Lowlands are prone to flooding, especially when rivers and tributaries merge. A study focused on the Meuse river and its tributaries found that flood peaks can coincide, causing water levels to rise significantly. By analyzing flood waves using a new method, researchers discovered that the timing of peak arrivals doesn't matter much because the waves last for about 9 days. Even with a 3-day lag between peaks, backwaters can still rise by 1.5 meters over 4 kilometers from the confluence.