斑块密度及土地利用结构信息熵呈高值分布;而在高海拔、坡度大的山地丘陵区,优势斑块明显,最大斑块所占景观面积的比例以及蔓延度指数呈高值分布。优化山区土地资源配置,促进贫困山区减贫发展,应充分考虑地形因素的影响作用,遵循因地制宜、因势利导和优势开发原则,重视优化土地利用结构与布局,加快推进山区精准脱贫、绿色发展和乡村振兴。     

地形起伏地区管道水联运充水排气过程分析

针对油气长输管道投产前通常会进行充水清管、调试和吹扫(常规称:水联运),由于埋地管道随地形起伏经过无数个相对高点和低点,管道充水前处于自然状态,一旦管内充水,就会将管内空气归聚成封闭空间,形成多个带压气团随水头移动,时而被压缩,时而被膨胀,从而造成管道断流,影响泵站正常工作,严重的还会导致管道泄压装置受损、爆管事故等问题,分析了管道水联运过程中不同地形起伏高点和低点带压气团的成因和状态,用实例计算了带压气团对管道水联运的影响及排除方法,从而为长输管道投产前正常的水联运作业提供借鉴。     

A new approach to the analysis of adjacencies: Potentials for landscape insights

Spatial adjacencies are a key-issue in environmental studies. Adjacency effects have been amply observed for biotic (plants and animals) and abiotic components of ecosystems. Particularly well-documented are the effects from human manufactures onto the contiguous vegetation mosaics of natural and semi-natural areas.In this work we first propose and reformulate association rules analysis (ARA), a relatively new data mining algorithm with very limited scientific applications so far, in the form of an in-depth investigation method of the spatial pattern of landcover and vegetation maps. We applied ARA to two very different study areas in Northern Italy, the first (Ceno valley) having a substantial human footprint and mapped at 1:25,000 scale, the second (Foses valley) being almost natural and mapped at 1:5000 scale.We were able to: (a) detect the entire network of spatial adjacencies among landcover types and (b) quantify the frequency and strength of detected adjacencies. Based on our spatial analysis, we also advanced hypotheses on both natural and man-driven vegetation dynamics. In addition, ARA allowed us to propose an index of naturality based on the discovered contiguities.Results show the skill of the proposed approach to characterize landcover spatial patterns for both mid-resolution and high-resolution maps. Furthermore the proposed approach bears a general interest, since it can be applied to the analysis of any landcover map.     

喀斯特高原山区土地潜在石漠化与地形因子的关系

选取位于贵州省普定县的后寨地下河流域中下游作为研究区,利用地理信息系统软件,解译出研究区2004年的潜在石漠化等级分布图,对海拔、坡度、坡向和坡位等地形因子同各等级潜在石漠化景观面积的相关关系进行定量分析。结果显示,研究区潜在石漠化景观在空间上呈不均匀分布;海拔、坡度和坡向等地形因子同潜在石漠化景观的多个等级斑块面积之间相关性显著(P<0.05或P<0.01);随着海拔的增加,低度和中度潜在石漠化面积所占比例逐渐增加,无石漠化和极低度潜在石漠化面积所占比例逐渐减少;随坡度的增加,无石漠化面积所占比例逐渐减少,低度、中度及极高度潜在石漠化面积所占比例逐渐增加;随着坡向由阴转阳,中度和高度潜在石漠化面积所占比例逐渐增加;而坡位与各等级潜在石漠化景观面积之间无显著相关性。     

中国西南地区时雨量分布特征与时月变化

利用2005-2017年夏半年国家大监站的逐小时降水量资料,14个要素被设计来进行多角度分析。多数要素与地形高度有良好的负相关关系。时段雨量最大值主要集中地是四川盆地西部,其次是贵州南部,云南南部边缘地带有少许站点,云贵高原主体及其与青藏高原交接带内没有最大值出现。多个要素在9到12时出现日变化最高峰。月际变化一般在7月出现最大值。随月份推进,强降水区会在贵州西南部、云南南部边缘出现后,跳跃到川渝地区出现。时段累积雨量最大值随时间增加而增加,多个要素的时间增加一倍时雨量增大10%到20%。以小时而言,西南地区降水几率平均为1/10,最多的可以达到1/4,最少的不到1/14。6月份降水时数最多,10月的雨时数仅次于6月,4月最少。连续时段与标准日界时段雨量的显著差异出现在川渝地区;白天12 h降水与夜间12 h降水的显著差异也出现在川渝地区。总体而言,连续时段的累积雨量大于标准日界的相同时间长度的累积雨量,白天降水量大于夜间降水量。     

