Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1016/j.jhydrol.2019.05.030 |
| Document | accepted manuscript |
| Title (Primary) | Influence of a subsurface cut-off wall on nitrate contamination in an unconfined aquifer |
| Author | Sun, Q.; Zheng, T.; Zheng, X.; Chang, Q.; Walther, M. |
| Source Titel | Journal of Hydrology |
| Year | 2019 |
| Department | ENVINF |
| Volume | 575 |
| Page From | 234 |
| Page To | 243 |
| Language | englisch |
| Keywords | Nitrate contamination; Subsurface cut-off wall; Seawater intrusion; Feflow; Tank experiments |
| Abstract | Due to shallow groundwater tables and easy water availability, many people live in coastal areas. Additionally, alluvial sediments from fluviatile and marine deposits are highly suitable for agricultural use, making coastal settlement even more desirable. However, groundwater nitrate pollution resulting from widespread application of fertilizers creates difficulties for water management officials. Cut-off walls are used to control seawater intrusion into coastal aquifers. However, until now, the effect of cut-off walls on the nitrate contamination of groundwater has been largely unknown. In this paper, the first investigation of the influence of a subsurface cut-off wall on nitrate contamination in groundwater is discussed. Two sets of laboratory experiments – one with and one without a subsurface cut-off wall – were performed to validate the effectiveness of the constructed numerical model. The effects of the subsurface cut-off wall height, distance between the subsurface cut-off wall and the saltwater boundary, and infiltration rates on nitrate distribution and contamination in groundwater were analyzed. Results showed that after the construction of the subsurface cut-off wall, the domain mean velocity decreased, the migration of nitrate pollutants to the saltwater boundary was reduced, and the nitrate-contaminated area expanded. Further, the morphology of the nitrate pollution plumes changed, an indentation appeared directly above the subsurface cut-off wall, the widths of the transition zones increased significantly, and the transition zones became more diffuse as one approached the saltwater wedge. Three indices were developed to quantify the degree of nitrate contamination. The relative height of the subsurface cut-off wall (H′) and the nitrate infiltration rate (Ni) were the two most significant factors determining the degree of nitrate contamination in groundwater near the subsurface cut-off wall. Therefore, we suggest that subsurface cut-off walls be designed such that their height lies below an experimentally determined critical height; thus reducing the infiltration rate of the contaminants produced during fertilization through water-saving irrigation techniques. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=22032 |
| Sun, Q., Zheng, T., Zheng, X., Chang, Q., Walther, M. (2019): Influence of a subsurface cut-off wall on nitrate contamination in an unconfined aquifer J. Hydrol. 575 , 234 - 243 10.1016/j.jhydrol.2019.05.030 |
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