] -. 



:-' i ESTJ.Y AND IRRIGATION 



Jone 



- rface run- ~ . . ~ 

 : i m ir_:r . - - : nntrS 



. - :h ihem: r.g 



periods c: jh and v-_-r; 



- the cr:c-:rt::-r. : ur. ier- 

 ".--.- -- n the t:ta" - in- 



_-;/-:- the str; - : rr.es st 



i-errttir.er.t :tr. i:r.^r t: 



en. tntifirrtt ftow throughout the 

 7 .'.- relative proportion of sur- 

 face -.:::-: ft to underground 

 ir_ the t:ta! su: : : : i stre 

 th : r main firtor in lefter- 



ng - haracter if regular or ir- 

 -nlar and its rxmomic for 



rr s^tiir.. :r : : Any 



ttnre f the drainage basin which 

 is to convert preck : .n- 



derground seepage helps by so mv 

 to make the stream regular and uni- 

 form in flow: and any feature which 

 --r.ds to shed precipitation as imme- 

 dii - mn-o^F, helps much 



to make thr stream .-regular and 



.-.' J-:'-' ~ -"- ~. ' '" 



f 



Forest c: e r : = . then, but one : : 

 many comple:: and inter-related fac- 

 tor h influence the character of a 



-earn. The more important of th- 



tors may be briefly summarized ^ 

 f : '.'. 



: Precipitation, its amount. 

 chi-~ - rain :r soow, and the 



I - >n through- 



ear. Gentle ra:r - 



tributed over many month r ter. i : 

 maintain constant underground seep- 

 -.d equable stream f. mat- 



hat the character f the drains 

 ba Hea - 



on the other hand, especially when 

 '~r~ : 



the - " .:--'- 

 with surf ace run- rf and :.i"=-r chan^. 

 able, intermittent f.-.-.v. This condi- 

 tion in its extreme t\-pe ed 

 in regions h^ tmct wet and c- 

 seasons like rn portioa 

 of the United 



for much of the 



cally dry or in flood. Oth.- 

 tions which : 

 modify to s 



uneven rainfall but can : - . holly 

 counter:. : 



- he t ipography of the drainage 

 -.-. 



7. ugh topography, with steep, di- 

 rect side slopes, tends of nee.-- : to 

 the rapid discharge of precipitation - 

 -face run-; ft rither than its gradual 

 -orption over the basin as under- 

 ground seepage. Moderate topogra- 

 ph : the other hand, with gentle 

 le 5". :pes. retard; the surface run- 

 rT and converts a larger proportion of 

 the precipitation into underground 

 g : hr permanent, stable supply 

 : -:-eam flow. Streams of rough to- 

 pography, more T- have rapid fall 

 and torrential current : th - - f mod- 

 erate topograph - . fall and slug- 

 2 -h current, factors which affect di- 

 the quickness with which a 

 precipitation upon the water- 

 shed is felt along the lower levels of 

 the stream and its character as regu- 

 lar or changeable. 



The simple or complex character of 

 the topography is another important 

 factor affecting the evenne^ : f stream 

 -:-7ims with few tributary 



basins, and those short, sharply de- 

 nned, and direct in coi:r- such as are 

 : nd usually in the newer geological 

 regions rise and fall rapidly in re- 

 rise to variations in precipitation, 

 the other hand, with many 

 tributaries of the long, winding, indi- 

 rect character common in the older, 

 heavily eroded sections, discharge 

 J iters -' '^. much longer pe- 



riod with iden and sharp varia- 



D flow. 



Finally, the presence or absence : 

 lakes, por. i- r swamj - in the drain- 

 ag- - very important topo- 



E> -phic feature in its bearing upon 

 the behav - f the stream. Even' 

 h aret .s a natural reserve i' 



ring and holding flood . iters. feed- 

 ing them out gradually, and th 

 equal: z g 'he flow of the stream 

 throughout the year. 



: ~'~ : - ge logical character of the 



- -inage basin. The character of the 



- rock has 'much t 1 with the 









