In large irrigation projects, observing and evaluating groundwater depth (GWD) for crop production is crucial. To accomplish these goals, GWDs are measured over certain time intervals, especially during irrigation season, when depth and level maps are prepared and analyses on the target are made. These maps are used for a multi-year observation of GWD. In this study, we present an alternative method that can be used for multi-year lowest GWD evaluations. The method evaluated the spatial and temporal relationships among the classes of GWD in the study area, in their typical locations (areas where the GWD classes are most frequently located), and the alternative GWD classes in those locations in any of the years of the analyzed time-series. As a case study, the method was applied to data of the multi-year (1990-2000) GWD observations in the Mustafakemalpasa (MKP) irrigation project (19.370 ha), which is located in the Marmara Region (northwest Turkey). The most widespread typical GWD class for the analyzed time period was identified as GWD-III (between 101-200 cm), which covered 98.18% of the total area.