A gemenci hulldmter rehabilitdcidja —
The Gemenc floodplain rehabilitation study
Resztvevd intezetek es temafeleldsdk:
Participating institutes and project managers:
Delfti Hidraulikai Intezet Delft Hydraulics P.O.Box 177,2600 M H Delft, The Netherlands Drs. Marcel Marchand VIzgazdalkodasi es Szennyvitiszh'tisi Intezet Institute For Ingland Water Management and Waste Water Treatment (RIZA) P.O.Box 17,8200 A A Lelystad, The Netherlands Drs. Eric Marteijn Vizgazdalkodasi Tudomanyos Kutatokozpont es VTTUKI Consult R t Water Resources Research Centre (VITUKI) and VITUKI Consult R t Kvassay Jeno ut 1., Budapest, H u n g a r y 1095 Dr. Peter Bakonyi Editors:
Szerkesztdk: Dr. Peter Bakonyi and Drs. R u u r d Noordhuis
Text:
Szdveg: Drs. Marcel Marchand and Dr. Peter Bakonyi
Photographs:
Fenykepek:
Barnabas Felso, Drs. Eric Marteijn and Misjel Decleer (Night Heron) Cimkep:
Cover photographs Barnabas Felso Graphics:
Grafika: Delft Hydraulics (chapter 1) and R I Z A (chapter 5) Oldalterv es nyomtatds:
Lay-out and R O M A I Kiadoi es Nyomdaipari BT.
printing:
BIBLIOTHEEK BOUWDIENST RIJKSWATERSTAAT NR. X Q g z . a 3 S ^ j
BIBLIOTHEEK Bouwdienst Rijkswaterstaat Postbus 20.000 3502 LA Utrecht
EGY HULLAMTER JOVOJE
A gemenci hulldmter rehabilitdcioja A Gemend Tajvedelmi Korzet egy Magyarorszag deli reszen elteriilo, kiveteles szepsegu dunai hullamter. Nagyreszt erdo boritja, es meg mindig fellelhetok rajta a korabbi termeszetes folyoparti kemenyfa aUomanyu erdok maradvanyai. A teriilet jelentos madarrezer^atum es egyedtilallo tartozkodasi helye tobb olyan vadfajnak, melyek viszonylag zavartalan arter megletet jeMk, habar az eredeti huUamteri okoszisztema egyes mas jellegzetes elemei mar elttintek A teriilet termeszetes allapotanak visszaallitasa kivanatos, am a teriilettel kapcsolatos kiOonbozo erdekek gyakran eros eUentmondasban vannak. Jelen kiadvany beteldntest nyujt Onnek abba a tanulmanyba, amely elo kfvanja segiteni egy, a teriilet osszes ^rikciojat figyelembe vevo, hullamteri rehabilitacios terv kialakitasat.
A FUTURE FOR A FLOODPLAIN
The Gemenc floodplain rehabilitation study TH e Gemenc Landscape Protection Area is a Danube floodplain of outstanding beauty, situated in the south of Hungary. It is largely forested, and remnants of the natural river fringe hardwood forests are still present. The area is an important game reserve and a unique habitat for several species of wild animals indicative for relatively undisturbed backswamps, although other characteristic elements of the original floodplain ecosystem are already lost. Rehabilitation of the area is desirable, but the various interests involved are often conflicting seriously. This brochure is an introduction to a study that has been set up to help develop a floodplain rehabilitation plan in which all functions of the area are taken into account.
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-ben a Kozlekedesi, Hirkdzlisi is Vizugyi valamint a Kbrnyezetvidelmi is Teruletfejlesztisi Miniszteriumok holland es magyar intizeteket biztak meg a gemenci hulldmter rehabilitdcios lehetosegeinek vizsgdlatdval. A megdllapodds szerint a tanulmdny, melyet a holland kormdny finansziroz, a teriilet vizgazddlkoddsdra koncentrdl, de figyelembe veszi a teruleten folyo egyeb gazddlkoddsi erdekeket is, ugymint az erdeszet, a vaddszat, a haldszat is az udulis irdekeit is. A tanulmdny stratigiai elemzis formdjdban kisziilt el, ami aztjelenti, hogy kulonbdzd stratigidkat is A gemenci huUamterelontes tartdssagi terkepe
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ELOZMENYEK
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ABOUT THE STUDY
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Inundation Duration Map of Gemenc Floodplain In 1992 the Ministry of Transport, Communication and Water and the Ministry of Environment and Regional Policy commissioned a combination of Dutch and Hungarian institutes to execute a study into the possibilities for the rehabilitation of the Gemenc floodplain. It was agreed that the study, financed by the Netherlands' Government, would focus on The water management of the area, but nevertheless to take into account the wider scope of the other management areas and interests such as forestry, hunting, fisheries and recreation as well.
azok kulonbdzo erdekekre gyakorolt hatdsait elemzi anelkul, hogy bdrmely strategidval vagy megolddssal szemben elfogultsdgot tanusttana. A strategiai denizes kulcsszava az objektivitds. Ez azt jelenti, hogy valamennyi feltetelezes es ertekeles szildrd alapokon nyugszik. A donteseket a donteshozoknak kell meghozniuk. E tanulmdny csak ugy segiti oket, hogy megmutatja az egyik vagy a mdsik strategia kovetkezmenyeit a rendelkezesre alio ismeretek, valamint a tudomdny dltal nyujthato legjobb modszerek es modellek felhaszndldsdval.
