In semiarid environments moisture availability is the primary factor that controls land productivity, however, no method to differentiate landscape portions with high moisture availability has yet been proposed for delimitation of crop management zones for precision agriculture. The objective of the present study was to develop a methodology to determine sites with different soil potential moisture availability to improve the delimitation of homogeneous crop management zones in semiarid environments. An altimetric survey was carried out in the field to obtain a DEM with a spatial resolution of 5 m. Subsequently, maps of slopes, area of flow accumulation, sub-basins of the Topographic Wetness index (TWI) were made. A potential moisture availability (PMA) map was generated by linking the TWI map with a map of previously reclassified sub-basins and homogeneous PMA zones were delineated. Soil profiles were sampled on transects through the PMA zones, and during three growing seasons soil moisture contents were recorded. The PMA zones had homogeneous soil types and moisture contents and differed from each other in soil profile depth and available moisture contents, especially in the more humid season. Soil moisture correlated well with the antecedent precipitation index (API) during crop growth and in the PMA zones with higher altimetry, while only weak relationships were found during fallow periods and for the lowest altimetry PMA zone. The proposed methodology was useful for identifying landscape portions with differences in potential moisture availability as the spatial-temporal variability was represented. The use of the API combined with the potential moisture availability allowed a better fit in its relationship with the soil available moisture contents (AMC).