AU
stream,
Stages III & IV
seawater with water of sufficiently low from the tunnels and the Chung Mei salinity to be acceptable for normal domestic use. It is easily seen that straight dilution would take a consi- derable time and waste freshwater in- flow; in order to reduce the time required for dilution and to conserve water. most of the seawater pumped from the cove before fresh- water was diverted into it. A further problem will arise as the salinity of the water trapped in Plover Cove is reduced; salts from the pore water in the sea-bed mud will diffuse into the fresher water above.
was
The effect of this diffusion has been calculated theoretically and, in order to simulate actual conditions, field lests were carried out using 10 in. and 48 in. dia. welded pipes sunk vertically into the sea-bed and, in ad- dition, laboratory tests were made in tanks up to 6 ft. dia. Good correla- tion was obtained between the theore- tical, field and laboratory results.
The many biological changes in- herent in the salt/brackish fresh water conversion will continue to be studied until the freshwater regime is estab- lished. The rapid lowering of salinity from about 33,000 p.p.m. in early 1967 to roughly 300 p.p.m. in the autumn of 1967 will kill most of the marine animals and plants in the re- servoir area. To reduce the amount of decaying matter, as much as pos- sible of the fish and plant life were removed during the periods of draw- down and subsequent dilution. The establishment of a freshwater regime will be speeded up by controlled stock- ing with selected fish and by the natural movement of freshwater an- imals and plants into the reservoir
Preliminary investigation and design work for stages III and IV has already been undertaken. However, construc- tion of these stages, which will utilize the extensive catchment areas to the south of Tolo Channel and east of Tide Cove, has not been authorised.
APPENDIX 'A'
PLOVER COVE WATER SCHEME STAGES I & II PRINCIPAL STATISTICS
Dams
PLOVER COVE MAIN DAM
Crest length Crest level
Max. construction
height
Av. depth of mud
dredged
Av. level of mud
Av. level of foundation Quantity of dredging Quantity of decom-
-74 ft. P.D. 7,000,000 cu.yd. 7,500,000 cu.yd.
Max. construction
height
60 ft.
PLOVER COVE SOUTHERN SUBSIDIARY DAM
Crest length
Max. construction
height
LOWER SHING MUN DAM
Crest length Max. height
Bellmouth spillway Spillway capacity
Reservoir capacity
Reservoir area
Quantity of materials
690 ft.
50 ft.
750 ft.
186 ft.
160 ft. dia.
20,000 cusecs
910 m.g.
57 acres
1,600,000 cu.yd.
LOWER SHING MUN SUPPLY BASIN
DAM
Length
Crest length
247 ft.
Max. height
47 ft.
Basin capacity
$ m.g.
LAU SHUI HEUNG IRRIGATION DAM
Crest length
140 ft.
Max. height
78 ft.
Reservoir capacity
27 m.g.
6,800 ft.
Reservoir area
8.2 acres
+36 ft. P.D.
HOK TAU IRRIGATION DAM
Crest length
200 ft.
127 ft.
Max. height
65 ft.
Max. height above
sea-bed
Reservoir capacity
32 m.g.
77 ft.
Reservoir area
7.1 acres
Max. depth of mud
dredged
56 ft.
RIVER INDUS FABRIDAM
107 ft.
41 ft.
-33 ft. P.D.
Height (fabridam only) Basin capacity
9 ft.
6 m.g.
TAU PASS FABRIDAM
65 ft.
5 ft.
1 m.g.
TAI PO TAU FABRIDAM
Length
125 ft.
Height (fabridam only) Basin capacity
12 ft.
62 m.g.
30,000 m.g.
Tunnels, Shafts & Culverts
Reservoir max. length
2,950 acres 31⁄2 miles
PLOVER COVE NORTHERN SUBSIDIARY DAM
Crest length
Section *River Indus to
Dia. (ft.)
Length (ft.)
650 ft.
Twin-42
20,400
FIG. 2
posed rock filling Quantity of rock fill Quantity of sand filling Spillway level Spillway length Spillway capacity Reservoir gross
capacity Reservoir useful
capacity Reservoir area
1,250,000 cu.yd. 2,250,000 cu.yd.
27 ft. P.D. 800 ft.
40,000 cusecs
39,000 m.g.
Length
Height (fabridam only) Basin capacity
NORTH-SOUTH SYSTEM
Tau Pass pipeline
CATCHWATERS
+94
TORAGE
STORAGE TO SUPPLY
E
+410
TAI MEI TUK
TAI MEI TUK
PUMPING STATION?
CATCHWATER
BA
TAU PASS CULVERT
TUNNELS AND INTAKES
+67
BC
STORAGE
PLOVER COVE
RESERVOIR
CA
M.S.L. +4
POSSIBLE
FUTURE
FROM STAGES
SOURCES
MAKE
Far East Architect & Builder October, 1967
+53
TAU PASS FABRICAM
(LOW LIFT)
RIVER INDUS PUMPING
STATION & FABRIDAM
то
TẠI LAM CHUNG
RESERVOIR
(HIGH LIFT)
CHINESE WATER
PLOVER COVE WATER SCHEME
DIAGRAMMATIC LAYOUT
59
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