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<br />10
<br />
<br />TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS
<br />
<br />SEQUENCE. Number the cards (Jines)
<br />used sequentially starting with a number that
<br />is the card 2 sequence number. plus L
<br />
<br />CARD. Card number. column 80, is 3.
<br />
<br />Card 4 - Subarea Roughness Coefficients
<br />
<br />The roughness coefficients for the ap- .
<br />proach- section subareas are entered in pairs
<br />along with two elevations. The program ac-
<br />commodates up to four subareas.
<br />
<br />These data allow the computer to vary n
<br />linearly from D1 at the lower elevation, b~
<br />
<br />to D3" at the qpper elevatio~ a. Therefore,
<br />
<br />below elevation b the roughness coefficient
<br />will equal.n ; between elevations b- and a,
<br />1
<br />the coefficient will vary linearly from nl to
<br />
<br />n ; and above elevation a, the coefficient
<br />3
<br />will equal n3'
<br />
<br />Elevations b and a are to the nearest
<br />foot, and a must be 1 foot or a multiple of
<br />1 foot higher than b. The values of n1 and
<br />
<br />n3 are the three digits to the right of the
<br />
<br />decimal in Manning's D. For example: An
<br />n of 0.035 would be entered as 035 with the
<br />decimal implied. The values of nl and n3
<br />
<br />can be the same or either can be higher than
<br />the other. A value must be entered for each
<br />n1, ,D3' a, and b space of each subarea.
<br />
<br />If there are fewer than four subareas,
<br />leave the unused part of the card blank but
<br />add the sequence number. which 'is 1 greater
<br />than that on the last card 3.
<br />
<br />The card number. column 80. is 4.
<br />
<br />Card 5 - Discharges
<br />
<br />List the selected discharges. in cfs (cubic
<br />feet per second), in ascending order. Do not
<br />select too Iowa discharge for wide box cul-
<br />verts or for wide, relatively fiat approach
<br />sections. The program can distribute the
<br />flow only uniformly across a section, no
<br />matter how a small flow may entrench or
<br />C'hannel itself: therefore a fallacious deter-
<br />Inination of supercritical now is made.
<br />
<br />Express the- discharge- as whole numbers,
<br />right justified. with no decimals or commas.
<br />
<br />up to 99999 cfs. If less than 12 discharges
<br />are desired, leave the remaining columns
<br />blank and complete the sequence number
<br />(previous sequence number, plus 1). The
<br />discharges are. entered in columns 1-5, 7-1t,
<br />13-17, 19-23, 25-29, 31-35, 37-41, 43-47,
<br />49-53. 55-59, 61-65, and 67-71.
<br />
<br />The card number, column 80, is 5.
<br />
<br />Card 6 - Tailwater Elevations
<br />
<br />List up to 10 selected tailwater elevations.
<br />in feet and hundredths. in ascending order.
<br />Make only the last one greater than the base
<br />elevation plus D for type 4 now. For cul-
<br />verts on very ste.ep slopes, this last tail water
<br />elevation must be high enough to submerge
<br />the inlet also; ther~fore. it is best to choose
<br />it greater than the base elevation plus D + z.
<br />The smallest tailwater elevation should be
<br />greater than 0.04 D plus the base elevation.
<br />Only one type 4 computation is required for
<br />each discharge because the headwater ele-
<br />vat.ion varies directly with the tailwater ele-
<br />vation. See Bodhaine (1968), figure 31.
<br />
<br />If option 1 (card 9, column 68) is chosen,
<br />one headwater elevation is computed for each
<br /><lischarge wUhout any infiuence from the tail-
<br />water. Provide one tailwater elevation,
<br />higher than the base elevation plus D, on
<br />card 6 so the computer will be able to follow
<br />the sequence of steps in the program.
<br />
<br />If less than 10 tailwater elevations are
<br />needed, leave the remaining columns blank
<br />and complete the sequence nu'mber (previous
<br />sequence number, plus 1), The 10 elevations
<br />(maximum, 999.99 feet), are listed in col-
<br />umns 1-6. 8-13, 15-20, 22-27, 29-34, 36-
<br />41, 43-48, 50-55, 57-62, and 64-69. Fixed
<br />decimals are in every seventh column start-
<br />ing with column 4.
<br />
<br />The card number. column 80, is 6.
<br />
<br />Card 7 - Discharge Coefficients,
<br />Types 1, 2, 3
<br />
<br />There are curvilinear relations between
<br />the discharge coefficients, C, for fiow types
<br />I, 2, and 3, and the headwater elevation.
<br />The relations are approximated and the cor-
<br />rect coefficient is computed from an input of
<br />discharge coeffiCients corresponding to four
<br />specific headwater elevations. List the net
<br />coefficients after adjustment for rOunding,
<br />
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