A PRACTICAL METHOD TO DETERMINE VERTICAL HYDRAULIC CONDUCTIVITY IN LOW-PERMEABLE SOIL

VERTICAL SATURATED HYDRAULIC CONDUCTIVITY OF SOIL ABOVE A DEEP WATER TABLE IS ONE OF THE MOST IMPORTANT CHARACTERISTICS GOVERNING FLOW AND TRANSPORT. THIS PARAMETER IS USED IN WATER BALANCE STUDIES OF CROP PRODUCTION, IRRIGATION AND DRAINAGE SYSTEM DESIGN, RANGELANDAND FOREST WATERSHED MANAGEMENT, SOIL CONTAMINATION ASSESSMENTS, AND REMEDIAL ACTION DESIGN. THE CURRENT METHODS EITHER REQUIRE ONE TO WAIT UNTIL STEADY-STATE IS REACHED, OR CONTAIN PROCEDURES THAT CAN LEAD TO SIGNIFICANT UNCERTAINTY IN RESULTS. THIS IS ESPECIALLY PROBLEMATIC FOR RELATIVELY LOW-PERMEABLE SOILS. WE PROPOSE TO DEVELOP A NEW PERMEAMETER TO DETERMINE VERTICAL SATURATED HYDRAULIC CONDUCTIVITY THAT IS ESPECIALLYADAPTABLE TO LOW-PERMEABLE SOIL. THE NEW METHOD WILL REDUCETHE TIME TO COMPLETE TESTS AND IT WILL LEAD TO MORE ACCURATERESULTS. UNLIKE ANY EXISTING FIELD PERMEAMETER, OUR METHOD WILL INCORPORATE MEASUREMENTS OF THE WETTING FRONT MOISTURE DISTRIBUTION TRANSIENT INFILTRATION. THIS MOISTURE DATA WILL BE COLLECTED BY A GEOPHYSICAL METHODS OR GRAVIMETRIC ANALYSIS. OUR GENERAL APPROACH IS TO FIRST REFINE THE MATHEMATICAL BASIS FOR THE ANALYSIS OF DATA. THE SECOND STEP IS FEASIBILITY ASSESSMENT THAT WILL LEAD TO THE DESIGN OF THE PROTOTYPE THAT CAN BE CONSTRUCTED AND TESTED IN PHASEII.