Parashat Lekh Lekha: What's Going On Here?

What's going on here? מַה זֶה?

Why is Mitzrayim spared from the famine?

When faced with a severe famine in Eretz Cana’an, Avram and Sarai decide to travel to Mitzrayim (Bereishit 12:10). Later on in Bereishit, the same thing happens again when the sons of Ya’akov travel down to Mitzrayim during a famine in search of food (Bereishit 41:57).
Why is Mitzrayim not affected by the famines in Eretz Cana’an?
One possibility is the difference between agriculture in Mitzrayim and Eretz Cana’an. The farms in Eretz Cana’an are dependent on rain. So, if there is a drought (meaning that there is no rain), the food can’t grow. Mitzrayim, however, had an irrigation system connected to the Nile river, so food could grow even when it wasn’t raining.