Ebben a kiadvdnyban a tanulmdny eredmenyeit foglaljuk bssze. Termeszetesen csak a tenyek, az dbrdk es az elert eredmenyek dsszefoglalojdt mutathatjuk be. Azok, akik a reszletek irdnt is erdeklodnek, mind a zdro jelentes, mind a nyolc aldtdmaszto dokumentum mdsolatdt megkaphatjdk dr. Bakonyi Petertol (VITUKI Consult Rt, 1095 Budapest, Kvassay ut 1.). A tanulmdnyokon kivtil egy szdmitogepes animdcioval tdmogatott demonstrdcios lemez is keszult, amely lepesrol lepesre bemutatja a tanulmdny egyes fdzisait es eredmenyeit.
A gemenci teriilet elsodleges hasznalata
Erdogazdalkodas Timbering Termeszetvedelem Nature protection
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Vadgazdalkodas G a m e management Egyebtevekenyseg Other activity
Primary use of Gemenc
The study was executed as a policy analysis, which means that it analyzes different alternatives on its impact on all the different interests, without an implicit bias towards one policy or solution. Objectivity is the keyword. This means that all assumptions and evaluations are made on explicit grounds. Decisions remain to be taken by the decision makers. The study only helps them by showing the consequences of one policy or another, on the basis of all the knowledge available and the best models and methods science can offer.
In this brochure one can read about the outcome of this study. Of course it only gives a summary of all the facts, figures and results which have been produced. For those who are interested, a main report and eight supporting working documents are available upon request at Drs. E.C.L. Marteijn of the Institute for Inland Water Management and Waste Water Treatment, P.O.Box 17, 8200 AA Lelystad, The Netherlands. Furthermore, a computer animated graphics demonstration diskette has been produced which shows the different phases of the study and its results step-by-step.
A gemenci teriilet, mint az europai hulldmteri erdok pilddja, nemzetkbzi irtekeket kepvisel. A gemenci teriilet mas hulldmterekkel ellentetben nem szenvedett kdrt a folyocsatorndzdstol es erdoirtdsoktol. Halo nagyszdmu dreg fdinak (foleg tblgyek is nydrfdk), melyek kedvezo tdpldkozdsi helyek kdzeliben taldlhatok, olyan madarak, mint a ritisas, fekete golya is barna kdnya kdltenek a Gemenci Erdoben. A teljes szaporoddsi idoszakban szdmos - a szomszidos kolonidkon ilo - bakcso tdpldlkozik a teruleten. Ezen fajok mindegyike szerepel
GEMENC:
A CSODALATOS HULLAMTERI ERDO GEMENC : A FORESTED FLOODPLAIN FULL OF WONDERS
The Gemenc area is of international value as an example of a European floodplain forest. Unlike many otherfloodplains the Gemenc area has not suffered from major damming and deforestation. Due to its large amount of older trees (especially poplar and oak) situated in a suitable feeding habitat, birds like Whitetailed Eagle, Black Stork and Black Kite breed in Gemenc. Throughout the entire breeding period many Night Herons of nearby colonies use the area for feeding. Without exception all these species are mentioned as
az europai folyok drtereinek rehabilitdcios terveiben es mint ilyenek magas okologiai erteket kepviselnek. Bar viszonylag kevesebbet tudunk a kisebb dllatokrol, ktilbnbsen a gerinctelenekrol, a teriiletet megldtogato bkologusok egybntetuen dllttjdk, hogy az erdo faunisztikailag igen gazdag. Azt is figyelembe kell venni, hogy a teriilet meg nagyjdbol megorizte a regebbi folyddgak es partok eredeti morfologiai eletter-szerkezetet. Ez a morfologiai vdltozatossdg, mely egy relative nagy terulettel pdrosul, tag teret biztosit a meg bsszetettebb hulldmteri bkoszisztemdk kialakuldsdhoz. A gemenci hulldmteret 1977-ben nemzeti jelentosegunek deklardltdk es az Orszagos Termeszetvedelmi Hivatal elnbke a 14/1977. szdmu hatdrozatdban vedette nyilvdnitotta. A gemenci teriilet ezen stdtusza, valamint a Gemenci Termeszetvedelmi Teriiletet magdba foglalo Nemzeti Park terve megkivdnja a jelenlegi termesztevedelmi helyzet es a javttdsdra irdnyulo lehetseges beavatkozdsok kritikus elemzeset. Az elmult
evekben a kbrnyezet irdnt megnbvekedett erzekenyseg uj gondolatokat vetett fel az integrdlt vizgazdalkodds teruleten. Ez a fejlodes uj tdvlatokat nyitott meg a gemenci teriilet fejlesztese elott.
target organisms in rehabilitation plans for European rivers and thus can be qualified as indicators of high ecological floodplain values. Although relatively little is known of the smaller animals, especially the invertebrate fauna, ecologists visiting the area all confirmed that, according to theit impressions, the forest is faunistically rich. Nevertheless, many of the formerly characteristic aspects of the floodplain ecosystem have already been lost in Gemenc. Fortunately, the area still has its more or less original morphological habitat structure of former river branches and levees. This morphological diversity combined with the relatively large size of the area offers ample opportunities for the development of a more diverse floodplain ecosystem. The Gemenc floodplain was qualified as an area of national importance and its protection was declared in 1977 by the president of the National Office for Nature Conservation in his resolution No. 14. This status of the Gemenc area as a Landscape Reserve and the plans for the creation of a National
Park incorporating the Gemenc Forest Landscape Reserve leads to the need for a critical assessment of the present nature conservation situation and to possible measures to improve this situation. Increased awareness on environmental matters over the last years has stimulated new ideas on integrated water management. This development has created a new perspective for the improvement of the Gemenc area.
