Using landscape indicators and Analytic Hierarchy Process (AHP) to determine the optimum spatial scale of urban land use patterns in Wuhan,China

Quantifying land use patterns and functions is critical for modeling urban ecological processes, and an emerging challenge is to apply models at multiple spatial scales. Methods of determining the optimum scale of land use patterns are commonly considered using landscape metrics. Landscape metrics are quantitative indicators for analyzing landscape heterogeneity at the landscape level. In this study, due to their widespread use in urban landscape analyses and well-documented effectiveness in quantifying landscape patterns, landscape metrics that represent dominance, shape, fragmentation and connectivity were selected. Five metrics include Patch Density, Contagion, Landscape Shape Index, Aggregation Index and Connectivity. Despite a wide application of landscape metrics for land use studies, the majority mainly focuses on the qualitative analysis of the characteristics of landscape metrics. The previous models are limited in exploring the optimum scale of land use patterns for their lack of quantitation. Therefore, taking the City of Wuhan as an example, the land use unit was treated as a patch, and the landscape pattern metrics at different spatial scales were calculated and compared so as to find the optimum one. Furthermore, a mathematical model of landscape metrics was proposed to quantify the scale effect of urban land use patterns, generating a complementary tool to select the optimum scale. In addition, Analytic Hierarchy Process (AHP) was introduced to determine the respective weights of the chosen landscape metrics in this model. Fractal dimension was ultimately applied to verify the chosen optimum scale of our study region. The results indicated that 60 m is confirmed to be the optimum scale for capturing the spatial variability of land use patterns in this study area.     

干湿循环效应下玄武岩纤维加筋黄土三轴剪切力学行为研究

通过干湿循环效应下的数字图像三轴剪切试验、CT扫描试验及扫描电镜SEM(scanning electron microscopy)试验,研究了玄武岩纤维加筋黄土干湿循环过程的三轴剪切力学行为及微细观结构演化机制。结果表明:随干湿循环次数增加,纤维含量较高试样的三轴剪切鼓胀破坏形态转变为剪切带破坏;干湿循环早期阶段,剪切破坏形态随纤维含量增加,由剪切带破坏转变为鼓胀破坏。干湿循环作用和纤维含量对应力-应变曲线的类型及特征无明显影响,均表现为应变硬化型。破坏偏应力随干湿循环次数增加而逐渐减小,但衰减速率逐渐减小;破坏偏应力随纤维含量增大先增加而后减小,呈抛物线变化特征,存在一个最佳纤维含量为0.6%。CT数均值ME值呈现与破坏偏应力相似的变化规律。干湿循环作用下筋-土界面产生一定的开裂和松弛现象,弱化了纤维的加筋效应,但与素黄土相比,纤维加筋黄土的微观结构表现出显著的整体稳定性。构建了干湿循环效应下玄武岩纤维加筋黄土的宏细观损伤变量,其表现出一致的变化规律。     

基于面向对象分类土地利用分析

以遥感技术为依托,研究了金普新区在成立以来的土地利用及变更情况。通过实验对比,选用了适合于高分辨率遥感影像的面向对象的分类方法对金普新区2013年的遥感影像进行了分类,成功获取了金普新区2013年的土地利用状况;然后应用金普新区2015年的地理国情普查数据,把普查数据成果与分类出的2013年金普新区土地利用状况有机结合,实现了对金普新区成立后的土地利用对比分析。     

小煤窑采空区物探技术在铁路工程地质勘察中的应用

综合勘探阶段的实际情况、探测深度和探测精度等因素,探讨了物探方法的选择及其组合特点,归纳了各种物探资料对应的小煤窑采空区的异常特征。通过单一或综合物探方法,结合地质调查及钻探资料,可划分出小煤窑采空区的发育段落并指导钻探孔位的布置,部分或比较宏观地解决了小煤窑采空区的勘察问题。同时,根据物探资料可对采空区的工程地质条件进行评价。     

浅谈低山丘陵地区1/5万地质灾害调查工作——以江西省定南县为例

近年来,全国各省市陆续在开展1/5万地质灾害调查工作,不同地貌区地质灾害发育情况不同,调查方法与要求亦有区别。平原岗丘地区往往存在地质灾害点达不到观测点数量要求,需要增加地质环境点来满足精度;而西南高山区灾害点少但规模大,许多灾害点往往要通过大比例尺的测绘才能调查清楚。相比之下,低山丘陵地区地质灾害点具有点多面广的特点,规模多为小型,调查任务艰巨。本文以江西省定南县为例,阐述低山丘陵地区1/5万县(市)地质灾害调查的技术方法与认识,以期对类似地区的调查有所帮助。     

Changes in major element hydrochemistry of the Pecos River in the American Southwest since 1935

The Pecos River, situated in eastern New Mexico and western Texas, receives water from a drainage area of 91 000 km². There are primarily two major water inputs, namely snowmelt from winter storms in the headwater region of the southern Rocky Mountains and runoff from warm-season monsoonal rainfall in the lower valley. The Pecos River suffers from high levels of total dissolved solids (TDS >5000 mg L⁻¹) under normal flow conditions. This not only poses serious problems for agricultural irrigation and safe drinking water supply, but also results in a permanent loss of biodiversity. This study examines changes in stream flow and water chemistry of the Pecos River over the last 70 a to better understand the long-term variability in stream salinity and the role of agricultural practices in salt transfer. A TDS record from the lower Pecos River near Langtry (Texas) back to 1935 was extracted to show a distinct pattern of decadal variability similar to the Pacific Decadal Oscillation (PDO), in which stream salinity is overall above average when the PDO is in positive (warm) phase and below average when the PDO is in negative (cold) phase. This is due to: (1) the dissolved salts contributed to the river are largely from dissolution of NaCl and CaSO₄-bearing minerals (e.g., halite and gypsum) in the upper basin, (2) the amount of the dissolved salts that reach the lower basin is mainly determined by the stream flow yield in the upper basin and (3) the stream flow yield from the upper basin is positively correlated with the PDO index. This further attests that large-scale climatic oscillation is the major source of long-term changes in stream flow and salinity of the Pecos River. On the other hand, there is also a strong indication that the rate of salt export has been affected by reservoir operations and water diversions for agricultural practices.     

测绘应急保障测绘装备和资料的管理研究

通过建立测绘装备和测绘资料数据库,进行装备和资料的查询、分发操作,满足应急保障分队的测绘保障,提高了应急测绘保障能力。