Downstream flows

Introduction

The management of downstream flows from hydropower projects is an essential element of sustainable hydropower development, but there can be disagreement amongst stakeholders over the objectives, magnitude and timing of flows required.

Hydropower projects can significantly alter downstream river flows by changing flow dynamics to follow energy demand, by reducing flow to a bypassed stretch, or by increasing flows due to diversions.

These alterations can lead advocates to call for increased or changed flow regimes for purposes other than hydropower generation, often to maintain and support a river’s ecological and morphological processes and its ability to deliver ecosystem services to people.

Compromises are necessary to satisfy downstream social and ecological objectives in partnership with a profitable and reliable hydropower project. Each case is individual and requires dedicated investigation of flow requirements.

Downstream flows objectives will differ greatly depending on the river, its communities and interactions, and the influence of hydropower on flows. A pragmatic approach is paramount, and collaborative approaches amongst major stakeholders are encouraged to better understand the river's ecological values and how best to protect and enhance these.