A mult evszdzad ota a folyoszabdlyozds celja az drvtzvedelem, a jobb hajozhatosdg es a jeges drvizek elkerulese volt. A felhagyott mellekdgak es dtvdgott kanyarulatok alacsonyabb dramldsi sebessegei ezen dgak feliszapoloddsdhoz es idoszakos eutrofizdciojdhoz vezettek. Igy tbbb mellekdg, kbztuk a Rezeti es a Ven Duna is, elkezdett feliszapolodni. A vizutdnpotlds - kiildndsen a szdrazabb idoszakokban - egyre csekelyebb lett. A Duna fomedreben eloallo nagyobb dramldsi sebessegek viszont a Duna meder berdgoddsdhoz es kbvetkezeskeppen a hulldmter kiszdraddsdhoz vezettek. Mindemellett, a gemenci teruleten folytatott erdeszeti tevekenyseg es vaddszat is kedvezotlenul hatott a hulldmter bkoszisztemdjdra es az azzal kapcsolatban alio vizgazddlkoddsra. A termeszetes erdok helyettesitese exotikus nydrfdkkal es mds gyorsan novo fafajokkal jelentosen csbkkentette mind a nbveny-, mind az dllatfa-
VALAMI MEGVALTOZOTT THINGS HAVE CHANGED OVER THE PAST Since last century, river training works have aimed at flood protection, better mvigability and prevention of ice-jams. Lower stream velocity in the abandoned side arms and cut-off bends has led to siltation and from time to time to eutrophication of the side arms. In this way many of the stream beds, including the large Rezeti and the Ven Duna have started to silt up. The inflow of water became more and more restricted, especially in dry seasons. Higher stream velocity in the main bed of the Danube has lead to its deepening and consequently to desiccation of the whole floodplain area. Besides, the forestry and hunting practices in the Gemenc area have imposed pressure on the natural floodplain ecosystems and associated water management. The replacement of natural forests with exotic poplars and other fast-growing trees causes a major decrease of
jok kulbnlegesen irtikes dllomdnydt. Ezzel bsszefiiggisben a fdk iletkor szerinti megoszldsa is egyre egybntetiibbi valt: a 20 eves dllomdny vdlt domindnssd, mig a 80-90 eves fdk egyre ritkdbban fordulnak eld. Pedig kiilonbsen ezek a nagy, oreg fdk, mint a tblgy es a fekete nydr, kedvenc piheno es fiszkelo helyei az olyan madaraknak, mint a fekete golya es a kormordn. A Gemenci Erdo szarvas es vaddiszno dllomdnya olyan szintet irt el, ami nines egyensulyban az erdo eltarto kapacitdsdval. A gemenci szarvas a termeszetes hulldmtiri bkoszisztema resze, de a vaddszati szokdsok is az erdo bkoszisztimdja megvdltozdsdnak kbvetkeztiben jelentos tulszaporoddsa tapasztalhato. A nagy vadsurusig jelei vildgosan megmutatkoznak az erdo termiszetes megujhoddsdnak hidnydban. Az udiilis szintin szerepet jdtszik a teruleten. Az udulissel kapcsolatos tevikenysig az elmult 20 evben ellendrizetlen is gyakran tbrvinytelen hitvigihdz ipitisekhez vezetett. E tevikenysig jelei elsdsorban a jobbparton mutatkoznak meg, de megtaldlhatok a Reziti Duna mellett, valamint a balparti nyaraloi-
both plant and animal species diversity. A related effect is that the age distribution of the trees is becoming more uniform: 20 year old stock is dominating while trees of 80 to 90 years old became rare. And especially these old and large trees, for instance Oaks and Black Poplars, provide favourite nesting and resting sites for birds like Black Stork and Black Kite. The game stock of Red Deer and Wild Boar has reached levels which are not in equilibrium with the carrying capacity of the Gemenc forest. The Red Deer of the Gemenc forest is a natural component of the floodplain ecosystem, but, due to hunting practices and changes in the forest ecosystems, there is currently a situation of serious overpopulation. The effect of the high wildlife density is clearly visible from the lack of natural forest rejuvenation at many places. Recreation plays a role in the area as well. Recreational activities in the past 20 years have led to uncon-trolled and often illegal building of weekend-cottages. Activities are concentrated on the right bank, but also along the bank opposite of Baja, and along the
pttkeziseknil is. Okologiai szempontbol az ilyen tertiletekhez kapcsolhato problimdk dltaldban lokdlisak (a megkbzeHtisi utvonalak melletti zavards, szemitlerakds, szennyvizkibocsdtds, vizudlis takards). A tovdbbi ipttkeziseket azilletekes hatosdgok ledlUtottdk. A Vin Duna melletti, Ersekcsandd 1 is Ersekcsandd 2, teriilet engedelyezett lesz az udiilis szdmdra, de nagyszdmu ipiiletet el kell majd tdvolitani. Azoknak, akiknek el kell hagyniuk a teriiletet, Gemencen kivul jelblnek ki uj uduloteruletet. Mdsriszrol viszont a gondosan megtervezett is menedzselt udulisi lehetosig fontos jellegzetessige a gemenci teruletnek, amely jelentos gazdasdgi irtiket kepvisel. A turistdk 125 000 ijszakdt tbltenek el evente Bajdn is Szekszdrdon is ezek 60-70 szdzalika kulfbldi. A Bajdtol dilre eso szigeten egy uj uduloteruletet fognak kiiptteni elsdsorban a kulfbldi vendigek odavonzdsa ciljdbol. A gemenci teriilet irdnt irdeklodo turistdk, mdjus is szeptember kbzbtt, kisvasuttal latogathatjdk a teriiletet. Manapsdg evente mintegy nigyezer latogatot vdrnak.
