Advanced

The effect of groundwater extraction on nitrate vulnerable recharge areas (NFI) in Denmark. MIKE SHE simulations of different extraction scenarios.

Gruschka, Sophie LU (2018) In ISRN VTGM01 20181
Engineering Geology
Civil Engineering (M.Sc.Eng.)
Abstract
This thesis aims to outline the effect of different abstraction scenarios on the extent of nitrate vulnerable recharge area (NFI) in two study areas in Denmark. NFI were designated in order to protect vulnerable groundwater resources from nitrate pollution, where the geology overlying the aquifers does not serve as a sufficient barrier.
NFI are officialy calculated by taking into consideration the recharge area at the permitted abstraction rates of the waterworks, however those rates are often much higher than their actual abstraction.

Two existing MIKE SHE groundwater models were chosen and several abstraction scenarios were simulated to compare the extents of groundwater recharge areas they yield. The studied areas were Halsnæs and... (More)
This thesis aims to outline the effect of different abstraction scenarios on the extent of nitrate vulnerable recharge area (NFI) in two study areas in Denmark. NFI were designated in order to protect vulnerable groundwater resources from nitrate pollution, where the geology overlying the aquifers does not serve as a sufficient barrier.
NFI are officialy calculated by taking into consideration the recharge area at the permitted abstraction rates of the waterworks, however those rates are often much higher than their actual abstraction.

Two existing MIKE SHE groundwater models were chosen and several abstraction scenarios were simulated to compare the extents of groundwater recharge areas they yield. The studied areas were Halsnæs and Brokilde in the north of the island of Sjælland.

The results of the simulations especially in Brokilde show a significant difference in NFI of 81 ha between the actual and the permitted scenario. Also scenarios in between the actual and the permitted abstraction were simulated, those follow the trend clearly. The results in Halsnæs were not that sharp, since the observed wells were not concentrated in one place as in Brokilde and abstraction rates were significantly lower.

The decrease of NFI for the actual abstraction rates can be of particular interest for municipalities, since the designation of NFI results in costs for reimbursing farmers for their effort to use less nitrate for example. In order to apply the results of this thesis to other areas, further investigation and the simulation of more abstraction scenarios are required. (Less)
Popular Abstract
Groundwater is vulnerable towards nitrate pollution originating from fertilizers. Some areas are more sensitive than others, due to the local geology as well as the amount of abstracted drinking water. How does the extent of nitrate vulnerable areas change with varying drinking water abstraction rates in waterworks?

Nitrate is harmful to humans, especially infants are subject to nitrate poisoning. When nitrate fertilizers are applied excessively on agricultural land, runoff into rivers and groundwater occurs. Since groundwater is the only source of drinking water in Denmark its protection is highly prioritized.

Areas where the groundwater is sensitive towards nitrate pollution and where waterworks withdraw drinking water are... (More)
Groundwater is vulnerable towards nitrate pollution originating from fertilizers. Some areas are more sensitive than others, due to the local geology as well as the amount of abstracted drinking water. How does the extent of nitrate vulnerable areas change with varying drinking water abstraction rates in waterworks?

Nitrate is harmful to humans, especially infants are subject to nitrate poisoning. When nitrate fertilizers are applied excessively on agricultural land, runoff into rivers and groundwater occurs. Since groundwater is the only source of drinking water in Denmark its protection is highly prioritized.

Areas where the groundwater is sensitive towards nitrate pollution and where waterworks withdraw drinking water are designated as specifically vulnerable in Denmark. If an area, especially farmland, is defined as such, the application of nitrate has to be limited in order to not put groundwater quality in danger.

The extent of those areas that are sensitive towards nitrate pollution is treated as static and calculated by means of the permitted abstraction rates of drinking water wells. Most waterworks abstract less than what they are allowed to, and thereby withdraw water from a smaller area. Hence, it is studied in this thesis how big the changes in areas sensitive towards nitrate pollution are for different abstraction rates in two areas in Denmark - Halsnæs and Brokilde.

Flow simulations in the subsurface are run in the groundwater modeling program MIKE SHE and the results are presented in maps, tables and graphs. Especially the variations in areas sensitive to nitrate pollution between the current abstraction rates and the maximum permitted rates are of interest.

In Brokilde, the change amounts up to 81 ha. That means that 81 ha of areas that are sensitive towards nitrate pollution might be saved if the calculation would take into account actual abstraction rates rather than the much higher permitted rates.

This number can be of importance for municipalities, since taking care of areas sensitive towards nitrate pollution is cost intense. They have to reimburse farmers for losses related to a change in their cultivation pattern or might even need to buy the land. (Less)
Please use this url to cite or link to this publication:
author
Gruschka, Sophie LU
supervisor
organization
alternative title
Effekten av grundvattenuttaget på nitratsårbara nybildningsområden (NFI) i Danmark – Simuleringar i MIKE SHE av olika utvinningsscenarier
course
VTGM01 20181
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
Groundwater modelling, MIKE SHE, Nitrate vulnerability, NFI, Brokilde, Halsnæs
publication/series
ISRN
other publication id
LUTVDG/(TVTG-5156)/1- 52/(2018)
language
English
additional info
Examiner: Jan-Erik Rosberg
id
8955936
date added to LUP
2018-08-15 10:40:03
date last changed
2018-08-15 10:40:03
@misc{8955936,
  abstract     = {This thesis aims to outline the effect of different abstraction scenarios on the extent of nitrate vulnerable recharge area (NFI) in two study areas in Denmark. NFI were designated in order to protect vulnerable groundwater resources from nitrate pollution, where the geology overlying the aquifers does not serve as a sufficient barrier. 
NFI are officialy calculated by taking into consideration the recharge area at the permitted abstraction rates of the waterworks, however those rates are often much higher than their actual abstraction.

Two existing MIKE SHE groundwater models were chosen and several abstraction scenarios were simulated to compare the extents of groundwater recharge areas they yield. The studied areas were Halsnæs and Brokilde in the north of the island of Sjælland.

The results of the simulations especially in Brokilde show a significant difference in NFI of 81 ha between the actual and the permitted scenario. Also scenarios in between the actual and the permitted abstraction were simulated, those follow the trend clearly. The results in Halsnæs were not that sharp, since the observed wells were not concentrated in one place as in Brokilde and abstraction rates were significantly lower.

The decrease of NFI for the actual abstraction rates can be of particular interest for municipalities, since the designation of NFI results in costs for reimbursing farmers for their effort to use less nitrate for example. In order to apply the results of this thesis to other areas, further investigation and the simulation of more abstraction scenarios are required.},
  author       = {Gruschka, Sophie},
  keyword      = {Groundwater modelling,MIKE SHE,Nitrate vulnerability,NFI,Brokilde,Halsnæs},
  language     = {eng},
  note         = {Student Paper},
  series       = {ISRN},
  title        = {The effect of groundwater extraction on nitrate vulnerable recharge areas (NFI) in Denmark. MIKE SHE simulations of different extraction scenarios.},
  year         = {2018},
}