526.
Aquifer loss (Tổn thát qua tầng chứa nước): The head loss at a pumped or
overflowing well associated with groundwater flow through the aquifer to the well
face.
527.
A q u ifer p ro p erties (C ác đạc tính tần g chứa nước): The properties of an aquifer
that determine its hydraulic behaviour and its response to abstraction.
528.
A q u ita rd (T ầng nước ngầm yếu): It is a formation which has low to medium
permeability which is not sufficient to be a soure of water to flow on a regional
scale, from one aquifer to the other due to leakage. Aquitards behave as semiconfining layers.
529.
A rtesian free flow (Dòng chảy tự do của giếng phun): Natural over ground flow
from well and springs in Ihe artesian basins.
530.
C onfined aq u ifer (T ầng chứa nước có áp): An aquifer bounded above and below
by impermeable beds. Bolh the aquifer and Ihe water it contains are said to be
531.
G ro u n d w a te r b alance (C án bằng nước ngầm ): It is a concept which slates that all
confined.
inputs of water in a defined space and time are equal to the sum of all outputs of
water, and the changes of water storage, in the same space and time.
532.
G ro u n d w a te r basin (Lưu vực nước ngám ): Physiographic or geological unit
containing at least one aquifer of significant area extent.
533.
Im perm eable m aterial (V ật liệu không thấm ): Material that does not permit water
to move through it at a perceptible rate under the hydraulic gradients normally
present.
534. In term ed iate zone (V ùng tru n g gian): It is the portion of the zone of aeration
which lies between Ihe soil water zone and the capillary fringe.
535.
L eaky aq u ifer (T ầng ngậm nước bán áp): Aquifer overlain and/or underlain by a
relatively thin semi-pervious layer, through which flow into or out of the aquifer can
take place.
536.
N a tu ra l rech arg c (Bổ cạp tự nhiên): It is that portion of water which pravitates to
the zone o f saturation under natural conditions.
537.
P eren n ial sp rin g (M ạch nước quan h năm ): A spring that discharges continuously
in all seasons o f the year.
538. P erm eab le m a terial (V ật liệu thấm ): Material that permits water to move through
it at perceptibleTates under the hydraulic gradients normally present.
539.
P o ten tio m etric su rface (M ực thủy tĩnh nước ngầm ): The surface that represents
540.
S a tu ra te d zone (V ùng bào lioà): That part of an aquifer, normally beneath the
Ihe static head of groundwaler.
deepest water table, in which ideally all voids arc filled with water under pressure
greater than atmospheric.
129
541.
Soil water zone (Vùng nước thổ nhuõng): Part of the zone of aeration lhal consuls
of soil and other materials near the ground surface, capable o f discharging water in
to the atmosphere by transpiration of plants or by evaporation. The zooe extends
from the ground surface to major root zone and the thickness varies with the soil
type and vegetation cover.
542.
Cone of water - table depression, or Cone of pumping deression (Nón trflng
nước ngầm hay nón trũng do bơm).
543.
Unconsolidated aq u ifer (T ầng chứa nước không cố kết): An aquifer in which a
water table serves as the upper surface of the zone of saturation.
544.
Zone of fluctuation of water tabic, or Zone of phreatic fluctuations (Vùng dao
dộng đường m ạt nước hay V ùng biến động nước ngầm ): The zone through which
the water table fluctuates from its highest to tile lowest level within the formation, in
response to the discharge and recharge conditions. Depending upon the position of
the water table in the zone, a part of the zone will lie in the zone of aeration and the
other part will lie in the zone of saturation.
II.1.5. DISCHARGE MEASUREMENTS - ĐO LƯU LƯỢNG
545
O pen C onduit, or O pen channel (Lòng d ẫn hở hay kênh hở): Any conduit in
which water flows wilh a free surface.
546.
D ischarge, or R ate of flow (Lưu lượng hay suất dòng chảy): The volume of water
which flows past a particular cross section of a channel or conduit in a unit of lime.
547.
