Analysis on characteristics of ice conditions in Ningxia-Inner Mongolia Reach of the Yellow River from 2021 to 2022

During the ice-flood season from 2021 to 2022, the ice conditions in Ningxia and Inner Mongolia reach of the Yellow River is generally stable, mainly characterized as follows:long duration of ice-run, late appearance of the first freezing-up date,large discharge of freezing-up, short length of freezing-up, small increment water storage, early break-up date and small ice flood peak. The main influencing factors of the above characteristics are analyzed from four aspects:thermaland hydrodynamicfactors, river boundary conditions and water regulation. The results show that:the main reason for long duration of ice-run, late appearance of the first freezing-up date, short length of freezing-up and early break-up date is that the overall temperature is higher than normal, and the distribution higher in the west and lower in the east; large discharge of freezing-up and continuous improvement of river channel conditions have enhanced the flow capacity during the ice flood season, which inhibited the increase of increment water storage in river channel to a certain extent, resulting in less increment water storage in river channel; the scientific and reasonable regulation of water projects has created favorable conditions for the steady freezing-up and break-up,which is an important measure in ice prevention.