Final answer:
The height of the water table above the drains can go up due to factors such as increased rainfall, obstruction of drainage paths, and decreased groundwater extraction.
Step-by-step explanation:
The height of the water table above the drains can go up due to a few factors. One factor is increased rainfall, which leads to more water infiltrating into the ground and raising the water table. Another factor is the obstruction of drainage paths, such as blocked drains or a high water level in nearby bodies of water, which can cause the water table to rise. Additionally, the water table can rise if there is a decrease in groundwater extraction, allowing the natural recharge to exceed the withdrawal.