Urban Deltas Worldwide is committed to keeping urban deltas better. Urban deltas are defined by the combination of a dynamic natural environment and dynamic urban development. These urban deltas can be found all over the world. But perhaps it would first be good to know how to recognize a delta in general? Deltas are areas where rivers branch off into the sea. The delta is an estuary made up of river silt. This is because the river silt is deposited against the coast. (Editorial Ensie, 2016)
In addition, the estuary owes its name to the fact that when you 'zoom out', you see a triangle relating to the main river and its branches. This name was coined by the Greek historian Herodotus when he researched the Nile River. You cannot recognize every delta by this shape. (Editorial Ensie, 2016)
Deltas can also have different advantages and disadvantages. Some examples of a delta are agriculture and recreational opportunities. Disadvantages that may be present are flooding and the rise of sea level.
Erosion
Urban Deltas Worldwide is currently working very hard on mapping the problems of erosion. You may not know much about what erosion is, so we would like to explain it to you.
Erosion is a natural process whereby natural forces erode the material. Natural forces, such as wind or water, move the particles to another destination.
Erosion can occur in different ways, but most often it is carried out by (liquid) water, wind, or ice. Some important natural factors also play an important role, such as climate, tectonic movement, topography, and the vegetation in the landscape. Below is a list of the most common types of erosion together with a brief explanation:
- Physical erosion: Physical erosion is the process whereby the physical properties of rocks change without a change in their basic chemical composition.
- Erosion by water: Erosion by water can be divided into several categories. Erosion by water occurs during precipitation, flooding, lakes, rivers, and oceans. It causes pieces of soil and sand to float along and the sediment to slowly wash away.
- Erosion by ice: rosion by ice often refers to glaciers. Glaciers often move slowly downhill and this movement causes the rocks to rub against the ground and erode. The rocks are crushed and the soil is created.
- Erosion by wind: The wind is a strong factor for erosion. This is because the wind can take small particles from the soil and carry them a long way. Therefore, wind erosion is mainly found in dry (steppes) areas.
- Other types of erosion: Another type of erosion is thermal erosion. This involves erosion by permafrost. Due to warm temperatures, ice-rich coastlines can break down into large chunks, taking valuable topsoil and vegetation with them. These chunks can eventually end up in the sea. (National Geographic, 2012)
Below is a video about coastal erosion in Australia produced by Behind the News. The video explains what coastal erosion is and what the problems and impact of this may be for the area in Australia.
Deltas
Below is a map with the locations of the deltas. Can you already find the delta you want to know more about? Under the map, you can click on the button of the delta you want to know more about, so check it out soon!