Table Y.   Design discharges for dam at La Calzada [Preliminary 080410].
Hydrograph	Flood discharge (m3/s)	Hydrograph volume (hm3)	Area-weighted 24-hr storm depth (mm)	Storm volume (hm3)	Runoff (%)
Principal spillway hydrograph 1	4,108	90	119	108	83
Emergency spillway hydrograph 2	4,799	114	146	132	86
Freeboard hydrograph 3	6,503	182	222	201	91
1 The principal spillway hydrograph (PSH) is used to determine: (a) the capacity of the principal spillway, (b) the emergency spillway crest elevation, and (c) the volume of retarding pool storage. 2 The emergency spillway hydrograph (ESH) is used to determine: (a) the capacity of the emergency spillway, (b) the maximum design-pool elevation, and (c) the volume of surcharge storage. 3 The freeboard hydrograph (FBH) is used to set the minimum dam-crest elevation, i.e., to establish the amount of freeboard.