Density dependent groundwater flow model of the shore and dune area of the Westhoek nature reserve (Belgium)

The Westhoek nature reserve is a dune area situated along the French-Belgian border. Below the dunes a fresh-water lens is found. A particular distribution of salt-water occurring above fresh-water is found under the adjacent shore. This less known water quality distribution is in dynamic equilibrium. A 2D density dependent groundwater flow model was made using the MOCDENS3D code. First, the groundwater flow and water quality evolution under the shore and in the dunes are modeled. Then the possible impact of sea level rise is simulated for a number of different scenarios. These scenarios reflect different reactions of coastal morphology and human intervention on the sea level rise. Depending on the scenario, the extent of the shore's salt-water lens can increase, decrease or even completely disappear. Simultaneously, the extent of the dune's fresh-water lens can significantly be altered. The simulations illustrate also, besides the effects of sea level rise, that changes in boundary conditions (drainage levels, shore morphology, sea water level), either natural or human induced, can importantly alter the water quality distribution. Because of the high ecological value of the area and the dune's importance for drinking water production, these changes should be well studied beforehand

The role of hydrogeological research in the realization of a combined pumping and deep infiltration system at the excavation ‘Duinenabdij’

Hydrogeological interventions in ecologically valuable areas must be well studied beforehand. Modelling of these interventions based on field observations and field studies is herein a valuable step. This is illustrated with an example in the western Belgian coastal plain. A new drainage system had to be designed for the preservation of the archaeological excavation site ‘OLV Ten Duinen’. This site is situated in a valuable and protected dune area. A system of pumping and deep infiltration of water was studied to optimise the draining of the site but to minimise the effects in the nearby dunes. A double pumping test was used to derive the relevant parameters. These were then used to simulate and find the optimal configuration of the extraction and deep infiltration wells

Modelling of density dependent groundwater flow in the south-western Belgian coastal plain

The study area is situated at the landward border of the Belgian western coastal plain at the right bank of the river Ijzer. The phreatic aquifer is of quaternary age. Until about the 12th century, the hydrology of the area was influenced by the North Sea. The area was criss-crossed by tidal channels and gullies and the aquifer was mainly filled with salt water. From about 1100 AD, the area was gradually reclaimed, halting the influence of the sea. The channels silted up. Fresh water started to infiltrate replacing the salt water. This leads to the actual distribution of fresh and salt water. Fresh water lenses are found below the creek ridges, the former tidal channels where the aquifer consists mainly of sandy sediments. In the adjacent area the phreatic aquifer consists of less permeable sediments (clay, silt and peat) and is still mainly filled with salt water. In these areas where the water table is slightly lower than in the creek ridges, only a thin lens of fresh water occurs above the salt water. A preliminary field survey was performed to compliment the existing data. In these field survey a number of drillings were executed and observation wells were installed. The variation of the salt content with depth was inferred from electrical conductivities measured with the focused electromagnetic induction method. A pumping test was performed to derive the hydraulic conductivity of the channel sediments. All these data were integrated in a 3D density dependent model, using the MOCDENS3D code to simulate the evolution of the water quality distribution from 1100 AD until a few centuries in the future. The simulations demonstrate that the fresh water lenses under the channels are formed in about 400 years. These fresh water lenses can only be considered as a limited water resource in this area. The influence of this drainage on the groundwater flow and water quality distribution is illustrated by the model. The mean drainage level is below mean sea level. In the creek ridges there is an important upward flow of fresh water under the drainage canals. In the adjacent areas with low permeable sediments the drainage and flow is very small. The salt water in these sediments is trapped since the land reclamation in the 12th century and will stay there for many centuries

Modeling of historical evolution of salt water distribution in the phreatic aquifer in and around the silted up Zwin estuary mouth (Flanders, Belgium)

The evolution of the salt-water distribution around the Zwin estuary mouth is modeled for a period of about five centuries. The modeled area is situated in the Flemisch coastal plain near the border of The Netherlands and Belgium. The Zwin estuary is the former waterway to the medieval seaports of Bruges and Damme. During the considered period this alluvial estuary silted up and the modeled area changes from an area around a tidal channel, over a mud flat to a rather complex polder dune area. The evolution is simulated by the 3D density depended groundwater flow model MOCDENS3D (Lebbe & Oude Essink, 1999). The row direction of the applied finite-difference grid is parallel to the present coast line. The simulation is based on old paintings and a large number of maps which allow a relatively detailed reconstruction of the evolution of the landscape. The results show the historical evolution of a large number of different inverse density problems in this area