Dead w ater (Nước tù): Water which is not flowing with a significant velocity.
^48.
S urface slope, Slope, YVaterslope (Độ dốc bề m ặt, độ dốc, độ dốc m ặt nnớc): The
inclination o f Ihe water surface expressed as change o f elevation per unit of slope
length; the sine of Ihe angle which ihe surfacc makes with the horizontal. The
langent of the angle is ordinarily used, no appreciable error resulting excepc for the
steepest slopes. Also called "waterslope" in Australia.
549.
Mean m onthly discharge (Lưu lirợng bình quân tháng): Discharge observed or
interpolated and averaged O' er a calendar month.
550.
Discharge Coefficient (Hệ so hru lượng): The ratio of the actual discharge to the
discharge calculated according to a theoretical formula.
551
Stage - discharge relation, R ating curve, D ischarge ratin g curve, or Station
ratin g curve (Q u an hệ mực nước • lưu lượng, dường cong mực nước - lưu lượng,
đường copq q u an hệ mực nước - lưu lượng trạm đo): A curve which expresses
graphically Ihe relation between ihc discharge and its corresponding slage (or
elavutiun of water surface) in a stream or conduit at a given point.
552.
Loope ra tin g curve (Đường cong quan hệ mực nước - lưu lượng dạng vòng day):
Is the result of the differences in ihe water surface slope and bed roughness in rising
and falling stages o f the hydrograph.
130
553.
Discontinuous rating curve (Đường cong mực nước - lưu lượng gián đoạn): Is
the result of the abrupt changes in bed configuration from a dum e bed with high
roughness and low velocity to a flat bed with lesser roughness and higher velocity.
554.
In sen sitiv e ra tin g cu rve (Đường cong m ực nước - lưu lượng p h án bãi ngập): This
type o f a curve results largely from over bank flow where the stream flow may
spread out from its well defined low-flow channel to cover a wide flood plain, where
a large increase in discharge may result in an almost negligible change in stage.
555.
S hiffting ra tin g cu rv e (Đường cong m ực nước - liru lương di chuycn): This type
of a curve reflects local changes in water surface slope, local scour or fill at the
rating section or if the shift is systematic with time, a long term aggradation or
degradation process.
556.
D ischarge m ass cu rv e (Đường cong lũy tích dòng chảy): A curve in which
cum ulated values o f recorded discharge arc plotted against time. The slope of the
curve at any time represents the discharge at that instant.
557.
R esidual d ich arg e m ass curvc, or R esidual discharge m ass d iag ram (Đường
cong lũy tích dòng chày hiệu số hoặc biểu đổ lũy tích (lòng chảy hiệu số): A
plotting of the year-to-year residual departure of discharge from the arithmetic
average accumulated for Ihe period under consideration.
558.
R atin g , C a lib ratio n , C a lib ratin g (Kiểm định): 1- The relation, usually determined
experimentally, between mutually dependent quantities, such as gauge and discharge
of a stream; current m eter vane revolutions and waler velocity. Also "calibration". 2The taking of measurement or the making of observations to establish a rating
"calibrating".
559.
R a tin g cu rv e (Đường cong kiểm clinh): A graphic representation of a rating.
560.
D isch arg e tab le, or R atin g (able (Bàng lưu lượng hay Bàng kicm định): A table
showing the relation between gauge height and discharge of (i) a stream or conduit at
a particular gauging stulion and (ii) oullcls, sluiccs, elc.
561.
S tre am gauging (Đo đạc Ihủv ván): The operation of measuring the velocity of the
flow of water in a channel or conduit, and the area of cross section of ihe flow for tile
purpose o f determ ining discharge.
562.
D ilution g auging, C hem ical gauging, C hcm ihydroinetry, R adioactive solution
gauging (Đo liru lượng bang pliương pliiíp dùng chất chi báo, phương p h áp lioá
học, phương p h á p llủiv hoá và plurơng pliáp dụng dịch plióng xạ) : A m ethod of
m easuring the flow o f water by introducing a constant flow of a solution of known
concentration for a sufficient lapse of lime at one section of Ihe water channel and
llien by determ ining the resulting degree of dilution of this solution at another
downstream section. "Chemical gauging", "electro-chemical gauging" and "radioactive
solution gauging" are different forms of dilution gauging.
