对H.A.爱因斯坦等国内外数10种不同形式和结构的泥沙启动条件进行分析研究，统一转化为无因此起动切力 θc=γc/(νc-ν)d 的形式，并分析计算出无粘性均匀沙的 θc 值。一般来讲， 是界于0.0231～0.0716之间的一个常数值。从分析结果可看出各种公式之间的差别，为使用选择公式提供了科学的依据。

Unsteady Water quality model with multiparameter for the river network has been studied in this paper. The model reflects the characteristics of the unsteady flow with different direction and that of the unsteady water quality under aerobic, anoxic and anaerobic conditions. The model includes the various equations for DO, COD, BOD5, NBOD, NH4+-N.All parameters in the model have been obtained by the research for the observation on the field and the experiment in the laboratory. An equation of longitudinal dispersion coefficient has also been developed. Appling the computing method of dynamic coupling, the model has been verified by the data observed on field. The model has been applied to the program for controlling water quantity and water quality in order to improve the water quality of the river network of Wuxi city in China.

The vertical turbulent mixing of the isodensity oscillation current in tide estuary has been studied in this paper, On the basis of the governing equation and character analysis of the tidal flow, the expression of time-space distribution of shear stress, which is influenced by gravity and inertia, has been derived. Considering the terms of gravity and inertia, the theoretical equation of turbulent exchange coefficient of the tide estuary flow has been developed. Then the vertical average and the time average equation have also been obtained .To verify those equations, the time-space distribution of vertical turbulent exchange coefficient in Yangtze Estuary has been calculated according to measure data. Its variation character with the flood and ebb tide has been analyzed.

本文根据苏州水网的特点，采用模拟试验和现场实测相结合、系统分解和综合相结合的方法，对水体中的CBOD、SOD、DO及NH4+-N等主要水质参数的变化规律和影响因素，进行了定量的研究，所得的结果为水污染的综合防治提供了科学依据。

本文针对平原河网地区，河道纵横交错、水流流向顺逆不定、水流中输送的物质浓度属非稳态非均匀变化等特点，推导得到了使用与各种流动情况下，求解河网对对流输移问题隐式差分方程的一套计算公式，及相应的河网计算方法。运用这一方法进行述职求解，不仅能反映上述各种特点，还具有所需的计算机内存少，计算速度快，易于掌握点击应用方便等优点。