Answer: Because the rivers are so small, people must travel by train.
Step-by-step explanation:
South Africa's rivers are quite seasonal to such a point that in rainy season the rivers seem like great rivers with quite a number of tributaries but as soon as the dry season comes, the rivers became so small that a significant portion of them devolve into mud pools.
For this reason, travel and exploration was limited in South Africa as river transport was a convenient way to do both. The country therefore was forced to rely on trains to foster inland exploration and travel.
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