563.
E lcctro - C hem ical gauging (Đo Uni lượng băng phương pháp hoá điện ): A
m ethod for Ihe m easurement of flow of water based upon the nearly linear relation
between the concentration and the cleclrical conductivity of a salt solution which
131
m akes it possible to determine the degree o f dilution by integrating a conductivity
time graph.
564.
Cloud - velocity gauging, Allen's method of velocity gauging, colour velocity
gauging (Đo lưu tốc theo phương pháp màn muối, phương pháp A-len, phương
ph áp nhuộm m àu nước) : A method of determining the velocity of a slug of dye
between two stations in the channel. This velocity, used as the mean velocity o f flow,
in the case of adequate spreading, multiplied by the cross-sectionaJ area of the
channel, gives the discharge. "Allen's method" and "colour-velocity method" arc
different forms of cloud-velocity gauging.
565. Float gauging (Đo vận tốc bằng phao): Measurement of velocities of water by
weighted floats for the determination of discharge.
566.
Spot m easu rem en t (Đo điểm ): A single and random measurement of a stream as
distinguished from a systematic or continuous record.
567. G auging statio n (T rạm thủy văn): A gauging station is a selected site on a stream
equipped and operated to furnish basic data from which systematic records of
discharge may be derived.
568. D ischarge site, G auging site, or Velocity - are a gauging statio n (Tuyến lưu
lượng, tuyến đo hay trạm đo lưu lượng theo phương pháp lưu tốc m ạt ngang): A
selected site on a stream for making observations of velocity and area of cross
section with a view to determining the discharge.
569. Dosing statio n (T rạm đo dòng chảy dùng dung dịch hoá học): In chemical
gauging, the station on the stream from where a chemical solution is fed into the
water.
570. Sam pling statio n (T rạm lấy m ẫu nước): In chemical gauging, the station
downstream of the dosing station from which samples of water are taken to find out
the concentration of ihc diluted chemical solution with a view to determining the
discharge.
571. Bench m ark (M ốc CƠ ban): A permanent point on a monument or permanent
structure, whose elevation above a datum is known or fixed by precise levelling, and
which is used as a point o f reference in the detemination of other elevations.
572. Gauging datum (Mặt chuẩn (mốc số 0) của trạm thủy văn): The elevation of the
zero of the gauge above a certain point.
573. P erm an en t gauging (T rạm đo cố định): A gauge which is permanent.
574. D irection peg (Tuyên ngắm): A point on the direction peg line through which ray
from one o f Ihe observation points passes when converging on Ihe pivot point.
575. C o ntrol, control section, com plete control, p a rtia control (M ạt cát khỏng chế,
tuyên ngang thủy văn, m ặt cắt khống chế đầy đ ủ, m ăt cắt khống chế toàn
ph ần ): 1- A section or reach of an open conduit or stream channel where artificial or
natural conditions exist, such as the existence of a dam or a strcatch of rapids, that
make the water level above it a stable index of the discharge. Controls may be
132
com plete or partial. "Complete control" exists where the elevation of the water
surface above the control is entirely independent of the fluctuations of water level
downstream o f it. "Partial control” exists where downstream fluctuations have some
effect on the upstream water level. 2- The cross section in a waterway which is the
bottle neck for a given flow and which determines the enorgy head required to
produce the flow. In the case of open channels, it is the poiru where the flow is at a
critical depth; hydraulic conditions above the point being wholly dependent upon the
characteristics of the control section and entirely in dependent of hydraulic
conditions below the point. In the case of closed conduits, it is the point where the
hydrostatic pressure in the conduil and cross-sectional area of flow are definitely
fixed, except where the flow is limited at some other point by a hydrostatic pressure
equal to the greatest vacuum that can be maintained unbroken al that point.
