﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  81 
  

  

  therefore, 
  that 
  a 
  forest-protected 
  area 
  will 
  show 
  less 
  evaporation 
  

   during 
  the 
  months 
  of 
  the 
  storage 
  period 
  than 
  will 
  an 
  area 
  which 
  

   is 
  fully 
  exposed 
  to 
  the 
  sweep 
  of 
  the 
  winds. 
  In 
  proof 
  of 
  this 
  it 
  

   may 
  be 
  cited 
  that 
  the 
  Hudson 
  area 
  shows, 
  on 
  an 
  average, 
  only 
  4.6 
  

   inches 
  evaporation 
  during 
  the 
  storage 
  period, 
  while 
  the 
  Genesee 
  

   area, 
  during 
  the 
  same 
  period, 
  shows 
  8.9 
  inches. 
  The 
  Croton 
  area 
  

   shows 
  6.85 
  inches 
  evaporation 
  for 
  the 
  same 
  period. 
  It 
  is 
  probable 
  

   that, 
  due 
  to 
  greater 
  elevation, 
  winds 
  are 
  more 
  searching 
  on 
  the 
  

   Genesee 
  area 
  than 
  on 
  the 
  Croton 
  area, 
  although 
  the 
  forestation 
  is 
  

   not 
  very 
  different. 
  It 
  is 
  also 
  probable 
  that 
  owing 
  to 
  proximity 
  to 
  

   the 
  ocean 
  the 
  humidity 
  is 
  greater 
  on 
  the 
  Croton 
  area 
  than 
  on 
  

   the 
  Genesee, 
  but 
  since 
  there 
  are 
  no 
  observations 
  this 
  latter 
  point 
  

   can 
  not 
  be 
  stated 
  except 
  as 
  an 
  inference. 
  At 
  Erie, 
  Buffalo, 
  

   Rochester 
  and 
  Oswego 
  the 
  conditions 
  are 
  somewhat 
  the 
  same 
  as 
  

   at 
  New 
  York 
  and 
  the 
  humidity 
  shown 
  by 
  tables 
  Nos. 
  3, 
  4, 
  7 
  and 
  8 
  

   is 
  not 
  very 
  different. 
  We 
  need 
  humidity 
  observations 
  for 
  the 
  

   upper 
  Genesee 
  in 
  order 
  to 
  settle 
  the 
  relation. 
  

  

  In 
  the 
  growing 
  period 
  vegetation 
  is 
  active 
  and 
  large 
  demands 
  

   are 
  made 
  upon 
  ground 
  water 
  to 
  supply 
  its 
  requirements. 
  Dur- 
  

   ing 
  this 
  period, 
  as 
  an 
  average, 
  2.57 
  inches 
  of 
  water 
  runs 
  off 
  from 
  

   the 
  Croton 
  area, 
  although 
  in 
  1880 
  only 
  0.68 
  inch 
  ran 
  off. 
  As 
  

   a 
  broad 
  proposition, 
  ground 
  water 
  tends 
  to 
  become 
  lower 
  and 
  

   lower 
  throughout 
  the 
  growing 
  period. 
  

  

  In 
  the 
  replenishing 
  period 
  the 
  average 
  runoff 
  from 
  the 
  Croton 
  

   area 
  is 
  3.42 
  inches, 
  from 
  an 
  average 
  rainfall 
  of 
  12.08 
  inches. 
  

   During 
  this 
  period, 
  broadly, 
  ground 
  water 
  is 
  rising 
  and 
  con- 
  

   ditions 
  tend 
  to 
  restore 
  themselves 
  to 
  that 
  at 
  the 
  beginning 
  of 
  

   the 
  storage 
  period. 
  The 
  varying 
  conditions 
  on 
  the 
  Genesee 
  and 
  

   Hudson 
  rivers 
  during 
  these 
  periods 
  may 
  be 
  seen 
  by 
  reference 
  to 
  

   the 
  tables 
  relating 
  to 
  those 
  streams. 
  

  

  One 
  great 
  advantage 
  of 
  dividing 
  records 
  into 
  these 
  periods 
  

   is 
  as 
  follows: 
  Since 
  evaporation 
  and 
  plant 
  absorption 
  are 
  light 
  

   during 
  the 
  months 
  of 
  the 
  storage 
  period, 
  it 
  follows 
  to 
  a 
  great 
  

   degree 
  that 
  the 
  amount 
  of 
  water 
  which 
  can 
  be 
  stored 
  is 
  exhibited 
  

   by 
  the 
  rainfall 
  of 
  the 
  storage 
  months. 
  Realizing 
  this 
  fact, 
  it 
  

  

  