"Components" are the building blocks of a recommended alternative. There are three types of components - lows, pulses, and floods. The lows component creates the foundation of the recommended time series. Lows are defined for each day in a water year (for each state in each system). Pulses and floods deviate from this base of lows. A recommendation (for one state in a system) can have many pulses and floods, but only one series of lows. Both pulses and floods are defined by timing, duration, magnitude, and duration of peak. This approach was developed by The Nature Conservancy (Richter et al. 2006) and was adapted in part from the "Building Block Methodology" (King et al. 2000) and the "Holistic Approach" (Arthington et al. 1992) methods for defining environmental flows (Figure 4), which were formalized and first used in South Africa and Australia in the 1990’s.
Figure 4. Low, pulse, and flood components creating a time series of recommendations in terms of flow.
