Both rivers and diversions in WEAP are made up of river nodes connected by river reaches. Other rivers may flow in (tributaries) or out (diversions) of a river. There are seven types of river nodes:
Reservoir nodes, which represent reservoir sites on a river. A river reservoir node can release water directly to demand sites or for use downstream, and can be used to simulate hydropower generation.
Run-of-river hydropower nodes, which define points on which run-of-river hydropower stations are located. Run-of-river stations generate hydropower based on varying streamflows but a fixed water head in the river.
Flow requirement nodes, which defines the minimum instream flow required at a point on a river or diversion to meet water quality, fish & wildlife, navigation, recreation, downstream or other requirements.
Withdrawal nodes, which represent points where any number of demand sites receive water directly from a river.
Diversion nodes, which divert water from a river or other diversion into a canal or pipeline called a diversion. This diversion is itself, like a river, composed of a series of reservoir, run-of-river hydropower, flow requirement, withdrawal, diversion, tributary and return flow nodes.
Tributary nodes define points where one river joins another. The inflow from a tributary node is the outflow from the tributary river.
Return flow nodes, which represent return flows from demand sites and wastewater treatment plants. (You may actually have return flows enter the river at any type of river node: reservoir, run-of-river, tributary, diversion, flow requirement, withdrawal, or return flow node.)
Streamflow gauges, which are placed on river reaches and represent points where actual streamflow measurements have been acquired and can be used as points of comparison to simulated flows in the river. Streamflow data is typically added using the ReadFromFile function. In results, look at Supply and Resources, River, Streamflow Relative to Gauge to view the report comparing actual and simulated streamflow.
Note: You can use WEAP's Automatic Catchment Delineation to help you define catchments and rivers.