 |
| Titel |
Landscape characteristics impacts on water quality of urban lowland catchments: monitoring the Amsterdam city area |
| VerfasserIn |
Liang Yu, Corné van der Vlugt, Joachim Rozemeijer, Hans Peter Broers, Boris van Breukelen, Maarten Ouboter, Pieter Stuyfzand |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114043
|
| Publikation (Nr.) |
 EGU/EGU2015-14332.pdf |
|
|
|
|
|
| Zusammenfassung |
| In Dutch lowland polder systems, groundwater quality significantly contributes to surface
water quality. This process is influenced by landscape characteristics such as topography,
geology, and land use types. In this study, 23 variables were selected for 144 polder
catchments, including groundwater and surface water solute concentrations (TN, TP, NH4+,
NO3-, HCO3-, SO42-, Ca2+, Cl-), seepage rate in mm per year, elevation, paved
area percentage, surface water area percentage, and soil types (calcite, humus and
lutum percentage). The spatial patters in groundwater and surface water quality can
largely be explained by groundwater seepage rates in polders and partly by artificial
redistribution of water via the regional surface water system. High correlations
(R2 up to 0.66) between solutes in groundwater and surface water revealed their
probable interaction. This was further supported by results from principal component
analysis (PCA) and linear regression. The PCA distinguished four factors that were
related to a fresh groundwater factor, seepage rate factor, brackish groundwater factor
and clay soil factor. Nutrients (TP, TN, NH4+ and NO3-) and SO42- in surface
water bodies are mainly determined by groundwater quality combined with seepage
rate, which is negatively related to surface water area percentage and elevation of
the catchment. This pattern is more obvious in deep urban lowland catchments.
Relatively high NO3- loads more tend to appear in catchments with high humus, but
low calcite percentage soil type on top, which was attributed to clay soil type that
was expressed by calcite percentage in our regression. Different from nitrogen
contained solutes, TP is more closely related to fresh groundwater quality than to
seepage rate. Surface water Cl- concentration has a high relation with brackish
groundwater. Due to the artificial regulation of flow direction, brackish inlet water from
upstream highly influences the chloride load in surface water bodies downstream,
especially in infiltrated urban catchments. We conclude that, apart from artificial
regulation, groundwater has significant impacts on surface water quality in the
polders. Especially in low-lying urban catchments surface water solute concentrations
like TP, TN, NH4+, HCO3-, SO42-, and Ca2+ can be predicted by groundwater
characteristics. These results suggest that groundwater quality plays a crucial role in
understanding and improving surface water quality in regulated lowland catchments. |
|
|
|
|
|
|