Reziti Duna summer-cottages have been built. From an ecological point of view the related problems are mostly local (disturbance along the access road, rubbish dumping, waste water discharge, visual hindrance). Further expansion of these resorts has been stopped by the competent authorities. In the area near the Vin Duna, Ersekcsandd 1 and Ersekcsandd 2, cottages will be allow-ed but a number of surplus houses will be removed. For the people that have to leave alternative places will be offered outside Gemenc. On the other hand, recreation, if properly planned and managed, is an important feature of the Gemenc area, which represents a significant economic interest. The number of registered overnight stays at Baja and Szekszdrd amounts to 125 000 a year, of which 60-70% by foreigners. On the island at the south side of Baja new recreation facilities will be built especially to attract foreigners. Tourists that are interested in Gemenc can make a trip by railway into the area in the period May-September. Yearly about 4000 visits are made to Gemenc in this way.
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Az eredeti dllapotdban a hulldmteri okoszisztema dllandoan vdltozik. A viz ereje folyamatosan dolgozik a folyo medren, a hulldmter talajdn es a novenyzeten: a homoru parton erozio lev fel mtg a domboru partot a lerakodo hordalek epiti. Igy meanderezikafolyo a medreben. Ezen munkdt vegzo erok, valamint az idoszakos draddsok es a jeg hatdsai nelktil a hulldmter lassan egy melyfekvesu erdove alakulna at, viszonylag keves kiilonbdzo elohellyel. Az egymdst koveto nbvenyzet vegiil statikus helyzetbe kerulne. A hulldmteri tdj egyeduldllo jellegzetessege a folyo dinamikdja. Mind az idoszakos elbntesek, mind a szelsoseges esemenyekfiatalon tartjdk az bkoszisztemdt: az elohelyek es a mikro-elohelyek sokasdga keletkezik, amely afajszdm novekedesehez vezet. Tekintsuk pelddul a vizi kornyezetet. Az dramlds sebessege az egyike a fo parametereknek, amelyek a novenyek es dllatok eletfeltetele.it meghatdrozzdk. A fo dramldsban az dramldsi sebesseg rendszerint tul nagy ahhoz, hogy a szdr nelkuli vlzinbvenyek megmaradja-
s
ARAMLO VIZ: A FOLYAMI TAJKEP KULCSA FLOWING WATER: THE KEY FACTOR IN A RIVER LANDSCAPE
In its virgin state, a floodplain ecosystem is ever changing. The forces of water are constantly working on the river bed, the soils and the vegetation on the floodplain proper: erosion takes place along the outer bends of the river while the sediments are deposited in the inner bend. In this way the river is meandering through its winter bed. Without these forces at work and without the periodical flooding and presence of ice the floodplain would gradually turn into a lowland forest with relatively few different habitat types. There would be vegetation succession until finally a static climax situation is reached The unique feature of the floodplain landscape is its river dynamics. Both the seasonal inundations and the extreme events are keeping the ecosystems young and lively: a multitude of habitats and micro-habitats are formed and consequently the diversity of species reaches high values. Take for instance the aquatic environment. Flow velocity is one of the main parameters determining the living conditions of plants and animals. In the main
nak. Csak az olyan nagyobb testu dllatok, mint a halak kepesek az drral szemben uszni es megakaddlyozni, hogy az dramlds elsodorja oket. A folyo kisebb mellikdgaiban az dramldsi sebessigek sokkal kisebbek. Ott vizinbvenyzetet es kisebb rovarokat taldlhatunk; mindegyik a megfelelo dramldsi sebessighez alkalmazkodott. Ezen nbvenyek es rovarok sokasdga odavonza a halakat, ami magdval hozza az olyan tipikus hulldmteri madarak megjelenesit, mint a fekete golya, bakcso is a nagykocsag. A mellekdgakon dtdramlo viz szinten eroziot es feliszapoldddst okoz, habdr sokkal kisebb mirtikben, mint a fodgban. Ennek ellenire kulbnbsigeket hoz litre a partok meredeksegeben; neha szakadopartokat alkot, illetve a folyoparti fdk a vizbe dolhetnek. E meredek partok idedlis kbltohelyei az olyan madaraknak, mintajigmaddr is a parti fecske. Szinten ez a megfelelo elShely az europai folyokbol majdnem teljesen eltunt nagy testu kiresznek (Palengenia). A vizbedolt fdk sem irtektelenek. Sot, idedlis elohelyet biztositanak mas ilolinyek szdmdra, melyek a ke-
miny alaphoz tapadhatnak. Ezen gerintelenek kbziil sok a vizet szuri at tdpldlik utdn kutatva, igyjdrulva hozzd a viz tisztttdsdhoz. A folyoszabdlyozds is a mellikdgak feliszapoloddsa az ev nagy resziben alacsony dramldsi sebessiget vagy ivpen stagndlo dllapotokat hozott litre a mellekdgakban. tgy az elozoekben leirt ilohelyek is fajok nagyresze eltunt. Ahogy Idthattuk a gemenci teriilet jelenleg veszit az eletkepessigebol mivel a viz alkotoereje lassankint gyengul. Ezirt tbbb strategidt dolgoztunk ki a viz szerepinek megerositisire.
stream, the flow is often too fast for sessile water plants to persist. Only larger animals like fish are capable of swimming against the current and preventing themselves from being swept away downstream. In the smaller side-channels of the river, the flow velocities are much smaller. There one will find water plants and small insects, each species adapted to a particular flow velocity. The abundancy of these plants and insects attracts fish, which on their turn are a welcome treat for typical floodplain birds such as the Black Stork, the Night Heron or the White-tailed Eagle. The flow of the water through the side-channels also causes erosion and sedimentation, albeit on a smaller scale and intensity than in the main river. Nevertheless it creates differences in bank slope and sometimes small clay cliffs are formed and trees on the riverbanks may fall into the water. The small cliffs are ideal for birds like Kingfishers and Sand Martins to breed in. It is also the right habitat for the large, characteristic mayfly Palengenia, which is almost extinct along the European rivers.
