The Red River has reached major flood stage of 30 feet between Fargo and Moorhead in 10 of the last 23 years and a total of 17 years since 1965. Before that, there was occasional flooding, but not above 30 feet, until you look way back to the terrible floods of 1897 and 1882.
Land use changes, such as the straightening of streams and coulees, improving drainage from agricultural fields and the very act of building dikes, all increase river levels during flooding and help explain the scourge of major flooding recently, but does not explain the floods back in the 1800s.
But consider this. Through the 1880s and 1890s, the average annual precipitation was about 24 inches a year. For most of the 1900s, it dropped to 19 inches a year. Since the 1990s, average annual precipitation is back up to 24 inches again. It floods more when it rains and snows more.