Groundwater from the Local Official Perspective (4-D Temporal)

In InterWET, the groundwater from the local official perspective gives a four dimensional view or temporal view of groundwater using maps and the GWLF Model.

Source Data for map: Environmental Resources Research Institute at The Pennsylvania State University.
 

The tables below give GWLF's estimates of groundwater flow for Spring Creek and its tributaries for the past 20 years based on observed weather data and predictions for the next 20 years based on simulated weather data.

Predicted Mean Groundwater Flows for Spring Creek
for the Past 20 Years and for the Next 20 Years

Predicted Mean Groundwater Flows for Spring Creek Tributaries
for the Past 20 Years and for the Next 20 Years

Remember from the runoff from the local official web page that predicted total runoff, and consequently the groundwater runoff, was too low for Logan Branch and too high for Spring Creek at Axeman, Houserville, and Buffalo Run, Cedar Run, and Slab Cabin Run.  This discrepancy was caused by the inability of GWLF to account for complex groundwater geology of the Spring Creek Watershed.  However, by the time Spring Creek reaches Milesburg, all of the "diverted" groundwater flow has become stream flow.  The table below compares the measured water balance at Milesburg with the water balance predicted by GWLF.
 

Precipitation = Evapotranspiration + Total Runoff

Total Runoff = Direct Runoff + Baseflow

Main Data Source: Larry E. Taylor, Water Budget for the Spring Creek Basin,Susquehanna River Basin Commission, 1997.

Notice the close agreement between measured and predicted water balance.  This seems to indicate that GWLF does an adequate job of predicting the water cycle, when all groundwater for the basin of study returns to the surface at Milesburg.
 

Click the button below to load the Groundwater Flow Calculator.

The calculator can be resized for your screen.

Source Data for map: Environmental Resources Research Institute at The Pennsylvania State University.

The output from the calculator reflects the mean annual change in the groundwater flow caused by a particular set of policies.  After selecting a set of policies, before clicking calculate, be sure to select whether to display the change as a percentage or in one of the 8 categories listed in the table below.

Percent Change Categories
 

Category	Percent Change Range
Large Decrease	X<-50
Medium Decrease	-50<=X<-25
Slight Decrease	-25<=X<-10
No Change	-10<=X<+10
Slight Increase	+10<=X<+25
Medium Increase	+25<=X<+50
Large Increase	+50<=X<+100
Very Large Increase	+100<=X

Experiment with policies and see how each kind of policy affects the groundwater flow.  The relationships that were shown in the researcher perspective still hold for these calculator.  Like surface runoff, the only policies that affect groundwater flow are those policies which affect land cover or soil.  Consequently, the only policies which affect groundwater flow are Land Use policies.  Notice that this effect is small, like with surface runoff.  Most of the changes percentages fall within the No Change category.

As mentioned on the runoff from the local official perspective web page, GWLF was also used to model changes in total runoff caused by policy change.  No change were found to occur to the mean annual total runoff.  On an annual basis, total runoff will not change, because the evapotranspiration in each subwatershed is not significantly impacted by the land use change caused by the policies.

More Details?

Back for Water Resources	Back for Perspectives	Home	Next for Water Resources	Next for Perspectives