基于原型观测的输水渠道糙率取值及变化分析

为了研究长距离渠道糙率的合理取值,依据北疆输水工程总干渠2011—2016年逐日水位、流量数据,采用曼宁公式反算典型断面糙率,并构建一维非恒定流水动力模型对渠段糙率进行校核,分析长距离渠道糙率在渠段间的差异及边壁粗糙度随运行时间的变化情况。结果表明:断面的实测糙率与顺直渠段糙率相符,总干渠顺直段糙率在0.015～0.016,弯道明显的渠段,弯度校正因子在1.15～1.50,大小与弯道复杂程度相关;渠道糙率随运行时间呈增长趋势,总干渠等效粗糙度中期运行的年增幅约为18.54%。

Variation analysis of roughness coefficient value for water conveyance channels based on prototype observation

To study the reasonable roughness value of a long-distance channel, the roughness for a typical section of the Beijiang Water Transfer Project was inversely calculated using Manning formula based on the prototype observation water level and discharge data from 2011 to 2016. One-dimensional unsteady hydrodynamic model was established to verify the roughness value and its spatial difference between channel sections and temporal variation with performance period was analyzed. The results show that the measured roughness of the section is consistent with that of the straight channel section, the roughness of the straight section of the main channel is from 0. 015 to 0. 016. Correction for the effect of channel curves is from 1. 15 to 1. 50, which is related to the complexity of the curve. The channel roughness increases with the running time, and the annual increase of the equivalent roughness K_s was 18. 54 %.