What is often a direct result of poor management of peak flows?

Poor management of peak flows typically leads to flooding and erosion in downstream areas, which is why this choice is the correct one. When stormwater management practices fail to adequately control or mitigate peak flow events—such as heavy rainfall or rapid snowmelt—there can be an overwhelming volume of water that moves quickly across the landscape. This can result in excessive runoff that surpasses the capacity of drainage systems and rivers, leading to flooding. As the water rushes downstream, it can cause significant erosion, degrading the banks of waterways and impacting ecosystems.

In contrast to this, options such as increased local biodiversity or higher water quality standards are generally not direct results of poor peak flow management. In fact, poor management would likely lead to degraded habitats and water quality issues due to sedimentation and pollutants being washed into water bodies. Additionally, lower construction costs do not align with the impacts of poor stormwater management, as insufficient management practices may actually increase long-term infrastructure costs due to the need to address the damage caused by flooding and erosion.