Impacts of irrigation and nitrate fertilization scenarios on groundwater resources quantity and quality of the Almyros Basin, Greece

Abstract

Irrigation and nitrate fertilization scenarios were combined and simulated for crop water irrigation demands and nitrogen applications based on experiments on crop cultivation practices. Two irrigation practices (deficit irrigation and rainfed conditions) were applied to the main crop types of the Almyros Basin, a coastal basin located in Thessaly, Greece. The Almyros groundwater system suffers from progressive water balance deficit, nitrate contamination and seawater intrusion due to groundwater abstractions for agricultural irrigation to cover crop water demands in the dry season. The impacts of the irrigation and nitrate fertilization scenarios on groundwater resources quantity and quality were simulated using an Integrated Modelling System consisting of models of surface hydrology (UTHBAL), groundwater hydrology (MODFLOW), crop growth/nitrate leaching (REPIC), contaminant transport (MT3DMS), and seawater intrusion (SEAWAT), for the historical period of 1991-2018. The results of the scenarios were evaluated with the indicators of Crop Water Productivity (CWP) for crop yields and irrigation water, Partial Factor Productivity (PFP) for Nitrogen Use Efficiency, and Economic Water Productivity (EWP) for the gross profits of the irrigation water.