An ocean current can be defined as a horizontal movement of seawater in the ocean. Ocean currents are driven by the circulation of wind above surface waters, interacting with evaporation, sinking of water at high latitudes, and the Coriolis force generated by the earth’s rotation. The nature of ocean currents has influenced human activities in the coastal regions.
Effects of warm ocean currents:
- The resultant high rainfall experienced has encouraged crop cultivation or rain fed-agriculture.This is common along the east African coast and West African coast where a number of crops are grown, e.g. cloves, sisal, and sugarcane along the East African coast. Along the West African coast crops like cocoa are grown in Ghana.
- The high rainfall experienced encourages the growth of forests and people may be involved in forestry activities, e.g. in Gabon, forestry activities such as lumbering are practiced. On the east African coast lumbering is also carried out in the mangrove forests.
- The high temperatures or warm conditions along the East African coast are conducive for the growth of coral polyps and the resultant rocks and land forms like coral reefs. These coral rocks have been a potential for the manufacture of cement from the coral limestone e.g. the Bamburi cement. In addition the coral reefs have been a tourist attraction and have promoted tourist activities along the coast of east Africa. Furthermore, the fringing reefs have tended to be a hindrance to deep sea fishing along the east African coast.
- The heavy rainfall that may result may be associated with thunderstorms which tend to be destructive to the crops and property and also disrupts the economic activities.
Effects of cold ocean currents
- The arid conditions lead to the growth of pastures of short grass which has encouraged pastoralism. It is important to note that pastoralism is common in semi-arid areas such as the Namib Desert and Kalahari Desert.
- The arid or desert conditions have promoted tourism. Such areas have been gazetted as wildlife conservation sites e.g. Namib Desert.
- The arid or desert conditions have also provided a conducive environment for the film industry. Film making has been carried out in the arid areas such as the Namib Desert.
- The ocean currents cause upwelling of ocean waters creating conducive conditions for the growth of plankton and this has encouraged fishing in these areas. The upwelling may be rich in phosphates and nitrates that promote plankton growth e.g. fishing has been an important activity in the coastal waters of Morocco, South Africa, Angola and Mauritania.
- Cold ocean currents lead to the formation of fog which tends to reduce on visibility over water and air thereby hindering navigation and aviation.