永定河是北京地区重要行洪河道。由于地理位置重要，被列为由国家防总直接调度指挥的全国四大防汛重点江河之一，与长江、黄河、淮河防汛等同。大兴管界合计堤防长度６２ｋｍ，左堤北京界内的平原堤防绝大部分均在大兴界内，因此大兴段防汛工作任务大，安全渡汛难度大，行... Yongding River is an important flood-driving channel in Beijing. Due to its important geographical position, it is listed as one of the four flood control key rivers in the country directly under the command of the State Direct Defense Agency and is equivalent to flood control in the Yangtze River, Yellow River and Huaihe River. Daxing pipe industry total embankment length 62km, the left bank of Beijing in the vast majority of the dike in the territory of Daxing within the boundary, so Daxing flood control tasks, safety floods difficult, line ...