Papers by Christian Anibas
Knowledge of groundwater-surface water interaction is important for the assessment of water resou... more Knowledge of groundwater-surface water interaction is important for the assessment of water resources and for the investigation of fate and transport of contaminants and nutrients. In streams and rivers exchange fluxes of water are sensitive to local and regional factors such as riverbed hydraulic conductivity and hydraulic gradients. Field monitoring in time and space is therefore indispensible for assessing the variability of groundwater-surface water interaction. Not only the complexity of the examined processes demand novel data processing and characterization tools, the amount of acquired data also urges for new modeling tools. These tools should be easily applicable, allow for a fast computation, and utilize the maximum amount of available data for detailed analysis, including uncertainties. Such analytical tools should be combined with modern field equipment, data processing tools, geographical information systems and geostatistics for best results. A simple and cost effectiv...
Model-based assessment of the potential of seasonal aquifer thermal energy storage and recovery a... more Model-based assessment of the potential of seasonal aquifer thermal energy storage and recovery as a groundwater ecosystem service for the Brussels-Capital Region Christian Anibas and Marijke Huysmans Vrije Universiteit Brussel (VUB), Department of Hydrology and Hydraulic Engineering, Brussels, Belgium ([email protected]) Urban areas are characterized by their concentrated demand of energy, applying a high pressure on urban ecosystems including atmosphere, soils and groundwater. In the light of global warming, urbanization and an evolving energy system, it is important to know how urbanized areas can contribute to their own energy demands. One option is to use the possibilities aquifers offer as an ecosystem service (BONTE et al., 2011). If used effectively an improvement in air and groundwater quality is achieved. Additionally, the more efficient distribution of the used energy may also lead to a decrease in primary energy consumption (ZUURBIER, 2013). Therefore, investigations of ...
Hydrological Processes, 2015
Knowledge on groundwater-surface water interaction and especially on exchange fluxes between stre... more Knowledge on groundwater-surface water interaction and especially on exchange fluxes between streams and aquifers is an important prerequisite for the study of transport and fate of contaminants and nutrients in the hyporheic zone. One possibility to quantify groundwater-surface water exchange fluxes is by using heat as an environmlental tracer. Modern field equipment including multilevel temperature sticks and the novel open-source analysis tool LPML make this technique ever more attractive. The recently developed LPML method solves the one-dimensional fluid flow and heat transport equation by combining a local polynomial method with a maximum likelihood estimator. In this study, we apply the LPML method on field data to quantify the spatial and temporal variability of vertical fluxes and their uncertainties from temperature-time series measured in a Belgian lowland stream. Over several months, temperature data were collected with multilevel temperature sticks at the streambed top and at six depths for a small stream section. Long-term estimates show a range from gaining fluxes of À291 mm day À1 to loosing fluxes of 12 mm day À1 ; average seasonal fluxes ranged from À138 mm day À1 in winter to À16 mm day À1 in summer. With our analyses, we could determine a high spatial and temporal variability of vertical exchange fluxes for the investigated stream section. Such spatial and temporal variability should be taken into account in biogeochemical cycling of carbon, nutrients and metals and in fate analysis of contaminant plumes. In general, the stream section was gaining during most of the observation period. Two short-term high stream stage events, seemingly caused by blockage of the stream outlet, led to a change in flow direction from gaining to losing conditions. We also found more discharge occurring at the outer stream bank than at the inner one indicating a local flow-through system. With the conducted analyses, we were able to advance our understanding of the regional groundwater flow system.
Heat transport modeling Temperature Hyporheic zone Groundwater-surface water interaction FEMME Be... more Heat transport modeling Temperature Hyporheic zone Groundwater-surface water interaction FEMME Belgium s u m m a r y A simple thermal mapping method for simulating seasonal and spatial patterns of groundwater-surface water interaction is developed and tested for a segment of the Aa River, Belgium. Spatially distributed temperature profiles in the hyporheic zone of the river are measured in winter and summer seasons of three consecutive years. Inverse modeling of the one-dimensional heat transport equation is applied to estimate vertical advective fluxes using the numerical STRIVE model and an analytical model. Results of the study show that seasonal flux estimates for summer and winter can be derived with a minimum data input and simulation effort. The estimated fluxes are analyzed via non-parametric statistical tests, while spatial interpolation techniques are used to generate maps of distributed flux exchange. The estimated seepage is compared with volumetric flux obtained from piezometer measurements and output of a groundwater model. The thermal method shows higher discharge rates in winter and that the relative contribution of exfiltration to the river discharge is higher in summer. A higher flux and a more heterogeneous flow pattern are observed in the upper reach of the river compared to the lower reach. This spatial difference shows the importance of the local geomorphology and to a lesser extent the hydrogeologic setting on hyporheic flux exchange in the river. A significantly higher flux is noted on the banks than in the center of the river, which is driven by the relatively high hydraulic conductivity of the river banks. It is concluded that bank flow in groundwater-surface water interaction deserves more attention. The main channel of the Aa River alone accounts for about 15% of the total river discharge at its outlet. As the developed thermal method is cost-effective, simple and fast, it is recommended for use in identifying zones of interest in initial stages of field investigations of groundwater-surface water interaction.
Spatially distributed hydrologic simulators, such as the Soil and Water Assessment Tool (SWAT), a... more Spatially distributed hydrologic simulators, such as the Soil and Water Assessment Tool (SWAT), are important tool for integrated river basin management, as they represent different spatial processes-like evapotranspiration (ET), interception, infiltration, groundwater-surface water interaction (GWSW)-at river reach or basin scale. SWAT calculates evaporation from interception, based on the amount of water stored on the canopy. A close look at the estimated ET for forested areas in the Zenne basin indicates that the actual implementation of this process in SWAT potentially underestimates the forest ET, namely when the maximum canopy storage is activated by the CANMX parameter and increased from zero. Consequently, we corrected the SWAT codes, in order to improve the intercept ET estimation. Another issue in SWAT is related to the GWSW interaction. In the actual version of SWAT, either seepage from the river bed or groundwater flow to the river take place. It is hence not possible to simulate both gaining and losing processes, e.g. when rivers seasonally alternate from losing streams to gaining streams and back. Therefore, we also modified the codes to allow either gaining or losing, depending on the groundwater discharge from the sub-basin. The objective of this study is to evaluate how the modified SWAT simulates the intercept ET and the GWSW interaction. It is shown that the modified SWAT substantially improves the variability of the intercept ET with land cover and gives similar water balance of the basin. Incorporating the gaining or losing streams option also improved the performance of the model. Our findings confirm the applicability of the modified SWAT, but further research on the use of remotely sensed data and environmental tracing techniques (temperature sensors or isotopes) are needed to support the results.
... Christian Anibas; Nele Desmet; Sofie Van Belleghem; Ronny Verhoeven [801000337840] - Ghent Un... more ... Christian Anibas; Nele Desmet; Sofie Van Belleghem; Ronny Verhoeven [801000337840] - Ghent University [email protected]; Patrick Meire. Title, An integrated model study on the role of lateral connections and process interactions in retention of matter in streams. ...
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Papers by Christian Anibas