To limit the probability that the inappropriate calculation of the hydraulic load will lead to inadequately sized drainage systems, which could lead to an inability to drain roofs or paved surfaces adequately, which could lead to flooding, which could lead to damage to the building or facility.
To limit the probability that inappropriate hydraulic load assumptions will lead to an inadequate design for roofs or drainage systems, which could lead to an inability to drain roofs effectively and in time, which could lead to water pooling, which could lead to the leakage of water, which could lead to damage to the building or facility.