History and development Lock (water navigation)

1 history , development

1.1 dams , weirs
1.2 flash locks
1.3 staunch
1.4 pound lock
1.5 turf-sided lock

history , development
dams , weirs

in ancient times river transport common, rivers shallow carry smallest boats. ancient people discovered rivers made carry larger boats making dams raise water level. water behind dam deepened until spilled on top creating weir. water deep enough carry larger boats. dam building repeated along river, until there steps of deep water.

flash locks

the development of dams , weirs created problem of how boats between these steps of water. , crude way of doing flash lock. flash lock consisted of small opening in dam, opened , closed. on thames in england, closed vertical posts (known rymers) against boards placed block gap.

when gap opened, torrent of water spill out, carrying downstream boat it, or allowing upstream boat man hauled or winched through against flow. when boat through, opening closed again. gate opened release flash downstream enable grounded boats off shoals, hence name.

this system used extensively in ancient china , in many other parts of world. method dangerous, , many boats sunk torrent of water. since system involved lowering level in pound, not popular millers depended on full head of water operate equipment. led constant battles, both legal , physical, between navigation , milling interests, rivers being closed navigation if there shortage of water. conflict, led adoption of pound lock in medieval china, means relatively little water consumed navigation.

staunch

a more sophisticated device staunch or water gate, consisting of gate (or pair of mitred gates) closed (and held shut water pressure) when river low, float vessels on upstream shallows @ times of low water. however, whole upstream head of water had drained (by auxiliary method approaching modern sluices) before boat pass. accordingly, not used obstacle passed mill weir.

pound lock

model of river pound lock, constructed in lankheet water park, netherlands

the natural extension of staunch provide upper gate (or pair of gates) form intermediate pound need emptied when boat passed through. type of lock, called pound lock known in imperial china , europe note change in terminology: on british canal, section of canal between locks called pound.

pound locks first used in medieval china during song dynasty (960–1279 ad).the songshi or history of song dynasty, volume 307, biography 66, records how qiao weiyue, high-ranking tax administrator, frustrated @ frequent losses incurred when grain barges wrecked on west river near huai’an in jiangsu. soldiers @ 1 double slipway, discovered, had plotted bandits wreck heavy imperial barges steal spilled grain. in 984 qiao installed pair of sluice-gates 2 hundred , fifty feet apart, entire structure roofed on building. siting 2 staunch gates close 1 another, qiao had created short stretch of canal, pound-lock, filled canal above raising individual wooden baulks in top gate , emptied canal below lowering baulks in top gate , raising ones in lower.

the turf-sided monkey marsh lock on kennet & avon canal @ thatcham


turf-sided lock

a turf-sided lock form of canal lock design uses earth banks form lock chamber, subsequently attracting grasses , other vegetation, instead of more familiar , widespread brick, stone, or concrete lock wall constructions. lock design used on river navigations in 18th century before advent of canals in britain. sides of turf-lock sloping so, when full, lock quite wide. consequently, type of lock needs more water operate vertical-sided brick- or stone-walled locks. on british canals , waterways turf-sided locks have been subsequently rebuilt in brick or stone, , few examples survive, such @ garston lock, , monkey marsh lock, on kennet , avon canal.