Reference evapotranspiration in July and August in El Abundante and Guaraquiche micro-watersheds, Jocotán, Guatemala

Abstract

Reference evapotranspiration (ETo) was analyzed for July and August, months associated with the midsummer dry spell, in the El Abundante and Guaraquiche micro-watersheds, Jocotán, Chiquimula, Guatemala’s dry corridor. FAO Penman-Monteith in CROPWAT was applied to maximum and minimum temperature, relative humidity, wind, and sunshine records from La Fragua, Camotán, and La Unión. Missing data (2.8%) was estimated by arithmetic means; potential outliers were identified by interquartile range and reviewed for climatic consistency. IDW interpolation used three stations and a power of 2. ETo in the upper, middle, and lower zones were 4.7, 4.9, and 5.0 mm/day in July and 4.8, 5.0, and 5.1 mm/day in August, respectively. Linear fits had positive slopes, higher in August, and coefficients of determination of 0.034–0.227, supporting descriptive interpretation. Low station density limits local representativeness. Results provide a historical reference for water management and consideration of future deficit risk in these basins, without predicting such deficits or determining irrigation depths.