基于无人机遥测技术的湿周法计算河流生态需水研究

Calculation of River Ecological Water Demand by Wet Perimeter Method Based on UAV Telemetry

保障河流生态需水是合理利用水资源、进行水生态保护的基石。目前湿周法是广泛使用的一种计算河流生态需水的方法,但如何在缺资料地区方便快速建立湿周-流量关系仍是一个难点。为解决这个问题,依托无人机航空摄影测量技术,获取河道大断面形态,提取水力参数,结合曼宁公式,计算河流生态需水。研究计算邛崃市南河流域的黄塔及两河口断面的生态流量,与根据历史流量资料、使用Tennant法计算的河道生态流量对比后得出如下结论:湿周法计算的两断面生态流量分别为9.38、5.33 m3/s,Tennant法计算的生态流量为11.96和6.6 m3/s,两者计算结果接近且符合流量分布规律,证明了将无人机技术应用到湿周法,计算河流生态需水方法可行,为缺资料地区计算河流生态需水提供了新途径,为水资源开发利用和水生态保护提供了重要依据。

Ecological water demand is an important research direction in the fields of ecology,hydrology,environmental science,etc.The ecological restoration of rivers or the development and utilization of water resources require preliminary studies on the ecological water de⁃mand of rivers.How to scientifically determine river ecological water demand is a significant premise and basis for protecting river ecosystem and rationally allocating river water resources.At the present time,there are innumerable methods for calculating the ecological water de⁃mand of rivers.The wet perimeter method is a widely used hydraulic method for calculating the ecological water demand of rivers.The wet pe⁃rimeter method is convenient and speedy to establish a reliable wet perimeter-flow relationship,but it is difficult to calculate the ecological water demand in ungauged watersheds.In order to solve this problem,this paper employs the aerial photogrammetry technology of Unmanned Aerial Vehicle(UAV)to obtain the large section shape of the river channel.The important hydraulic parameters,such as roughness and hydraulic slope,are acquired by analyzing and processing UAV images.Astable wet perimeter-discharge relationship is established with the Manning formula.The slope method is used to determine the curve inflection point,and the minimum ecological water demand of the river is calculated with reference to the inflection point.Two cross-sections(Huangta and Lianghekou)of the Nanhe River Basin in Qionglai City are selected as study sections to calculate the ecological flow.The conventional calculation approach with the Tennant method based on historical flow data is used as a comparison and reference to judge the rationality of the calculation results.The results indicate that the ecological flow of the two sections calculated by the wet perimeter method are 9.38 and 5.33 m3/s,respectively,while the ecological flow calculated by Ten⁃nant method is 11.96 and 6.6 m3/s.The two results are close and consistent with the flow distribution law,which proves that it is feasible to apply UAV technology to the wet cycle method to calculate river ecological water demand.The method for calculating river ecological water demand is feasible,providing a new way for calculating river ecological water demand in areas lacking data and an important basis for water resources development and utilization and water ecological protection.However,since UAV technology cannot measure large underwater sections,for the watersheds without hydrological observation stations nearby,how to carry out a reasonable cross section generalization and coupling with the above-water section when applying the wet cycle method,and how to verify the rationality of the calculated ecological flow and other issues need further research.