Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hess-2017-55
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
20 Feb 2017
Review status
A revision of this discussion paper is under review for the journal Hydrology and Earth System Sciences (HESS).
Modeling nitrate from land-surface to wells' perforations under agricultural land: success, failure, and future scenarios in a Mediterranean case study
Yehuda Levy1, Roi H. Shapira2, Benny Chefetz3, and Daniel Kurtzman4 1Hydrology and Water Resources Program, The Hebrew University of Jerusalem, The Edmond J. Safra Campus – Givat Ram, 9190401 Jerusalem, Israel
2Mekorot, Israel National Water Company, Lincoln 9, 6713402 Tel-Aviv, Israel
3Department of Soil and Water Sciences, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 7610001 Rehovot, Israel
4Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, HaMaccabim Road 68, 7505101 Rishon LeZion, Israel
Abstract. Contamination of groundwater resources by nitrate leaching under agricultural land is probably the most troublesome agriculture-related water contamination worldwide. Deep soil sampling (10 m) was used to calibrate vertical flow and nitrogen-transport numerical models of the unsaturated zone under different agricultural land uses. Vegetable fields (potato and strawberry) and deciduous orchards (persimmon) in the Sharon area overlying the coastal aquifer of Israel were examined. Average nitrate-nitrogen fluxes below vegetable fields were 210–290 kg ha−1 yr−1, and under deciduous orchards, 110–140 kg ha−1 yr−1. The output water and nitrate-nitrogen fluxes of the unsaturated zone models were used as input data for a three-dimensional flow and nitrate-transport model in the aquifer under an area of 13.3 km2 of agricultural land. The area was subdivided into four agricultural land uses: vegetables, deciduous orchards, citrus orchards and non-cultivated. Fluxes of water and nitrate-nitrogen below citrus orchards were taken from a previous study in the area. The groundwater flow model was calibrated to well heads by changing the hydraulic conductivity. The nitrate-transport model, which was fed by the abovementioned models of the unsaturated zone, succeeded in reconstructing the average nitrate concentration in the wells. However, this transport model failed in calculating the high concentrations in the most contaminated wells and the large spatial variability of nitrate concentrations in the aquifer. To reconstruct the spatial variability and enable predictions, nitrate fluxes from the unsaturated zone were multiplied by local multipliers. This action was rationalized by the fact that the high concentrations in some wells cannot be explained by regular agricultural activity, and are probably due to malfunctions in the well area. Prediction of the nitrate concentration 40 years in the future with three nitrogen-fertilization scenarios showed that: (i) under the business as usual fertilization scenario, the nitrate concentration (as NO3) will increase on average by 19 mg L−1; (ii) under a scenario of 25 % reduction of nitrogen fertilization, the nitrate concentration in the aquifer will stabilize; (iii) with a 50 % reduction of nitrogen fertilization, the nitrate concentration will decrease on average by 18 mg L−1.

Citation: Levy, Y., Shapira, R. H., Chefetz, B., and Kurtzman, D.: Modeling nitrate from land-surface to wells' perforations under agricultural land: success, failure, and future scenarios in a Mediterranean case study, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-55, in review, 2017.
Yehuda Levy et al.
Yehuda Levy et al.
Yehuda Levy et al.

Viewed

Total article views: 369 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
312 43 14 369 4 18

Views and downloads (calculated since 20 Feb 2017)

Cumulative views and downloads (calculated since 20 Feb 2017)

Viewed (geographical distribution)

Total article views: 369 (including HTML, PDF, and XML)

Thereof 361 with geography defined and 8 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 27 May 2017
Publications Copernicus
Download
Short summary
Nitrate-nitrogen is a groundwater contaminant worldwide, that originates commonly from agricultural fertilization. In this work, we built a computer model which follows the fate of nitrogen from land surface to deep (~ 100 m) and distant (~ km) groundwater wells. The model succeeded estimating total groundwater nitrate, yet failed to point-estimate contaminated wells, extra assumptions fixed it. This enabled prediction of future groundwater-nitrate which revealed the need to reduce fertilization.
Nitrate-nitrogen is a groundwater contaminant worldwide, that originates commonly from...
Share