Final answer:
Urban stormwater is problematic due to contamination, sewage overflows, and flooding, and green infrastructure helps mitigate these issues by enhancing natural absorption and reducing runoff.
Step-by-step explanation:
Urban stormwater is a problem because it can lead to the contamination of natural water bodies with pollutants, the overflow of sewage systems, and increased flooding risks. Impermeable surfaces such as concrete and asphalt in urban environments prevent water from naturally soaking into the ground, leading to more runoff. Green infrastructure, like green roofs, rain gardens, and permeable pavements, plays a vital role in addressing this problem by mimicking natural processes to manage stormwater in an environmentally friendly way. By increasing absorption and reducing runoff, green infrastructure helps to improve water quality and reduce the impact on downstream environments. Reforestation and proper water resource management are also key in providing downstream water quality benefits, particularly in regions that are experiencing agricultural expansion, climate change, and population growth, which can affect drinking water supplies and flood risks.