Theory question 102
Farm Surveying and Planning(a) Describe briefly the Gunter's chain.
(b) A farmer surveyed his triangular farmland with a base length of 2 km and a perpendicular length of 1200 m. Calculate the area of the farm.
(c) State four necessary precautions that should be taken in order to eliminate errors when chaining a farmland.
(d) List four factors required in choosing a site for a new school garden.
Show the model answer
(a) Metal chain of 100 links joined by small rings, with a brass handle at each end; total length 66 ft (20.12 m), each link 7.92 inches (20.1 cm); tallies mark every 10 links; used for measuring distances
(b) Area = ½ × base × height = ½ × 2000 m × 1200 m = 1,200,000 m² = 120 hectares (1.2 km²)
(c) Any four: pull the chain straight and taut; keep it horizontal on slopes (step chaining); check for twisted or bent links and correct its length; align with ranging poles; count arrows/chain lengths carefully; record readings immediately
(d) Any four: fertile, well-drained soil; nearness to water supply; accessibility/nearness to school; gentle slope; security; adequate size; free from flooding and shade
Show the working for the area and give it in m² and hectares.