Question

Why the majority of the known harappan settlements are located in the semi arid regions having low underground water level?

Answer 1

as at that period people were herders wanders they begin farming then they moved to water points near water sources

Answer 2

Harappa and Mohenjo-daro were found when railway engineers were building a train line there and observed locals getting large blocks of stones from somewhere. The aridness preserved those cities as humidity can destroy most human artifacts. Also, the aridness prevented the future settlements of the area, while a fertile area would be settled a thousand times then.