button and clicking Browse... to select an existing time series file or clicking Create a new file… to open the ‘Create a new file’ dialogue.
If groundwater is included in the Basin modules (cf. Section 4.1.1), three groundwater properties must be specified: groundwater extraction method (Groundwater options), the catchment from which groundwater is extracted (Supply catchment), and the groundwater use time series.
There are three different options for using groundwater to fulfil the Water user demand:
· Fraction of total demand. This method will attempt to fulfil the Water user demand by taking a fraction of the demand from the groundwater. This option corresponds to a specified sharing of the surface water and the groundwater resources. If there is limited water available either in the surface water or the groundwater the demand will not be fulfilled.
· Fraction of remaining demand. This method will attempt to use groundwater to fulfil a fraction of the total Water user demand that cannot be fulfilled by surface water. If the fraction is set to 1.0 it means that the Water user first extracts surface water and then fulfils the remaining demand using groundwater. This option corresponds to specified priority between surface water (first priority) and groundwater.
· Absolute demand. This method will subtract absolute groundwater demand from the total water user demand to calculate surface water demand. If absolute groundwater demand is greater than total water user demand, surface water demand will be zero. If there is limited water available either in surface water or in groundwater, the water user demand will not be fulfilled.
In this field you can specify the Catchment from which the groundwater is supplied. Only valid Catchments for which groundwater aquifers exist will be displayed in the drop down menu.
Depending on the groundwater option selected, either a groundwater fraction use time series or a groundwater absolute use time series must be specified.
This is done by clicking on the button and clicking Browse... to select an existing time series file or clicking Create a new file… to open the ‘Create a new file’ dialogue.
Note that the groundwater use time series may optionally include two additional items: Lower groundwater extraction limit and Upper groundwater extraction limit, where the upper groundwater depth limit specifies the depth at which groundwater extraction may start to be reduced, and the lower groundwater depth limit specifies the groundwater depth at which no more extraction is allowed.
If the groundwater depth (at the beginning of the time step) is smaller than the upper limit, there is no reduction of the extraction (a reduction factor equal to 1 is applied).
If the groundwater depth is between the upper and the lower limit, a linear interpolation is performed on the reduction factor.
Complete reduction (reduction fraction equal to 0) takes place when the groundwater depth is larger than the lower limit. If only one of the two time series is given, the change in reduction factor goes abruptly from 1 to 0, when the groundwater depth crosses this limit.
Note: The Upper groundwater depth limit should be given a value, which is smaller than the lower groundwater depth limit.
