Abstract
Study area:
Fensholt D3, Denmark
Study focus:
Spatial patterns of drain flows are controlled by the climate, landscape, and tile installation. We assessed the combined effect of topography and geology on spatial pattern of drain flows in 10 m resolution using numerical modelling. We developed three groundwater models using different geological models by integrating high-resolution data from geophysical methods with field estimates of hydraulic conductivity. The mapping and modelling revealed small geological features of higher hydraulic conductivity in clayey till.
Hydrological Insights
The results showed that the spatial patterns of groundwater discharge to recharge ratio (drainage fraction, DF) are driven by topography; the models had a high DF in local depressions and a low DF in local hills. The DF was related to Topographical Position Index (TPI), which suggests that the DF is controlled by small-scale topography both upstream and downstream of the local area of evaluation. We found that geology amplifies the spatial patterns of drain flows; a higher hydraulic conductivity relative to a lower hydraulic conductivity increases the change of tile drain flow for a one-unit change in the TPI. This is attributed to a change from small-scale flow systems to field-scale flow systems. The study suggests that topography helps to delineate high and low DF. However, geology controls the magnitude of DF, thus emphasizing the importance of mapping and modeling of geology for managing moraine agricultural areas in landscapes.
Fensholt D3, Denmark
Study focus:
Spatial patterns of drain flows are controlled by the climate, landscape, and tile installation. We assessed the combined effect of topography and geology on spatial pattern of drain flows in 10 m resolution using numerical modelling. We developed three groundwater models using different geological models by integrating high-resolution data from geophysical methods with field estimates of hydraulic conductivity. The mapping and modelling revealed small geological features of higher hydraulic conductivity in clayey till.
Hydrological Insights
The results showed that the spatial patterns of groundwater discharge to recharge ratio (drainage fraction, DF) are driven by topography; the models had a high DF in local depressions and a low DF in local hills. The DF was related to Topographical Position Index (TPI), which suggests that the DF is controlled by small-scale topography both upstream and downstream of the local area of evaluation. We found that geology amplifies the spatial patterns of drain flows; a higher hydraulic conductivity relative to a lower hydraulic conductivity increases the change of tile drain flow for a one-unit change in the TPI. This is attributed to a change from small-scale flow systems to field-scale flow systems. The study suggests that topography helps to delineate high and low DF. However, geology controls the magnitude of DF, thus emphasizing the importance of mapping and modeling of geology for managing moraine agricultural areas in landscapes.
| Original language | English |
|---|---|
| Journal | Journal of Hydrology: Regional Studies |
| ISSN | 2214-5818 |
| Publication status | Submitted - May 2023 |