What are two primary causes of saltwater intrusion in coastal wetlands?

Saltwater intrusion in coastal wetlands primarily occurs due to the interconnected relationship between freshwater and saltwater systems, where the balance can easily be disrupted. The correct answer highlights tropical storms and canals as significant causes of this issue.

Tropical storms, including hurricanes, can result in storm surges that push saltwater into estuarine and freshwater systems, altering salinity levels and affecting the health of coastal ecosystems. This influx of saltwater can overwhelm the natural barriers that typically keep freshwater in place.

Additionally, the construction of canals has drastically changed water flow patterns in coastal Louisiana. Canals can allow saltwater from the Gulf of Mexico to penetrate further into freshwater areas, exacerbating the problem of saltwater intrusion as they create pathways for saltwater movement. The combination of these two factors leads to significant ecological impacts, affecting plant life, fish species, and the overall health of wetlands.

Other choices, while potentially contributing to environmental changes, do not directly address the mechanisms of saltwater intrusion in the same way. Urban development and agriculture can lead to increased water consumption and land alteration, but they are not immediate causes of saltwater moving into the wetlands. Temperature changes and drought can influence water levels and ecosystem health but do not result in the physical intrusion of saltwater