hydrographic survey & its purposes by d.m siddique

7/30/2019 Hydrographic Survey & Its Purposes By D.M Siddique

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Date: 08/11/2012

Hydrographic SurveyingLecture 17 : Hydrographic survey and its

purposes

Dr. Mohsin Siddique

NU-FAST Lahore Campus

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Hydrographic Survey

Hydrograph survey include all types of hydrological observations

which are necessary for the design of hydraulic, or marine

structures.

Hydrograph survey is the branch of surveying which deals with

any body of still or running water such as a lake, harbor, stream or

.

water features.

Hydrographic survey is the science of measurement and

description of features which affect maritime navigation, marineconstruction, dredging, offshore oil exploration/drilling and related

activities.

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Hydrographic Survey

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Gold Coast Lake Saif ul Maluk



Hydrographic Survey

Tarbela dam

Indus river



Hydrographic Survey

The illustration highlights the importance of

accurate and reliable hydrographic survey

information for safe and efficient navigation.

Bathymetry surveying by Echo sounding.

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Note: Depth of the seabed

below the survey vessel is

known as sounding



Hydrographic Survey

Hydrographic sur vey includes the following

1. Rain gauging

2. River gauging

3. Marine survey

1. Rain au in :

The amount of rainfall in the catchment area of a basin or a river isgenerally recorded. This helps to predict the probably run-off

through the basin or river

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Hydrographic Survey

2. River gauging:

River gauging involves the measurement of discharge of a river and

the establishment of a gauge post on one of its banks.

This is done to directly read the Highest Flood Level (HFL) so that

the warning may be given to surrounding areas.

Measurement of river discharge require surveys for river cross-

sectional area and flow velocity

3. Marine survey:

It involves marking of shore line at high and low tides, determining

depth of water around the harbor by echo-sounder, current and tideobservations, and preparing of maps etc.

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Purposes of Hydrographic Survey

(1). Measurements of tides for sea coastal work , such as

construction of sea defense works, jetties and harbors, for the

establishment of a leveling datum, and for reducing sounding

(2) Determination of bed depths, by sounding

(a). For navigation, i.e., for tow out routes for production

p at orms ut a so inc u ing t e ocations o roc s, san ars,navigation lights and buoys

(b). For location of underwater works, volumes of underwater

excavation etc,;

(c). In connection with irrigation and land drainage schemes

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Purposes of Hydrographic Survey

(3) Determination of direction of currents in connection

with

(a). location of sewer outfall

(b). determination of areas subjected to scour and siltation

(c). for navigational purposes.

(4) Measurement of quality of water and flow of water inconnection with water schemes, power schemes and flood

control.

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Methods of Hydrographic Surveying

Horizontal control: It may consists of triangulation along the

coast or shoreline. To provide additional control theodolite

traverses are run in between triangulation stations.

The triangulation work is known as primary horizontal control andtheodolite traversing in known as secondary horizontal control.

Vertical control: A number of precision bench marks are

established along the shore line. They are used for checking and

setting tide gauges in which sounding are referred to find the depth

of water. Hence vertical control must be established to connect thegauges with shore elevations and also with each other.

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Thank you

Questions….

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hydrographic survey & its purposes by d.m siddique

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