Lesson Note On Hydrographic Surveying

Hydrographic Surveying
	Definition: It is the branch of surveying which deals with any body of still or running water such as a lake, harbor, stream or river. Hydrographic surveys are used to define shore line and under water features. Objects of Hydrographic Surveying: Hydrographic surveying are carried out for one or more of the following activities. Measurement of tides for sea coast work E.g. construction of sea defense works, harbors etc, for the establishment of leveling datam and for reducing sounding. Determination of bed depth, by soundings For navigation Location of rocks, sand bars, navigation light. Fro location of under water works volumes of under water excavation etc. In connection with irrigation and land drainage schemes.
Determination of direction of current in connection with The location of sewer any pipe or channel that carry waste water out falls.   Determination of area subject to silt and seour the eating of the place. Fornication purposes. Measuremenment of quantity of water and flow of water in connection of water schemes, Power scheme and flood controls. Why we need Hydrographic Surveys - Uses & Applications of Hydrographic Survey Offshore engineering and the shipping industry have continued to expand. Drilling rigs (extracting oil, gas etc from deep sea) locating up to 125miles offshore, search for resources particularly oil and gas. Offshore islands are constructed of dredged material (to bring material form some where and dump there) to support marine structure. Harbor depth up to 80 is required to accommodate larger ships and tankers. Containerization has become an efficient and preferred method of cargo handling. The demand for recreational transportation ranges form large pleasure cruise ships to small sail bonds. Cruise ships to small sail bonds. Hydrographic surveys are made to a quire and present data on oceans, lakes and harbors. It comprises all surveys made for The determination of shore lines, soundings (measurement of depth below the water level) characteristics of bottoms, areas subjected to Suring and silting, depth available for navigation and velocity as well as characteristics of flow of water. The location of lights rocks sand balls, buoys ( anything that floats on the surface of water) Establishing Horizontal and Vertical Controls (Click Here) The first step in making a hydrographic survey is to control both horizontal and vertical. Horizontal Controls: In an extensive survey, the primary horizontal control is established primarily by running theodolite and tape traverse before the triangulation station. Tthe traverse lines being run to following the shore lines approximately. In survey of less extent the primary horizontal control only is required and is established by running a theodolite and tape traverse sufficiently close to shore line. For rough work, the control may be established by running a theodolite and staid traverse or plane table trader. Vertical Controls: These are based upon a series of bench marks established near the shore line by spirit leveling and these serve for setting and checking tide gages etc to which the sounding are referred. River Surveying The survey of the shore line of a river is made by running a theologize and tape traverse on a shore at a convenient distance form the edge of the water. If the river is narrow, a single theologize and tape traverse is on one bank and both banks. Located by staid or plane table methods. Sounding Surveying The measurements of depths below the water surface is called Sounding. The object of making soundings is to determine the configuration of the bottom of the body of water. This is done by measuring form the boat, the depth of water at various points

Units of Conversion

Units of Conversion

Length:

1 inch= 2.54 cm
1ft= 30.48 cm
     = 0.3048m
     = 3.281 ft

1m = 3.281 ft
1mile= 1.609km
1 naut mile= 1.852 km

Area:

1 Are= 100sq.m
          = 1 Gunta

1 Gunta= 33’X33’
1 acre = 43560 ft2
           = 4047 m2
           =0.4047 ha
1ha     = 10000m2
           = 100 areas
           = 2.471

Volume:

1Cu.ft= 28.32 lit
1 imp-gal = 4.546 lit
1m3= 35.315 Cu.ft
        = 1000 lit
1ha.cm = 100m3

Flow Rate:

1 cumec = 35.31 cusec
1m3 /s = 35.41 Cu.ft /s

Pressure :

1 atm= 1 bar
         = 1 kg/cm2
         = 14.7 psi
         =30 inch of Hg
         = 76 cm of Hg

Weight:

1kg = 2.2 lbs
1lbs= 453.6gms

1 carat= 200 mg

1 km2= 100 ha
          = 247 acres
     
1mile2 = 640 acres
            = 259 ha
            = 2.59km2

Power:

1 H.P = 74
          = 0.746 K.W

1 K.W. = 1000 watt
             = 1.31 H.P

Lesson Note On Programming Languages

Programming Languages

Two types of computer languages are used for programming, namely Low Level Languages and High Level Languages. Low Level Languages are further classified as Machine Languages and Assembly Language. High Level Languages are Fortran, Cobol, C, C++, Pascal, Java, etc

Low Level Languages:

Machine Language:

The lowest form of computer language is Machine Language.  Computer CPU can understand only instructions, written using pattern of 0s and 1s i.e. binary language. Hence, in machine language, instructions are formed with different combinations of the bits 0 and 1. For example, 001010110011 could represent an instruction in machine language. The instruction is followed by the data, if needed, in binary form. CPU of every computer (Microprocessor) is capable of executing a particular set of instruction in binary form. This set contains instructions for arithmetic operations, control, input and output operations. The programs written in machine language are called Object Programs. Coding the program in binary form is very tedious. Moreover, the bit patterns for every instruction in a set of about millions of such patterns are difficult to remember. Therefore, a symbiotic language called as Assembly Language was developed.