The fallen trees in the water are not "lost". On the contrary, they create an ideal habitat for yet other animals, which find in it a stronghold to stick to. Many of these aquatic macro-invertebrates filter the water for food. In this way they contribute to the purification of the water. The river training works and the siltation of the side-channels have led to the virtual absence of flow through the side-channels during large parts of the year. Hence, many of the habitats and species described above, have disappeared. As we have seen, the Gemenc area is currently losing its vitality because the creative force of the water is being suppressed little by little. Therefore, we have designed a number of strategies, each of them aiming at reinforcement of this role of the water
A stratigiai elemzis, a modellek is kulbnbdzo tudomdnydgak szakertoi velemenyinek felhaszndldsdval sikeresnek bizonyult. A helyi szakirtok es irdekcsoportok hathatos resztvetelevel a lehetsiges beavatkozdsok sordt tdrtukfel es vizsgdltukfeliil. Figyelembe veve a hullamtiren taldlhato viztestek jelenlegi helyzetit hdrom kulbnbozo stratigidt dolgoztunk ki, melyek a hulldmter termeszeti ertekeinek rehabilitdciojdt tuzik ki celul:
I. valtozat a mellekagak vizellatasanak javftasa E kialakttds celja, hogy hdrom kordbbi folyokanyart, a Grebeci Dundt, Rezeti Dundt es a Ven Dundt, valamint kit mellekdgat, a Moric Dundt is a Kdddr Dundt helyredllitsunk. Alapveto eel, hogy ezekbe az dgakba nagyobb vtzhozamot vezessiink, kulonbsen az alacsony dunai vizdlldsok mellett. Ez megakaddlyozza a rossz vizminosigi viszonyok kialakuldsdt is javitja a
REHABILITACIOS STRATEGIAK STRATEGIES FOR REHABILITATION The policy analysis of the project, using models anexpert opinions from a range of disciplines has proven to be fruitfull. With crucial participation of local experts and interest qroups, possible rehabilitation measures have been designed and screened. Taking the current situation of the water bodies within the floodplain area as a starting point, three alternative strategies aiming at the rehabilitation of the nature values in the area have been formulated:
Alternative I: improvement of the side-arms The objective of this alternative is to restore three of the former river meanders; the Grebeci Duna, the Reziti Duna and the Vin Duna, and two lateral sidechannels; the Moric Duna and the Kdddr Duna. Essential in this restoration is that higher discharges in these branches will occur, especially at low Danube discharge situations. This should prevent bad water quality cir-
viz, valamint a vizi organizmusok cserejet a Duna es a mellekdgai kozott.
II. valtozat: a regi mellekagak osszekotesevel egy nagy mellekag kialakitasa. Ez a megoldds jelentdsen megvdltoztatja a viz dramldsdt a hulldmteren keresztul. Az eldnye az, hogy a meglevd holtdgak osszekotesevel jelentos esest tudunk elddllitani a vizkivetel es a torkolat kozott, ami javitja az dtfolydsi viszonyokat es csdkkenti az dgak feliszapoldddsdt. Mdsreszrdl viszont megepUesehez jelentos mennyisegu kotrdsra van szukseg.
eszaki resze (Keselyus) sokkal nedvesebb lesz. Egy mocsdrszeru teriilet alakul ki, amely a hulldmter talajvizet tdpldlja. Termeszetesen a Sid vizszintjenek megemelese megvdltoztatja a Sio vizgazddlkoddsdt is. A szdmttdsok azt mutatjdk, hogy a vizszint 90 mBfszintre tortend emelese kb. 500 ha teriiletet ontene el a Sio torkolati muve felett evente ketszer 5-7 napon at dprilisban ill. mdjusban. A vegetdcios modell szerint ez nem kdrositja az erdot sem bkologiai, sem gazdasdgi szempontbol.
III. valtozat: Sio-vfz felhasznalasa. Jelenleg a Sio - idoszakosan - a Balaton vizet szdlUtja a Dundba. Ebben a vdltozatban a vizet eloszor tdroljuk, majd felhaszndljuk a hulldmter vizelldtdsdnak javitdsdra. Ennek kovetkezteben a hulldmter
cumstances and enhance a free exchange of water and aquatic organisms between the river Danube and its side-arms.
Alternative II: creation of a large side-channel through connection of old side-arms. Through this alternative the flow patterns of water through the floodplain change considerably. The advantage of connection of the different existing side-channels is that the entire head from intake to outlet can be put to use, enhancing the throughflow and reducing silting up of the channels. On the other hand the construction entails large amounts of soil replacement.
Alternative III: using water from the Sio. In the present situation the Sid - from time to time - brings water from Lake Balaton directly to the
Danube. In this alternative the idea is first to store this water and then to use it for improving the water availability in the floodplain. Thus the Keselyus area in the northern part of the floodplain would become considerably more wet. At some sites marshes would develop as important ecologocal habitats, that would recharge the ground water of the floodplain. Of course increasing the water levels of the Sio will also have effect on the water management situation upstream of the Sio. It has been calculated that an increase of the water level to 90 mBf implies that an area of 500 ha upstream of the location where the Sid water enters the floodplain would be inundated two times 5-7 days in April and May. According to the vegetation model this will not damage the forests, neither from ecological nor from commercial point of view.
