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21.
应用Mapgis软件处理无基础数据的地质图件时,存在后期使用困难、精度不高、绘图速度慢的问题。本文总结一套有效的方法,将图形文件,转成数据文件,便于后期数据分析利用,以地质灾害危险性评估工作中要求提供的5年平均沉降速率图为例,对等值线逆向数值化进行演示。 相似文献
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AbstractA general linearized wave equation for a stratified rotating fluid is derived and applied to obtain a dispersion relation for waves of short latitudinal extent in a thin shell of fluid. Long period wave solutions in three ocean models are compared: (1) for a stratified ocean with both components of the rotation vector; (2) for a stratified ocean without the horizontal component of rotation, and finally, (3) for a homogeneous ocean without horizontal rotation. The inclusion of the horizontal component of the Earth's rotation is found to have no noticeable effect on the dispersion relation of long period waves; its only influence is the introduction of a vertical phase shift in the motions. The origin of this phase shift is found in the tendency of the motions to satisfy the Taylor-Proudman theorem. The phase shift is of possible oceanographic relevance only for bottom-trapped buoyancy waves in a relatively weak stratification. The differences between the three ocean models are also discussed with the help of graphs of the numerically integrated dispersion relations. The relative influences of shell thinness and stratification in inhibiting the influence of the horizontal component of the earth's rotation are also briefly discussed. 相似文献
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ＴＨＥＥＦＦＥＣＴＯＦＣＯＮＴＯＵＲＨＥＤＧＥＲＯＷＳＯＮＣＯＮＴＲＯＬＯＦＳＯＩＬＬＯＳＳＣＡＩＱｉａｎｇｇｕｏ１,ＬＩＳｉｌｏｎｇ２ａｎｄＷＡＮＧＸｉｌｏｎｇ３ＡＢＳＴＲＡＣＴＡｎａｌｙｓｉｓｗａｓｃｏｎｄｕｃｔｅｄｂａｓｅｄｏｎｏｂｓｅｒｖａｔ... 相似文献
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两类度日模型在天山科其喀尔巴西冰川消融估算中的应用 总被引：1，自引：0，他引：1
采用辐射传输参数化方案估算太阳入射短波辐射,并以小时气温作为输入数据,在200、100和50 m 3种海拔梯度下,分别应用传统度日模型和改进度日模型对科其喀尔巴西冰川2008年夏季消融区非表碛覆盖区消融进行了模拟分析.研究表明:太阳小时入射总辐射计算与实测结果具有较好的一致性;科其喀尔巴西冰川度日因子存在明显的时空差异性;随着空间分辨率提高,2类度日模型的模拟效果都变好;在200和100 m海拔梯度下,改进度日模型的模拟结果优于传统度日模型,而在50 m海拔梯度下,无明显改进. 相似文献
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提出基于曲线弯曲识别的等高线簇结构化方法,实现等高线簇中所蕴含的地形结构的提取。首先对基于Delau-nay三角网的曲线弯曲识别方法进行改进,包括伪弯曲的合并、弯曲基点的调整及小弯曲的删除方法;基于此,建立弯曲间的层次嵌套关系及平行相邻关系,实现曲线弯曲的识别方法;然后,根据单条等高线间的空间关系,对弯曲类型进行判断;结合曲线间的空间邻近度计算方法,将等高线簇中的成组弯曲进行提取;最后完成了地形结构的识别,实现了等高线簇的结构化。该方法不仅对地形中的山谷进行提取,并且提取出了其对称结构即山脊。试验结果与水系叠置显示,所提取出的地形结构基本合理,证明了该方法的有效性。 相似文献
27.
Abstract Geographical Information Systems (GIS) are becoming basic tools for a wide variety of earth science and land-use applications. This article presents linear programming (LP) as a promising tool for spatial modelling within a GIS. Although LP is not properly a spatial technique, it may be used to optimize spatial distributions or to guide the integration of variables. An example of the use of LP in land-use planning is described, with minimizing rural unemployment as the main goal. Technical, financial and ecological constraints are established to show the influence of several limitations on achieving the optimal solution. LP makes it possible to achieve optimal land-use, where the objective is maximized and the constraints respected. LP can also be used to simulate different planning scenarios, by modifying both the objective function coefficients and the constraints. The integration of LP and GIS is presented in two phases: (i) acquisition of attribute data for the LP model, and (ii) modelling and mapping the results. 相似文献
28.
Effects of grass contour hedgerow systems on controlling soil erosion in red soil hilly areas,Southeast China 总被引：6，自引：0，他引：6
Soil erosion by water is a well-recognized serious environmental problem in the world.While contour hedgerow systems are an effective method for soil water conservation,there are a few studies on its effect in the red soil hilly areas in Southeast China.With a fixed field experiment,we constructed a runoff plot at hilly area in Zhuji County,Zhejiang province,to evaluate the effect of the grass hedgerows in soil water conservation,and to determine the optimized hedgerow patterns.Hemerocallis citrine(HC)and Ophiopogon japonicas(OJ) were selected to build the hedgerows in patterns of one row and two rows.The REE method was used to trace the source of the sediment for a better understanding of the characteristic and mechanism of erosion with hedgerows control.Our results showed that(1) hedgerows reduced erosion and surface runoff by 31.99-67.22%and 15.44-45.11%,respectively;(2) hedgerows delayed the development of rills;(3) hedgerows reduced the soil nutrients loss;(4) hedgerows reshaped the soil physical properties,especially in increasing > 0.25 mm water-stable aggregates.Taken together,our results suggest that two-row OJ is the optimized contour hedgerow pattern in the experiment condition,and downward sloping land should have the highest priority to take measures for soil water conservation.This research comprehensively studied the effects and mechanism of contour hedgerows in controlling soil and water loss in red soil hilly areas,Southeast China,so that the practice of soil and water conservation can be implemented more effectively in these areas. 相似文献
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