POSSIBLE EFFECTS OF GROUND WATER LOWERING ON SOME PEAT SOILS IN SJÆLLAND     

dr. agro. LEIF PETERSEN  mag.scient. HENRIK BREUNING MADSEN 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):25-35

Petersen, Leif og Madsen, Henrik Breuning: Possible Effects of Ground Water Lowering on Some Peat Soils in Sjælland. Geografisk Tidsskrift 77:25–35 København, June 1, 1978.

In four peatlands in the central part of Zealand nine profiles have been investigated to estimate the effect of a lowering of the groundwater level.  相似文献   

The antecedent soil moisture condition of the curve number procedure     

L. SILVEIRA  F. CHARBONNIER  J. L. GENTA 《水文科学杂志》2013,58(1):3-12

Abstract

Estimation of direct runoff, peak discharge or hydrographs is often necessary in small to medium-sized ungauged basins. Different models are used in practice for these purposes, depending on the type of problem, the available data and the prevailing runoff mechanisms in the study basin. This paper discusses the applicability of the curve number procedure developed by the US Soil Conservation Service (SCS) to estimate direct runoff in basins characterized by small to gentle undulating slopes mainly covered with natural grasslands. Rainfall and runoff data measured in the Cañada de Los Chanchos basin in Uruguay is used to fit the curve numbers and to analyse the antecedent soil moisture condition proposed by the SCS.  相似文献   

Assessment of sliver polygons in geographical vector data     

M. Delafontaine  G. Nolf  N. van de Weghe  M. Antrop  Ph. de Maeyer 《International journal of geographical information science》2013,27(6):719-735

As positional error is a major issue in the assessment of spatial data quality, its propagation has been studied widely in map overlaying. However, few studies deal with a manifest consequence of positional error in map overlaying, namely sliver polygons. Sliver polygons are generally treated as awkward by-products that need to be removed quickly. Nevertheless, as they represent spurious areas, their nature and properties carry useful information, for example, for land use/cover assessment. Therefore, next to sliver removal, there is a need for intelligent detection and eventually further analysis of sliver polygons. This article proposes a general, semi-automated method for the assessment of slivers in vector polygon layers. A case study in Flanders (Belgium) illustrates a possible application in area estimation evaluation of land use allocation classes.  相似文献   

Overlap of global Köppen–Geiger climates,biomes, and soil orders     

Robert V. Rohli  T. Andrew Joyner  Stephen J. Reynolds  Thomas J. Ballinger 《自然地理学》2013,34(2):158-175

Climate types, biome types, and soil orders are commonly used among physical geographers in research and to describe natural environmental characteristics. However, little attempt has been made to quantify the percentage of global land surface that is covered by combinations of climate types, biomes, and soil orders. This research overlays a world map of 31 climate types produced based on the Köppen–Geiger criteria using gridded NCAR/NCEP reanalysis monthly mean surface air temperature and precipitation data from 1981 to 2010 with global maps of eight biomes adapted from World Wildlife Federation and 12 soil orders from United States Natural Resources Conservation Service. Areas covered by each of the 2976 combinations are then calculated. Results suggest that, as expected, a few climate/biome/soil combinations are most common, such as desert climate/desert biome/entisols, tundra climate/tundra biome/gelisols, and desert climate/desert biome/aridisols. The local nature of soil properties causes small enclaves of unexpected combinations of climate, biome, and soils, and the 10 most extensive climate/biome/soil combinations occupy only one-quarter of the global land surface. The strong correspondence between climate and biome types validates the Köppen–Geiger criteria for categorizing climates based on vegetation realms, even today, despite the general paucity of data available when the criteria were established.  相似文献   

基于集群MPI的图层级多边形并行合并算法     

范俊甫  马廷  周成虎  季民  周玉科  许涛 《地球信息科学学报》2014,16(4):517-523

在集群环境下,基于MPI并行编程模型和OGC简单要素规范进行并行多边形合并时,需要处理叠加图层间要素的“多对多”映射关系,由于空间上相邻的多边形在要素序列上并不一定连续,导致无法按要素序列为子节点分配任务,给并行任务映射带来了困难。本文以集群环境下的并行多边形合并算法为研究对象,通过比较叠加分析中两种多边形映射关系对算法并行化带来的影响,基于R树空间索引、MySQL精确空间查询,以及MPI通信机制,提出了6种不同的并行任务映射策略;通过实验分析和比较了6种策略的优劣。结果显示：基于R树预筛选的直接合并策略,在各算法中具有最高的串行计算效率和优秀的并行性能表现。虽然MySQL精确空间查询的预筛选过程较为耗时,但可有效地过滤掉不真正相交的多边形,从而提高合并操作的效率。因此,在集群MPI环境下,基于R树和MySQL精确空间查询的预筛选策略是解决并行任务映射难题,实现图层级多边形并行合并算法的有效途径。  相似文献   

