Environmental flows: Building block methodology

Abstract

The Building Block Methodology was one of the earliest holistic methods globally for assessing environmental flows and remains one of the few that has a detailed users' manual. It was developed in real water-development projects in South Africa, starting in the late 1980s when the government and water scientists became concerned at the condition of the nation's rivers. It is a prescriptive approach that describes the flows required to maintain a chosen ecological condition in the river. It does not provide detailed predictions of ecological change or the social implications of river change and was not designed to address the requirement for larger (>1:2 yr) floods although this is now sometimes included.