Answer:
they planted in the mouth of rivers, dug irrigation ditches.
Step-by-step explanation:
The mesa people grew corn in the desert
by planted in the mouth of rivers, dug irrigation ditches. The desert has close to zero amount of precipitation which makes farming difficult. The crops here have no access to rainfall which is the more reason why they planted the crops nearby a water body suit as in the mouth of rivers, dug irrigation ditches etc.