Because the Yodogawa was prone to massive floods inflicting extensive damages on the people who lived in the river basin, the Meiji government began a major public works project on the river in 1896. A lock (completed 1907) and a weir (completed 1910) were constructed at Kema. These facilities eased ship traffic as well as allowed adjustment of the amount of water flowing into the former Yodogawa river (the Ogawa).Both structures were made of brick with granite blocks at key structural points. The present lock and weir were completed in 1974, but the Old Number 1 Kema Lock and Weir from the turn of the 20th century are preserved in the Yodogawa Riverside Park as National Important Cultural Properties.