| The lower Yellow River is a wandering channel with intense building-up, the channel tends to be scoured and silted and the water stage is uncertain. With intensified shrink of the lower channel over the past ten-odd years, flood carrying capacity of the channel has dropped, and water stage at the same discharge has been gradually rising. According to statistics, in the year 2000, water stages at discharge of 3000 m3/s in all river stretches downstream of Huayuankou were 2 m higher than those in 1950.In the lower Yellow River basin, riverbed varies greatly from year to year, and more in one year. The silt conditions changes greatly between a flood. The stage discharge relation just like a loop. These changes bring many difficulties to our forecast. Moreover, the condition of the water level has affinity with the assign of water conservancy project , conservation area and so on. Since protection of projects and operation of flood detention areas in lower reaches are closely related with water stage, water stage is an indispensable important factor for forecasting. Especially in late years, the forecast of the water level is more and more important.The analysis of the influence factor to the change of lower Yellow Rive water level and the forecast projects of flood crest stage are showed in this paper. On the basis of analysis of factors causing changes in water stage in lower Yellow River, this paper uses multivariate regression to build flood-peak stage linear regression forecast models for seven hydrological stations at lower reaches.The forecast projects and the results of all the models have a precision of over 75%. According to the ,the general flood forecasting models are the first grade, except that the Jiahetan and Gaocun are the second grade. Therefore the forecasting model could be used to forecast the flood peak level of every gauges in downstream Yellow River. The model is the technical support of flood control in downstream Yellow River with high practicability.
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