Length of navigable inland waterways ： refers to the length of the natural rivers , lakes , reservoirs , canals , and ditches open to navigation during a given period , which enables the transport by ships and rafts 内河航道里程：也称“内河通航里程” ，是反映内河水运网规模、水平和发展情况的主要指标；是指在一定时期内，能通航运输船舶及排筏的天然河流、湖泊水库、运河及通航渠道的长度。
