What is the main function of a gravel diaphragm in stormwater systems?

The primary function of a gravel diaphragm in stormwater systems is to maintain sheet flow. Gravel diaphragms are typically installed in areas where stormwater needs to be dispersed uniformly across a surface. By allowing water to flow over a wider area rather than concentrating in a single point, gravel diaphragms help to mitigate erosion and encourage infiltration into the surrounding soil. This spread of water aids in preventing localized flooding and promotes hydrologic balance in the landscape.

Maintaining sheet flow is critical for effective stormwater management because it reduces the velocity of the flowing water, minimizing soil disturbance and helping to maintain the integrity of the surrounding ecosystem. This function aligns with the objectives of sustainable stormwater management, which include promoting infiltration and reducing runoff.

In contrast, options relating to enhancing sediment discharge, increasing erosion rates, or decreasing vegetation density do not align with the beneficial role of a gravel diaphragm. The diaphragm focuses on promoting even distribution and infiltration rather than contributing to negative impacts on the environment.