Impact of fiscal deficit on inflation in Sri Lanka: an econometric time series analysis

There is a relationship between the fiscal deficit and inflation, which was confirmed empirically in several studies conducted in many countries. Sri Lanka has been encountering the problem of inflation for the recent years. But in Sri Lanka, this proposition has not yet been studied scientifically. Therefore, this study was going to fill this gap. The objective of this study was to test the impact of fiscal deficit on inflation in Sri Lanka. For this study, the annual time series data were used during the period of 1959 to 2013. The fiscal deficit, exchange rate, government expenditures and import outflow were used as independent variables while the Colombo consumer price index was considered as dependent variable. In addition, the multiple regressions model was used to test the impact of fiscal deficit on inflation. Based on the regression results, the fiscal deficit preserved the positive relationship with inflation in Sri Lanka at one percent significant level. Therefore, this study confirmed that the fiscal deficit accelerates the inflation in Sri Lanka

Fresh-salt water distribution in the central Belgian coastal plain: an update

The 1974 map showing the depth of the fresh-salt water interface (defined by 1500 mg/l total dissolved solids concentration) in the Belgian coastal plain is a vital document for hydrogeologists. Since its publication, new data have been collected. These comprise water quality analyses and borehole measurements ordered by the Flemish Environmental Agency, the Flemish Land Use Agency or from dissertations and new lithological data synthesised by the HCOV (Hydrogeological Code Flemish Subsurface) mapping. The aim of this paper is to compare the new information with the 1974 map and provide an update for the central part of the Belgian coastal plain. This resulted in only minor differences. The main adjustments are the identification of a number of additional areas where the phreatic aquifer is completely filled with fresh water, incorporation of insights of the groundwater flow system in the dunes, shore and sea and, some small changes in the position of transition zones between fresh-water lenses and adjacent areas where salt water occurs at very shallow depth. The general conclusion is that comparison with new field data obtained in the more than 30 years after its publication, confirms and strengthens the validity of the map

Salt water intrusion modeling in the Flemish coastal plain based on a hydrogeological database

The Flemish Environment Agency (VMM) is responsible for providing recommendations related to the withdrawal of groundwater in the phreatic aquifer of the Flemish Coastal Plain. To assess the impact of this withdrawal on the freshwater heads and on the distribution of fresh and salt water in the aquifer, the agency uses a 3D density dependent groundwater flow model MOCDENS3D (Lebbe & Oude Essink 1999). Although a large number of hydrogeological data were already collected and stored in a database of the agency, the draw up of the input file for this model was very time consuming. Therefore, an interface was needed between the model and the hydrogeological database to reduce the time for the set up of the needed input files

Which medical disciplines diagnose and treat melanoma in Europe in 2019? A survey of experts from melanoma centres in 27 European countries

Background and objectives The incidence of melanoma is increasing. This places significant burden on societies to provide efficient cancer care. The European Cancer Organisation recently published the essential requirements for quality melanoma care. The present study is aimed for the first time to roughly estimate the extent to which these requirements have been met in Europe. Materials and methods A web-based survey of experts from melanoma centres in 27 European countries was conducted from 1 February to 1 August 2019. Data on diagnostic techniques, surgical and medical treatment, organization of cancer care and education were collected and correlated with national health and economic indicators and mortality-to-incidence ratio (MIR) as a surrogate for survival. Univariate linear regression analysis was performed to evaluate the correlations. SPSS software was used. Statistical significance was set at P < 0.05. Results The MIR was lower in countries with a high health expenditure per capita and with a higher numbers of general practitioners (GPs) and surgeons (SURG) per million inhabitants. In these countries, GPs and dermatologists (DER) were involved in melanoma detection; high percentage of DER used dermatoscopy and were involved in the follow-up of all melanoma stages; both medical oncologists (ONC) and dermato-oncologists administered systemic treatments; and patients had better access to sentinel lymph node biopsy and were treated within multidisciplinary tumour boards. Conclusion Based on these first estimates, the greater involvement of GPs in melanoma detection; the greater involvement of highly trained DER in dermatoscopy, dermatosurgery, follow-up and the systemic treatment of melanoma; and the provision of ongoing dermato-oncology training for pathologists, SURG, DER and ONC are necessary to provide an optimal melanoma care pathway. A comprehensive analysis of the melanoma care pathway based on clinical melanoma registries will be needed to more accurately evaluate these first insights