Investigation of canal structures Session objectives –Spell out the purpose of CM & CD works –Describe the procedure for preparation of site survey plan –List out various survey techniques adopted –Enlist different items to be obtained –Explain the field work to explore LS,CS, Alignment of stream or road etc. and their importance –Speak out the other important items to be taken care of –Explain the need for sub-soil strata exploration and how to depict it on the site survey plan –Discuss about a model check slip –Describe about the brief site survey report

Investigation of canal structures Introduction Purpose Agency Quantification

List of items to be collected List of Benchmarks Hydraulic particulars List of structures existing u/s & d/s of the proposed structure Index plan Village plan Leads of constn. material

Conducting survey work 1. Block leveling –In general a contour map of area about 400 m all-round to a scale of 1cm = 10 m –Specific guidelines are available vide annexure –Contours at 1 m are drawn and interpolated at 0.30 m –Special features viz mounds, dips, & other natural topographical features, presence of monuments etc. are to specifically mentioned in the plan

Conducting survey work Contd. 2.Longitudinal section of canal, drain or road –The LS is to be taken 1KM on either side of crossing at the same interval as adopted earlier –The LS is to be plotted to scale of 1.Horizontal --- 1cm = 10 m 2.Vertical cm = 1 m

Conducting survey work Contd. 3. Plan of drain or road –The plan of drain or road is to explore through chain & compass and drawn on the contour plan to know the course 4. Cross sections of drain or road –CS are to taken at 100 m, 200 m, 400 m, & 800 m along the drain with levels at 3m, interval –Useful for computation flood discharges

Conducting survey work Contd. 5. Catchment area of the stream –The catchments area of the stream is to actually traced on the ground it is area is less than 1 Sq. Mile with chain & compass using closed traverse –If the catchments area is more than 1 Sq. mile, it is to be obtained from the toposheet

Conducting survey work Contd. 6. Other particulars to be furnished –Details of sub-soil strata Explored through trial pits-number depends on the size of the structure & site condition A minimum of 3 pits for a small structure-one at both the abutments, one at the pier Bore holes –Maximum flood levels

Other points to be kept in mind 1.Possibility of diverting the stream or road 2.Each crossing is to be treated as an independent one however close they may be 3.Before commencement of work it is beeter to check the instruments for their accuracy 4.As far as possible all crossings should be at right angles

5. Check slip 6. Brief report of the site survey

THAN ‘Q’