Response Functions - Assumptions Supporting Response Functions
Response functions cannot be universally applied to all situations.  The validity of response functions is linked to the concept that responses, such as river depletion from pumping, are additive and proportional to the pumping or recharge rate.  This assumption is valid in many ground water environments.  Each situation should be evaluated by a qualified professional hydrologist, however, to determine if any of the following excluding conditions are likely to have a significant effect on the ground water flow system in the area of interest.  


These conditions need to be evaluated, not just for the development of response functions, but for their application to each specific circumstance.  If ground water elevations are changing dramatically in a given situation, then the above conditions are more likely to occur, and response functions should not be used.

Response functions generated by field measurements, analytical techniques, or numerical models will be burdened with all of the assumptions of the method used in their development.  For example, if the Jenkins (1968) analytical technique is used to generate the response functions, then one of the assumptions underlying the response functions is that the stream is straight and fully penetrating.  If a numerical model is used to generate the response functions, then the accuracy of the response functions is directly dependent on the accuracy of the numerical model's calibration and the underlying conceptual model.  In many cases, this will be the greatest source of error in application of response functions.

Information supplied by Idaho Water Resource Research Institute, University of Idaho December 1998
Authors: Dr. Gary Johnson, Donna Cosgrove, and Mark Lovell.
Graphics: Sherry Laney and Mark Lovell of Idaho Water Resources Research Institute.
All State of Idaho images and graphics created with GIS files obtained through Idaho Department of Water Resources Public Domain GIS unless otherwise noted.
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