Assembly Language:

Assembly language consists of symbiotic words called mnemonics and it was extensively used during 1950. Symbolic instruction codes like ADD, SUB, MULT, DIV, IN, OUT etc. are used for operations of addition, subtraction, multiplication, division, input, and output respectively on the data. A set of such instruction codes were put together to form a program and store in memory, means were provided to translate these codes in to their machine language counter parts. The translated program is then directly executed. The assembly language instruction set is different for different microprocessors.

High Level Language:

It is easier to write program in Higher Level Language (HLL) than Assembly Language. Moreover, a program written in HLL can be used on any computer irrespective of the type of microprocessor and HW in computer, provided it has a compiler for the HLL used for programming.

Advantages of HLL Programming are:

1. Easier to learn as compared to assembly languages.
2. Most of the instructions are as like simple English.
3. Better documentation is provided for HLL.
4. The executions do not depend on type of HW in computer.

Some of the popular HLL are BASIC, FORTRAN, COBOL, PASCAL, C, etc. Every HLL has a vocabulary of specific words (commands) and set of rules to use these words called syntax. The set of commands include instructions for various operations like arithmetic and logic operations on the data, input and output and control statements. However, computer needs special means to convert a program written in HLL to machine language. These translators are called interpreters or compilers.

Lesson Note On Types of Computer Software

Types of Software

Software is Mainly Classified as:

1. System Software and Operating Systems
2. Application Programs
3. General Purpose Packages

System Software and Operating Systems:

System software includes programs that simplify use of computers, provide man machine communication and control & drive all input/output devices interfaced to a Computer. The type and utilities depend on the type of computer. However, most of them have system programs like monitor, operating system, editor etc.

BIOS (Monitor):

BIOS are a program that is stored in ROM and perform basic functions required in a microcomputer. These functions mainly include:

i) Power ON self Test which tests error free working of RAM, all I/O devices and reports accordingly.

ii) Managing the control devices.

iii) Control execution of program.

Operating System:

Computers need a set of program called Operating System to keep it working. These programs may not be used for a specific problem execution but they enable the computer to do all the different jobs in proper order and at the required time. For example, they keep track of the priority of different jobs and load the jobs in to the CPU for execution in correct sequence. OS also include programs, called utilities, which are useful to maintain day to day activities of the computer system like Copy, delete, sort, save, rename, print a file etc.

The Functions of the Operating System Include:

1. Scheduling and loading of programs or subprograms and continue the job processing sequence.

2. Control hardware resources such as Input/ Output devices, Secondary storage Devices etc.

3. Protect Hardware, Software form improper use.

4. Communication with user through commands and response.

5. File management and software management.

6. Memory management.

Operating system is a most powerful and important software in a computer. The HW along with OS and other SW forms a complete computer system.

The Most Popular Operating  Systems are

i) DOS
ii) WINDOS
iii) UNIX/LINUX

Application Program:

These are program written for a specific job to meet the requirements of a particular user. For example program for pay billing in an organization, statistical data analysis, admissions at MAU are all application program. These are generally written in different high level computer languages and then complied to translate them in an executable from.

General Purpose Packages:

A general purpose package of software is collection of generalized application programs and utilities for a particular type of job so that it can be easily usable by nonprograming persons. Because of which they are called as user friendly programs. With ease of use in mind, selection of commands through menus is frequently incorporated in the design of these general purpose packages. These menus present options which enable the user to select an appropriate course of action, exactly similar to presenting menu to a customer in a restaurant. The users do not need to remember what to do next. Package programs are available for applications which are common to many users. Some example of popular software package are WordStar, MS-Word, Word Prefect for word processing, dBase, Fox Pro for database management, LOTUS, MS- EXCEL for spreadsheet.

Advantages of these Packages Include:

1. The users himself need not write programs in HIL.
2. Easy to use and user friendly.
3. Small application programs may be developed by an user as per requirement using a set of commands available in these package.
4. Documentation on how to use and maintain the software is provided by the vendor.

Some Instruments for Setting out Right Angles

Instruments for Setting out Right Angles

Cross staff:

The cross staff is used for

a) Finding out foot of the perpendicular from a given point to a line
b) Setting right angle at a given point on a line

There are three forms of cross staff

1. Open cross staff
2. The French and
3. The Adjustable
4. Optional Square
5. Prism square, the first one is commonly use.

