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close this book Aquaculture - Training manual
close this folder Chapter thirteen: Program design - week four
View the document Session IV-1: Introduction to surveying
View the document Session IV-2: Surveying projects
View the document Session IV-3: Pond interview - week four
View the document Session IV-4: Trainee evaluation of training - week four

Session IV-1: Introduction to surveying

Total tune: 5 hours

Objectives:

• Familiarize trainees with use and care of surveying equipment;

• Instruct trainees in basic surveying techniques;

• Introduce surveying record keeping system.

Overview: This session will introduce the concepts,methods and equipment used in surveying, a skill that will be extremely important for site selection and pond design. Trainees must become comfortable and familiar enough with these concepts and instruments to be able to apply them to new situations. The session begins with classroom instruction which includes a discussion on the purpose and uses of surveying and an introduction to the equipment and techniques. Field practice is interspersed with classroom work to give trainees hands-on experience and help reinforce the information they receive.

10 minutes - classroom

1. Trainer leads discussion of the definition and importance of slope:

• Ask people to compare object heights at various distances by eye;

• Introduce dumpy level;

• Brainstorm uses for dumpy level (building roads, building bridges, laying out water systems).

10 minutes - classroom

2. Trainer points out parts of a Dumpy Level:

• Scope (will see horizontal and vertical cross-hairs);

• Focus knob (200 foot accuracy);

• Thumb knobs to adjust level;

• Table and compass.

20 minutes - classroom

3. Trainer demonstrates how to set up tripod and level instrument:

• Set tripod to comfortable height, attach dumpy level, level dumpy level.

During this demonstration, trainer also emphasizes the importance of proper care and handling of this equipment, i.e., avoiding over-tightening of screws, stabilizing tripod, proper replacement of level in case, working in rain, etc.

 

10 minutes- classroom

4. While instrument is set up, trainer shows how to use table and compass to determine angle between two points and does a simple example between two objects.

 

20 minutes - in classroom or outside

5. Trainer demonstrates use of the stadia rod for measuring differences in elevation:

• Reading the measurements on the rod (may be calibrated in feet and tenths of feet,meters and centimeters, etc.);

• Taking a reading off an object with a known height;

• "Rocking" the stadia rod for accurate readings;

• Using hand signals for communication.

20 minutes - in large classroom, hallway or outside

6. Trainees figure out their pace by walking off a measured distance (100 feet) several times while counting steps.

2 hours 15 minutes

7. Field Practice: If possible, work in groups of four or five trainees, each group having its own set of equipment. A trainer should be assigned to each group.

• 30 minutes. Set up three different stations and have each trainee take readings from the same point (level is set up once and remains in place) and record their readings. Readings of each station should be identical among all the trainees, but some differences will probably occur. Use this to initiate discussion of what different readings mean, how errors in reading can be made and the effects of these errors. Also use the change in readings between stations to discuss and illustrate slope.

• 45 minutes. Set up three permanent stations for each group. Have each trainee practice setting up the dumpy level and taking readings of the three stations. Discuss reasons for differences between people's readings. This will introduce the concept of height of instrument.

• 1 hour. Set up flags at ten different stations which cannot all be seen from one point. Tell the trainees that the first station has an elevation of 100 feet. Tell the trainees that they must determine the elevation at each of the other stations, as well as the average slope between the first and last stations. Each small group does this.

35 minutes - classroom

8. Have the different groups compare how they did the last exercise. This will help introduce the concepts of bench mark, elevations based on a known, back-sighting and record keeping. Trainer now introduces the standard record keeping system that will be used throughout training. Have trainees practice this by putting either a set of sample data or some of their readings from the last exercise into a format like the following:

Station

Back Sight (FS)

Height of Instrument (HI)

Front Site (FS)

Elevation

Remarks

B.M.

1.5

-

-

100.0

 

-

-

101.5

-

-

 

1

-

-

5.3

96.2

 

2

2.1

-

5.5

96.0

 

-

 

98.1

-

-

 

3

-

-

3.6

94.5

 

4

1.8

-

4.1

94.0

 

-

-

95.8

-

-

 

Note: Elevation = HI - FS; HI = Elevation + BS.

10 minutes- classroom

9. Allow time for a question and answer period to discuss ideas that came up in small groups during field practice and to address any remaining points of confusion.

Resources and Materials:

• This session can be facilitated by a staff member or by a guest expert;

• The classroom should be set up so that everyone has a clear view of the demonstrations. Milk boxes, stools or other objects of different heights will be helpful for illustrating slope and elevation changes;

• Blackboard, chalk, eraser and/or newsprint, markers and flip chart stand;

• Prepared poster with blank record-keeping format sheet,to be filled in as part of instruction on this topic;

• Surveying equipment sets, each set to include: tripod,stadia rod, dumpy level, tape measure, several surveying flags.

Trainer Notes:

• Although one person will be the main facilitator, a trainer should work with each small group;

• Trainers should all be aware of exactly what is to be covered during each phase of this set of activities. Although there are alternative methods that can be used for certain aspects of surveying (for example, record-keeping format), all staff must be consistent and work with a standardized version that is agreed upon before the session;

• Some trainees may have prior experience with surveying or progress at a faster rate than others. Additional practice exercises can be given to these trainees. In fact, since this session takes up most of a day, the remainder of the day can be used for additional practice for all trainees. Some suggestions for other exercises include:

• Running circuits: Have trainees run a series of readings around an obstacle necessitating movement of the instrument several times. When they re-read the first station after completing the circuit, the elevation should be the same as what they initially determined it to be. If this does not work out, they should assess possible causes for the error and repeat until they can be accurate;

• Survey a line of ten or twenty stations at five or ten foot intervals with a slope of 1% between stations;

• Survey across a broad dip in the land or a wide ditch. Imagine you have to build a four foot wide, level walkway across the dip, with several sets of supports along the bridge to hold it up. Determine the heights of each set of supports as they would need to be built;

• The day after the introduction to surveying takes place, a quiz can be given to check trainees understanding of and ability to apply the material. The following is a sample quiz:

 

QUIZ

Name:_____________________________

1. Three 2 sites lie on a straight line. The distance from Site 1 to Site 2 is 40 feet and from Site 1 to Site 3 is 85 feet. The surveying instrument was initially located at Station A from which Sites 1 and 2 could be seen. It was then moved to Station B from which Sites 2 and 3 could be seen. The following survey data was obtained:

Station A

Station B

Back sight of Site 1 = 3.8

Back sight of Site 2 = 4.5

Front sight of Site 2 = 1.9

Front sight of Site 3 = 2.3

Organize the above data in a standard format and calculate the following:

• The slope from Site 1 to Site 2;

• The slope from Site 2 to Site 3?

2. A bench mark (BM) with an elevation of 100 feet and 5 sites lie on a straight line. The distance between consecutive sites including the BM is 25 feet. In order to view each of these sites it was necessary to move the surveying instrument twice. The following survey data was obtained:

Station A

Station B

Station C

Back sight on BM = 3.0

Back sight on Site 2 = 3.1

Back sight on Site 4 = 6.1

Front sight on Site 1 = 3.2

Front sight on Site 3 = 1.7

Front sight on Site 5 = 6.8

Front sight on Site 2 = 2.4

Front sight on Site 4 = 5.7

 

Organize the above data into a standard format and calculate the elevations of Sites 1 through 5. Also calculate the following:

• The slope between Sites 2 and 4;

• The slope between Sites 1 and 5;

• The slope between Sites 3 and 4;

• The slope between Sites 2 and 5.