航道等级，是指全国统一的航道定级标准规定的航道级别。某一等级的天然、渠化河流及人工运河的航道尺度、船闸尺度、跨河建筑物的通航净空等，都应符合航道定级标准规定与要求。
流域空间结构演化主要受航道等级、城市居中性以及腹地大小的影响。
Basin spatial structure evolution is affected by factors of rank of riverway, geometric centrality of cities, and size of hinterland.
但长期以来国家对柳江航道投入的资金不足，造成柳江航道等级偏低，航运资源未得到充分利用。
But the state has long been lack of investment to Liujiang channel, causing the low level of Liujiang channel, shipping resources are not fully utilized.
本文界定高等级航道水上服务区的概念，并对服务区的功能进行详细分析；
The thesis explains the concept, classification of the serving area on water at first, analysing about the function of it at the same time;
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