Study On Ice Floods Of Ningxia-inner Mongolia Reach Of Yellow River

The threat of ice is an important problem closely related to the high latitudes and cold regions.When the river surface exists ice cover,it increased the contact area of channel flow section,reduced hydraulic radius,and increased resistance to water flow.The change of flow conditions often trigger ice floods,which endangered the safety of bridges,culverts,channel projects and other hydraulic structures.The research has an important theoretical significance for gasp the macroscopic regularity of ice floods development by studying the change rules of each ice factors,ice river storage,the attenuation of ice flood waves.It also has an important practical significance for prevent ice floods.Different degrees of ice floods occurs every year in the Ningxia-Inner Mongolia reach of Yellow River.Taking Ningxia-Inner Mongolia reach for research objects,based on prototype observation data from 2006 to 2017.The main research work is summarized as follows:(1)Taking Bayangaole,Sanhuhekou,Toudaoguai hydrological station for research objects,organize and calculate each ice condition factors eigenvalues for the past eleven years during ice-flow period,ice-frozen period and ice break-up period,statistic and analysis the function relationships between each ice conditon factors eigenvalue.Comparing the differences of ice factors eigenvalue between the three hydrological stations,calculate and analysis interannual variation of each ice condition factors eigenvalues.(2)Taking Bayangaole-Sanhuhekou reach and Sanhuhekou-Toudaoguai reach for research objects.Calculate channel storage increment during different periods.Statistic and analysis the function relationships between channel storage increment and ice condition factors.Comparing the differences of channel storage increment between the two reachs.(3)To explore the applicability of Muskingum Method applied to the ice age,this paper analysis from the water balance equation and river channel storage equation,and analysis of the relationship between parameters of Muskingum Method and river roughness as well.Based on the principle of least squares,using MATLAB software to calculate and fit,obtained the parameter values of Muskingum Method during different time periods.Validated the reliability of the calculated parameters.The results show that the calculated values and measured values are similar,the overall error is very low,so using Muskingum Method applied to the ice age is feasible.(4)The development of ice cover can be divided into two parts: ice cover thickening and ice cover thawing,calculate the Muskingum parameter values under different ice cover development process,establishing the relationship between ice thickness and Muskingum parameter values,analysis of the regularity of ice flood wave propagation during different development of ice cover.The results show that ice cover thickening and ice cover thawing have differences in the attenuation of ice flood waves.