Bananas growing near a stream. Image credit MediaWiki.

Bananas growing near a stream. Image credit MediaWiki.

ZIMSEC O Level Geography Notes: River Processes: Stream bank cultivation

  • Stream bank cultivation refers to the practice of growing or cultivation of crops near a wetland, stream or river.
  • Sub-Saharan Africa has faced political, socio-economic problems in the recent times.
  • These problems have been in brought about by erratic rainfall patterns in the region.
  • In Zimbabwe, erratic rainfall patterns, lack of employment and poverty has led to the cultivation of stream banks.
  • An example of areas that experience a lot of streambank cultivation are the peri-urban areas of Seke-Chitungwiza.
  • Crops are grown mostly for domestic consumption although horticultural activities such as vegetable grown is sometimes carried out with most of the produce sold at local farmer’s markets.

Results

  • Stream bank cultivation results in siltation and the choking of rivers and dams.
  • It also leads to eutrophication as fertilizers containing nitrates are washed into the rivers.
  • It also leads to the disturbance of natural ecosystems.

Gold Panning

Korokoza's panning for gold. Image credit Bulawayo24.com

Korokoza’s panning for gold. Image credit Bulawayo24.com

Results

  • It results in the siltation and choking of rivers and dams.
  • It leads to pollution as dangerous chemicals like mercury an cyanide are released into streams.
  • The disturbances of ecosystems.

Urbanization

Urbanisation leads to increased overland flow. Image credit zimbojam.com

Urbanisation leads to increased overland flow. Image credit zimbojam.com

Results

  • Results in increased pollution and disturbances of ecosystems.
  • Increased impervious surfaces result in increased overland flow, shorter lag time between a storm and a surge in discharge and increased incidences of flooding downstream.

River diversions

Water Canal. Image credit  texasbeyondhistory.net

Water Canal. Image credit texasbeyondhistory.net

  • Sometimes river water is diverted through man made canals, dames and pipelines to supply water for irrigation, industrial and domestic use.
  • The Pungwe Project in Mutare is an example.
  • The result is decreased discharge and the formation of more deposition features.
  • This may also lead to the shortage of water downstream.

 

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