Relationship of Uncertainty Between Polygon Segment and Line Segment for Spatial Data in GIS     

LIU Chun  TONG Xiaohua 《地球空间信息科学学报》2005,8(3):183-188

The mathematic theory for uncertainty model of line segment are summed up to achieve a general conception, and the line error band model of εp is a basic uncertainty model that can depict the line accuracy and quality efficiently while the model of εm and error entropy can be regarded as the supplement of it. The error band model will reflect and describe the influence of line uncertainty on polygon uncertainty. Therefore, the statistical characteristic of the line error is studied deeply by analyzing the probability that the line error falls into a certain range. Moreover, the theory accordance is achieved in the selecting the error buffer for line feature and the error indicator, The relationship of the accuracy of area for a polygon with the error loop for a polygon boundary is deduced and computed.  相似文献   

七大江河流域面雨量计算方法及应用   总被引：41，自引：10，他引：41  

徐晶  林建  姚学祥  毕宝贵  吴昊 《气象》2001,27(11):13-16

参考我国水文部门和各省气象台的做法，比较客观地确定了全国七大江河流域（松花江、辽河、海河、黄河、淮河、长江、珠江）及其支流域的边界，将全国划分为71个子流域，并实现了各支流域内计算机自动选取代表测站。同时研究了各种面雨量计算方法的优缺点，最后选定泰森多边形法为面雨量计算的主要方法。2000年6－9月在中央气象台进行了面雨量预报业务试运行，每天定时完成将24小时常规雨量资料和加密雨量资料合并作为实况资料，并将中央气象台短期降水预报指导产品24、48小时雨量预报场转换成站点降水，在此基础上计算各支流域的实况和预报面雨量，同时实现了面雨量实况和预报在MICAPS下的显示。  相似文献   

在不完整地震目录下的未来缺震数估计     

朱建钢  张耀国 《四川地震》1992,(4):37-43

依据所关心地区的地震目录,建立起古登堡-里克特关系,并据此而推断该地区未来的缺震数,是一种常用的做法。然而,如果该地区的震级-频度关系是非古登堡-里克特的,或者即使是但由于地震目录不全(指历史地震目录的中小地震缺失和现代仪器记录的弱小地震缺失)而使震级-频度曲线呈系统性上凸,都将严重影响对未来缺震数的估计。本文指出,无论是哪一种情况,甚至是两种情况的耦合,折线型震级-频度关系都是合乎逻辑的处理方法。本文侧重于概念、实例,而在下文中则致力于算法推导和理论试验。  相似文献   

一种多边形交、并、差运算的有效算法   总被引：6，自引：0，他引：6  

于雷易  边馥苓  万丰 《武汉大学学报(信息科学版)》2003,28(5):615-618

以周培德的Z5-4算法为参考，提出了一种简单多边形交、并、差运算算法——IBO算法。该算法能够处理二维现实世界中的各种情况，对于地理信息系统的空间分析有较好的应用价值。  相似文献   

面雨量计算方法及其在海河流域的应用   总被引：25，自引：2，他引：25  

毕宝贵  徐晶  林建 《气象》2003,29(8):39-42

参考我国水文部门和省气象台的方法，比较客观地确定了华北地区海河流域及其支流域(七条河系：滦河河系、北三河河系、永定河河系、大清河河系、子牙河河系、南运河河系、徒骇马颊河河系；一个区；海河下游区)的边界，实现了在各支流域内计算机自动选取代表测站，计算各支流域的实况和预报面雨量，对2001年汛期面雨量做了集成预报试验。另外，将2000年6～8月及2001年6～7月滦河的面雨量与潘家口水库的入库流量进行了对比分析。  相似文献