Please Explain What Irrigation of Crops is

and if you could please tell me what a city needs to consider related to it.

Irrigation of crops is watering crops. When irrigating crops near a city, one must consider several issues:
drainage: the city should have good drainage to make sure that the water does not go into the city
water shortages: irrigating crops requires much water, so the city may need to consider using treated sewage water to water plants and prevent shortages.

Watering.