Data Requirements for Calibrating Hydrologic Models.

The mathematical models for water flow and transport of pollutants are powerful tools for evaluating sites for various land uses.  The assessment of soil and ground water pollution and determining site suitability for land-based waste management systems are common examples.   These mathematical models require reliable input data to provide accurate results.  The primary required parameter common among all the models is the saturated hydraulic conductivity (K_sat) for both vadose zone assessment and ground water modeling.  Other parameters of interest include soil water characteristic curve, drainable porosity (specific yield), and thickness of the aquifer under consideration.  The most practical method for determining K_sat of the vadose zone is the constant head well permeameter technique, also known as the bore hole permeameter method.  Below the water table (i.e., aquifer), the slug test and pump test are the most common methods of measuring K_sat.  Both these techniques require knowledge of the thickness of the aquifer.  The drainable porosity can be determined from the soil water characteristic curve, or it can be estimated through the assessment of the drainage volume for a given level of drop in water table. The most common procedures for obtaining field and laboratory data, as well as the integrity of data collection will be discussed.