In regulated river systems, storages control the supply of water to consumptive and non-consumptive users, and may also provide flood mitigation, social and environmental services. In a river model, they represent places where water is stored along the river, such as dams, reservoirs, weirs and ponds. Storages operate by maintaining water mass balance.
In Source, the storage node operates by calculating the minimum and maximum discharge based on current inflows and user defined discharge, gain and loss relationships. They maintain water balance and assume that the change in storage height across a time-step is small compared to the storage fluxes. Additionally, it assumes that any flows fluxes into or out of the storage are distributed throughout the time-step. Flows and changes in storage volume are calculated by integrating across the time-step.
For all storages in Source, four aspects must be configured as a minimum in the node’s feature editor:
- Details of the storage such as its dimensions and capacity;
- Inflows to storages such as stream flow from upstream catchments, rainfall over the storage surface area, recharge from groundwater, and runoff from the catchment surrounding the storage;
- Outflows from the dam, which could be initiated either through controlled releases (to fulfill downstream demand) or uncontrolled flows; and
- Losses that constitute evaporation from the storage surface area and seepage to groundwater.
The editor’s main window (Feature Editor 14) allows you to specify storage details. These are outlined in Table 8. You are recommended to use the same units as those in Dimensions, but you can change them by clicking on their respective units buttons.
Releases from storages are normally assumed to be constant through the time-step (limited by volume to the minimum or maximum release curves). Enabling the
Adaptive Storage Release Method
checkbox generates a release curve based on the orders combined with the outlet curve. With this option, the storage would release at maximum release rate where the storage couldn’t release at ordered rate. The storage would release at minimum release rate when it was greater than the order. The adaptive storage release method will generate small artifacts when switching between the order and maximum/minimum release rates. However, it should provide better handling of releases when there are multiple outlets
with big operating ranges.