Hydro-ecological relations in the Delta Waters

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Table 1 PCB levels in ees of grebes from the Haringvliet basin and sore clean reference amas (values in ~g/kg) basin areas PCB 138 4 900 - 18 500 120 - 1 450 PCB 153 9 MO - 16 500 205 - 2 $50 PCB 186 1 850 - 3 450 10 - 195 Recent research also show8 that cormrants, a fish-eat*g spaeies at the end of the fopd chain, are reproducing far leas snecessfully iU the northern part of the Delta region (Biesbasch) than in other areas (Boudewijn, et al. 1989). In a number of colonies along the major rivers (IJssel. Rhine and Waal) the reproduction rate is two to three rirpes higher than in the Biesbaach, and it is four tines highex in areas witb a relatively low level nf palltLTian. (See Table 2). Table 2 Number of puns leaving the nes per clutch, in a d e r connorant colonties in 1988. of &ss with a MBj or river areas Biesbosch reiatfrely low level of gollrttion OV Oude Venen (Friesland) BW B~ede Water CVoorne) W Wijhe (Gelderse IJseel3 0 OZst (Gelderso TJssel) P Pannerden (Upper Rhine) W Baaften (Waal) bB Dordrse BSeabosch
Bio-essay Weriments with polluted sediment from Due of the smaller harbours in the Delta region (&resicens) revealed effects on oyster larvae (Crassostrea Awulatal and a ernstacean Lhthypreia). Even when B large proportion of Clew sediment was added to the polluted harbour sludge, mortality rates were demonstrably affected by pollution (Hnrk, 19883. The effects of increasing pollution in water md riverbeds are al-so noticeable in the Western Srheldt estuary. The popuLation of hatbaur seals (Phoca vitulina) has now disappeared. Food chains in rhe eastern part of the estuary have been dfsthed and the number of benthic organisms significaatly raduced. It is acknowledged that the amounts of cabmiwu now exceed acceptable leveLs for hum consumption. particularly in flounder (Platickthys flesus), in shellfish such as mussels (Mytilus edule) aad in sea plants such as Aster tripolium and Salicornfa spec., foutld in the Lad of Saeftinghe area. 6 CONCLXISIONS AI43 FINAL ReMaaKS Although water quality and the condition of the beds we*e not taken intn consideration at the time of the origtnal decisions concerning the phasing and implementation 05 the Delta Plan, it is now recognized that the separation of parts of the Delta from the waters of the Rhine and Eeuse, as part of the compartmentalization programme for the regiwn, has played a significant role in wtntainSs& a satisfactory level of quality in the majority of the beds in the Delta. As a result, the quality of the sediment in tlle central secrion of the estuary is clese to natural backgrrrwd levelS. However, the closure of an estuary such as the Rarin8vliet ean lead to large amounts of polluted river ~ilt settling in new sedimentation areas. An other ntethod af controlling the distribution of contaminated rmaterial is to limit the tkrou~hpm of water if sluices for water management are available in the colnpartment~llzation-dams. This idea has, for instance, been incorporated into the plan for managing the quanrity of water of Lake Zaoin.
Page 1 and 2: Netherlands organkation fw applied
Page 4 and 5: TNO Commlitee on Hydrological Resea
Page 6 and 7: 2 RIVER WATER AM) THE QPALITH OF TB
Page 8: B.J.M. Baptist BIJkswaterstaat. Tid
Page 11 and 12: This approach will put to use what
Page 13 and 14: Estuaries that have not been influe
Page 15 and 16: 2 CHIWGES XN TEE DELTA The Delta ar
Page 17 and 18: area decltned cnnside~ably, leadins
Page 19 and 20: Plan, then it is apparent tbt the s
Page 21 and 22: Tiddl flats df the Eastem Seheldt v
Page 23 and 24: tracefore possible to convert the a
Page 25 and 26: Figsrlre 7 Changes in the cadrnrum
Page 27 and 28: prevention measures are desirable h
Page 29: elationships between different spec
Page 33 and 34: considerable thought to drawing up
Page 35 and 36: ShLOUONS, W. and BYSINK, W.D., 1981
Page 37 and 38: are taken. The first year after the
Page 39 and 40: The Hollands DiepJnaringpllet is pa
Page 41 and 42: In 1976 the determination of chlozo
Page 43 and 44: , 0.66 m 0,s - 0.02 1989 I 0.86 - 0
Page 45 and 46: Table 3 Eutrophication of the Volke
Page 47 and 48: Laks Volkarek ---- Lake Zoom 0.40 0
Page 49 and 50: 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$3 in an increase of
Page 68 and 69: model calculations reveal that a ni
Page 70 and 71: Table 3 PreUmInary carbon budget of
Page 72 and 73: Water life of Lake Grevelingen
Page 74 and 75: macrophytes livkg on or rooting in
Page 76 and 77: less predictable for water managers
Page 78 and 79: ILWNEWIJK, A.. KEIP, C., 1988. De v
Page 80 and 81:
XBE CHANGING TmAL LAMXiCAPE I N TEE
Page 82 and 83:
The storm surke of L&Z1 A.D., knorm
Page 84 and 85:
osi* rn@8IOIP m .SL 4 Has F~~ULB 3
Page 86 and 87:
During the 19th century man starts
Page 88 and 89:
mudflats have retreated some 100-20
Page 90 and 91:
aq811~33a.e~ pue 3pTatlJS uxaJsafi
Page 92 and 93:
Erosion by waves of sandy shoals (c
Page 94 and 95:
Lt has been estimated that the sedi
Page 96 and 97:
Implementafion of the Delta Project
Page 98 and 99:
ECOLOGICAL DEVELOWdENT OF SALT MAKS
Page 100 and 101:
fn tidal water systems sedimentatio
Page 102 and 103:
hierarchical position. Tn the egtua
Page 104 and 105:
Of course. tke environmental change
Page 106 and 107:
wind erasson, desaliuation, aeratio
Page 108 and 109:
Fonner tirtal flats with saltmarsh
Page 110 and 111:
Grevelingen. Lake Veere and Krammer
Page 112 and 113:
As mentioned above aa important que
Page 114 and 115:
A seaond important perspective for
Page 116:
BEEEXNX, W.D. and 80ZBf&. J. L9M. T
Page 119 and 120:
are determining the dfstrlbution af
Page 121 and 122:
this volume or in Duutsaa, et aL, 1
Page 123 and 124:
artificial waterflow was created af
Page 125 and 126:
of waterbirds occur regulsrly. The
Page 127 and 128:
. DISTRIBUXIOBI OF WATEJBIRoS OVER
Page 129 and 130:
small bird$ 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.
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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