A Gemenci hulldmter vizgazddlkoddsdnak megjavUdsa nem megy ingyen. E stratigiai elemzis keretiben is el kellett vigezni a szukseges beruhdzdsi es fenntartdsi kbltsegek szdmttdsdt. Egy rbvid kbltseg-haszon elemzisevel probdltuk kimutatni az egyes vdltozatoknak a kulbnbbzo erdekekre gyakorolt hatdsdt. Az I.vdltozat a meglevd holt- es mellikdgak kotrdsdt irdnyozza elo. Az elemzes eredmehyei azt mutatjdk, hogy a Ven, a Moric es a Kdddr Duna (I/c, I/d is lie vdltozatok) esetiben az bkologiai rehabilitdcio elfogadhato dron elvigezheto. A Grebeci Duna fejlesztise (l/a valtozat) nagyon nagy mennyisegu kotrdst iginyelne ami ezirt meglehetosen kbltsiges lenne. A Rezeti Duna (Ifb valtozat) morfologiai viszonyai miatt meg nagymennyisigu kotrds sem segitene szdmottevoen az bkologiai helyzeteh. A II. valtozat egy hosszabb, riszben mestersiges mellekag kialakitdsdt irdnyozza el. A ll/c valtozat a Gribeni, Reziti, Csertai is Nyiki Holt-Duna vonaldt haszndlja fel, mig a Ilfb valtozat az ennil rbvidebb VehDuna, Csertai is Nyeki Holt-Duna nyomvonalat kbve-
M l AZ ARA? WHAT WOULD IT COST? The improvement of the water management of the Gemenc floodplain cannot be obtained without money. In the frame of this policy analysis the costeffectiveness analysis of the alternatives had to be done as well. It is meant to show the economic influences of the different alternatives with regard to the different interests. Alternative I envisages the dredging of the existing side-branches of the Danube. The analysis results show that ecological rehabilitation can be attained at reasonable costs for the Ven, Moric and Kdddr Duna (alternatives lie, Vd and lie). Improvement of the Grebeci Duna (alternative Va) will entail huge amounts of dredging and is therefore quite expensive. Due to the hydrological characteristics of the Reziti Duna (alternative lib) here even major dredging does not seem to result in a significant improvement of the ecological situation. Alternative 11 aims for a longer, partially artificial side branch. Two sub-alternatives have been worked out. Alternative Wa uses parts of the Grebeci, Reziti,
ti. Habdr a Il/a valtozat esetin a kezdeti kotrdsi kbltsig viszonylag magas, a beruhdzds hatikonysdga kedvezo a valtozat hossza is a kis fenntartdsi kotrds igenye miatt. Tehdt ez egy igeretes alternatwdnak tunik. A rbvid mellekag (Il/b valtozat) nimi bkologiai javuldst eredminyez. A Il/b. valtozat eseten kisebb indulo, de nagyobb fenntartdsi kbltsiggel kell szdmolnunk, mert ez esetben a nagyobb dtdramlo vizhozam nagyobb hordalekmenynyisiget szdlUt az uj mellekdgba, ahol az nagyobb feliszapoloddshoz vezet. A II. valtozat beruhdzdsi kbltsigeit erosen megnbvelik a bajai hulldmteri hid alatti dtvezetes epttesi kbltsigei. A III. valtozat nemileg eltir filoz6fia.jd.val igyekszikjavttani a hulldmter vtzelldtdsdn. Mig azl.es a II. valtozat dramlo vizter letrehozdsdval prolodl javitani a hulldmteren levo drterek vvzminosigin es bovtteni a vizi ilohelyek szdmdt, addig a II. valtozat egy nedves, mocsaras teriiletet hoz litre is ezen keresztul tdpldlja a hulldmter alatti talajvizet. Ehhez a Sio vizet haszndlja fel azon idoszakaszban, amikor a Balaton vizfeleslegit vezeti a Dundba. Ismit kit alvdltozat jbhet szoba. A
Csertai and Nyiki Holt Duna, while alternative Il/b links the Vin, the Csertai and the Nyiki Holt Duna resulting in a shorter path. Although for the long lateral channel (alternative Il/a) the initial dredging costs are relatively high, the cost-effectiveness of the alternative is favourable due to its length and low maintenance dredging costs. Hence, this alternative is also promising. The short lateral channel (alternative II) shows some improvement of the ecological situation. Alternative Il/b invokes somewhat less initial investment but higher maintenance costs because of the higher through-flow carrying higher amounts of sediment into the side branch. In both cases the cost of enlarging the channel below the Baja-Bdtaszek floodplain bridge increases the investment price considerably. Alternative III uses a somewhat different approach to the improvement of the water management. While the first two alternatives try to bring flowing water into the floodplain, thus improving water quality, enhancing habitat diversity and facilitating the more frequent flooding of certain parts of the floodplain
Ill/a valtozat szerint a Sio folyot felduzzasztjdk, a vizet 10-15 napig tdrozzdk mikbzben a gemenci drtir iszaki riszit gravitdcids uton vizzel Idtjdk el. A Ill/b alvdltozat szerint uszo szivattyudllomds segttsegivel emelnek a tbltiseken at a Sio vizit az drtirre. A kit megolddsi valtozat kbltsigei meglehetosen eltirek. A Ill/a valtozat jelentos beruhdzdssal indul (4--500 mill. Ft), a fenntartdsi kbltsigek viszont alacsonyabbak. A Hlfb valtozat kezdetben nem igehyel beruhdzdst mivel a szivattyudllomdsok a vtzugyi szolgdlattol kblcsbn vehetdk. Mas-: riszt azonban maga a szivattyuzds kbltsiges is majd minden ivben elvigzendo.
forest, alternative III aims to create an artificial wetland which may supply the groundwater in this way. For this purpose alternative III uses the clean water of lake Balaton when it is released. Again there are two sub-alternatives. Alternative Ill/a periodically dams up the Sio river, stores the water for a period of 10-15 days and in the mean time gravitationally supplies water to the northern part of the Gemenc floodpain. Alternative Ill/b uses a floating pump station to pump the Sio water over the dykes. The costs are quite different in the two cases. Alternative Ill/a starts with a large investment but then the maintenance costs are lower. Alternative Ill/b needs no initial investment as the pumping stations can be borrowed from the water management. On the other hand pumping is costly and has to be done almost every year.
