Integrated water management and regionalisation of the Republic of Slovenia

This article tackles the problem of regionalisation of Slovenia from the integrated perspective of water management. When propositions to divide Slovenia into several regions (provinces) (with proposals to make between 3 and 14 regions) were made, very different and numerous parameters have been taken into account. The article examines the regionalisation problem from the integrated water management perspective that was introduced into the Slovenian water legislation by the European Water Directive, adopted in 2000. The article also summarises the main directions of integrated water management, contained in Water Act that was adopted in 2002 and is still in force. On the basis of integrated water management foundations in European legislation, the article uses the division of Slovenia into water districts as a professional basis for a comparison between different proposals for division of Slovenia into regions. Although it is true that a hydrographical division of Slovenia into water districts cannot be the most important basis for regionalisation, one may notice that a division of Slovenia into three regions (Western Slovenia (Koper), Central Slovenia (Ljubljana), Eastern Slovenia (Maribor)) and partially division into six regions would be Ally in line with bases for integrated and (by definition) territorial water management

Estimation of magnitudes of debris flows in selected torrential watersheds in Slovenia

In this paper the application of different methods for estimation of magnitudes of rainfall-induced debris flows in 18 torrents in the Upper Sava River valley, NW Slovenia, and in 2 torrents in Pohorje, N Slovenia is described. Additional verification of the methods was performed in the torrential watersheds with active debris flows in the recent past (Predelica and Brusnik in the Soca River basin, W Slovenia). For some of the methods, the knowledge of morphometric characteristics of a torrential watershed, torrential channel and torrential fan is enough. For other methods, a mathematical tool (HEC-HMS) had to be applied in order to develop a hydrologic run-off model of precipitation that can trigger debris flows. Computed debris-flow magnitudes were of the order between 6,500 m(3) and 340,000 m(3). Their values are a function of torrential watershed parameters, such as: watershed area, Melton number, fan gradient, and torrential channel gradient. The investigated fans were classified into 3 groups with regard to the debris-flow hazard: debris-flow fans (hazard exists), torrential fans (no hazard), and transitional fans (debris flows are possible, but with low possibility). A limit between debris-flow fans and torrential fans is proposed: Melton number 0.3 and torrential fan gradient 4 degrees, that is, 7%. Out of 24 investigated torrential fans, 13 fans were classified into the group of debris-flow fans, 5 fans were classified into the group of torrential fans, and the rest 6 fans were classified into the group of transitional fans

Assessment of hydrological and seasonal controls over the nitrate flushing from a forested watershed using a data mining technique

A data mining, regression tree algorithm M5 was used to review the role of mutual hydrological and seasonal settings which control the streamwater nitrate flushing during hydrological events within a forested watershed in the southwestern part of Slovenia, characterized by distinctive flushing, almost torrential hydrological regime. The basis for the research was an extensive dataset of continuous, high frequency measurements of seasonal meteorological conditions, watershed hydrological responses and streamwater nitrate concentrations. The dataset contained 16 recorded hydrographs occurring in different seasonal and hydrological conditions. Based on predefined regression tree pruning criteria, a comprehensible regression tree model was obtained in the sense of the domain knowledge, which was able to adequately describe most of the streamwater nitrate concentration variations (RMSE=1.02mg/l-N; r=0.91). The attributes which were found to be the most descriptive in the sense of streamwater nitrate concentrations were the antecedent precipitation index (API) and air temperatures in the preceding periods. The model was most successful in describing streamwater concentrations in the range 1-4 mg/l-N, covering large proportion of the dataset. The model performance was little worse in the periods of high streamwater nitrate concentration peaks during the summer hydrographs (up to 7 mg/l-N) but poor during the autumn hydrograph (up to 14 mg/l-N) related to highly variable hydrological conditions, which would require a less robust regression tree model based on the extended dataset

Alpine hazard and risk management in protected areas: the case of the Triglav National Park, Slovenia\ud

