(a) On an outline map of West Africa, show (i) one area having less than four months of rainfall annually (ii) one area having rainfall all the year round (...

Answer Details

(a)

1. The Sahel region, which includes parts of Mauritania, Mali, Niger, Chad, and Sudan, experiences less than four months of rainfall annually.
2. The coastal region of West Africa, including countries like Nigeria, Ghana, and Ivory Coast, experiences rainfall all year round.
3. The high pressure belt in January is located over the Sahara desert and the Sahel region.

(b)

The three reasons for the length of the rainy season in the Sahel region (area with less than four months of rainfall annually) are:

1. The Intertropical Convergence Zone (ITCZ): During the rainy season, the ITCZ, a low-pressure zone where the trade winds converge, moves southwards towards the Sahel region. This brings moist air, which leads to rainfall.
2. Monsoon winds: The Sahel region is influenced by the West African monsoon winds, which bring moist air from the Atlantic Ocean. These winds help to sustain the rainy season.
3. The Gulf of Guinea: The warm waters of the Gulf of Guinea also contribute to the length of the rainy season in the Sahel region. The warm waters evaporate, and the moisture is carried inland by the monsoon winds.

(c)

The three problems that rainfall may pose to agriculture in the coastal region of West Africa (area with rainfall all year round) are:

1. Soil erosion: Heavy rainfall can cause soil erosion, which can wash away fertile topsoil and leave the land less productive. This is a major problem in areas with steep slopes and poor soil structure.
2. Flooding: Excessive rainfall can also cause flooding, which can destroy crops and homes, and lead to the loss of life. Flooding can also cause soil saturation, which can lead to the loss of soil nutrients and make it difficult for crops to grow.
3. Plant diseases: Rainfall can increase the incidence of plant diseases, which can reduce crop yields. Moisture-loving fungi and bacteria thrive in wet conditions and can infect crops, leading to poor quality and reduced yields.