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7nt~le 2, Tcbu!-~ien of s:at..:.,hed area r. that rill rro.luc~ ~ .lo~a of 4 FYS or le~~ in <br />div~rsia^ ditch ea coos! rucLc:; at va:-vin}; ;;ra~i,cnts using '.'rappdr's st nn:iand <br />ditch design. _ - -------- - - - <br />Peak ;lnw :~f a:<, a~at ershe5 Max. ~.az~crshed <br />Gradient (1) rite (GP>) (2) area Irr a area ~:?~~ <br />Q 2 ~': , 24 hr . event (3 ) ] 0 rr , 2= !: :- ,~.e^[ l3 ) <br />.02 14.00 ?640 acres (i) <br />.03 7.62 ?6,0 (4) <br />.04 4.95 >640 (4) <br />.O5 3.54 >6!a0 (4) <br />.06 2.69 500 <br />.05 1.75 300 <br /> a <br />. 10 1 . 25 1.50 <br />.12 0.95. 100 <br />.14 0.75 100 <br />.16 0.62 GO <br />.78 0.52 50 <br />.20 0.44 40 <br />2^_ 0.38 30 <br />. <br />4 0 <br />34 20 <br />.2 . <br />.26 0.30 20 <br />.28 0.27 20 <br />.30 0.24 20 <br />(I) Gradient of ditch (vertical drop r horizontal distance) <br />10/01 acres <br />JD <br />30 <br />20 <br />10 <br />(2) Deri.~ed from `]awning's equation, see next page <br />(3) From Table 1. 1'he exact allowable watershed area is g:ea[er in :host cases. <br />(4) Equals one squarz mile, i.e. is the upper limit o: watershed size `or L`~is Design. <br />HIiN/ js <br />M/~/12/62 <br />• <br />T-5 <br />.'s'at <br />