576.
Shifting control, or Unstable control (Mạt cát không chế di động hay Mạt cát
không ch ế không ổn định): A station is subject lo shifting control when the stagedischarge relation changes, either gradually or rapidly, as the result physical changes
in the control.
577.
G au g in g , or G age (T hủy chi): 1- An instrument, contrivance, graduated scale or
ther device installed at a gauging station for observing or recording the stage of a
stream. It may be an automatic gauge recorder or a non-recording gauge. 2- Height
recorded by the gauge.
578.
T em p o rary gauge (T rạm thủy vân tạm thời): A gauge, connected 10 the permanent
gauge, for the purpose of recording watcr-surface levels under the prevailing
conditions.
579.
G au g e line (Tuyên do): The line across a channel passing through a given gauge.
580.
G au g e line p illars (Cọc q u a n trá c m ục nước): The structural landmarks fixing the
position o f the gauge line.
581.
C h a in g auge, or T ap e gauge (Thước đo nước bàng xích hay dày): Device
consisting of a tagged or indexed chain or other line allached to a weight which is
lowered to the water surface, whereupon the gauge height is read on graduated staff
or opposite an index. Especially suited to bridges.
582.
F loat gauge (T rạm đo nước bằng pliao): Consists essentially of a float of wood,
cork, or usually hollow zinc or coppcr which rides on the liquid surface and rises or
falls with it, its movement being indicated on a scale.
583.
Inclin ed g auge, Sloping gauge (T húy chi nghiêng): A staff gauge on a slope,
graduated to read vertical heights above a datum. Sometimes referred to as a "sloping
gauge".
584.
Slope gauge (T uyến độ doc): Gauges with the same datum fixed above and below a
discharge section for the pirpose of determining the water-surfacc slope belween the
gauge run.
585.
S taff gauge (Thước đo m ực nước): A graduated scale on a staff, plank, metal plate
pier, wall, ect., by which the elevation of the water surface may be read.
133
nguon tai.lieu . vn
Aquifer loss (Tổn thát qua tầng chứa nước): The head loss at a pumped or
overflowing well associated with groundwater flow through the aquifer to the well
face.
527.
A q u ifer p ro p erties (C ác đạc tính tần g chứa nước): The properties of an aquifer
that determine its hydraulic behaviour and its response to abstraction.
528.
A q u ita rd (T ầng nước ngầm yếu): It is a formation which has low to medium
permeability which is not sufficient to be a soure of water to flow on a regional
scale, from one aquifer to the other due to leakage. Aquitards behave as semiconfining layers.
529.
A rtesian free flow (Dòng chảy tự do của giếng phun): Natural over ground flow
from well and springs in Ihe artesian basins.
530.
C onfined aq u ifer (T ầng chứa nước có áp): An aquifer bounded above and below
by impermeable beds. Bolh the aquifer and Ihe water it contains are said to be
531.
G ro u n d w a te r b alance (C án bằng nước ngầm ): It is a concept which slates that all
confined.
inputs of water in a defined space and time are equal to the sum of all outputs of
water, and the changes of water storage, in the same space and time.
532.
G ro u n d w a te r basin (Lưu vực nước ngám ): Physiographic or geological unit
containing at least one aquifer of significant area extent.
533.
Im perm eable m aterial (V ật liệu không thấm ): Material that does not permit water
to move through it at a perceptible rate under the hydraulic gradients normally
present.
534. In term ed iate zone (V ùng tru n g gian): It is the portion of the zone of aeration
which lies between Ihe soil water zone and the capillary fringe.
535.
L eaky aq u ifer (T ầng ngậm nước bán áp): Aquifer overlain and/or underlain by a
relatively thin semi-pervious layer, through which flow into or out of the aquifer can
take place.
536.
N a tu ra l rech arg c (Bổ cạp tự nhiên): It is that portion of water which pravitates to
the zone o f saturation under natural conditions.
537.