1. Open Cross Staff:

It is a simple. It consists of two parts: - 1) the head; 2) the leg. The common type of cross staff consists of 4 metal arms with vertical slits for sighting through.

The head is fixed to the top of an iron stand about 1 .2 to 1.5 m long this is driven in to the ground.

For setting perpendiculars lines, one pair of opposite arms is aligned with the chain line. It is specially used for setting off and marking contour lines.

To find the foot of perpendicular from a given point to a given lines:

To take offset, the cross staff is held vertically on chain where the offset is likely to occur, and turn until one pair of opposite slits directed to arranging rod at the forward end of the chain line, the offset is taken is bisected. If not the cross staff is moved forward or back word the chain line until the line of sight through the pair of slits at right angle the chain lines, does bisect the point.

In setting out a right angle at point on the chain line:

The cross staff is held vertically over the given point on the chain and turn until the ranging road at either end of the chain line is bisected the line of slight through 1 pair of the opposite slits. Then the line through the other pair of slits which is at right angles to the chain line through the other pair of slits which is at right angles to the chain line. Line may be marked by a ranging rod at inconvenient point on the sighted.

2. French Cross Staff:

The octagonal form cross staff is the French cross staff. It consists of an octagonal brass tube with slits on all eight sides. If has an alternate vertical slit and an opposite vertical window with a vertical horse hair or affine wire on each of the four sides. These are used for setting our right angles. On the other side are vertical slits, which are at 45 degree to those previously mentioned, for setting out angles of 45 degree.

The base carries a socket so that it may be fitted on the pointed staff when the instrument is to be used. The sight being too close (only 8 cm apart) it is inferior to the open type.

3. Adjustable Cross Staff:

It consists of a brass cylindrical tube about 8 cm in diameter and 1 cm in deep, and is divided in the centre. The upper cylinder can be rotated relatively to the lower one by a circular rack and pinion arrangement actuated by screw. Both are provided with sighting slits. The lower part is graduated to degrees and sub divisions, while the upper one carries a vernier. Thus it may be use for setting out angles of any magnitude. It has a magnetic compass at the top, which may serve to take the bearing of the line.

4. Optional Square:

An optional square is an compact hand instrument used in setting out right angles with greater accuracy than a cross staff. It consists of a circular box about 5 cm in diameter and  1.25 cm deep in which two mirrors are fitted at right angles to the plane of instruments . The mirror ‘h’ called the horizontal glass which is half silvered and half uncovered. The mirror ‘I’ is known as index glass is known as wholly silvered. There are three openings on the side of box at e, b and ,c. the opening e is pin whole for eye , b is small rectangular slot placed opposite to pin hole and c is large rectangular slot placed at right angle to line joining e & b

The surveyor simply turns the optical square upside down which throws the aperture for the object on that side.

5. Prism Square:

It is a modern instrument and is a very use full for setting out right angles. It is based on the same principles as the optical square and is used in same manner. It requires no adjustment, since the angle between reflecting surface of the prism (45 degree) is fixed. It is unaffected by dust & can be used in poor light. For taking offset to an object the observer holds the instrument in his hand & slights directly over the prism at ringing of station.

Some Instruments Used for Measuring Distance:

Instruments Used for Measuring Distance:

1. Chain 

1. Metric chain
2. Steel band chain
3. Günter’s Chain
4. Revenue Chain
5. Engineers chain

2. Arrows (chain pins)

3. Tapes

1. Cloth or linen Tape
2. Metric Woven Metallic Tape
3. Metric steel Tape
4. Invar tape.
5. Synthetic Tape.
6. Wooden pegs.

5. Ranging Road.

6. Ranging Poles.

7. Offset Rod.

8. Laths

9. Whites

10. Plumb Bob

1. Chain

The chain is composed of 100 or 150 pieces of galvanized mild steel wire 4mm in diameter called links. The end pf each link are bent into a loop and connected together by means of three oval rings. The ends of the chain are provided with brass handles for dragging the chain on the ground. The length of link is the distance between the centers of the two consecutive middle rings. The end links includes the handles. Metallic tags or indicators are fixed at various distinctive of the chain to facilitate quick reading.

a. Metric surveying chains:

The chains are made in lengths of 20 and 30 meters. To enable the reading of factious of a chain, tallies (tags) are fixed at every five meter length and small brass rings are provided at every meter length. To facilitate holding of the arrows in position with the handle, a groove is cut on the out side surface of the handle. The handle joints are flexible. the tallies used for marking the distances in a metric chain are marked with letters ‘Me’ and ‘m’.

b. Steel Band Chain:

It consists of a ribbon of steel with bras handle at each end. It is 20 or 30long and 16 mm wide. It is wound on an open steel cross or on the metal reel in a closed case. The graduations are etched as meters decimeters, centimeters on one side and 0.2 m links on the other. Brass tallies are fixed at every 5 m length of the band.

c. Günter’s Chain:

It is 66 fit long and is divided into 100 links. Each link is 0.66 ft long. It is very convenient for measuring distance in miles and furlongs. Also for measuring area and when the units of area is an acre

d. Revenue Chain:

It is commonly used for measuring fields in cadastral survey. It is 33 ft long and divided into 16 links. Each link is 2.0625 ft long.

e. Engineer’s chain:

It is 100 ft long and it is divided into 100 links. Each link is 1 ft in a length. Used in all Engineering surveys.

