﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  793 
  

  

  tion 
  of 
  uniform 
  distribution 
  of 
  lockages, 
  there 
  must 
  necessarily 
  be 
  

   considerable 
  waste. 
  Taking 
  into 
  account 
  the 
  actual 
  water-surface 
  

   area 
  of 
  the 
  summit 
  level 
  of 
  (71,900 
  x 
  334) 
  = 
  24,014,600 
  square 
  feet, 
  

   and 
  assuming 
  an 
  inflow 
  of 
  1300 
  cubic 
  feet 
  per 
  second, 
  without 
  any 
  

   outflow, 
  the 
  increase 
  in 
  depth 
  per 
  hour 
  becomes 
  0.19 
  foot, 
  or 
  in 
  

   three 
  hours 
  the 
  increase 
  in 
  depth 
  would 
  become 
  0.58 
  foot. 
  How- 
  

   ever, 
  if 
  there 
  were 
  no 
  lockages 
  for 
  three 
  hours, 
  the 
  depth 
  would 
  

   not 
  increase 
  as 
  rapidly 
  as 
  this 
  because 
  of 
  the 
  leakage 
  at 
  gates 
  and 
  

   sluices 
  and 
  wastage 
  on 
  the 
  spillways. 
  In 
  order 
  to 
  illustrate 
  this 
  

   matter 
  we 
  may 
  consider 
  the 
  following 
  tabulation, 
  in 
  which 
  the 
  

   heads 
  are 
  given 
  in 
  inches 
  and 
  feet. 
  The 
  coefficient 
  used 
  for 
  the 
  

   computation, 
  as 
  derived 
  from 
  Bazin's 
  experiments, 
  is 
  applicable 
  

   to 
  a 
  flat-crested, 
  or 
  nearly 
  flat-crested, 
  weir 
  from 
  6 
  to 
  7 
  feet 
  wide. 
  

   The 
  quantity 
  of 
  discharge, 
  Q, 
  in 
  cubic 
  feet 
  per 
  second, 
  is 
  given 
  per 
  

   linear 
  foot 
  of 
  crest 
  and 
  also 
  for 
  2500 
  feet 
  of 
  crest. 
  

  

  Q 
  per 
  linear 
  foot 
  Q 
  for 
  2500 
  feet 
  

  

  Feet 
  

  

  Coefficient 
  

  

  of 
  crest, 
  in 
  

  

  cubic 
  feet 
  per 
  

  

  second 
  

  

  of 
  crest, 
  in 
  

   cubic 
  feet 
  

   per 
  second 
  

  

  0.083 
  

  

  2.20 
  

  

  0.053 
  

  

  133 
  

  

  0.167 
  

  

  2.20 
  

  

  0.150 
  

  

  375 
  

  

  0.250 
  

  

  2.35 
  

  

  0.294 
  

  

  735 
  

  

  0.330 
  

  

  2,42 
  

  

  0.459 
  

  

  1,148 
  

  

  0.417 
  

  

  2.47 
  

  

  0.665 
  

  

  1,663 
  

  

  Head 
  

   Inches 
  

  

  1 
  . 
  

  

  2 
  

  

  3 
  

  

  4 
  

  

  5 
  

  

  It 
  appears 
  from 
  the 
  foregoing 
  that 
  when 
  the 
  water 
  rises 
  to 
  a 
  

   depth 
  of 
  only 
  one 
  inch 
  on 
  such 
  a 
  crest, 
  the 
  discharge 
  over 
  2500 
  

   linear 
  feet 
  would 
  become 
  133 
  cubic 
  feet 
  per 
  second, 
  while 
  for 
  

   two 
  inches 
  depth 
  it 
  becomes 
  375 
  cubic 
  feet 
  per 
  second, 
  and 
  for 
  

   three 
  inches 
  depth, 
  735 
  cubic 
  feet 
  per 
  second, 
  and 
  so 
  on 
  up 
  to 
  

   1663 
  cubic 
  feet 
  per 
  second 
  for 
  a 
  depth 
  of 
  five 
  inches. 
  However, 
  

   the 
  wastage 
  would 
  be 
  less 
  than 
  these 
  figures 
  indicate, 
  because 
  

   of 
  the 
  outflow 
  from 
  leakage 
  and 
  the 
  wastage 
  over 
  the 
  crest. 
  

   Under 
  the 
  existing 
  conditions 
  of 
  the 
  proposed 
  deep 
  waterways 
  

   summit 
  level, 
  whenever 
  there 
  is 
  an 
  interval 
  of 
  two 
  or 
  three 
  

   hours 
  without 
  lockages 
  the 
  wastage 
  over 
  the 
  long 
  spillways 
  at 
  

   the 
  ends 
  of 
  the 
  level 
  will 
  amount 
  to 
  several 
  hundred 
  cubic 
  feet 
  

   per 
  second. 
  This 
  quantity 
  may 
  probably 
  be 
  reduced 
  somewhat 
  by 
  

   the 
  use 
  of 
  flashboards, 
  to 
  be 
  set 
  in 
  place 
  and 
  taken 
  off 
  as 
  neces- 
  

   sary, 
  although, 
  in 
  view 
  of 
  the 
  sudden 
  flood 
  rises 
  of- 
  the 
  Mohawk 
  

   river 
  and 
  consequent 
  necessity 
  for 
  removing 
  the 
  flashboards 
  fre- 
  

   quently, 
  the 
  writer 
  considers 
  that 
  such 
  remedy 
  would 
  be 
  some- 
  

   what 
  unsatisfactory. 
  The 
  safer 
  way, 
  without 
  doubt, 
  is 
  to 
  provide 
  

   a 
  liberal 
  wastage 
  requirement. 
  On 
  this 
  basis, 
  from 
  150 
  to 
  250 
  

  

  