【摘要】 <正> 引言本文研究的滹沱河平原段长180公里,它是洪、枯水期分明,季节性显著的河流。此平原河段可分两种河系（图1）:从黄壁庄至深泽为辫状河系（A 段）,长100公里,海拔96.3—35.3米,地面坡降1.29—0.53米/公里,游荡性指数（b）为4.03,A₁工作点附近河段的平均河宽为1700米;从深泽更多还原

【Abstract】 Hutuo River in Hcbei province may be divided into two morphological reac-hes.The upper reach is a braided river,about 100 km.from Huangbizhang toShunzhe.The lower reach is a slightly meandering stream,80km.from Shunzheto Xian—Cotmty,where it connects with Fuyan River,flowing down into BouhaiGulf.In braided river,the longitudinal bars are mostly composed of the followingvertical beddings from bottom to top:lag deposits of poorly bedded gravels andsands,horizontal beddings of upper flow regime,large scale trough beddings,small scale trough beddings and parallel beddings of lower flow regims. Near the lateral margins of longitudinal bar,although most beddings of the verticalsection are similar to those mentioned above sequence,yet instead of horizontalbeddings of upper flow regime,large scale tabular cross beddings take place,indic-ating that they are formed by sandwave migration of relative lower flow regime.The average thickness of recent longitudinal bar deposits of braided course isvery thin,only about 1.0 m.In slightly meandering stream,trenched profile sections show that two diffe-rent vertical sequences of point bar accur.At the leeside of point bar,where flowis gentle,large scale trough beddings predominate,the whole section is similar tothe fining—upward model of point bar deposits as stated by J.R.L.Allen（1970）.whereas,at the stoss side of point bar,where flow is swift,large scale longitudinalcross beddings predominate,which consist of a bundle of cross beds in different directions,and no rhythmic variation of grain size appears in the vertical section.The average thicknees of recent point bar deposits is above 2.0 m.The sequential beddings of natural levee from bottom to top are:r₂ smallripple bedding,r₃ ripple bedding,r₄ supperpose bedding,r₃ ripple bedding,r₂small ripple bedding,r₁ parallel bedding.They are the deposits along high riverbanks by relatively slow—moving flow during flood period.Beddings r₂ to r₄ andr₃ to r₁ represent the semicyles of upraizing and receding of flood respectively.更多还原