基于河渠连接度的哈尼梯田景观水源稳定性评价

保持梯田水源的稳定供给是世界文化景观遗产——红河哈尼梯田文化景观持续存在的关键。本文以地处遗产核心区的全福庄河小流域为研究对象,在快鸟影像和实地调查基础上获取流域内河流-沟渠的空间分布和结构特征数据,选择坡度与距河渠的距离等两个阻力因素,应用ArcGIS中的最小费用距离模型对流域的河渠连接度进行分析。结果表明:(1)河流-沟渠廊道网络系统的线点率、连接度、环度指数值均高于河流与沟渠本身;(2)单独以河流和沟渠为源对梯田进行灌溉的阻力较河流-沟渠廊道网络系统高。以河渠廊道网络系统为源时梯田总面积的66.4%为稳定区;(3)在考虑自灌和多源灌溉梯田的情况下,大鱼塘样区水源的高度稳定区和较高稳定区的面积分别提高了3.9%和5.7%;小寨样区水源的高度稳定区和较高稳定区的面积分别提高了3.2%和5.9%,不同程度提高了梯田景观的水源稳定性;(4)据实地调查验证,基于最小费用法的河渠连接度分析能够为梯田水源的合理划分提供保障,为未来梯田景观持续稳定提供决策支持。

Directional drilling in unstable environments

Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.