分布式地貌瞬时单位线在闽江流域的应用探究

Construction and Application of Distributed Geomorphologic Instantaneous Unit Hydrograph in Minjiang River

无资料或资料匮乏地区的汇流问题是水文科学研究的热点和难点.在这类问题上,地貌瞬时单位线成为了可靠的解决办法.本文基于现有的单元流域划分方法,以汇入最高级河道的河网集水区为基准重新制定单元划分方案.提取每个单元流域内的地形地貌参数,将伽马分布地貌瞬时单位线应用在各单元流域上,从而构建了分布式地貌瞬时单位线.同时,选取了闽江建阳流域作为研究区域,耦合蓄满产流模型模拟历史洪水过程从而进行方法的应用和验证.结果表明:各单元间的地貌瞬时单位线存在明显区别,单元间汇流特性差异显著.由1988~1999年25场洪水的模拟结果显示,径流深相对误差的绝对值小于20%的有23场,峰现时差在2 h以内的有20场,洪峰模拟效果最好,25场洪水均满足许可误差要求,且误差平均值为3.5%,确定性系数的平均值为0.844,最高可以达到0.962.综上表明,本文所提的单元划分方法合理且可行,能够很好地适用在无资料地区的洪水预报问题上.

To calculate basin confluence in ungauged regions is a hot and challenging research issue.In these cases,geomorphic instantaneous unit hygrograph(GIUH)has become a reliable and effective solution.In this paper,based on the existing methods,the sub-catchment division scheme is redesigned by partition the river flowing into the highest channel.Terrain and geomorphologic parameters in elementary watersheds are extracted and the gamma-type geomorphologic instantaneous unit hydrograph is applied to subregions in order to establish distributed GIUH.Jianyang Basin in Minjiang river is selected for application and validation of the coupling saturation excess runoff model.Results shows that concentration characteristic in each elementary basin has significant difference.The simulation results of 25 floods from 1988 to 1999 show that there are 23 cases in which the absolute value of the relative error of runoff depth is less than 20%,and 20 cases in which the time difference of peak is less than 2 hours.Especially flood peak simulation is the best,all storms satisfy the permissible error and average error is only 3.5%.The average of deterministic coefficient is 0.844,and maximum is up to 0.962.In summary,it is shown that the method proposed in this paper is reasonable and feasible,and it can be well applied to flood forecasting in ungauged areas.