An assessment of nutrient runoff from agricultural catchments in Malta

Abstract

Nutrient runoff in agricultural areas is a major problem for the Mediterranean island of Malta. Agricultural runoff can degrade the environment, human health, and groundwater recharge. Ensuring that nutrient contamination of the environment is monitored and managed properly will help to facilitate a sustainable future for Malta which is a country with limited natural freshwater resources. It is important to investigate how and which nutrients are the most prevalent so that informed management decisions can be implemented. This study looked at how land use affects nutrient discharge in agricultural watersheds and valleys in Malta. The methods involved collecting water samples from the Wied il-Għasel watershed on multiple days during and after a rainfall event and analyzing them in relation to the site’s land cover. Nutrient concentrations were determined through photometric analysis, while Geographic Information Systems (GIS) were used to map these concentrations and compare them to the site’s land cover. It was found that a strong correlation exists between agricultural land and nitrate values. Also nitrate values surpass the limit set by the European Union. It was also found that rain events and rain intensity have a strong correlation with an increase in runoff contaminated water in the agricultural valley. Future management plans for the study site should include continuous monitoring of nitrate levels to ensure compliance with NVZ requirements and to track any emerging trends in contamination. Studies on groundwater recharge would also be recommended to improve understanding of how nitrate pollution from different agricultural land uses impacts Malta’s groundwater bodies. This study highlights the need for regular, site-specific monitoring and aims to support the development of more informed land management strategies that protect both water resources and agricultural productivity.