138 lines
4.7 KiB
Plaintext
138 lines
4.7 KiB
Plaintext
DNERSON anus AND mums
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Diversion drains are genlly sloping drains used lo lead
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walk! away lrnni valleys and siredrris and rum sloragis
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and irriglllon syslenis, or Inbo sand laeds or swala lor
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absorpcion. ll low earrlrewalls are raised arross ihe flow
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channels or larger diversion drains, ihese lheri id as a
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series ol rniniswales ior rpe e lree sues, while
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surplus waler llows on in siorages. Diversion drains
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diner horn swales iri lhal lhey are lriiill lo lioio aller rain
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lirorn overland llow or norn leeder siroainsl They are
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lire riorrrial and essenilal eonnedors ol daoi series bill"
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on ihe xeyline sysierns, so lhal ihe overflow oi one darn
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enlers uie leeder channel 0! ihe nerl.
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slash diversion sysieins need carelul planning and
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survey, wish drain bases sloping as hnle as P6000 in
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line sands. Darn eresls and irrigalion drains need
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equally carelnl placerrieril. Evan wilhoul e slreain
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Intake, diversion drains wIl| gaiher waler lrorri
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overland now in as linle as 14.5 cm ll/l inehl 0! rain
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over 14 hours, ro lhal isolaied dams are normally find
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wllh diversion drains even in quile dry eounlry.
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Diversion drains can be led lo broad level swaler in
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drylands, or rnade o: sirnple eoncrele or sione walls
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across solid rock laces ln ihe Canary islands, lhese
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gaiher nxk run-oil which is led lo undergmund cave
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slorages or large open lanla. Slmple sliding gaies ms
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or in ihe downhill banks ol such drains allnw
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eonlrolled now, conlrolled irrigalion, and iin noodsl
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oyepassing of dams,
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Splll gales ran loe nxsn leonerele slide holders arid
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apronrl or MOVEABLE lplaslie sheels weighled wxlh a
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chain sewn iiilp lhe lool, and supporled aeross ihe
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drain by a lighl pipe sleeved iniir lhe iopl lheso laller
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are called -nags- irignie 7.27),
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slide gales an open on m ridge lines, and waler lhen
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spreads downlull. while plaslic ilags an be placzd and
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laheri up ai any pouil along a drain This enables one or
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iwo people lo waler mm ha «no—6m aeresl iii a
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rruvrniog li rs also an eneciive wridlire cenlrel syslern
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in loresled areas. Forsophislicaied wildlirecrr irrigaiion
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eonlrol, holh slide gales and dainelaase gale valves can
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he rerriolely operaled, by radio signal and slorage
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balleries or huned eleclaical eonduils, lo power srnall
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oiolors m hydraulic slides A eornplele wlldfue mnliol
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can b: achieved by darris and sheei irrigaliorr, and
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using inn-lied senaers and airlooialae sprflbgik: such
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syslerns reineve ihe i-isk lor limhyum, and allow
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ioresis io regenerale iri seoriond :ms,
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p mplpr drains. These drainsmr rarher, sealed
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Inlemflmifid in lhe opposrle lense lo diversion
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drains These eorihworlss are specilioally designed (by
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Harry Whmlnglun oi Wrsl Auslralial lo prevenl
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overland wdluflow and walerloggirig which I“; ihe
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elleel or collapsing che drylarid valley or downslope
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soils 0! a desen ioil ealena Thus. ihey ideally lolally
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inlercepi overland now, and direel ii lo sirearns or
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vallgy run—olls.1hey can he envelope a are swales,
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laui lhey diner riorn diversion drains and swales in llial
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lheir (onslmmon alwlyd involves ihe rainrnirig (by
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bulldozu oladel ol subsoil layers hard againsl ihe
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duwnhl“ hanlc. This ellecilvely prevenls or impedes
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waier seepape lhrougri ihe downhill wall ol ihe
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inleirepler bank. Moreover, lhey are always 1.52.5 iii
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(SH?) deep, carefully rpaeed, and elleclively slep run
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only overland now bu| also sall waier seepagsr in
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shallow sand searris lri elreel, lhey isolaie large lrloeld
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ol soil horn walerlogging and sail seepage
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Alier ihis preparalion, irees can or planled in
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previously desenined sails
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Where deeper sand seams carrying sally walor are
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loomed, lhase can be ireiiched ool and slapped with a
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veriical plaalie barrier, backed by corripaeled clay on ihe
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uphill side.
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Made lo lluw al I‘WD lo used crosseslope
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inlercrpiorr elieclively col up incipienl or degraded
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croplands sublecl lo desenineanon inio blocks or rm rn
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lsan leell lo a maximum ol 3m m19851eel) Wide.
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isolaling eaeh blo(k lrorri llooding and ihe sally
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cascade [low horn uphill. surplus waier is carried on
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in slreanis lnlercepler banks also eul on seepage lrorri
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sail hkzs, and ean diverl early lsalledl overland now
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around sallparis, leliing laler lresh iloodwaier lrll ihe
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pans or shallow lahs
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kgadu drain5 or banks are inlendrd lo spill a lhin
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rheel n1 surplus (overflow) waier dawn a lrroad grassy
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slope, e her lor irrigalion or (u! deserlsl lo prevenl
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channel mm! and gidlying. niey are nonnally rnade lo
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asuh: 7.2a
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nlvEnsluu mums
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uni-is mus, mm M- imn warm lo nuns, m wum menann
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llov am! semi ll m sloiaurs Ynly arr pm or any rainvaler
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harvsnw-l mien
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M9472
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minus 111
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me
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A ironic slim an! end snowed w m channel Mk1. ihe ulnar
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women iry a ehain loirns a iii-roomy darn. uuxlnv mi channel In
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llood onl and impair land flammll
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169
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