View Full Document. Ultimate base level for all rivers is sea level - Longitudinal profile: way to show a riverâs overall vertical drop. Shows the elevation of its channel bottom from the headwater areas to its downstream termination (the riverâs mouth).
The population is as diverse as it is large, with some 250 ethnic groups. Nigeria's three largest ethnic groups are: Hausa-Fulani (29 percent of the population), Yoruba (21 percent) and Igbo, or Ibo (18 percent).he population is as diverse as it is large, with some 250 ethnic groups. Nigeria's three largest ethnic groups are: Hausa-Fulani (29 percent of the population), Yoruba (21 percent) and Igbo, or Ibo (18 percent).
The President of the Federal Republic of Nigeria is the head of state and head of the national executive of Nigeria. The President of Nigeria is also the commander-in-chief of the Nigerian Armed Forces. The President is elected in national elections which take place every four years. The first President of Nigeria was Nnamdi Azikiwe, who took office on 1 October 1963.