Why was the Lingqu Canal built? to irrigate farmland to improve trade routes to allow the Emperor to travel by water to other parts of China to transport troops and supplies

to transport troops and supplies

Explanation:

The greatest canal built under Qin Shi Huangdi was the Lingqu Canal, which was built to transport supplies for the army. It connected two major rivers and allowed Qin Shi Huangdi's empire to expand in the southwest. A common Chinese saying is, "In the North there is the Great Wall; in the South there is the Lingqu canal."