Focused Flows to Maintain Natural Nursery Habitats

Abstract

Regulatory standards for environmental flows to estuaries are not common, but are required in Texas, USA. This has led to adoption of complex freshwater inflow regimes that reflect seasonal and yearly fluctuations that vary geographically throughout the State. The flow regimes are based on dilution of saline water with fresh water in whole systems. Because the estuaries are large lagoons, large volumes of fresh water are required to meet standards. However, this volume of water is not available during dry periods. A new concept, “Focused Flows,” is presented for lower flow volumes that would maintain ecological health of the upper reaches of estuaries during droughts. The concept is based on maintaining ecological integrity of nursery habitats, which is an important ecological function of estuaries. These focused flows would protect estuaries during droughts and allow the estuary to recover more quickly when the hydrology turns back to an average or high flow periods. This approach could be applied globally where increasing water infrastructure and deficits are a concern or increasing aridity due to climate change is reducing river flows to coasts.

Keywords

• Environmental flow
• Freshwater inflow
• Focused flows
• Nursery habitats
• Management
• Hydrology