Final answer:
Urbanization can increase stream discharges by creating more impervious surfaces, causing greater surface runoff and potentially leading to stream bank erosion and flooding. It can also degrade water quality through heightened pollutant loads and disrupt aquatic life, including insects and fish diversity, due to changes in water chemistry and flow.
Step-by-step explanation:
The probable effect of an increase in urbanization within a community, or upstream of it, on the stream discharges within that community includes several impactful changes to the natural water cycle and river ecosystems. Urbanization typically leads to more impervious surfaces like roads and buildings which reduce the amount of water that can infiltrate the ground, increasing surface runoff and potentially increasing the volume and speed of stream discharges following rain events. This surge in discharge can erode stream banks and contribute to flooding. Simultaneously, the loss of natural vegetation due to urban development can result in greater pollutant loads entering waterways, thereby worsening water quality.
The alteration of natural water flow can manifest in altered water temperatures, flow characteristics, and sediment transport, all of which can affect the ecological balance of river systems. In urban settings, the likelihood of chemical pollutants and trash entering the water system increases, potentially harming aquatic life and disrupting biodiversity. Human practices such as handling of sewage, industrial waste disposal, and the lack of adequate water infrastructure can exacerbate these effects, leading to challenges in managing drinking water supplies and increasing the risks associated with flooding.
Additionally, aquatic insects may be affected by polluted water conditions, as they are sensitive to changes in water chemistry and sedimentation. Fish diversity in streams is also impacted by urbanization. The types of fish that can tolerate or even thrive in altered conditions are often the ones that become more prevalent, while those needing pristine environments may decline or disappear.