Hydro-ecological relations in the Delta Waters

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hierarchical position. Tn the egtuarine situation the water regime is one of the met essential factors detemising processes in soil. gegstation and fa-. The relation between the average salt concentation and the distrlbotion of some vegetation types is a sood example wf this dominance (Big. 3). Ae saon ae great changes occur in the outer cmpartntents of the made1 /by human interference of other), this has impertaut consequences for the hierarchically lowar parts. Cholllges in the lower camgartments have Lesa cons+quenees on the system a5 a whule. Figure 4 (derived from Reftlnk, 1979) gzves a good exwle nf such a situation. In the wet autnmn of 1961 severe waterlogged conditions occurred on a higher salt marsh in the Grevdingen estaary. This was the primclry cau6e for a die-bmk of the vevetation of Halimione pnztulacoides on that WSh. In the long run there was, however, no chenge of the saltmarsh ecssyatem as a whole and after sonre years the orfgmal vegetation could recover. The erosion of a tidal flat or a salt marsh and the developmt of new onea elsewhere in the same tidal system are an exmple of the same e).clic dynaunica on a larger scale of space and tb. The con$truction af the DelCa Works resulted in quite different types of ecological dynamics. The water syetm a5 a whole changed t~tally and resulted in a cmplere new and irrevexsihle development of water and lad (Beeftink. 1987). After the fidehtx~g of rhe dmh many of the estuafkre plants and animals died and nerv species had to celonize the disturbed ecobystems. Id Che beginning the daminaring species in the vegetation changed from year tcr pear. Later on changes took place much more gradually. There were also marked differexices between habitats. The vegetation of the lowar salt mrshes died totally sithin two or three years. The higher salt marshes were well adapted 60 less frequent inundations and vegetation changed gradually after the disappearance of the tides. In tha reed marshes and willow woedlands of the brackish and fresh estuaries the same pattern occurred. Theae vegetattons actually did not die, btrt durtng some S to l@ years after damming their species composition and structure changed very mufh.
NUWBER OF BREEDING PAIRS 70 Fieure 5 Development of three breeding bird populations on the Hompelvoet, a newly created island in Lake Oreuelingen. Crosses: Kentish Plover (Charadrius alexandrinus); triangles: Redsbank (Tringa totanus); circles: Willow Warbler (Phylloscopus trocNus). Data kindly submitted hy 6.J. Slab, National FQrest Service in the Netherlands, Goes. HEAN SEA LEVR FRESH BRACKISH SALT Figure 6 Distribution of some vegetation types in relation to height and tidal flooding before the construction of the Delta Works. The following vegetation types are indicated (Westhoff and Den Held, 1969) : Fresh: a. Scirpus, b. Phragmites, c. Salicion alhae; Brackish: a. Scirpus. b. Phragmitas, c. grassland (Lolio- PotentFUIon): Sdt: a. Salicarnion, b. Spartinion, c. Puccinellion, d. Armerion
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Netherlands organkation fw applied
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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
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Figsrlre 7 Changes in the cadrnrum
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prevention measures are desirable h
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elationships between different spec
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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
Page 51 and 52: Table 5 gives estimtes of the phosp
Page 53 and 54: In principle, two states of equilib
Page 55 and 56: Zooplankton (Alma affinis) Pike (Es
Page 58 and 59: EUTROPHICATION OF ESTUAAIES AND BRA
Page 60 and 61: The average discharge of Xhine and
Page 62 and 63: and only l-2% cows frm the aive Sch
Page 64 and 65: highest trophic potential: nutrient
Page 66 and 67: period 1980-19$3 in an increase of
Page 68 and 69: model calculations reveal that a ni
Page 70 and 71: Table 3 PreUmInary carbon budget of
Page 72 and 73: Water life of Lake Grevelingen
Page 74 and 75: macrophytes livkg on or rooting in
Page 76 and 77: less predictable for water managers
Page 78 and 79: ILWNEWIJK, A.. KEIP, C., 1988. De v
Page 80 and 81: XBE CHANGING TmAL LAMXiCAPE I N TEE
Page 82 and 83: The storm surke of L&Z1 A.D., knorm
Page 84 and 85: osi* rn@8IOIP m .SL 4 Has F~~ULB 3
Page 86 and 87: During the 19th century man starts
Page 88 and 89: mudflats have retreated some 100-20
Page 90 and 91: aq811~33a.e~ pue 3pTatlJS uxaJsafi
Page 92 and 93: Erosion by waves of sandy shoals (c
Page 94 and 95: Lt has been estimated that the sedi
Page 96 and 97: Implementafion of the Delta Project
Page 98 and 99: ECOLOGICAL DEVELOWdENT OF SALT MAKS
Page 100 and 101: fn tidal water systems sedimentatio
Page 104 and 105: Of course. tke environmental change
Page 106 and 107: wind erasson, desaliuation, aeratio
Page 108 and 109: Fonner tirtal flats with saltmarsh
Page 110 and 111: Grevelingen. Lake Veere and Krammer
Page 112 and 113: As mentioned above aa important que
Page 114 and 115: A seaond important perspective for
Page 116: BEEEXNX, W.D. and 80ZBf&. J. L9M. T
Page 119 and 120: are determining the dfstrlbution af
Page 121 and 122: this volume or in Duutsaa, et aL, 1
Page 123 and 124: artificial waterflow was created af
Page 125 and 126: of waterbirds occur regulsrly. The
Page 127 and 128: . DISTRIBUXIOBI OF WATEJBIRoS OVER
Page 129 and 130: small bird$ 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.
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PISCIVORES Litfle Grebe Great Crest
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IPYBRO-EGOLOOIOAL BELATIONB ZN THE
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apart from upstream purification; -
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Storm surge barrier Eastern Scheldt
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- In addition to existing managemen
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Nature is pliable. Belattvely young
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Ro. 1. No. 2. SQ. 3. Investigations
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25. The relation between water quan
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Hydro-ecological relations in the Delta Waters

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