ill HKKNT MKTKIO 71 



15- M. l> mark* to refer the gages to a fixed datum, and 



t< in. 1 1. .it.- \sh. -ill. r tin- gages remain at the correct elevation. 

 :i. Mm. -inn - iii proieei th- automatic water stage register 



\\lit-u II-.. 1. 



4. Mm. tut.- ii"in \shiih ilischarge measurements are 

 mad. 



5. Stay line and head line to hold the meter in a vertical 



position \\li.-n -.im. Ino .ui.l \rln IK observations are made. 



6. Crulu.it. -.1 Ini.-- t.> imlie.iir the |HUHIS of observation. 



7. Mm. -tun - (<> . ..nil..! .UK! regulate the relation between 



-l.iue .md di-eh.irp- .it pl.irr- \\lirn- ii.ilur.il i-Miitm! i- l.i- kniu'. 



It. ins 3 to 6 an- illuMr.it. .1 in Fig. 21, which shows a 

 upu-al gaging station, \\lnl.- id-m 7 is illustralctil in Kip. 17. 

 Full details are given in (U. S. Geological Survey) Water 

 Supply Paper No.. 37 1 . 



GAGES 



The entire process of collecting stream flow data by current 

 mrirr methods, i^ IKI-. d un th < <>n>tancy of the relation between 

 gage height and discharge. Hence, the correct installation of 

 the gage and its correct reading are fundamental!) important. 

 Errors in reading or recording the gage height are known to 

 be the reason for the majority of inaccuracies in stream gag- 

 ing work. 



The in-iiu in. -MI- that have been used for indicating the 

 it i. ni of water surface of rivers, lakes, and other bodies of 

 \\.itc-r in. IN le grouped into t\vo general classes, comprising 

 respertm IN mm n cording gages and recording water stage 

 registers, the grouping depending on the method of obtaining 

 the reeord. whether t.l ings by an observer at stated 



int.Tvals from a scale l...ml. <>r <>th<T d<-N iee, or by some 

 automatic meehani*m. 



NON-RECORDING CAGES 



Non-recording gages in common use are the vertical or 

 inelined staff gage, the hook gage, the chain gage, and 

 the float gage. 