A gemenci teriiletet olyan osszetett szerkezet jellemzi ahol a folyami es az okologiai folyamatok szoros egymdsrahatdsban vannak jelen. Amint az a jelen strategiai elemzesbol kitunik, a rendszerbe valo bdrmilyen beavatkozdsnak egy sor, mind pozitiv, mind negativ elemeket tartalmazd hatdsa lesz. Az egyes vdltozatoknak a fodg es a mellekdgak hidrologidjdra es morfologidjdra valamint a mellekdgak vizminosegere gyakorolt hatdsait egy egydimenzios modell segitsegevel elemeztiik. Egyik valtozat sem okozfo-
MlK A KOVETKEZMENYEK? WHAT ARE THE CONSEQUENCES ?
The Gemenc area can be characterized as having a complex structure in which river and ecological processes closely interact. As can be learned from this policy analysis any intervention in this system will have a range of effects, both positive and negative. The impacts of the alternatives on the hydrology and morphology of the side arms and main channel and on the water quality within the side arms have been assessed with one-dimensional mathematical models. None of the alternatives are expected to cause problems
lydszabdlyozdsi problemdt ugy, mint az drvizi biztonsdg csbkkeneset, jegtorlaszkepzddest vagy hajdzdsi nehezseget. A vizminoseg javuldsa vdltozatrdl-vdltozatra modosul; taldn az I/a (Grebeci), I/c (Ven) es az I/d (Moric) valtozat adja a legjobb eredmehyt. Az erdeszetre gyakorolt hatds, amit a terinformatikai rendszer segitsegevel hatdroztunk meg, kicsi. A haldszat kbrulmehyei minden valtozat eseteben javulnak csakugy, mint az udulesi lehetsegek. Vegiil megdllapithatd volt, hogy egy egeszseges vizgazddlkoddssal, amely figyelemmel van a teriileIa Grebeci
Altternatfva:
lb Rezeti
Ic Ven
ten jelen levo, kulbnbbzd erdekekre, a gemenci hulldmter rehabilitdcidja megvaldsithatd. Tekintettel a Gemencen meg mindig meglevd kiemelkedd termeszeti ertekekre a javulds lehetdsege igen jd. Gemencet, a hasonld Duna-menti hulldmterek rehabilitdcidjdndl, peldakent tekinthetd.
Id Moric
Ie Kadar
Hossz (km)
8,3
15,2
4,3
4,1
2,1
Okologia
+
0
+
+
Vizminoseg
+
0
+
Fo1yosza ba1yozas
0
0
Beruhazas (mFt) Fenntartas (mFt) Koltseghatekonysag (mFt/km)
350 50 48
..>• Alt. Osszesen 34
Ha Hosszii mellekag
lib Rovid mellekag
Ilia Sio (zsilip)
IHbSiol (szivattyu)
22
8,8
n.a.
n.a.
+
+
0/+
+
+
+
0
0
0/-
+
+
0/-
0
0
0
0
0
0
60 30
0 80
90 10
20 30
644 54
214 184
450 280
0
n.a.
19
24
24
32
45
n.a.
_
++
++
0/+
+
+
520 200
616 n.a.
Erdeszet
-
-
-
-
0
Halaszat
+
0
+
+
+
•
Lid tiles
+
0/+
+
+
0
++
+
0/-
0
Vadaszat
0
0
0
0
0
0
0
0
0
Jetmagyanizat: ++ = jelentosjavulis, + = enyhc javulas / pozili'v hatas, 0 = nines valtozas, - = negati'v hatas, n.a. = nem alkalmazhald
Ia Grebeci
Alternatives:
lb Rezeti
Ie Ven
Id Moric
Alt. I. Total
Ie Kadar
Length (km)
8.3
15.2
4.3
4.1
2.1
Ecology
+
0
+
+
Water quality
+
0
+
River management
0
0
350
34
Ila Ixing lateral
Hb Short lateral
Ilia Sio (weir)
Hlb Sio (pump)
22
8.8
n.a.
n.a.
+
+
0/+
+
+
+
0
0
0/-
+
+
0/-
0
0
0
0
0
0
60
0
90
20
520
644
214
450
0
50
30
80
10
30
200
54
184
280
616
48
n.a.
19
24
24
32
45
n.a.
n.a.
Forestry (ha lost)
-
-
-
-
0
-
-
++
++
Fisheries
+
0
+
+
+
+
0/+
+
+
Recreation
+
0/+
+
+
0
++
+
Hunting
0
0
0
0
0
0
0
Investment cost (in million HUF) Maintenance cost (present value)in million Ft) Cost effectiveness (million HUF/km)
evil
0 0
Legend: ++ = significant improvement, + = some improvement / positive effekt, 0 = no change, - = negative effect, n.a. = not applicable,
with regard to river management requirements such as safety against flooding, ice dams and navigation. Improvements of the water quality vary for the different alternatives, of which alternative I/a (Grebeci), I/c (Ven) and I/d (Moric) probably give the best results. The impacts on forestry, as assessed by using the Geographical Information System developed for the Gemenc area, are quite small. For fishery most alternatives show an improvement, while the recreation potential is enhanced.
