A node represents a physical component such as a demand site, wastewater treatment plant, groundwater aquifer, reservoir or special location along a river. Nodes are linked by lines that represent the natural or man-made water conduits such as river channels, canals and pipelines. These lines include rivers, diversions, transmission links and return flow links. A river reach is defined as the section of a river or diversion between two river nodes, or following the last river node. WEAP refers to a reach by the node above it.
Each node (except demand sites and tributary nodes) may have a startup year, before which it is not active. With this feature you can include nodes in the analysis that may be built after the Current Accounts Year, or selectively exclude nodes from some scenarios. To exclude a node from a scenario entirely, set it to be not active in the Current Accounts and then enter 0 for the startup year. WEAP will ignore any nodes (not active in the Current Accounts) with startup year equal to 0.
To capture the features of most water systems, different types of components (or nodes) are incorporated in WEAP. Below we present detailed descriptions of each type of component. In Calculation Algorithms we present the set of rules defining system water allocation and storage in successive time periods.