Further regional and spatial development of the\ud Republic of Slovenia is based on a wide share of\ud protected areas that pose significant demands for\ud spatial planers. As an example of links between spatial\ud planning and management of protected areas, in this\ud paper we deal with the Triglav National Park (TNP)\ud in NW Slovenia, particularly with the proposal for its\ud 2014–2023 management plan and to which extent\ud this plan takes into account specific conditions that\ud arise from risk areas due to natural hazards as a\ud significant water management expert foundation\ud for planning the use of space. The paper explicitly\ud demonstrates that the determination of hazard and\ud risk areas in Slovenia is truly necessary, and that only\ud a detailed determination of hazard and risk areas in\ud scales 1:1000 to 1:5000 makes possible detailed spatial\ud planning and thus also the management of protected\ud areas. From the discussion, it also follows that the\ud proposed TNP management plan should be upgraded\ud in the field of research by establishing a Scientific\ud (research) council at the TNP Administration, and\ud by establishing a specific targeted research program\ud focused on research in TNP

Delineation of risk area in Log pod Mangartom due to debris flows from the Stoze landslide

The paper shows in detail the case of delineation of risk area in the village of Log pod Mangartom in the Koritnica River valley due to possible debris flows that might in future be triggered on the Stoze slope above the Mangart Mountain pasture. On the basis of field and laboratory investigations of the debris flow of November 17, 2000, that devastated the Koritnica River valley, the possible scenarios of triggering new debris flows on the Stoze slope were investigated. For the determination of debris flow hazard area in the Koritnica River valley, the results of one- and two-dimensional modelling of selected debris flows of known magnitudes and different viscosities were applied. For the determination of risk area, the existing and the possible new infrastructures were taken into account, and the risk area was divided into 3 zones. The paper presents the expert bases summarised by the legislator in the relevant decree issued by the Government of the Republic of Slovenia on the conditions and limitations governing the construction in the debris-flow risk area of Log pod Mangartom. This regulation is the first of its kind in Slovenia

Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007

During a weather front that passed over large parts of Slovenia on 18.9.2007, extreme rainfall events were triggered causing several severe flash floods with six casualties. Out of 210 municipalities in Slovenia, 60 were reporting flood damages, and the total economic flood damage was later estimated at close to 200 million Euro; highest damage was claimed by A1/2elezniki municipality in NW Slovenia. The main purpose of the study presented in this paper was to put together available meteorological and hydrological data in order to get better insight into temporal and spatial dynamics and variability of the flash flood event along the Selska Sora River flowing through the town of A1/2elezniki. The weather forecast by the Environmental Agency of the Republic of Slovenia (ARSO) lead to early warning of floodings but has underestimated rainfall amounts by a factor of 2. Also meteorological radar underestimated ground rainfall as much as by 50%. During that day, in many rainfall gauging stations operated by ARSO in the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm in 24 h or 157 mm in 2 h. Some of the measured rainfall amounts were the highest registered amounts in Slovenia so far. Statistical analysis using Gumble distribution was performed and rainfall return periods were estimated. When assessing rainfall return periods, a question of the sampling error as a consequence of short rainfall records used was raised. Furthermore, measured rainfall data were used to reconstruct hydrographs on selected water stations along the Selska Sora River. The cumulative areal precipitation for the Selska Sora River catchment upstream of Zelezniki amounted to 219 mm, while the modeled effective precipitation used to simulate the hydrograph peak was only 57 mm. The modeled direct runoff coefficient therefore amounts to 0.26. Surprisingly low value is mainly caused by the applied unit hydrograph method that seeks to meet the peak discharge rather than hydrograph volume. However, the spatial distribution of the rainfall in the area was highly variable and present spatial positioning of rain gauges is obviously inadequate for proper representation of the actual spatial amount of rainfall. The study confirmed that post-flood investigation should focus on discharges and hydrological response of the catchment rather than simply analyzing statistical characteristics of rainfall

Using a laser measurement system for monitoring morphological changes on the Strug rock fall, Slovenia

