Comparison of Spatial Interpolation Methods for Lithologic Characterization of Shallow Aquifer Systems
Jonathan P. Aguilar1 and Wilfredo P. David2
A major constraint to accelerated shallow tubewell (STW) irrigation development is the lack of information on shallow aquifer systems. Such information is vital to the proper planning and development of STWs.
Geographic Information System (GIS) is a useful tool for delineating shallow aquifer areas or systems. Meanwhile, selecting the interpolation method best suited to a given dataset is an important first step in delineating aquifer systems.
The dataset in the study consists of the well logs for Cagayan and Isabela as compiled by the Regional Field Unit 2 of the Department of Agriculture; Three GIS spatial interpolation methods such as (IDW, Kriging, and Spline) were applied to the dataset. Maps of lithologic properties classifying different strata were generated.
The results showed that all three interpolation methods are applicable. For simplicity and practicality, it is recommended that IDW interpolation method be used for this type of dataset. However, caution must be exercised in using the IDW interpolation method for other datasets in other areas. Preliminary investigation on the adequacy and reliability of data points should be first carried out before a judicious choice of interpolation method can be made.
Keywords: shallow aquifer systems, spatial interpolation methods, geographic information systems
1 University Researcher, and 2 Professor, Land and Water Resources Division, Institute of Agricultural Engineering, College of Engineering and Agro-industrial Technology, University of the Philippines Los Baños, 4031 College, Laguna, Philippines.