If the rivers were dredged near Taipei their beds would be below sea-level, and would soon be silted up again by sand from the estuary.
台北市政府養護工程處副處長王文說：「治河要看河性，沒有一成不變的辦法。」他指出，一般人認為淡水河河床逐年淤高，應該要疏濬，其實根據實際觀測分析，淡水河因上游水庫擋沙，河床未顯著升高，疏濬河床，泥砂容易回淤，經濟效益很低。