数字水系的集水面积阈值研究
首发时间:2006-06-12
摘要:通过流域汇流对集水面积阈值的敏感性分析,发现随着集水面积阈值的增大,各栅格至流域出口水流汇集时间的分布越发分散,流域平均汇流时间变长,流域调蓄能力变大;河道汇流特性与坡面汇流特性相差越大,各栅格汇流时间的分布越集中,流域平均汇流时间对集水面积阈值的变化就越敏感;流域面积越小,流域平均汇流时间也对阈值越敏感。流域各栅格汇流时间的分布和对径流过程的分析同时显示,随着阈值的增大流域汇流的变化主要表现在洪峰的减小和退水过程变长两方面,峰现时间的变化并不明显,洪峰峰值不断减小;且流域调蓄能力对阈值的敏感性与坡面调蓄能力正相关,与河道调蓄能力反相关;流域面积越小,调蓄能力对阈值就越敏感。流域汇流对阈值的敏感性说明,选取合适的阈值对于提高数字水系和汇流网络对流域汇流特性的描述能力是必不可少的。文中还分析了常用的几种确定集水面积阈值的方法,作者认为由于统计计算中的均化作用,以地貌学中“凸面向凹面的转折点即为阈值”的理论为基础选取方整个流域的阈值并不合适。并提出利用DEM和电子水系地图相结合的方法,以实际水系的河网密度为评判标准选取合适阈值。结果显示,利用该方法确定阈值所得到的数字水系与实际水系在水系密度、河网形态和河网发育程度上都比较一致,利用这种法确定阈值可以得到更高精度的数字水系
关键词: 数字水系 数字高程模型 集水面积阈值 流域特征提取 流域汇流
For information in English, please click here
Study on Contributing Area Threshold Used in Extracting Digital Channel Networks
Abstract:Extracting digital channel networks from digital elevation models (DEMs) is the first step of most distributed hydrologic models. And determination of critical contributing area is one key of extracting river network. The study about sensitivity of runoff routing to critical contributing area showed that with the increasing of critical contributing area, basin mean concentration time became longer, concentration time from each grid to the outlet distributed more dispersedly, and basin storage capability was increasing. It could also be found that the more different the characteristics of slope runoff and channel runoff were, the more sensitive the basin mean concentration time was to the change of critical contributing area. And the discharge of flood peak was decreasing. Their sensitivity was increasing with rising of slope storage capability, decreasing of channel storage capability and increasing of watershed area. But the change of peak lag was unapparent. The sensitivity of basin recession showed that it was necessary to select right threshold for it would make digital channel networks express the recession property better. Several methods of determining critical contributing area in common use were analyzed, too. The conclusion showed that some of them got thresholds in eyeballing which was imprecise and the range of optional value was too wide, some were unfit for using in basins. Then a new method of looking electric water system map as data source of factual water system was used to determine critical contributing area. Two catchments were used as examples and the fractal dimension of factual and digital water system were also calculated and compared. The conclusion showed that the factual channel network was consistent with the extracted digital channel network at channel density, morphology of water system and the growth of channel network. So digital water system with more precision may be gotten with the new method.
Keywords: digital river network DEM contributing area threshold watershed characteristics flood routing
论文图表:
引用
No.7089636531150109****
同行评议
共计0人参与
勘误表
数字水系的集水面积阈值研究
评论
全部评论0/1000