Hydro-ecological relations in the Delta Waters

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The preseat knarledge of birds in the Delta area and the data presented in this paper result from the wtrrk of many people. Eluch is due to Rijkswaterstaat, Tidal Waters Division (the f~mer Delta Department) which sponsored a project in which Riikswaterataat (Hen!+ Baptist, Eris Narceijn and Peter Xeiniager) carried out the monthly counts and breeang bird surveys, the Delta Institute for Eydrobiplogical Research. Yerseke (Xob Lambeck and eolleagnea) which started a ringing pragramme 19 co-operation With Eijkswaterstaae, end the Uaiversicg of Gent which stuared same aspects of the feeding ecohgy of waders (Patzick mire, Jan Seys, Johan Stuair. Fred Tesk and Tom Ysebaert). 2 DEGCRDTION OX THE AREA As the ecological conditions are so different between the basizis and because they have changed oonsiderably, a brief description of the Delta area (Rig. 1) is even. More details can be found elsedere in NETHERLANDS Pigure 1 !4ap lapof hasins the Delta area with the location of the different
this volume or in Duutsaa, et aL, 1982. The situation is descriBed up to 1984 since the data on birds presented in thia paper are restricted to the period 1976-1984. The major physical and chemical characteristics of the afferent basins are given in Table 1. For each OS the tidal areas, the surface of salt marshes, tidal flats, tidal waters (the area permanently covered by water) and adjacent wetlands (creeks, "inlagen" and grasslands which are used by birds either as resting or as additivnal feediqg sites) is given. For tbe lakes the surface of deep water ( > 1.5 m), @hallow wager ( 1.5 m) and sbwes is given. Shores are the very shallow areas ( F 0.2 m) of the lake of the majority of the areas perraanently exp~sed after the fomatlon of the lake and now used by weterbirds Kagrieultural land, nature reserve etc.) as well as the adjacent wetlands. The Voordelta is that part of the North Sea just off the Delta area. It consists bf a system of chwnels and shallow areas. Salintry atrd turbidity are high. The sandy beaches are subject to hem wave action and su£fer from a very high ~ecreation pressure. More details of thia area and the changes occurring here ate described by Mulder, 1989. The Westerschelde is the only rema*ning true estuary in the Delta. The freshwater input frqm the river Schelde is small (on average 100 m3/sec), hence the braokish part is limited to the area beMwn Ancwerpen and Hansweert. From the mouth tmards Antwerpen a gradient of decreasing salinity, oxygen and transparency. and of inereasing suspended meter and nutrients is found (Humel, et al, 19881. Large mid- and sandflats occur all over the eatuary. "Bet Verdronken Land van Saeftinghe". in the brackish part BE the estuary, i5 the largest salt marsh (8250 ha) of the whole Delta area. The esnurry is characterized by a large anthropogenic stress due to discharges of inorganic and organic eontamfnants, mfnly by the river Sahel.de, but alsa from othar effluenrs slew the Westerschelde itself, and due to intensive dredging activities for shipping. In the Oesrerschelde rhe input Q£ fresh water is so small, that the area is better characterized as a sea arm than as an estuary. Salinity is high and constant; turbidity, concearrations of nutrieets and pollutants are low. Before the constructioo of the
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Netherlands organkation fw applied
Page 4 and 5:
TNO Commlitee on Hydrological Resea
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2 RIVER WATER AM) THE QPALITH OF TB
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B.J.M. Baptist BIJkswaterstaat. Tid
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This approach will put to use what
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Estuaries that have not been influe
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2 CHIWGES XN TEE DELTA The Delta ar
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area decltned cnnside~ably, leadins
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Plan, then it is apparent tbt the s
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Tiddl flats df the Eastem Seheldt v
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tracefore possible to convert the a
Page 25 and 26:
Figsrlre 7 Changes in the cadrnrum