A medium-ranged high performance handheld reflectorless laser measurement system, was used for a morphological survey on the Strug rock fall in W Slovenia in the period from August 2003 to August 2004. The purpose was to evaluate its potential for monitoring ground surface changes in rock fall source areas and to help evaluating morphological changes by measuring distance from fixed points. In the area, 21 fixed geodetic points have been established. Altogether, seven measurement sets with more than 5500 points have been gathered in the rock fall area. Choosing a point cloud with a density of less than 1 point per 10 m(2) on a very rough rock fall surface failed to be a good solution. The changes on larger areas were shown by displacements of selected significantly large-sized rock blocks with a volume of several m(3). Because only smaller changes were observed between the single field series, the rock fall surface generally remained unchanged. Local surface changes of the order of 1 m or more, were clearly shown by measurements in the selected referenced cross sections. The usage of these cross sections gave a possibility to evaluate volumetric changes on the surface. The laser measurement system provided a good replacement for the classical terrestrial geodetic survey equipment, especially when performing remote monitoring of morphological changes in rock fall hazard zones, however, the case is different when fixed points are to be measured precisely

Rainfall interception by two deciduous Mediterranean forests of contrasting stature in Slovenia

Measurements of precipitation above the canopy, throughfall and stemflow were\ud made on the south and north-facing slopes of a deciduous forest on the experimental\ud watershed of the Dragonja river in SW Slovenia. The Dragonja watershed was\ud chosen for the experimental watershed, being of interest because of intensive natural\ud reforestation in the last decades that caused a decrease in minimum and maximum\ud flows. At the same time no noticeable precipitation and temperature changes were\ud observed. Two forest plots were selected. One is located on the north-facing slope\ud (1419 m2) and the other on the south-facing slope (615 m2). Analyses and modelling\ud were made for a one-year period from October 2000 to September 2001. The leaf\ud area index (LAI) was estimated by three methods, one direct and two indirect ones.\ud The obtained values of LAI with the direct method were 6.6 and 6.9 for the south and\ud north slopes, respectively. Measurements and regression analyses gave the mean\ud annual throughfall value (± standard error) on the south plot 67.1 (± 9.6) % of gross\ud precipitation, and 71.5 (± 11.6) % on the north plot. The average stemflow values\ud were 4.5 (± 0.8) % of gross precipitation in the south plot and 2.9 (± 0.6) % in the\ud north plot. The average annual interception losses amount to 28.4 (± 4.1) and 25.4 (±\ud 4.0) % for the south and north slopes, respectively. In the study a significant influence\ud of the south-east wind was proven. With regression analyses and the classification\ud decision tree model it was established that at the events with more than 7 mm of\ud precipitation and south-east wind with a speed higher than 4 m/s an unusually low\ud amount of throughfall occurred and thus high interception losses. The analytical\ud Gash model of rainfall interception (Gash, 1979; Gash et al., 1995) was successfully\ud applied. The results of the modelling corresponded well to the observed values and\ud were within the limits of the standard error of the observed values

Analysis of floods using satellite images - case study of the 2007 torrential flood in the Selška valley

An application of data mining for the determination of flooded areas was published in the Journal Geodetski vestnik (no. 54/2010-4). This paper analyses the usefulness of these results for further analyses of hydraulic parameters. The velocity and discharges were computed for six locations. The study showed that the flooded areas determined by satellite images can be used for further analyses. Nevertheless, other layers have to be sufficiently precise, especially the digital terrain model (DTM). DTM 12.5 was used. The study showed that DTM 12.5 is not precise enough. The observed area is very rough and the hydraulic parameters (cross sectional area of flow, wetted perimeter, hydraulic radius, river-bottom slope, flow velocity, discharge) cannot be detected with sufficient precision. Consequently the calculated hydraulic radiuses, velocities and discharges are out of expectations. In the first part of the article, some basic information about remote sensing and its techniques is presented. Some practical examples of their usage (especially satellite images) for the observation of natural disasters are also given