【摘要】 本文导出了菱形沙洲、等腰三角形沙洲发育长度的理论公式，不规则沙洲也可概化为钻石形沙洲来求解．文中以长沙的许家洲与长江下游的世业洲为例作了证明．理论公式的建立对河道整治、通航、防洪与沙洲的开发均有意义．更多还原

【Abstract】 The formula for estimating the length of shoal in river with rhomb shape or isosceles triangle shape is deduced. The irregular shoals are generalized as diamond shape shoals. Examples are given for demonstration.更多还原