Arrange the common river management techniques into hard and soft engineering categories:
1️⃣ Hard Engineering: Dams
2️⃣ Hard Engineering: Flood walls
3️⃣ Hard Engineering: Channelization
4️⃣ Soft Engineering: Wetland restoration
5️⃣ Soft Engineering: River renaturalization
6️⃣ Soft Engineering: Floodplain management