Coastal and Oceanic Landforms (40. River Delta)

                                                                                                                                         Back to Coastal and Oceanic Landforms

• River Delta formed by;

                       Deposition of the sediment at the mouth of a river.

• River flows into;

                    ocean

                    sea

                    estuary

                    lake

                    reservoir

The Ganges Delta, India

• Obtaining a more stable steeper slope.

• Depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition.

                           -examples of  avulse : the Mississippi and Ural River deltas

• Deltas are classified to the main control on deposition.

• which is usually either a river, waves, or tides.

                        1.wave dominated deltas.

                          Wave erosion controls the shape of the delta.

                          River mouth is deflected along the coast line.

                         Deltas of this form, such as the Nile Delta.

Ganges Delta

                   2.Erosion /tide dominated deltas.

                       Mainly submarine.

                       Prominent sand bars and ridges.

                       Produce a "dendritic" structure.

                       Differently from river- &  wave-dominated deltas

                       It is abandoned.

                  3.A Gilbert delta 

                       Formed by coarse sediments.

                      Opposed to gently-sloping muddy deltas. 

                      Mountain river depositing sediment into a freshwater lake

                      Located on coasts tidal range

Nile Delta

              4.Inverted river delta. 

                 Located inside a large valley.
                 Divide into multiple branches in an inland area.
                 Only to rejoin and continue to the sea.
                 Often occur on former lake beds.

                                     examples

                                                      Inner Niger Delta.

                                                     Peace–Athabasca Delta . 

                                                     Okavango Delta in Botswanais.

Okavango Delta

5.Alluvial fans

Deltas are differentiated from alluvial fans.

 Deltas have a shallow slope.

Contain fine-grained sediment;
                                     sand & mud
Flow into a body of water.

Have coarse-grained sediments.

• The most famous delta is the Nile River.

• The Ganges/Brahmaputra  is the world's largest delta.

•  Notable deltas include ;

Fly River                                 Cauvery                                                Niger River

Tigris-Euphrates               Rhine                                                       Po

Rhône                                     Danube                                                   Ebro

Volga                                      Lena                                                          Indus

Ayeyarwady                       Mekong                                                   Huanghe

Yangtze                                 Sacramento-San Joaquin                Mississippi

Orinoco                                 Paraná

Mississippi River Delta

Yellow delta