DROUGHT AND ENVIRONMENTAL FLOWS: A FEW ISSUES

Most of the theory and procedures for establishing environmental (instream) flows is about the establishment of an environmental streamflow that meets the ecological needs of the aquatic ecosystem in normal conditions. When an environmental flow is established by water administration agencies the requirements are considered reasonable by many of the stakeholders. Little thought is given to the impact of drought on the ability to implement an environmental streamflow. When a drought occurs, conflict between various stakeholder groups can become intense with a strong tendency to set an established environmental flow aside because there is an “emergency” (the drought). Environmental flows could be established with the drought response being an integral part of the overall water administration plan. This poster explores some of the links between droughts and environmental flow by using indices to aquatic drought severity that show how the length of a drought can be very important to the aquatic ecosystem and it is the response to extended droughts that may be more important than the normal environmental flow requirements.. Not least of these issues is the definition of drought and just what streamflows are needed by fish (and other aquatic animals) during a drought in order to have a sufficient adequate stock of animals to repopulate stream following a drought. Another consideration is that droughts can be beneficial to the aquatic ecosystem by changing the competitive advantage between species.