[EMAIL PROTECTED] wrote: > Adrian Stott wrote... > >Martin Clark <[EMAIL PROTECTED]> wrote: > >>Adrian Stott wrote... > >> >"Ralph Rawlinson" <[EMAIL PROTECTED]> wrote: > >>>> Locks 1 and 2, originally next to the junction with the River Irwell, > >>>>have been replaced > >>>>by a single deep lock situated to the west of the railway further away > >>>>from the river. > >>> > >>>(sort of XP from URW) > >>> > >>Since you have copied and pasted your reply to me in URW, I shall copy > >>and paste my reply to you, for the benefit of any readers here who don't > >>receive URW... > > > >Ditto (sort of). > > > >One answer is side ponds on the deep locks. > [snip figures] > >So if the double-depth lock is equipped with two side ponds, no > >backpumping is required, as its use will consume the same amount of > >water as the standard-depth lock (with no side ponds) above it..
Wrong. The amount it will use will be a function of both the number and area of the sideponds. The above would only be true if the sideponds happened to have exactly the same plan area as the lock chamber, and that both the lock and the sideponds have vertical sides. > > > Ditto, ditto. (Why are we having the same discussion in two places?) > In the specific case we are talking about, Middlewood Deep Lock, back > pumping will definitely be required for the forseeable future, as there > is no canal in place feeding water into the pounds above. It wouldn't > matter how many side ponds were constructed, once the water has gone > down, there would be no way to refill the upper levels. ...and in the 'unforeseeable' future, the two sets of triple staircase locks at Nob End will be feeding rather more water down the canal than the single locks need anyway, depending on losses through evaporation, transpiration, seepage...
