The Grand Canal cut through the lower reaches of these rivers and fused them into one outlet to the sea, in the form of the current Hai He.[2] In 1863 seagoing ships could reach the head of navigation at Tongzhou, but the crooked river was difficult for large vessels.[3] During the Boxer Rebellion, Imperial Chinese forces deployed a weapon called "electric mines" on June 15, at the Baihe river before the Battle of Taku Forts (1900), to prevent the western Eight-Nation Alliance from sending ships to attack.To alleviate flooding, reservoirs have been built and artificial channels dug to divert excess water directly into the sea.Due to industrial and urban development in the Hai He Basin, the volume of water flow has greatly decreased.