Chapter 5 - Current trends, gaps, and future prospects in e-flow science: allocating environmental water needs under a changing world

Abstract

Environmental scientists have predicted that an increase of future water demand for agriculture, industry, and human consumption combined with the anticipated climate change will inevitably impact the availability and distribution of global water resources. Undoubtedly, human society is called to adapt to these changes in a sustainable way that covers the human needs for water and at the same time secures ecological requirements for the environment. In practice, water managers face the challenge of balancing human and ecological water requirements under the setting of global change that involves large environmental and socioeconomical changes. To this end, river scientists are using the concept of environmental flows (e-flows) to define the quantity of water that is required for freshwater ecosystems to maintain their function and structure and deliver the water-related services to human societies. Although certain advancements in e-flow science have been made, scientists and water managers have acknowledged that several gaps and issues remain, particularly when it comes to the practical implementation of the e-flows for an integrated water management approach. This chapter, with the aid of a scoping review, explores trends in the research related with the allocation of water resources according to human and ecological requirements and attempts to address major challenges that any future assessment scheme will have to face. In a way it examines the progress in the topic of e-flows during the last few years with emphasis placed on whether scientists address well-known issues and concerns. The findings of the review confirm that several issues persist as most of the reviewed studies are limited to a small spatial scale, disregard the ecohydrological relationships and do not take into consideration the implications caused by future environmental and socioeconomic change. The need to make progress and overcome these issues is highlighted and the emerging research opportunities are discussed. New research may focus on key aspects of e-flows such as the development of new sophisticated ecohydrological models that accurately predict ecosystem functions to flow alterations, the ability to discriminate the effects of flow alterations from other coacting stressors, and the quantification of the impact of flow alteration on the delivered ecosystem services. Broadening the perspective of e-flows will contribute to integrated catchment management to embed more realistic definitions of the minimum ecological water requirements.