Final answer:
To control erosion at the inlet end of a culvert, you can install a riprap apron, increase the size of the culvert, or add vegetation, with all options being viable solutions.
Step-by-step explanation:
To control erosion at the inlet end of a culvert, you can undertake several measures. One effective method is installing a riprap apron, which consists of placing large stones or concrete chunks at the inlet to dissipate energy and minimize scour and erosion. Another approach is to increase the size of the culvert, allowing it to handle larger volumes of water and reduce the velocity at which water enters, thereby decreasing erosion potential. Additionally, adding vegetation to stabilize the soil can help prevent erosion by using plant roots to bind the soil and absorb some of the water. Hence, the correct answer would be All of the above.