﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  435 
  

  

  heaviest 
  rainfall. 
  In 
  case 
  there 
  happens 
  to 
  be 
  gagings 
  of 
  the 
  

   stream, 
  the 
  maximum 
  runoff 
  may 
  be 
  obtained 
  from 
  the 
  gagings, 
  

   but 
  thus 
  far 
  there 
  are 
  gagings 
  of 
  comparatively 
  few 
  of 
  the 
  New 
  

   York 
  streams, 
  and 
  probably 
  the 
  flood-flow 
  will 
  require 
  to 
  be 
  com- 
  

   puted. 
  As 
  to 
  just 
  how 
  this 
  is 
  accomplished 
  is 
  foreign 
  to 
  the 
  

   purpose 
  of 
  this 
  report, 
  but 
  it 
  may 
  be 
  simply 
  stated 
  that 
  there 
  is 
  

   no 
  special 
  difficulty, 
  provided 
  that 
  the 
  data 
  of 
  catchment 
  and 
  

   rainfall, 
  together 
  with 
  the 
  steepness 
  of 
  slope, 
  length 
  of 
  catchment, 
  

   etc. 
  are 
  known, 
  in 
  computing 
  a 
  flood-flow 
  from 
  which 
  a 
  bridge 
  

   opening 
  may 
  be 
  ascertained 
  that 
  will 
  be 
  large 
  enough 
  to 
  carry 
  

   the 
  maximum 
  flood. 
  

  

  Lack 
  of 
  data 
  a 
  source 
  of 
  difficulty. 
  One 
  difficulty 
  in 
  design- 
  

   ing 
  regulation 
  works 
  arises 
  from 
  lack 
  of 
  data 
  and 
  in 
  order 
  to 
  

   render 
  data 
  of 
  this 
  character 
  accurate 
  within 
  2 
  or 
  3 
  per 
  cent 
  

   there 
  should 
  be 
  a 
  record 
  about 
  thirty 
  years 
  long. 
  Such 
  a 
  record 
  

   should 
  include 
  rainfall, 
  maximum, 
  or 
  flood-flows, 
  and 
  minimum, 
  

   or 
  low-water 
  flows. 
  In 
  this 
  way 
  only 
  can 
  accurate 
  knowledge 
  of 
  

   the 
  regimen 
  of 
  streams 
  be 
  gained. 
  

  

  River 
  conservancy 
  in 
  England. 
  Germany 
  and 
  France. 
  In 
  

   England, 
  largely 
  due 
  to 
  the 
  prevalence 
  of 
  the 
  common 
  law 
  rule 
  

   that 
  every 
  riparian 
  proprietor 
  owns 
  to 
  the 
  thread 
  of 
  the 
  channel, 
  

   river 
  conservancy 
  has 
  not 
  made 
  the 
  progress 
  which 
  it 
  should. 
  The 
  

   taxpayers 
  have 
  generally 
  insisted 
  that 
  all 
  who 
  are 
  to 
  be 
  taxed 
  

   have 
  a 
  voice 
  in 
  determining 
  the 
  kind 
  of 
  regulation 
  to 
  be 
  carried 
  

   out. 
  The 
  result 
  is 
  that 
  many 
  important 
  works 
  have 
  not 
  been 
  

   undertaken, 
  and 
  on 
  many 
  streams 
  the 
  work 
  has 
  been 
  carried 
  

   out 
  piecemeal, 
  thus 
  greatly 
  increasing 
  the 
  expense, 
  with 
  ineffectual 
  

   results. 
  

  

  In 
  Germany 
  the 
  system 
  is 
  quite 
  different. 
  Here 
  the 
  State 
  

   assumes 
  control 
  of 
  the 
  main 
  and 
  navigable 
  rivers, 
  defraying 
  the 
  

   expenses 
  of 
  their 
  management 
  out 
  of 
  tolls 
  collected 
  from 
  those 
  

   using 
  the 
  streams 
  for 
  navigation, 
  mill 
  power 
  and 
  other 
  purposes. 
  

   The 
  State 
  claims 
  absolute 
  ownership 
  in 
  the 
  waters 
  and 
  prevents 
  

   any 
  interference, 
  even 
  with 
  tributary 
  streams. 
  In 
  some 
  cases 
  

   the 
  riparian 
  owners 
  may 
  combine 
  for 
  purposes 
  of 
  draining 
  lands 
  

   and 
  flood 
  protection. 
  On 
  application 
  to 
  the 
  government 
  they 
  are 
  

   constituted 
  a 
  conservancy 
  authority, 
  armed 
  with 
  powers 
  to 
  compel 
  

   those 
  who 
  fail 
  in 
  their 
  duty 
  to 
  construct 
  the 
  necessary 
  protection 
  

  

  