Growing drought hazard and water demand for agriculture, ecosystem conservation, and tourism in the Hungarian Drava river floodplain call for novel approaches to maintain wetland habitats and enhance ...agricultural productivity. Floodplain rehabilitation should be viewed as a complex landscape ecological issue which, beyond water management goals to relieve water deficit, ensures a high level of provision for a broad range of ecosystem services. This paper explores the hydrological feasibility of alternative water management, i.e., the restoration of natural reservoirs (abandoned paleochannels) to mitigate water shortage problems. To predict the efficiency of the project, an integrated surface water (Wetspass-M) and groundwater model (MODFLOW-NWT) was developed and calibrated with an eight-year data series. Different management scenarios for two natural reservoirs were simulated with filling rates ranging from 0.5 m3 s−1 to 1.5 m3 s−1. In both instances, a natural reservoir with a feeding rate of 1 m3 s−1 was found to be the best scenario. In this case 14 days of filling are required to reach the possible maximum reservoir stage of +2 m. The first meter rise increases the saturation of soil pores and the second creates an open surface water body. Two filling periods per year, each lasting for around 180 days, are required. The simulated water balance shows that reservoir–groundwater interactions are mainly governed by the inflow into and outflow from the reservoir. Such an integrated management scheme is applicable for floodplain rehabilitation in other regions with similar hydromorphological conditions and hazards, too.
Rijeke Drava i Sava su od pamtivijeka u krajevima njihova srednjeg i donjeg toka imale visok vodostaj u proljeće i jesen, te su poplavljivale dva puta godišnje. Velike vode su plavile poljoprivredna ...zemljišta i šume, pašnjake, voćnjake, ali i naseljena mjesta. Pri tome su uništavale usjeve, rušile nasipe i kuće, a nerijetko odnosile i ljudske živote. Plavljenja uz vodotok Drave kod Osijeka i Save kod Broda na Savi (današnji Slavonski Brod) sustavno su zapisivana u kronikama franjevaca tijekom 19. stoljeća. Budući da su velike vode bile stalna pojava s golemim posljedicama, započeli su radovi na obrani od poplava, i to rekonstrukcijom (povisivanje, prelamanje i održavanje) starih nasipa i izgradnjom novih uz dogradnju hidromelioracijskih objekata. Med strok signutim, nisu stvoreni uvjeti za održivi sustav obrane od velike vode pa su se radovi na zaštiti od poplava nastavili kroz
Rijeka Drava i njezina pritoka Mura opjevani su motivi kajkavskih tradicijskih pjesama Međimurja, Podravine i Hrvatskog zagorja. One predstavljaju stvarne zavičajne rijeke koje su istodobno i fizička ...razdjelnica i komunikacijski put, od kojih se istodobno i zazire i živi. Katkad opjevane kao mitske vode između stvarnoga i onostranog svijeta, nisu izrijekom imenovane. Tajanstvene močvare, mora, rijeke, jezera, bezdani i zdenci, oko kojih se kreću božanstva ili nadnaravna bića, svjedoče o povijesnom susretanju i prožimanju hrvatske pretkršćanske i kršćanske duhovnosti.
Universal Kriging has not until now been used for mapping of geological data in Croatia. However, it is one of the most frequently used methods of Kriging, probably the most adequate in cases when ...the input data is marked by a common trend. That exact feature is often an attribute of deep geological data, and thereby that of structural maps. Mapped surfaces in a row of examples have a structural trend towards one cardinal direction, or a sequence of geological structures, like anticlinorium, is a part of a structural unit of a higher order such as regional monocline. An example is given of geographical trend recognition in e-log Z’ surface spread in Šandrovac Field as well as successful mapping of that marker depth variable by using Universal Kriging.
•Freeze-up became ∼9days later and break-up became ∼10days earlier since AD 1875.•The duration of ice-cover decreased by 14days on a century average.•The number of total ice-affected days decreased ...by 31days on a century average.•Drava river ice is a powerful proxy for the winter temperature of Central Europe.
River ice is principally controlled by atmospheric conditions, especially temperature, so these records provide useful information on the climate in general. A more than 130-year-time-series of ice-on and ice-off, and freeze-up and break-up dates was analysed from 4 selected hydrological stations along the lower course of the River Drava since the beginning of river ice observations the start- and end-dates of ice phenomena on Drava River have displayed a significant trend. Freeze-up dates have shifted to ∼9days later, and break-up dates to ∼10days earlier. A similar trend is present in the dates of ice-on and ice-off; these dates have shifted to ∼23days later and ∼17days earlier per 100years on average. These changes have resulted in a pronounced reduction in the ice-covered and ice-affected seasons, too. The duration of ice-cover has decreased by ∼14days and the total number of ice-affected days has decreased by ∼31days over a century on average on the lower course of the Drava. Interannual variability was compared to local and regional instrumental temperature records. The strongest correlation was found between ice-off and January–February mean temperatures (r=0.81, p<0.05), and between the total number of icy days and the mean winter temperature (r=0.88, p<0.05). Statistical evidence indicated, however, that the subdued climate control from the 1970s is probably due to anthropogenic intervention in the upper course (e.g. reservoir construction, hydropower management). Spatial correlation analysis revealed that the temperature signal carried by the river ice records of the Drava prior to the anthropogenic disturbance seems to be a powerful proxy for the winter temperature of Central Europe.
Wetlands in large river floodplains are endangered biodiversity hotspots in need of active conservation measures. Most rehabilitation interventions target water replenishment and disregard other ...possible threats, especially those which operate at the landscape level and cause changes detectable over a period of decades. Twenty years’ changes of wetland vegetation were evaluated on the Drava floodplain, Hungary, where large-scale hydrological interventions have not been implemented during this time. Archive data from the 1990s were compared to data from 32 oxbows resurveyed in 2015. After scrutinizing scientific values and limits of archive datasets, we judged them appropriate for drawing robust landscape-level conclusions. Frequency of habitats and of selected species, diversity indices and diversity profiles were compared. Increased frequency of shrub and forest habitats, decreased frequency of dystrophic and protected species, and decreasing diversity of habitats and communities were detected. In the Drava floodplain hydroseral succession is the key natural process. Drought, riverbed incision, nutrient pollution, spread of invasive species, succession, and game and fish overpopulation were identified as further landscape-level threats. Water replenishment schemes can improve the conditions through slowing down or reverse succession. However, habitat and vegetation changes indicated that other threats to biodiversity are still present.
Sonar survey of shallow water bodies has challenged scientists for a long time. Although these water courses are small, still they have an increasing ecological, touristic and economical role. As ...maritime sonars are non-ideal tools for shallow waters, the bathymetric survey of these rivers has been taken with cross-sectional methods. Due to recent developments, interferometric surveying technology have also burst into the market of recreational-grade fish-finders. The objective of the current study was the development of a novel, complex and integrated surveying technique which is affordable, robust and applicable even at low water levels. A recreational-grade sonar system was assembled and mounted on a double-hull vessel and connected with a geodetic Global Navigation Satellite System (GNSS) device. We have developed a novel software which enables the bridging between a closed sonar file format and the commonly used Geographic Information System (GIS) datasets. As a result, the several month-long conventional bathymetric survey of the 146 km-long reach of the Drava River was reduced to 20 days and provided channel bathymetry of many orders of magnitude higher than the classical methods. Additionally, a large number of spatial derivatives were generated which enables the analysis of channel morphology, textural variation of channel sediments and the accurate delineation of navigational routes.
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