Nitrogen Mass Balance and Pressure Impact Model Applied to an Urban Aquifer

Mitja Janža,Brigita Jamnik,Simona Pestotnik,Joerg Prestor

doi:10.3390/w12041171

Mitja Janža, Brigita Jamnik + Show 2 more

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https://doi.org/10.3390/w12041171

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Abstract

The assurance of drinking water supply is one of the biggest emerging global challenges, especially in urban areas. In this respect, groundwater and its management in the urban environment are gaining importance. This paper presents the modeling of nitrogen load from the leaky sewer system and from agriculture and the impact of this pressure on the groundwater quality (nitrate concentration) in the urban aquifer located beneath the City of Ljubljana. The estimated total nitrogen load in the model area of 58 km2 is 334 ton/year, 38% arising from the leaky sewer system and 62% from agriculture. This load was used as input into the groundwater solute transport model to simulate the distribution of nitrate concentration in the aquifer. The modeled nitrate concentrations at the observation locations were found to be on average slightly lower (2.7 mg/L) than observed, and in general reflected the observed contamination pattern. The ability of the presented model to relate and quantify the impact of pressures from different contamination sources on groundwater quality can be beneficially used for the planning and optimization of groundwater management measures for the improvement of groundwater quality.

Highlights

In 2018, 55% of the world’s population lived in urban areas, and this proportion is expected to increase to 68% by 2050 [1]
The estimated sources of nitrogen from the sewer system and from agriculture are distributed over an area of 19.84 km2 (34%) and 27.81 km2 (48% of model area), respectively
Modeled spatial distribution of nitrate content in groundwater pointed out the leaky sewer system as the prevailing source of nitrogen load inducing locally high nitrate concentration

Summary

Introduction

In 2018, 55% of the world’s population lived in urban areas, and this proportion is expected to increase to 68% by 2050 [1]. With 74% of its population living in urban areas in 2018, is expected to reach an urban population of 80% in 2040 and approaching 85% by 2050 [1]. Considering this population growth in light of climate change projections, the estimates show that with current practices, the world will face a 40% shortfall between the forecasted demand and available supply of water by. Proximity of the resource, and the relatively low cost of pumping wells make groundwater an increasingly important source for city populations in the future

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