Assessment of groundwater quality for agricultural irrigation in alluvial plains

Abstract:

Water that looks perfectly clean can still damage soil structure and poison crops-the only way to know is to test it. This research assessed the irrigation suitability of groundwater from 72 tube wells across the alluvial plains of Emilia-Romagna and Piedmont, northern Italy, using 12 physico-chemical parameters and seven water quality indices. Samples were collected during pre-monsoon (April 2023) and post-monsoon (October 2023) periods. Based on the USSL classification, 34.6% of wells fell in the excellent (C1-S1) category, 28.4% were good (C2-S1), 21.8% moderate (C2-S2), 10.4% poor (C3-S2), and 4.8% unsuitable (C4-S3). EC ranged from 0.42 to 2.14 dS m⁻¹, and SAR from 1.8 to 9.6. A spatial gradient was observed: wells in the eastern Po plain showed higher salinity and sodium hazard than those in the western Piedmont section. Nitrate exceeded the 50 mg L⁻¹ threshold in 18.1% of wells, concentrated near intensive livestock zones. These results provide a spatially referenced baseline for groundwater irrigation management in the northern Italian plains.