With reference to an example which you have studied, describe and explain ONE way that humans can have an effect on river processes or marine (sea) processes or mass movement. - Leaving Cert Geography - Question 1 - 2007

Dredging increases the navigability of waterways for ships and boats, allowing for increased transport and commercial activities. However, this process can disrupt local ecosystems by altering habitat structures, leading to the displacement of fish and aquatic life. Moreover, dredging can increase the rate of sediment displacement, potentially causing increased turbidity (cloudiness) in the water, which affects photosynthesis in aquatic plants and can lead to further ecological imbalance.

Dredging changes the physical environment of the riverbed, removing habitats for aquatic species, which can lead to a decline in biodiversity. Sediment-laden areas, crucial for species like fish, are often destroyed.

The removal of sediment during dredging results in increased turbidity, affecting light penetration into the water. This can impact aquatic plants' growth, disrupting the entire food chain.

Dredging modifies natural sediment transport processes, which can lead to increased erosion in some areas, altering river dynamics and impacting downstream ecosystems.

By changing the riverbed structure, dredging can alter flow patterns, leading to potential flooding in areas not previously prone to such events, which affects human settlements.

The stirring up of sediment can release previously buried pollutants, leading to increased levels of harmful substances in the water that can further harm aquatic life and contaminate water supplies.

While dredging can enhance commercial shipping routes, it can also result in economic costs associated with environmental damages, requiring investment in restoration efforts.

Dredging in certain areas can disturb organic sediments, leading to the release of stored carbon into the atmosphere, contributing to climate change.

Communities relying on local fisheries may face significant impacts from dredging as altered habitats affect fish populations, impacting local economies and food security.

A valid example of dredging impacts can be observed in the Mississippi River, where extensive dredging activities have led to drastic changes in local ecosystems and water quality.