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prevention measures are desirable h
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elationships between different spec
Page 31 and 32:
Bio-essay Weriments with polluted s
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considerable thought to drawing up
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ShLOUONS, W. and BYSINK, W.D., 1981
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are taken. The first year after the
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The Hollands DiepJnaringpllet is pa
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In 1976 the determination of chlozo
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, 0.66 m 0,s - 0.02 1989 I 0.86 - 0
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Table 3 Eutrophication of the Volke
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Laks Volkarek ---- Lake Zoom 0.40 0
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4 WAGBEET MEdSIIRaS TO PEEVBT OR LT
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Table 5 gives estimtes of the phosp
Page 53 and 54:
In principle, two states of equilib
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Zooplankton (Alma affinis) Pike (Es
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EUTROPHICATION OF ESTUAAIES AND BRA
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The average discharge of Xhine and
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and only l-2% cows frm the aive Sch
Page 64 and 65:
highest trophic potential: nutrient
Page 66 and 67:
period 1980-19$3 in an increase of
Page 68 and 69:
model calculations reveal that a ni
Page 70 and 71: Table 3 PreUmInary carbon budget of
Page 72 and 73: Water life of Lake Grevelingen
Page 74 and 75: macrophytes livkg on or rooting in
Page 76 and 77: less predictable for water managers
Page 78 and 79: ILWNEWIJK, A.. KEIP, C., 1988. De v
Page 80 and 81: XBE CHANGING TmAL LAMXiCAPE I N TEE
Page 82 and 83: The storm surke of L&Z1 A.D., knorm
Page 84 and 85: osi* rn@8IOIP m .SL 4 Has F~~ULB 3
Page 86 and 87: During the 19th century man starts
Page 88 and 89: mudflats have retreated some 100-20
Page 90 and 91: aq811~33a.e~ pue 3pTatlJS uxaJsafi
Page 92 and 93: Erosion by waves of sandy shoals (c
Page 94 and 95: Lt has been estimated that the sedi
Page 96 and 97: Implementafion of the Delta Project
Page 98 and 99: ECOLOGICAL DEVELOWdENT OF SALT MAKS
Page 100 and 101: fn tidal water systems sedimentatio
Page 102 and 103: hierarchical position. Tn the egtua
Page 104 and 105: Of course. tke environmental change
Page 106 and 107: wind erasson, desaliuation, aeratio
Page 108 and 109: Fonner tirtal flats with saltmarsh
Page 110 and 111: Grevelingen. Lake Veere and Krammer
Page 112 and 113: As mentioned above aa important que
Page 114 and 115: A seaond important perspective for
Page 116: BEEEXNX, W.D. and 80ZBf&. J. L9M. T
Page 119: are determining the dfstrlbution af
Page 123 and 124: artificial waterflow was created af
Page 125 and 126: of waterbirds occur regulsrly. The
Page 127 and 128: . DISTRIBUXIOBI OF WATEJBIRoS OVER
Page 129 and 130: small bird$ extludiag them vill net
Page 131 and 132: In order to lsok for relatiouehips
Page 133 and 134: Table 3 Biomass of macroroobenthos
Page 135 and 136: freshwater basins. Clearly the pres
Page 137 and 138: scmthem bottueary o-f the winter di
Page 139 and 140: OCLURRENCE AND DIET QF B ~T .tUQ 80
Page 141 and 142: 5.2 H- factors Next to all fartors
Page 143 and 144: Bewick's Swans (Cygnus columbariusl
Page 145 and 146: m's activiries do not always have t
Page 147 and 148: measure affecting food supply or av
Page 149 and 150: DOQiWT$QS, G. 4 TWISK, F., 1987. De
Page 151 and 152: MEININGEB, P.L. and HAPEREX, A.M.M.
Page 153 and 154: PISCIVORES Litfle Grebe Great Crest
Page 156 and 157: IPYBRO-EGOLOOIOAL BELATIONB ZN THE
Page 158 and 159: apart from upstream purification; -
Page 160 and 161: Storm surge barrier Eastern Scheldt
Page 162 and 163: - In addition to existing managemen
Page 164 and 165: Nature is pliable. Belattvely young
Page 166 and 167: Ro. 1. No. 2. SQ. 3. Investigations
Page 168 and 169: 25. The relation between water quan
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Hydro-ecological relations in the Delta Waters

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