短语词组短语river -delta depositional 河流river lower delta plain 河控下三角洲平原river estuary delta area 河口三角洲地区river mouth delta 河口三角洲yellow river delta delta 黄河三角洲yellow river subaqueous delta 黄河水下三角洲braided river -delta 辫状河三角洲 返回 river delta