﻿82 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  has 
  been 
  the 
  writer's 
  habit 
  for 
  several 
  years, 
  in 
  storage 
  projects, 
  

   to 
  first 
  tabulate 
  rainfall 
  in 
  the 
  manner 
  indicated. 
  Such 
  pro- 
  

   cedure 
  has 
  the 
  advantage 
  that 
  it 
  leads 
  one 
  away 
  from 
  the 
  con- 
  

   templation 
  of 
  mere 
  detail. 
  There 
  is 
  a 
  positive 
  disadvantage 
  in 
  

   considering 
  the 
  monthly 
  quantities, 
  for 
  which 
  there 
  is 
  no 
  com- 
  

   pensation. 
  The 
  division 
  into 
  the 
  three 
  periods 
  exhibits 
  the 
  more 
  

   important 
  characteristics 
  without 
  overburdening 
  the 
  mind. 
  It 
  

   is 
  believed 
  that 
  a 
  considerable 
  advance 
  on 
  ordinary 
  practice 
  has 
  

   been 
  made 
  by 
  proceeding 
  in 
  the 
  manner 
  stated. 
  

  

  THE 
  RELATION 
  OF 
  RAINFALL 
  TO 
  RUNOFF 
  

  

  The 
  runoff 
  of 
  a 
  stream 
  is 
  influenced 
  by 
  many 
  complex 
  condi- 
  

   tions 
  — 
  as, 
  for 
  instance, 
  amount 
  of 
  rainfall 
  and 
  its 
  intensity, 
  

   nature 
  of 
  soil, 
  slope 
  of 
  surface 
  and 
  area 
  and 
  configuration 
  of 
  

   catchment 
  basin. 
  It 
  is 
  also 
  influenced 
  by 
  geologic 
  structure, 
  for- 
  

   ests, 
  wind, 
  force 
  of 
  vapor 
  pressure 
  and 
  other 
  elements. 
  Data 
  are 
  

   still 
  lacking 
  for 
  a 
  really 
  satisfactory 
  discussion 
  of 
  the 
  question, 
  

   although 
  they 
  have 
  accumulated 
  so 
  rapidly 
  during 
  the 
  last 
  few 
  

   years 
  that 
  many 
  conservative 
  conclusions 
  can 
  be 
  drawn 
  which 
  

   may 
  be 
  accepted 
  as 
  substantially 
  true. 
  

  

  As 
  a 
  result 
  of 
  many 
  years' 
  study 
  of 
  the 
  problem 
  indicated 
  by 
  

   the 
  heading 
  of 
  this 
  chapter 
  the 
  writer 
  has 
  come 
  to 
  the 
  conclusion 
  

   that 
  no 
  general 
  formula 
  is 
  likely 
  to 
  be 
  found 
  expressing 
  accu- 
  

   rately 
  the 
  relation 
  of 
  rainfall 
  to 
  the 
  runoff 
  of 
  streams, 
  for 
  streams 
  

   vary 
  widely 
  in 
  their 
  behavior, 
  and 
  when 
  they 
  do 
  agree 
  the 
  agree- 
  

   ment 
  is 
  usually 
  accidental. 
  As 
  a 
  general 
  proposition 
  we 
  may 
  

   say 
  that 
  every 
  stream 
  is 
  a 
  law 
  unto 
  itself. 
  

  

  The 
  final 
  formula 
  of 
  runoff 
  for 
  a 
  given 
  stream, 
  therefore, 
  will 
  

   differ 
  in 
  some 
  particulars 
  from 
  that 
  for 
  every 
  other, 
  except 
  that 
  

   there 
  may 
  be 
  accidental 
  resemblances 
  as 
  regards 
  slope, 
  shape 
  of 
  

   catchment 
  area, 
  surface 
  geology 
  or 
  some 
  other 
  peculiarity. 
  It 
  is, 
  

   however, 
  true 
  that 
  an 
  empirical 
  formula 
  may 
  be 
  made 
  for 
  certain 
  

   classes 
  of 
  streams 
  which 
  will 
  give 
  approximately 
  the 
  runoff 
  for 
  

   a 
  series 
  of 
  years. 
  

  

  