Complex sentence: The Kech River is a seasonally-flowing right-bank tributary that flows in from Iran, whereas the Mirani Dam is located on the Dasht, to irrigate the surrounding areas, flood control in the region and to provide drinking water to city of Gwadar.
Split into simpler sentences: The Kech River is a seasonally-flowing right-bank tributary that flows in from Iran, whereas the Mirani Dam is located on the River Dasht. It is built to irrigate the surrounding areas, flood control in the region and to provide drinking water to city of Gwadar.