Answer:
It creates an area of fertile soil and slow-moving water for farming.
Step-by-step explanation:
Delta rivers are rivers that extend over a rectangular shape and have spread across several riverbed arms. These rivers were very important for the establishment and growth of ancient civilizations. This is because they are rivers that are located in flat areas or with very low slope, with high levels of soil fertility and waters with slow and non-violent flow. These characteristics are great for the establishment of agriculture that was essential for these civilizations. An example of this is the Egyptian civilization that grew on the banks of the Nile River, a delta river.