P eren n ial sp rin g (M ạch nước quan h năm ): A spring that discharges continuously
in all seasons o f the year.
538. P erm eab le m a terial (V ật liệu thấm ): Material that permits water to move through
it at perceptibleTates under the hydraulic gradients normally present.
539.
P o ten tio m etric su rface (M ực thủy tĩnh nước ngầm ): The surface that represents
540.
S a tu ra te d zone (V ùng bào lioà): That part of an aquifer, normally beneath the
Ihe static head of groundwaler.
deepest water table, in which ideally all voids arc filled with water under pressure
greater than atmospheric.
129
541.
Soil water zone (Vùng nước thổ nhuõng): Part of the zone of aeration lhal consuls
of soil and other materials near the ground surface, capable o f discharging water in
to the atmosphere by transpiration of plants or by evaporation. The zooe extends
from the ground surface to major root zone and the thickness varies with the soil
type and vegetation cover.
542.
Cone of water - table depression, or Cone of pumping deression (Nón trflng
nước ngầm hay nón trũng do bơm).
543.
Unconsolidated aq u ifer (T ầng chứa nước không cố kết): An aquifer in which a
water table serves as the upper surface of the zone of saturation.
544.
Zone of fluctuation of water tabic, or Zone of phreatic fluctuations (Vùng dao
dộng đường m ạt nước hay V ùng biến động nước ngầm ): The zone through which
the water table fluctuates from its highest to tile lowest level within the formation, in
response to the discharge and recharge conditions. Depending upon the position of
the water table in the zone, a part of the zone will lie in the zone of aeration and the
other part will lie in the zone of saturation.
II.1.5. DISCHARGE MEASUREMENTS - ĐO LƯU LƯỢNG
545
O pen C onduit, or O pen channel (Lòng d ẫn hở hay kênh hở): Any conduit in
which water flows wilh a free surface.
546.
D ischarge, or R ate of flow (Lưu lượng hay suất dòng chảy): The volume of water
which flows past a particular cross section of a channel or conduit in a unit of lime.
547.
Dead w ater (Nước tù): Water which is not flowing with a significant velocity.
^48.
S urface slope, Slope, YVaterslope (Độ dốc bề m ặt, độ dốc, độ dốc m ặt nnớc): The
inclination o f Ihe water surface expressed as change o f elevation per unit of slope
length; the sine of Ihe angle which ihe surfacc makes with the horizontal. The
langent of the angle is ordinarily used, no appreciable error resulting excepc for the
steepest slopes. Also called "waterslope" in Australia.
549.
Mean m onthly discharge (Lưu lirợng bình quân tháng): Discharge observed or
interpolated and averaged O' er a calendar month.
550.
Discharge Coefficient (Hệ so hru lượng): The ratio of the actual discharge to the
discharge calculated according to a theoretical formula.
551
Stage - discharge relation, R ating curve, D ischarge ratin g curve, or Station
ratin g curve (Q u an hệ mực nước • lưu lượng, dường cong mực nước - lưu lượng,
đường copq q u an hệ mực nước - lưu lượng trạm đo): A curve which expresses
graphically Ihe relation between ihc discharge and its corresponding slage (or
elavutiun of water surface) in a stream or conduit at a given point.
552.
Loope ra tin g curve (Đường cong quan hệ mực nước - lưu lượng dạng vòng day):
Is the result of the differences in ihe water surface slope and bed roughness in rising
and falling stages o f the hydrograph.
130
553.
Discontinuous rating curve (Đường cong mực nước - lưu lượng gián đoạn): Is
the result of the abrupt changes in bed configuration from a dum e bed with high
roughness and low velocity to a flat bed with lesser roughness and higher velocity.
554.
In sen sitiv e ra tin g cu rve (Đường cong m ực nước - lưu lượng p h án bãi ngập): This
type o f a curve results largely from over bank flow where the stream flow may
spread out from its well defined low-flow channel to cover a wide flood plain, where
a large increase in discharge may result in an almost negligible change in stage.
555.
