Astronaut Photography - Observing Earth's Systems from Space

Deltas

Just as changing landscapes affect humans, human can change the landscape. Deltas around the world are undergoing changes caused by human management of streams whose sedimentary deposits built the deltas over thousands of years. Crew Earth Observations will monitor Deltas and adjacent dynamic coastal zones to support change monitoring and planning efforts of scientists and governments.

Humans have been farming the Nile Delta for thousands of years, using the fertile delta soils for agriculture. The Aswan Dam, completed in 1970 to control flooding on the Nile River, has cut off the process that for thousands of years maintained the Delta through annual flooding cycles that spread fertile sediments across the Delta and into the Mediterranean Ocean. Sediment is now impounded in Lake Nasser, and the Nile Delta, shown below in 1984, is being eroded by wave and current action along the Mediterranean coast.

Globally, many deltas are undergoing dramatic changes. Where dams impound the sediment supply, deltas are subsiding. Ground water withdrawal in coastal areas is compounding the subsidence process. Where soil runoff has been increased by land clearing related to development, forestry, and agricultural, deltas are growing and coastlines are transforming. Deltas are sensitive indicators of dynamic coastal transformation occurring as the result of natural and human changes along coastlines, which are often prompted by population growth. The Crew Earth Observations program is monitoring deltas around the world to support research into the effects of both natural and anthropogenic processes, as well as the effects of sea level rise induced by global warming.

Foreword >>
Introduction >>
Crew Earth Observations >>
          Dynamic Events >>
          Coral Reefs >>
          El Nino >>
          Smog >>
          Volcanic Eruptions >>
          Deltas >>
          Urban Areas >>
          Glaciers >>
References >>