蜿蜒河流长期演变过程数学模型.pdf

摘要探索河流长期演变规律是河流动力学中的一个基本问题。数学模型被广泛的应用于蜿蜒河流长期演变过程的研究中,本文希望建立数学模型来模拟和解释自然河流的演变动力过程。通过将河湾长期演变的研究理论运用于实际,指导人们正确的认识、开发和利用河流资源,更好的开展流域规划、河道整治及生态环境修复等工作。对非线性河流动力学的基本理论原理作了简要概述,介绍了河流演变过程的平衡态及非平衡态问题,并在基础上逐步建立河流平衡及扰动发展方程。运用自然模型法,采用清水冲刷成功地塑造了室内天然小河。实验研究了不同的初始河流几何边界条件以及水流条件对河流演变的影响。研究发现流量对河流展宽幅值影响最大。水流入射角的大小与河流展宽幅度及河流弯曲度的变化没有必然的联系,300入射角时小河的河流展宽及弯曲度变化最明显。入射角对河流演变的作用只是短期的,且在演变初始阶段影响较大。受初始边界条件的影响,河流向下游演变具有滞后性及曲率变化的传递性等特点。实验分析了河流演变过程中的泥沙分选现象。运用数学模型模拟了蜿蜒河流长期演变过程,分析了演变过程中的动力特性。模拟结果表明:蜿蜒河流存在着最不稳定波长,河流的演化是从最不稳定波长发育开始,扰动波不能长期保持,河流自身具有滤波功能。模拟了蓟运河长期演变过程,分析了蓟运河地形沉积过程及上、中、下游的演变趋势。简要分析了蓟运河未来长期演变对海河流域生态环境及生产生活的影响。关键词:蜿蜒河流河流演变数值模拟 ABSTRACT Explore the long-term evo lution is a basic problem of river dynamics. Mathematical model was widely used intheresearch ofthe long-term evolution process ofmeandering rivers,in thisarticle,1 want toestablishmathematical model to simulate and explain theevolution ofnaturalriverdynamic bend inthe evolution ofthelong—term research theory topractice,guiding people recognize and develop andutilizetheriver resources correct,bettercarrying outwatershed planning, riverregulation andecological environment restorationandother works. Inthispaper,the basictheory ofnonlinear riverdynamics theory hasbeen briefly paper introduces the evo lutionprocess oftheriverequilibrium and non-equilibrium problems and establishes river’S balance and disturbance development equation onthebasisofthe theory. Using thenatural model method,an indoor essfully portrayed withthescouring experiment includesthestudy oftheinfluence ofriverchannel evolution process duing todifferentinitialrivergeometric boundary conditions and revealthatflow ismostly influence are no necessarily relationships among thesizeof theinflow angle and river’Sstretcherrange and thechanges ofriverbenddegrees, when theinflow angle is30”,changes ofriverwidth and curvature arc more obvious. The inflowangle affectstheriverevol