S hiffting ra tin g cu rv e (Đường cong m ực nước - liru lương di chuycn): This type
of a curve reflects local changes in water surface slope, local scour or fill at the
rating section or if the shift is systematic with time, a long term aggradation or
degradation process.
556.
D ischarge m ass cu rv e (Đường cong lũy tích dòng chảy): A curve in which
cum ulated values o f recorded discharge arc plotted against time. The slope of the
curve at any time represents the discharge at that instant.
557.
R esidual d ich arg e m ass curvc, or R esidual discharge m ass d iag ram (Đường
cong lũy tích dòng chày hiệu số hoặc biểu đổ lũy tích (lòng chảy hiệu số): A
plotting of the year-to-year residual departure of discharge from the arithmetic
average accumulated for Ihe period under consideration.
558.
R atin g , C a lib ratio n , C a lib ratin g (Kiểm định): 1- The relation, usually determined
experimentally, between mutually dependent quantities, such as gauge and discharge
of a stream; current m eter vane revolutions and waler velocity. Also "calibration". 2The taking of measurement or the making of observations to establish a rating
"calibrating".
559.
R a tin g cu rv e (Đường cong kiểm clinh): A graphic representation of a rating.
560.
D isch arg e tab le, or R atin g (able (Bàng lưu lượng hay Bàng kicm định): A table
showing the relation between gauge height and discharge of (i) a stream or conduit at
a particular gauging stulion and (ii) oullcls, sluiccs, elc.
561.
S tre am gauging (Đo đạc Ihủv ván): The operation of measuring the velocity of the
flow of water in a channel or conduit, and the area of cross section of ihe flow for tile
purpose o f determ ining discharge.
562.
D ilution g auging, C hem ical gauging, C hcm ihydroinetry, R adioactive solution
gauging (Đo liru lượng bang pliương pliiíp dùng chất chi báo, phương p h áp lioá
học, phương p h á p llủiv hoá và plurơng pliáp dụng dịch plióng xạ) : A m ethod of
m easuring the flow o f water by introducing a constant flow of a solution of known
concentration for a sufficient lapse of lime at one section of Ihe water channel and
llien by determ ining the resulting degree of dilution of this solution at another
downstream section. "Chemical gauging", "electro-chemical gauging" and "radioactive
solution gauging" are different forms of dilution gauging.
563.
E lcctro - C hem ical gauging (Đo Uni lượng băng phương pháp hoá điện ): A
m ethod for Ihe m easurement of flow of water based upon the nearly linear relation
between the concentration and the cleclrical conductivity of a salt solution which
131
m akes it possible to determine the degree o f dilution by integrating a conductivity
time graph.
564.
Cloud - velocity gauging, Allen's method of velocity gauging, colour velocity
gauging (Đo lưu tốc theo phương pháp màn muối, phương pháp A-len, phương
ph áp nhuộm m àu nước) : A method of determining the velocity of a slug of dye
between two stations in the channel. This velocity, used as the mean velocity o f flow,
in the case of adequate spreading, multiplied by the cross-sectionaJ area of the
channel, gives the discharge. "Allen's method" and "colour-velocity method" arc
different forms of cloud-velocity gauging.
565. Float gauging (Đo vận tốc bằng phao): Measurement of velocities of water by
weighted floats for the determination of discharge.
566.
Spot m easu rem en t (Đo điểm ): A single and random measurement of a stream as
distinguished from a systematic or continuous record.
567. G auging statio n (T rạm thủy văn): A gauging station is a selected site on a stream
equipped and operated to furnish basic data from which systematic records of
discharge may be derived.
568. D ischarge site, G auging site, or Velocity - are a gauging statio n (Tuyến lưu
lượng, tuyến đo hay trạm đo lưu lượng theo phương pháp lưu tốc m ạt ngang): A
selected site on a stream for making observations of velocity and area of cross
section with a view to determining the discharge.
569. Dosing statio n (T rạm đo dòng chảy dùng dung dịch hoá học): In chemical
gauging, the station on the stream from where a chemical solution is fed into the
water.
