Earth Science 101: What Is a Delta in Geography?

By Staff WriterLast Updated Apr 3, 2020 6:31:20 AM ET
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A river divides into smaller river and empties into a body of water, creating an area known as a delta. Sometimes, a delta can empty into land, but this doesn't occur very often.

How a River Delta Forms

A river delta is formed when a river divides into several smaller rivers. These rivers create a triangle shape, like the Greek letter delta, as they empty into another body of water. The rivers run slowly at the mouth of the delta, depositing rich soil called silt. The silt is what creates the delta. Deltas are rich areas for wildlife and plants. The soil is ideal for agriculture because of the many mineral deposits. Most deltas are just above sea level. Deltas can vary in size and structure due to climate and geology.

Parts of the Delta

The delta consists of three parts: the upper delta plain, lower delta plain and subaqueous. The upper delta plain is the area closest to land with the least amount of water. The portion closest to the sea to the body of water where the rivers flow is the subaqueous. It is below the water level and usually past the shoreline. It is influenced by the waves and tides. The lower delta plain is where the finest silt is found in the middle of the delta. It sits between dry land and the wetland.

Habitat of the Delta

Deltas are considered wetlands, and they are home to plants and wildlife. The plants found in the deltas are often used for traditional medicine. Deltas are also well known as a habitat for hibiscus and lilies. Animals that can be found in the delta include fish, oysters, insects, birds and several predatory animals.

Importance of the Delta

For thousands of years, river deltas have impacted civilizations. Their fertile soil has provided a place for people to grow plants, get medicinal herbs and hunt wildlife for food. Today, deltas are still important to those who live around them. In addition to providing food and medicine, deltas are also a source of gravel and sand, which is important for building infrastructure. Deltas are also an important habitat for many species.

Examples of Deltas Around the World

Mississippi River Delta: This delta is in the state of Louisiana. It provides a source of fishing and transport for people in the area. It is also home to many types of wildlife. An important note about the Mississippi River Delta is that it can protect the area from the impact of hurricanes. The delta acts as a barrier between the Gulf of Mexico and populated areas. When a hurricane makes landfall near the delta, it weakens before hitting inland. This lessens the impact of the storm on communities.

Nile River Delta: This delta is in Egypt and empties into the Mediterranean Sea. It begins north of the capital city of Cairo. It has served as an important area for farmers for thousands of years and is still critical for agriculture.

Ganges-Brahmaputra Delta: This delta spans between Bangladesh and India. It is the largest delta in the world and empties into the Bay of Bengal.