Decision-support systems for groundwater protection: innovative tools for resource management

Governmental authorities are forced by law to make decisions within the framework of European, national and regional directives in the fields of spatial planning, groundwater and environmental protection. These tasks can be supported by a decision-support system, which integrates data from various sources and helps to make decision processes more effective and transparent. Basic work for such a decision support system has been done in a transnational and interdisciplinary project (Interreg II C: KATER), including metadata definition, metadata system, cartographic tools and GIS tools. The direct integration of these tools and information in the decision process will be implemented in the next few years (project KATER II).     

Accurate area determination in the cadaster: case study of Slovenia

This paper discusses methodological problems of accurate area determination in the cadaster. The paper contrasts the ambiguous legal definition of the parcel boundary and parcel area in relation to the theoretically well-defined geodetic parcel boundary and the geodetic parcel area on the reference ellipsoid. To align with the real world, parcel area must account for terrain elevation. Various approximate methods for area determination which can be used in the cadaster are tested. A highly accurate method for parcel area computation is proposed, based on an equal-area projection. Considering the geodetic parcel area as a reference, the achievable accuracy of different methods is evaluated. For this analysis, the coordinates of the parcel boundary points are treated as error-free. Finally, the relevance of various systematic errors is discussed in relation to the statistical uncertainty of the parcel area, which could be gained by an a real-time kinematic GNSS survey. A case study is presented for the territory of Slovenia, its georeferencing rules, land demarcation pattern, and characteristics of its topography. Based on the results of this study, some general recommendations for the parcel area determination are given.     

The effect of providing probabilistic information about a tornado threat on people’s protective actions

National Weather Service issues deterministic warnings in a tornado event. An alternative system is being researched at National Severe Storms Laboratory to issue Probabilistic Hazard Information (PHI). This study investigated how providing the uncertainty information about the tornado occurrence through PHI changes people’s protective actions. In an experiment, visual displays of the probabilistic information and deterministic warnings were presented to fifty participants to report their expected protective actions in different scenarios. It was found that the percentage of people who expected to immediately take shelter right after receiving the weather information increased exponentially as their proximity to the threat decreased. When there was more chance that the information about occurrence of a particular tornado was false rather than true, in scenarios that the likelihood of the threat occurrence was less than 50%, providing it through PHI lowered the percentage of people who immediately took shelter. The ordinal logistic regression models showed that the probability of taking protective actions significantly changes by providing the uncertainty information when people have less than 20 min lead time before getting impacted by the threat. When the lead time is less than 10 min, the probability of immediately taking shelter increases to 94 from 71%, and when the lead time is more than 10 but less than 20 min, that probability increases from 53 to 70%, if they are provided with the probabilistic information. Presenting the likelihood of any tornado formation in the area did not have significant effect on the people’s protective actions.     

Factors influencing the hydraulic properties of wells in dolomite aquifers of Slovenia

The influence of eight factors on hydraulic parameters (transmissivity, hydraulic conductivity, specific capacity, specific capacity index and maximum yields) are analysed, with data based on hydrogeological reports of 298 wells in dolomite aquifers in Slovenia. Influence of lithological properties is very significant, with the highest values of analysed variables observed in pure late-diagenetic intensely fractured Cordevolian dolomites, followed by Anisian and Late Triassic (‘Main’ dolomite) dolomites with high carbonate content and high primary porosity. The hydraulic parameters are not dependent on aquifer age, partial penetration, and well depth. The effects of depth to the water table and existence of low permeability overburden are not of major importance. The hydraulic parameter values are higher the closer to a river the wells are located, and topographic setting has a major effect. From the well reports, it was not always deduced whether the values of hydraulic conductivity and transmissivity stand for the values of the fractures or of the matrix, so it is proposed that when there is doubt as to whether these values are properly calculated, the most accurate parameters that can be used for a further prediction of aquifer yield are the specific capacity and, to a somewhat lesser extent, the specific capacity index.

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Résumé  L’influence de 8 facteurs sur les paramètres hydrauliques (transmissivité, perméabilité, débit spécifique, courbe caractéristique et débit critique) est analysée sur des données issues des rapports de 298 puits dans les aquifères dolomitiques de Slovénie. L’influence des propriétés lithologiques est très significative : les valeurs les plus élevées sont observées dans les dolomies cordevoliennes pures, intensément fracturées et de diagénèse tardive, puis dans les dolomies de l’Anisien et du Trias Supérieur, avec une teneur élevée en carbonates et une forte porosité primaire. Les paramètres hydrauliques ne dépendent pas de l’age de l’aquifère, de la pénétration partielle ou de la profondeur. Les effets du niveau piézométrique et de l’existence d’une couverture peu perméable sont mineurs. Les paramètres hydrauliques augmentent à proximité des rivières, et la topographie a une influence majeure. Les rapports de forage ne stipulent pas systématiquement si les valeurs de perméabilité et de transmissivité sont relatives au réseau de fractures ou à la matrice ; il a par conséquent été proposé qu’en cas de doute sur le calcul de ces valeurs, les paramètres les plus significatifs pour remonter à la productivité de l’aquifère soient le débit spécifique et, dans une moindre mesure, la courbe caractéristique.

