Union of Concerned Scientists

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Human Influences on Water. Human activities significantly affect water flow, availability, and quality.

• Gulf Coast residents use fresh water for drinking, irrigation, industrial uses, and recreation.
• More fresh water will be needed in the future for a growing population and an increase in farming and industrial usage.
• Building dams and levees, diverting rivers, and draining wetlands change natural landscapes, waterways, and ecological functions and, in the process, the water cycle.

Global Warming Influences on Water. With a changing climate this region is likely to see significant and problematic changes in its freshwater resources.

• Rainfall patterns in the region are likely to become more erratic, with heavy downpours and longer dry periods in between.
• For most of the immediate Gulf coastal zone, rainfall will likely be lower.
• These drier conditions will interact with other global warming impacts, such as sea-level rise, to exacerbate water conditions—for example, contributing to salt water intrusion into underground aquifers.
• It is not yet clear whether upland parts of the region will experience wetter or drier conditions. Faced with this uncertainty, a prudent steward such as a city manager will assess and manage the potential impacts of both a drier and wetter scenario.

Preparing for the Changes. Public and private sector water managers must increase their flexibility and adaptive capacity to respond quickly and appropriately as water conditions change. These managers must:

• Record, assess, and monitor our water resources and how this water is being used;
• Plan for both supply and demand, now and in the future;
• Protect the water needs of natural ecosystems in the competition for available water;
• Allocate water resources to the highest priority uses, at maximum efficiency, and in a just manner.