Final answer:
The union of the Blue and White Nile rivers at Khartoum creates the Nile, which historically flooded to enrich the soil but now is controlled for irrigation, leading to increased crop growth but soil salinization issues.
Step-by-step explanation:
The result of the collision of the Blue and White Nile rivers is the formation of the Nile River at Khartoum, Sudan's capital. Before the construction of the Aswan High Dam, the Nile flooded annually, depositing silt and nutrients that were essential for Egypt's agriculture. However, this also caused damage to infrastructure. Today, the Nile's water is controlled and used for irrigation, allowing more crops to be grown annually. Nevertheless, the prevention of natural flooding has led to a buildup of salt in the soil, with the adverse effect of declining soil quality and agricultural yields.
In historical context, the Nile River has supported civilizations such as the pharaohs of Egypt and the Aksumite Kingdom in Ethiopia, and it has seen cultural shifts with influences from as far as the Arabian Peninsula. The river's annual flooding enriched the soil and supported Egyptian farmers since ancient times. However, technological advances like the introduction of the water wheel and controlled irrigation systems have transformed agricultural practices in Nile Valley civilizations.