The over-all conclusion is that by a sound water management which integrates the different interests in the area, the rehabilitation of the Gemenc floodplain is possible indeed. Taking into account the relatively high nature values still present in Gemenc, the potential for improvement is high. Gemenc could be used as an example for the restoration of similar floodplains along the Danube.
l \ jelen strategiai elemzes a gemenci drteri erdonek a vizgazdalkodds javitdsdval valo rehabilitdcios lehetosegeit vette vizsgdlat aid. Ennek kereteben hdrom fo valtozat is osszessigeben kilenc alvdltozat keriilt feldlhtdsra. Minden egyes vdltozatot aldvetettik okologiai, vizgazddlkoddsi, koltseg, erdogazddlkoddsi, haldszati is udulesi szempontu vizsgdlatnak. A kbvetkezo lepesben ki kell vdlasztani az egyes vdltozatok sikerrel kecsegteto elemeit is azokat a gemenci hulldmter fenntarthato fejlesztesenek is rehabilitdcidjdnak integrdlt vizgazddlkoddsi tervebe kell illeszteni. Ezt a dbnteshozoknak - a lakossdg is a nem-kormdnyzati szervezetek hathatos bevondsdvai - kell elvegezniuk. Mikdzben a figyelmunket a vizgazddlkoddssal kapcsolatos beavatkozdsra forditjuk, a beavatkozdsi tervet ki lehet egesziteni a kapcsolodo teriiletek - erdeszet, vadgazddlkodas is Mules szempontjaival is.
A KOVETKEZO LEPES
This policy analysis has aimed to investigate the possibilities of rehabilitation of the Gemenc floodplain forest through the improvement of its water management. It has revealed three main alternatives and altogether nine sub-alternatives. Each of the alternatives have been analyzed for ecological, river management, cost effectiveness, forest management, fishery and recreational use point of view. The next step is to choose the promising elements of each of the alternatives and to combine them into an integrated management plan for the sustainable development and rehabilitation oj the Gemenc floodplain. This should be done by the decision makers with the intense involvement of public opinion and non-governmental organizations. Besides dealing with measures related to the water system, the management plan could be extended with new management options in related fields of interest, such as forestry, game management and recreation.
Jelen tanulmany kereteben a Delfti Hitiraulikai Intezet, a RIZA, a VTTUKI es mas intezmenyek vegeztek kutatasokat. Eredmenyeiket az alabbi jelentesek tartalmazzak: Osszefoglalo jelentes: A gemenci hullamter rehabilitacioja. Munkadokumentumok: 1. Vegetacios tanulmanyok: A. Okologiai es vegetacios tanulmanyok a gemenci hullamteren, Del-Magyarorszagon (Ir. J.G.M. Rademakers) B. A novenyzet es a hidrologia/geomorfologia osszefuggese a gemenci hullamteren (Drs. M.M. Schoor es Drs. L van Splunder) 2. A mellekagak vizellatasanak javftasa a Gemenci Termeszetvedelmi Teruleten (VTTUKI) 3. Hidraulikai es morfologiai modellezes (Ir. E. van Velzen es Ing. J. van Zetten) 4. Vizminosegj modellezes (Ir. S. de Groot es Ir. M. Bokhorst) 5. Vegetacios modellezes (Dr. B. Pedroli) 6. A gemenci teriilet gazdasagi elemzese (Drs. P.J.A. Baan) 7. A gemenci teriilet teririiormatikai rendszere (Dr. B. Pedroli es R. van Buren) 8. Okologiai tanulmanyok (Drs. M.M. Marchand, Drs. E.C.L. Marteijn, A. Klink es B. Kalocsa) A jelentesek masolatat az alabbi amen lehet beszerezni: Institute for Inland Water Management and Waste Water Treatment (RIZA) Drs. E.C.L. Marteijn P.O.Box 17, 8200 AA Lelystad Hollandia vagy VTTUKI Consult Rt. Dr. Bakonyi Peter Budapest Kvassay Jeno lit 1. 1095
In the framework of the presented study research activities have been undertaken by Delft Hydraulics, RIZA, VTTUKI and others. These activities and their tesults are presented in the following reports: Gemenc Hoodplain Rehabilitation Study; Main Report Working Dokuments: 1. Vegetation Studies: A. Vegetations-okologische Untersuchung im Donau-Auenwaldgebiet von Gemenc, Sudungarn (Ir. J.G.M. Rademakers) B. The relation between Vegetation and Hydrology/Geomorphology in the Gemenc Floodplain (Drs. M M . Schoor & Drs. I. van Splunder) 2. Restoration of the fresh water supply of side branches in the Gemenc Protected Landscape area (VITUKI) 3. Hydraulic and morphological modelling (Ir. E. van Velzen & Ing. J. van Zetten) 4. Water Quality modelling (Ir. S. de Groot & Ir. M. Bokhorst) 5. Vegetation modelling (Dr. B. Pedroli) 6. Economy of the Gemenc area (Drs. P.J.A. Baan) 7. The Geographic Information System for the Gemenc area (Dr. B. Pedroli & R van Buren) 8. Ecological Studies (Drs. M.M. Marchand, Drs. E.C.L. Marteijn, A. Klink & B. Kalocsa) Copies of these reports can be obtained at the Institute for Ingland Water Management and Waste Water Treatment (RIZA), P.O.Box 17, 8200 AA Lelystad, The Netherlands (Drs. E.C.L. Marteijn), or at VITUKI Consult Rt., 1095 Budapest, Kvassay Jeno ut 1. (Dr. Peter Bakonyi).