OPTIMAL BATHYMETRY OF TYRRHENIAN SEA BY STOCHASTIC INTERPOLATORS1

ABSTRACT: The analysis of the sea depth in the vicinity of a thermal power plant is important in view of the heat dispersion and transport of the cooling water discharged from the energy production processes. The bathymetry of the Tyrrhenian Sea in the area facing the thermoelectric plant being built at Montalto di Castro, Italy, is reconstructed with the aid of the kriging technique. The large number of measurements (2038) precludes the use of a global interpolation model. At the same time, the steepness of the variogram suggests that the stochastic process is likely non-stationary. The latter problem is managed by detrending the observed records with a fourth-order polynomial drift determined with the least squares method. The global approach is replaced with local models with an influence radius of 70 m and a minimal number of interpolation records equal to 10. The detrended residuals appear to be second-order stationary having an isotropic vaniogram that is fitted equally well by a linear or a spherical function. The average size of the local interpolation models is 28, which ensures a high cemputational efficiency. The bathymetry of the sea area of interest is then reconstructed over a regular grid with a total of 3570 nodes. The estimation standard deviation maps show that the accuracy of the prediction is even greater than the prescribed tolerance (= 0.2 m) and indicate that future data collection campaigns require a less dense and, therefore, less expensive recording network. The redundant measurement profiles are identified. Their elimination still allows for bathymetry estimates affected by interpolation errors that fall within the project specifications.     

应用GIS技术制作环境专题图

探讨了GIS技术及其特点,并结合河北省水质环境专题图的制作阐述了ArcGIS在环境专题图方面的应用。     

A Faster and Economical Approach to Floodplain Mapping Using Soil Information

Flood inundation maps play a key role in assessment and mitigation of potential flood hazards. However, owing to high costs associated with the conventional flood mapping methods, many communities in the United States lack flood inundation maps. The objective of this study is to develop and examine an economical alternative approach to floodplain mapping using widely available soil survey geographic (SSURGO) database. In this study, floodplain maps are developed for the entire state of Indiana, and some counties in Minnesota, Wisconsin, and Washington states by identifying flood‐prone soil map units based on their attributes. For validation, the flood extents obtained from SSURGO database are compared with the extents from other floodplain maps such as the Federal Emergency Management Agency issued flood insurance rate maps (FIRMs), flood extents observed during past floods, and flood maps derived using digital elevation models. In general, SSURGO‐based floodplain maps (SFMs) are largely in agreement with other flood inundation maps. Specifically, the floodplain extents from SFMs cover 78‐95% area compared to FIRMs and observed flood extents. Thus, albeit with a slight loss in accuracy, the SSURGO approach offers an economical and fast alternative for floodplain mapping. In particular, it has potentially high utility in areas where no detailed flood studies have been conducted.     

小流域土壤矿质氮与地形因子的关系及其空间变异性研究

为掌握小流域土壤特性与地形因子的关系及其空间变异规律,采用经典统计学与地统计学相结合的方法,对黄土高原水蚀风蚀交错带小流域土壤矿质氮与地形因子的关系及其空间变异性进行了系统研究,结果表明:①硝态氮的变异程度为强变异性,铵态氮、坡度、坡向则为中等变异性,土壤类型、土地利用对矿质氮的变异程度有极显著影响;②各研究特性在采样尺度内表现出不同程度的空间依赖性,铵态氮、海拔为强烈的空间依赖性,而硝态氮、坡度及坡向则为中等的空间依赖性;③分维数与空问异质比所揭示的结果具有一致性,各变量的分维数从大到小依次为:硝态氮(1.982 6)＞坡向(1.976 7)＞坡度(1.9420)＞铵态氮(1.879 1)＞海拔(1.746 1);④硝态氮在0°与90°,45°与135°方向上具有各向同性结构,而海拔为各向异性结构,其余的研究特性则表现出微弱的各向异性;⑤海拔、铵态氮具有很强的空间自相关性,硝态氮则为空间不相关;硝态氮与铵态氮、坡度与坡向之间具有极显著的正相关性,而铵态氮与海拔、坡度与海拔之间则为显著的负相关,表明在水蚀风蚀交错带铵态氮和坡度的空间分布具有海拔梯度性.