A pilot regional scale model of land use impacts on groundwater quality
Abstract
Purpose
Major land use changes can have a significant impact on the environment, e.g. increased leaching and run‐off losses of nutrients and water contamination. Nitrate (NO3–) can be easily leached and, when present at high concentrations in drinking water, can be a health hazard. This paper seeks to report an easy‐to‐use computer model designed to provide predictions of possible impacts on groundwater NO3– concentration on a regional scale.
Design/methodology/approach
The model takes into account NO3–‐N concentrations from various land use activities, land surface recharge rates (as affected by soil water retention capacity, land management, irrigation and rainfall), and mixing of surface recharge and river recharge. Spatial information on land use and groundwater recharge sources are lumped into groundwater management zones (100‐500 km2), and vertical concentration profiles of NO3– in groundwater are estimated from a one‐dimensional dispersion model. The model is applied to the 2,300 km2 Central Canterbury Plains of New Zealand.
Findings
A scenario analysis for the Bankside groundwater management zone showed that the NO3–‐N concentration at the groundwater surface could increase from 7.8 mg N L‐1 to 11.3 mg N L‐1 if all the land used for sheep farming is replaced by dairy farming (increasing dairy land from 21 per cent to 64 per cent of the total land area). However, the impact of such land use changes on the NO3–‐N concentration 50 m below the groundwater surface was relatively small, resulting in an increase of NO3–‐N concentration from 0.4 to 0.5 mg N L‐1. This is because of the significant mixing of surface recharge with river recharge at this depth.
Originality/value
The model can serve as a useful tool for first‐order estimation of possible trends of NO3–‐N concentration profiles in aquifers as a result of land use changes.
Keywords
Citation
Di, H.J., Cameron, K.C., Bidwell, V.J., Morgan, M.J. and Hanson, C. (2005), "A pilot regional scale model of land use impacts on groundwater quality", Management of Environmental Quality, Vol. 16 No. 3, pp. 220-234. https://doi.org/10.1108/14777830510591651
Publisher
:Emerald Group Publishing Limited
Copyright © 2005, Emerald Group Publishing Limited