Print Email Facebook Twitter The Effect of Brackish Water Extraction on the Brackish Upconing Below the Horstermeer Polder Title The Effect of Brackish Water Extraction on the Brackish Upconing Below the Horstermeer Polder: Creating a 3D Regional Variable-Density Groundwater Model using MODFLOW 6 and FloPy Author De Smet, Sanne (TU Delft Civil Engineering and Geosciences) Contributor Bakker, M. (mentor) Smits, F.J.C. (mentor) Bloemendal, Martin (graduation committee) Schoups, G.H.W. (graduation committee) Degree granting institution Delft University of Technology Date 2021-07-09 Abstract Extensive usage of vital freshwater is highly undesirable in the current era of climate change and population growth. However, the 6 millionm3/y of brackish seepage that occurs in the deep Horstermeer Polder, located in between the cities of Amsterdam and Hilversumin the Netherlands, is mitigated by using up to 207 millionm3/y of freshwater. This is very unsustainable, especially since thepressure on the freshwater reserves in the Netherlands is rising. Therefore, this research focuses on evaluating a new mitigation measure of the brackish upconing below the polder: the extraction of brackish water. In March 2021 AD, a pilot well has been installed in the polder, and its effects were assessed in this research. To enable the evaluation, an extensive analysis of all available measurements of the geology, hydraulic head, and chloride distribution in the area was performed, and a 3D regional variable-density groundwater model using MODFLOW 6 was built. The model result has a reasonable good agreement with these measurements, since at 70% of the measurement locations, the simulated hydraulic head deviates less than 30 cm, and at 80% of them, the simulated chloride concentration deviates less than 200 mg/l. Moreover, compared to previous research, the representation of the brackish upconing was significantly improved. The effects of the pilot well were calculated using five different operational settings. The results indicated that a shallow well, starting below -50 m NAP, reduces the chloride load in the polder more than a deep well (-100 m NAP). However, even in the best scenario, i.e. an active shallow well with a constant pumping rate of 100 m3/h, the reduction of the chloride load is limited to 5.5%. In perspective, these results suggested that at least 24 of these wells are needed to lower the chloride concentration in the discharge water out of the polder to 250 mg/l. On the contrary, the shallow wells cause a considerable average drawdown of 4 cm at surface level in a radius of 50 meters around the well, which might result in damage to wooden pile foundations in the northeast of the polder. Subject variable-density groundwater modellingbrackish upconingHorstermeer Polderbrackish groundwater extraction To reference this document use: http://resolver.tudelft.nl/uuid:6116ea9d-a67e-49ce-a991-121d36b3d746 Coordinates 52.248118, 5.073741 Part of collection Student theses Document type master thesis Rights © 2021 Sanne De Smet Files PDF Final_MSc_Thesis_Horsterm ... deSmet.pdf 31 MB Close viewer /islandora/object/uuid:6116ea9d-a67e-49ce-a991-121d36b3d746/datastream/OBJ/view