上海中心城区河流水系百年变化及影响因素分析

分析上海中心城区河流水系1860~2003年变化情况,研究表明:①140余年来中心城区有历史记载河流消失至少310条段,总长超520 km,水面积减少约10.46 km²,水面率下降3.61%。中心城区所在水利片河流水系结构破坏,水系分枝比受河道消亡影响明显降低,水系分维数异常;②中心城区河流水系阶段性集中消亡,消亡驱动力因消亡时期而异;③初步估算,140余年来中心城区河道槽蓄容量减少超过2 029×10⁴m3、单位面积可调蓄容量减少5.06×10⁴m³/km²。河道槽蓄容量较百年前减少超过80%,城市河网调蓄能力明显削弱,且1950~1990年市政雨水泵站累积增加数目与同期区域内河道累积消失数量、长度和槽蓄容量间均呈显著正相关性。

Variation of River System in Center District of Shanghai and Its Impact Factors During the Last One Hundred Years

Based on the data of disappeared rivers from 1860 to 2003 in center district of Shanghai,the variation of river system and its environmental impact were analyzed.The research results showed that:(1) Over 260 rivers,with a length about 470 km disappeared in center district of Shanghai during the past 140 years.The water area and water surface ratio reduced 9.42 km² and 3.25%,respectively.The structure of river system was destroyed greatly.High-urbanization lessened the branching ratio,which leaded to an abnormal fractal dimension.(2) The rivers in the center district centralizedly disappeared during several phases.The reasons for river disappenring were altered in different times.From 1860 to 1949,the reasons included roads building,natural oblivion,concession expansion and residence zone building.From 1949 to 2003,those were city planning construction and residence zone building.(3) At a rough estimate,from 1860 to 2003,the substantive disappeared rivers caused the total river storage capacity and per area river storage capacity reduce about 20.92?10⁶m³ and 50.6?10³m³/km²,respectively.Now,the total river storage capacity reduced near 80% compare with that of 140 years ago,so the ability of storage capacity was greatly weakened in the center district of Shanghai.The number of cumulative built municipal pumping stations was significantly positively related with cumulative number,cumulative length and cumulative storage capacity of disappeared rivers from the 1950s to the 1990s.