2. Arrows (chain pins):

They are also called as marking or chaining pins and are used to mark the end of chain during the process of chaining. They are made up of good quality hardened and tempered steel wire of 4mm in diameter. The arrows are made 400 mm in length. They are pointed at one end of inserting in to the ground. The other end is in to a ring.

3. Tapes:

a. Cloth or Linen Tape:

Used for taking subsidiary measurements, such as offset. It is very light and handy. It is easily affected by damp. If wet it shrinks. It stretches easily and likely to twist.

b. Metric Woven Metallic Tape:

They are available in 2, 10, 30, and 50 meters. The tape is made of yarn and metal wire. A metal ring is attached to the outer end of tapes. The length of the tape includes the metal ring. At every centimeter a black line 8 to 10 mm in height is drown. Every 5 centimeters is marked with an arrow in black. Every decimeter and meter is marked with a back line extending over the full width of the tape/ the graduation marks at every decimeter and meter are numbered with black and red figures, respectively.

c. Metric Steel Tape:

Tape is available in 1, 2, 10, 30, and 50 meters. The tape is of steel or stainless steel. The outer end is provided with a ring. The length of the tape includes the metal ring. The tape is marked with a line at every five millimeters, centimeters, decimeters, and meter. Every decimeter and meter shall be marked with Hindu Arabic numerals in bold. When the button release devised is pressed, the tape automatically rewind in to the case.

d. Invar Tape:

For highest precision work the invar tape in used. It is made of an alloy of steel and nickel (36%).

It is 6 mm wide and may be obtained in length of 30m and 100m. It is not calibrated through its length but has terminal lines. Each terminal division has ten 1 mm division. It is very expensive.

e. Synthetic Tape:

The tapes are manufactured of glass glass fiber having PVC coating. They are graduated every 10 mm and figured every 100 mm. Meter, figures are shown in red. They are convenient for measuring shorts lengths.

Instruments for marking stations:

1. Wooden Pegs:

These are used to mark the positions. They are made of hard timber and tapered at one end. They are usually, 2.5 cm square and 15 cm long. But in soft ground 40 to 60 cm long and 4 to 5 cm square is suitable. They should be driven in the ground with about 4 cm lengths, projecting above the ground.

2. Ranging rods:

Used for making the positions of stations and for ranging. They are made of seasoned timber of teak, blue pine, sisov or deodar. They are circular or octagonal in cross section of 3 cm diameter. Lower shoe is 15 cm long. They are made in two sizes as 2 meters and 3 meters and are divided in to equal parts each 0.2 m long. They are painted alternatively black and white or red and white. Now a day instead of timber, mild steel hallo pipes are used.

3. Ranging Poles:

Similar to the ranging rods but are heavier, they vary in length from 4 m to 6 m or more. Used in the case of very long lines.

4. Offset Rod:

Similar to the ranging rod, they are usually 3 m long and is divided into parts each 0.2 m length. Top is an provided with an open ring for puling or pushing the chain through a hedge. It has two short narrow vertical slots. It is used for aligning short offsets.

5. Laths:

Useful for ranging long lines, also used over uneven ground where the ranging rod is not visible due to obstructions, they are light, cheap, being white; they are easily visible at a great distance. Unusually 1.0m long

6. Whites:

When the ranging rod is not available or insufficient, whites are used. These are thin strip of bamboo and 40 cm to 1 m in length. One end is sharp and the other end is split for inserting pieces of white papers. They are also useful for temporary marking of counter points.

7. Plumb Bob:

The plumb bob is required when measuring the distance along slopes in order to transfer points to the ground. It is also used for testing the verticality of ranging poles.

Difference between Plane and Geodetic Surveying

Difference between Plane and Geodetic Surveying

Plane Surveying	Geodetic Surveying
Curvature of the earth is not taken in to consideration	In this curvature of earth is considered.
In plane Surveying, line joining any two points of triangle formed by any three points is considered as straight line and plane triangle are assumed to be plane angles.	In geodetic surveying line joining two points of triangle formed by three points is considered as curved line of spherical triangle and angles of triangle are considered as spherical angles.
This survey is done on smaller area less than 250km2	This survey is done on large area greater than 250 km2
Required accuracy is competitively low.	High accuracy is required
Simple methods and instruments can be used as the required accuracy is low.	Very refined methods and instruments are used.