24 BULLETIN 1358, U. S. DEPARTMENT OF AGRICULTURE 
EARTHEN DAM AND SPILLWAY DESIGN ~ 
PROFILES OF EARTHEN DAMS 
POOR GOoD 
SPILLWAY __ 
AN UNEVEN OR SAGGED CREST DAMS WITH LEVEL TOP (OR CREST) 
LINE MEANS CONCENTRATION LINES RESIST FLOOD DAMAGE BEST. 
OF POSSIBLE OVERFLOW WATERS SHOULD A FLOOD OVER-TOP SUCH 
IN THE LOW PLACES FOLLOWED DAMS, THE WATERS WILL OVERFLOW 
BY MORE RAPID CUTTING AND AS A THIN SHEET OF MINIMUM 
GREATER LIKELIHOOD OF THE DAM EROSIVE POWER. 
WASHING OUT. 
SPILLWAY CROSS SECTIONS 
POOR GOOD 
= TRE 
STINE A 
WIDE FLAT C ANNE LoS Sin 
FLOOD WATERS CONCENTRATE FLOOD WATERS PASS THROUGH 
IN CHANNEL. CUTTING OF SPILL- IN.A WIDE THIN SHEET. EROSION 
WAY AND END OF DAM GREATLY OF SPILLWAY AND UNDERCUTTING 
INCREASED. OF END OF DAM REDUCED TO THE 
MINIMUM. 
REEATAION OF SElhEEWAYV 0; DAM 
(a) USUAL TYPE |(b)OCCASIONAL TYPE | (c) PREFERRED TYPE 
SPILLWAY AT LOWER END] SPILLWAY AT UPPER END] SPILLWAY ENTIRELY 
Of BEOODED AREA OP FECODED AREA APART FROM DAM 
SPILLWAY SPILLWAY 
4 z 
= hs 
SS 4 
. 
aw 
Bes 
3 
\\\ 
POOR FROM SILTING BETTER FROM SILTING ALSO BETTER FROM 
STANDPOINT. STANDPOINT BUT MORE | SILTING STANDPOINT BUT 
EXPENSIVE THAN IN BE Sih OR sipmiEsels iii Ese 
TF R=: @)c BECAUSE CHEAPEST. 
FIGURE 2 
