Atmospheric Modeling and Analysis Research
Stream Routing and Reservoirs
Stream Routing Model
The Variable Infiltration Capacity, or VIC, hydrology model produces runoff and baseflow at each model grid cell for each model time step. An off-line streamflow routing model is used to simulate the processes of water accumulation and transport (Lohmann et al., 1998). The flow can exit each grid cell in eight possible directions, but all flow must exit in the same direction. Thus, the stream network and flow direction needs to be established for each grid cell.
The U.S. Geological Survey's National Hydrology Dataset (NHD+) stream network identification is used to define the flow direction and the connections of the stream network. Once the water flows into the channel, it does not flow back out of the channel and is removed from the hydrological cycle of the grid cells. The daily surface runoff and baseflow produced by VIC is first transported to the outlet of each cell, and then routed into the river network to the basin outlet.
Reservoir or River Management Model
The reservoir is responsible for observed changes in river discharge. The reservoir model has several control variables that define the operating strategies for guiding a sequence of releases to meet a large number of demands with different objectives, such as flood control, hydropower generation and irrigation water demand.
The reservoir model used in this research is based on the model developed by Haddeland et al (2006). The operation is assumed to follow simple rule curves which are specified according to the purpose of the dam, as defined in the Army Corps of Engineer's National Inventory of Dams (NID) (1900-2009). An optimization scheme based on the Shuffled ComplexEvolution Metropolis algorithm (SCEM-UA) (Vrugt et al., 2003) is used to calculate optimal releases given reservoir inflow (as simulated by VIC) storage capacity and downstream water or power demands. The reservoir model is run at a daily time step. However, water demands are calculated on a monthly basis.