The correct answer to this open question is the following.
The Indus Valley Civilization interacted with the river networks in the region in such a way to take advantage of the sea trade networks to other regions of the world such as Central Asia and the Middle East. The Indus Valley Civilization prospered through trade and agriculture. The flood of the river made the soil of the region very fertile and when they knew how to control the flood, many benefits arose. That is how the minimize any detrimental effects of the location in such a dense river network. There were important routes for trade, such as the one developed from Harappa to Mesopotamia.