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Resumen  Se analiza la influencia de ocho factores sobre parámetros hidráulicos (transmisividad, conductividad hidráulica, capacidad específica, índice de capacidad específica, y rendimientos máximos) en base a datos de reportes hidrogeológicos de 298 pozos en acuíferos de dolomía en Eslovenia. La influencia de las propiedades litológicas es muy significativa con los valores más altos de variables analizadas presentes en dolomías Cordevolianas con diagénesis tardía fracturadas intensamente, seguidas por dolomías (dolomía “Principal”) del Anisiano y Triásico Tardío con alto contenido de carbonato y alta porosidad primaria. Los valores de los parámetros hidráulicos no son dependientes de la edad del acuífero, penetración parcial, y profundidad del pozo. Los efectos de profundidad al nivel freático y existencia de cobertura de baja permeabilidad no son de importancia fundamental. Los valores de los parámetros hidráulicos son más altos mientras más cerca de un río se localizan los pozos y el ámbito topográfico tiene un efecto principal. No se pudo deducir de los reportes de los pozos si los valores de transmisividad y conductividad hidráulica representan valores de las fracturas o de la matriz, de modo que se propone que cuando exista duda en cuanto a que si estos valores se han calculado de manera adecuada, los parámetros de mayor precisión que pueden utilizarse para una predicción futura del rendimiento del acuífero son la capacidad específica y, en menor medida, el índice de capacidad específica.

     

Distribution of macrophytes and condition of the physical environment of streams flowing through agricultural landscape in north-eastern Slovenia

The distribution and abundance of macrophytes, land-use beyond the riparian zone, characteristics of the riparian zone and selected channel properties have been studied in 9 streams flowing through an agricultural landscape in the north-eastern part of Slovenia. The streams studied supported a rich macrophyte community. Altogether, 53 plant taxa were observed on 93 km of the streams. Canonical correspondence analysis indicated that 10 out of the 11 parameters examined significantly influenced macrophyte distribution. Of these, substrate characteristics and riparian vegetation type were the most influential. Species composition analysis revealed that the majority of species indicated moderate nutrient load while, in the more strongly modified reaches, species indicating eutrophic conditions, i.e. Myriophyllum spicatum and different species of genus Potamogeton, were more abundant.     

Removal of H2S from crude oil via stripping followed by adsorption using ZnO/MCM-41 and optimization of parameters

In the present work, H₂S of crude oil was removed via a two-step method including stripping followed by adsorption. First, ZnO/MCM-41 adsorbents containing 5, 17.5 and 30 wt% of zinc were synthesized and characterized using XRD and nitrogen physisorption. Then, these materials were used as adsorbents for the removal of the H₂S stripped from crude oil. At second step, the H₂S of crude oil was extracted to gas phase by hot stripping. The obtained extract was collected in a storage tank for the subsequent H₂S adsorption process. A three-factor Box–Behnken design with five center points and one response was performed for the optimization of adsorption of H₂S. The influence of process parameters and their interactional effects on the adsorption of H₂S were analyzed using the obtained adsorption experimental data. A model including three important factors, i.e., temperature, space velocity and amount of supported zinc and their interactions, was developed to generate the optimum condition. The point of Zn = 30 wt%, T = 300 °C and space velocity = 3,000 h^?1 had the optimum point with the highest break point time (t _bp = 973 min).     

Modelling hysteresis effect in Scintrex CG‐3M gravity readings

Significant hysteresis effects after transport in the upright position are found during measurement for the purpose of calibration of Scintrex CG‐3M gravimeters serial numbers 4372 and 4373. The effects amount to 0.60 and 0.15 μms^?2 during the first 10 minutes and an additional 0.35 and 0.10 μms^?2 during the next 10 minutes after transport for gravimeters 4372 and 4373, respectively. Such significant and not completely homogenous effects do not completely cancel out when forming gravity differences. An iterative MATLAB algorithm has been developed that models hysteresis effects using exponential functions that account for shifts in time and eliminates the hysteresis effects from the measurements. The method facilitates determination of an exponential function of hysteresis from multiple observation series with different unknown offsets and significant noise that prevents the application of conventional methods. Hysteresis elimination from measurements for the purpose of calibration resulted in (mostly significant) increases in the precision of adjusted calibration constants for both gravimeters. It is shown that, in order to obtain reasonable results, modelling the hysteresis effects should be based on approximately 30 minutes of readings. Finally, one can conclude that hysteresis effects surely do build up during transport, contrary to statements by Scintrex.