| Freezing is a general phenomenon in the cold area. Ice flood is a rise of water when ice is hindered in river course. Ice will not only influence shipping, transportation, hydraulic power, water and sewage, but also lead to ice flood and cause huge losses when ice blocks the river course severely.There are two kinds of flood: rain gush flood and ice flood. Ice flood is sudden, speedy, permanent, disastrous. It exists in the Inner Mongolia Reach and in the ShanDong Reach of the Yellow River. Every year ice flood is frequent in the Inner Mongolia Reach. In recent years it is more severe because of temperature changes, mankind activities, scouring and silting.The special geographical position, hydrometeorological condition, river course characteristics are main reasons for ice flood. Firstly, Inner Mongolia Reach lies in the top north of the Yellow River. It flows from south to north. The temperature of upper reach is higher than that of lower reach, therefore, the river freezes up from lower reach to upper reach and breaks up from upper reach to lower reach. Secondly, Inner Mongolia Reach lies in inland area. It is far from ocean and controlled by Mongolia high-pressure. It belongs to the continental climate. Annual rainfall is little. Summer is hot and short. Winter is cold and long. Ice period remains four or five months. Thirdly, there are many river bends and shoals in the Inner Mongolia Reach. Ice flood will occur in these places at the break-up time. It is valuable and meaningful to make factor analysis for ice flood and model research for freeze-up time and break-up time.The thesis reviews the historic and present situations of the Yellow River, makes factor analysis for ice flood, simulates and forecasts freeze-up time and break-up time on the basis of fuzzy set theory. The results are reasonable and precise. In the end, the knotty problems are given to obtain feedback information for the future researches.
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