570. Sam pling statio n (T rạm lấy m ẫu nước): In chemical gauging, the station
downstream of the dosing station from which samples of water are taken to find out
the concentration of ihc diluted chemical solution with a view to determining the
discharge.
571. Bench m ark (M ốc CƠ ban): A permanent point on a monument or permanent
structure, whose elevation above a datum is known or fixed by precise levelling, and
which is used as a point o f reference in the detemination of other elevations.
572. Gauging datum (Mặt chuẩn (mốc số 0) của trạm thủy văn): The elevation of the
zero of the gauge above a certain point.
573. P erm an en t gauging (T rạm đo cố định): A gauge which is permanent.
574. D irection peg (Tuyên ngắm): A point on the direction peg line through which ray
from one o f Ihe observation points passes when converging on Ihe pivot point.
575. C o ntrol, control section, com plete control, p a rtia control (M ạt cát khỏng chế,
tuyên ngang thủy văn, m ặt cắt khống chế đầy đ ủ, m ăt cắt khống chế toàn
ph ần ): 1- A section or reach of an open conduit or stream channel where artificial or
natural conditions exist, such as the existence of a dam or a strcatch of rapids, that
make the water level above it a stable index of the discharge. Controls may be
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com plete or partial. "Complete control" exists where the elevation of the water
surface above the control is entirely independent of the fluctuations of water level
downstream o f it. "Partial control” exists where downstream fluctuations have some
effect on the upstream water level. 2- The cross section in a waterway which is the
bottle neck for a given flow and which determines the enorgy head required to
produce the flow. In the case of open channels, it is the poiru where the flow is at a
critical depth; hydraulic conditions above the point being wholly dependent upon the
characteristics of the control section and entirely in dependent of hydraulic
conditions below the point. In the case of closed conduits, it is the point where the
hydrostatic pressure in the conduil and cross-sectional area of flow are definitely
fixed, except where the flow is limited at some other point by a hydrostatic pressure
equal to the greatest vacuum that can be maintained unbroken al that point.
576.
Shifting control, or Unstable control (Mạt cát không chế di động hay Mạt cát
không ch ế không ổn định): A station is subject lo shifting control when the stagedischarge relation changes, either gradually or rapidly, as the result physical changes
in the control.
577.
G au g in g , or G age (T hủy chi): 1- An instrument, contrivance, graduated scale or
ther device installed at a gauging station for observing or recording the stage of a
stream. It may be an automatic gauge recorder or a non-recording gauge. 2- Height
recorded by the gauge.
578.
T em p o rary gauge (T rạm thủy vân tạm thời): A gauge, connected 10 the permanent
gauge, for the purpose of recording watcr-surface levels under the prevailing
conditions.
579.
G au g e line (Tuyên do): The line across a channel passing through a given gauge.
580.
G au g e line p illars (Cọc q u a n trá c m ục nước): The structural landmarks fixing the
position o f the gauge line.
581.
C h a in g auge, or T ap e gauge (Thước đo nước bàng xích hay dày): Device
consisting of a tagged or indexed chain or other line allached to a weight which is
lowered to the water surface, whereupon the gauge height is read on graduated staff
or opposite an index. Especially suited to bridges.
582.
F loat gauge (T rạm đo nước bằng pliao): Consists essentially of a float of wood,
cork, or usually hollow zinc or coppcr which rides on the liquid surface and rises or
falls with it, its movement being indicated on a scale.
583.
Inclin ed g auge, Sloping gauge (T húy chi nghiêng): A staff gauge on a slope,
graduated to read vertical heights above a datum. Sometimes referred to as a "sloping
gauge".
584.
Slope gauge (T uyến độ doc): Gauges with the same datum fixed above and below a
discharge section for the pirpose of determining the water-surfacc slope belween the
gauge run.
585.
S taff gauge (Thước đo m ực nước): A graduated scale on a staff, plank, metal plate
pier, wall, ect., by which the elevation of the water surface may be read.
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