Szabolcs Czigány

Analysis of soil boundary conditions of flash floods in a small basin in SW Hungary

Flash floods are one of the most significant natural hazards of today. Due to the complexity of flash flood triggering factors, to prevent or mitigate flood triggered losses, numeric model based flood forecasting models are capable tools to predict stream water levels. The main goal of the current research was to reproduce two flow peaks with the HEC-HMS rainfall-runoff model and test the model sensitivity for various input parameters. To obtain sufficient input data, we monitored soil depth, maximum infiltration rate, soil moisture content, rainfall, time of concentration and flow. To obtain input data, parameters were calculated, measured in the Sás Valley experimental watershed (SW Hungary) or optimized with the built in function of the HEC-HMS. Soil moisture was monitored in the 1.7 km2 pilot catchment over the period between September 2008 and September 2009. HEC-HMS had a good performance reproducing the two events, however simulated flow time series are highly influenced by the antecedent soil moisture, infiltration rate and canopy storage. Outflow modeled data were verified for two flood events (June 4, 2008 and July 9, 2009). The HEC-HMS was over-sensitive for input soil moisture and with increasing input rainfall and increasing outflow, larger simulation errors were observed.

Hydromorphological assessment of the lower Hungarian Drava section and its floodplain

The hydromorphological properties of rivers and their floodplains receive increased attention both in basic research and water management. A comparison of hydromorphological parameters before and after river regulation (involving floodplain drainage) provides important information for river management, particularly floodplain rehabilitation. The paper assesses a selected reach of the Drava River and the corresponding floodplain utilising two international approaches, the REFORM framework and the Italian Morphological Quality Index.

Playing on reality: do geomodels improve the perception of geographical terms?

ABSTRACT Remodeling of geography education has been an ongoing challenge recently. Constructivist pedagogy, employing tools of problem and model-based learning, offers new opportunities to meet these challenges. Geomodels, flumes and stream tables may ease the understanding of geographic processes through hand-on-experience for students. With a computer-controlled geomodel, we analyzed the development of 36 high school students’ terminology in the fields of potamology and remote sensing. Potamology terms, provided after the experimental session, were more focused and reflected the information perception and fixation during the experiment. Three weeks later the terminology of the students indicated a partial fixation of the relevant terms. When students’ terminology on remote sensing was analyzed, the pre-experiment terms were loosely connected to the topic. Over the class, students’ terminology increased in the field of potamology. Although it became more topic-specific and focused, students’ remote sensing terminology still contained a large number of off-topic terms by the end of the experiment and three weeks later. Our findings revealed one of the major weaknesses of the Hungarian educational system, i.e. teachers are forced to follow the conventional geographical curricula, therefore hindering their adaptation to cutting-edge educational methods and the learning-by-doing approach of the Western European and North American syllabi.

Oxbow Lakes: Hydromorphology

Cut-off oxbows are the most remarkable fluvial landforms and the most valuable wetland habitats in the protected floodplain of the Lower Drava River in Hungary. Their geomorphic evolution, however, has not been studied yet. Recently, a complex hydromorphological survey of oxbows covered their geographical position, connection with the main Drava channel, water balance, hydrogeological properties, water retention capacity and groundwater flow in their environs. The purpose of the investigations was to assess the potential for oxbow lake and floodplain rehabilitation. Two zones of oxbows, possibly differring in age and geomorphological evolution (the date of cutoff), have been identified and preliminarily described. The focus of research was on the Cun-Szaporca lake system, part of the Danube-Drava National Park and a Ramsar area, where the clogging of the oxbow bed, a critical factor of transmissivity, was analyzed in detail. For planning landscape-scale rehabilitation (the Old Drava Programme) more information on the old courses of the Drava and its preserved but gradually disappearing traces (the present-day oxbow lakes) would be necessary.

Interpolation and 3D visualization of soil moisture

Adaptation to climate change demands the optimal and sustainable water management in agriculture, with an inevitable focus on soil moisture conditions. In the current study we developed an ArcGIS 10.4. platform-based application (software) to model spatial and temporal changes in soil moisture in a soy field. Six SENTEK Drill & Drop soil moisture sensors were deployed in an experimental field of 4.3 hectares by the contribution of Elcom Ltd. Soil moisture measurement at each location were taken at six depths (5, 15, 25, 35, 45 and 55 cm) in 60-minute intervals. The model is capable to spatially interpolate monitored soil moisture using the technique. The time sequence change of soil moistures can be tracked by a Time Slider for both the 2D and 3D visualization. Soil moisture temporal changes can be visualized in either daily or hourly time intervals, and can be shown as a motion figure. Horizon average, maximum and minimum values of soil moisture data can be identified with the builtin tool of ArcGIS. Soil moisture spatial distribution can be obtained and plotted at any cross sections, whereas an alarm function has also been developed for tension values of 250, 1,000 and 1,500 kPa.

Flash Flood Analysis for Southwest-Hungary

The 15–18 May 2010 flood events on the watershed of the Bukkosd Stream, SW Hungary, are described, their general topographic and hydrologic characteristics are analyzed using the HEC-HMS numeric runoff model, and geomorphological impacts are surveyed. In addition to extreme rainfall volumes, the major reasons found to contribute to extreme impoundment were the fluctuating and locally reduced width of the valley, the confluence of tributaries, which create intermittent bottlenecks for drainage, and high soil moisture contents, which also caused slope instability in deeper soil mantle. Flash flood hazard is closely associated with landslide hazard in upland valleys.

Urban Geomorphological Processes in Pécs, Southwest-Hungary, Triggered by Extreme Weather in May and June 2010

In urban areas with increased surface runoff, high-intensity rainfalls may inflict serious damages to various structures. Authors analyze extreme precipitation events with the purpose of compiling an urban geomorphological hazard map for Pecs, drawing on the experience gathered from the May to June events in 2010. DEM and digitized cadastral maps were employed to survey the spatial distribution of the extraordinary events, their impacts on geomorphic processes and the resultant damages. The findings confirm that the incorporation of stormwater management into the urban hydrologic master plan could be highly beneficial for Pecs and many other municipalities. This way localized flooding could be avoided or reduced to manageable levels.