## Exercise 2---Effects of using improper scale offset 

-   **The line shown on the rating on the next page was drawn using
    rating table 1.0 (on third page). Rating tables are often used to
    display the discharge predicted for a given gage height. These
    tables are developed by interpolating between input points, which
    are points where you tell the computer what the discharge is for a
    given gage height. Input points are shown using asterisk on the
    attached tables.**

-   **Your assignment is to plot 3 or 4 points between gage heights of
    6.10 and 8.20 using data from rating table 1.1 (on fourth page).
    Figure out where these points fall in relation to the rating curve
    drawn below. Why don't they plot on the line?**

### 

### ADAPS did the interpolation using the wrong offset for the curve in Table 1.1, so the interpolation was done incorrectly. The offset of 0.0 used in Table 1.1 was too low resulting in a concave-downward line.

### ![](media/image1.wmf){width="8.995138888888889in" height="6.648611111111111in"} 

### 

1 UNITED STATES DEPARTMENT OF INTERIOR - GEOLOGICAL SURVEY - WATER
RESOURCES DIVISION PAGE 1

EXPANDED RATING TABLE TYPE: LOG

06000001 DATE PROCESSED: 11-14-1991 @ 14:57 BY KLWAHL

ADAPS TRAINING SITE NO. 1 DD: 1 TYPE: 001 RATING NO: 1.0

OFFSET: 5.0 BREAK,OFFSET: (6.1,5.0) START DATE/TIME: 10-01-91 (0001)

BASED ON \_\_\_\_\_\_\_ DISCHARGE MEASUREMENTS, NOS \_\_\_\_\_\_\_\_,
AND \_\_\_\_\_\_\_\_, AND IS \_\_\_\_\_\_ WELL DEFINED BETWEEN
\_\_\_\_\_\_ AND \_\_\_\_\_\_ CFS

COMP BY \_\_\_\_\_ DATE \_\_\_\_\_\_\_\_ CHK. BY \_\_\_\_\_ DATE
\_\_\_\_\_\_\_\_

Prob. 4 \-- Correct offset

GAGE DIFF IN Q

HEIGHT DISCHARGE IN CUBIC FEET PER SECOND (STANDARD PRECISION) PER

(FEET) .0 .1 .2 .3 .4 .5 .6 .7 .8 .9 FOOT

6.0 10.0\* 11.6 13.2 15.0 16.8 18.8 20.8 22.8 25.0 19.2

7.0 27.3 29.6 32.0 34.5 37.0 39.7 42.3 45.1 48.0 50.9 26.5

8.0 53.8 56.9 60.0\* 63.3 66.7 70.2 73.8 77.4 81.1 84.9 35.0

9.0 88.8 92.7 96.7 101 105 109 113 118 122 127 42.2

10.0 131 136 141 146 150 155 160 165 171 176 50.0

11.0 181 186 192 197 203 208 214 220 226 231 56.0

12.0 237 243 249 255 262 268 274 281 287 293 63.0

13.0 300\* 306 313 319 326 333 339 346 353 360 67.0

14.0 367 374 381 388 395 402 410 417 424 432 72.0

15.0 439 447 454 462 470 477 485 493 501 509 78.0

16.0 517 525 533 541 549 558 566 574 583 591 83.0

17.0 600 608 617 625 634 643 652 661 669 678 87.0

18.0 687 696 706 715 724 733 742 752 761 771 93.0

19.0 780 790 799 809 819 828 838 848 858 868 98.0

20.0 878 888 898 908 918 928 939 949 959 970 102

21.0 980 990 1000 1010 1020 1030 1040 1050 1070 1080 110

22.0 1090 1100 1110 1120 1130 1140 1150 1160 1180 1190 110

23.0 1200 1210 1220 1230 1240 1260 1270 1280 1290 1300 110

24.0 1310 1330 1340 1350 1360 1370 1390 1400 1410 1420 120

25.0 1430 1450 1460 1470 1480 1500 1510 1520 1530 1550 130

26.0 1560 1570 1580 1600 1610 1620 1640 1650 1660 1680 130

27.0 1690 1700 1710 1730 1740 1750 1770 1780 1790 1810 130

28.0 1820 1830 1850 1860 1880 1890 1900 1920 1930 1940 140

29.0 1960 1970 1990 2000 2010 2030 2040 2060 2070 2090 140\*

30.0 2100\*

1 UNITED STATES DEPARTMENT OF INTERIOR - GEOLOGICAL SURVEY - WATER
RESOURCES DIVISION PAGE 1

EXPANDED RATING TABLE TYPE: LOG

06000001 DATE PROCESSED: 11-14-1991 @ 14:58 BY KLWAHL

ADAPS TRAINING SITE NO. 1 DD: 1 TYPE: 001 RATING NO: 1.1

OFFSET: .0 BREAK,OFFSET: (6.1,.0) START DATE/TIME: 10-01-91 (0010)

BASED ON \_\_\_\_\_\_\_ DISCHARGE MEASUREMENTS, NOS \_\_\_\_\_\_\_\_,
AND \_\_\_\_\_\_\_\_, AND IS \_\_\_\_\_\_ WELL DEFINED BETWEEN
\_\_\_\_\_\_ AND \_\_\_\_\_\_ CFS

COMP BY \_\_\_\_\_ DATE \_\_\_\_\_\_\_\_ CHK. BY \_\_\_\_\_ DATE
\_\_\_\_\_\_\_\_

Prob 4 \-- Incorrect offset

GAGE DIFF IN Q

HEIGHT DISCHARGE IN CUBIC FEET PER SECOND (STANDARD PRECISION) PER

(FEET) .0 .1 .2 .3 .4 .5 .6 .7 .8 .9 FOOT

6.0 10.0\* 11.0 12.2 13.4 14.7 16.1 17.7 19.3 21.1 14.4

7.0 23.0 25.1 27.3 29.7 32.2 35.0 37.9 41.0 44.3 47.9 28.7

8.0 51.7 55.7 60.0\* 62.6 65.3 68.0 70.9 73.8 76.8 79.9 31.4

9.0 83.1 86.3 89.7 93.1 96.7 100 104 108 112 116 36.9

10.0 120 124 129 133 138 142 147 152 157 162 47.0

11.0 167 173 178 184 190 196 202 208 214 220 60.0

12.0 227 234 240 247 254 262 269 277 284 292 73.0

13.0 300\* 305 311 316 322 328 333 339 345 351 56.0

14.0 356 362 368 374 381 387 393 399 406 412 63.0

15.0 419 425 432 438 445 452 459 465 472 479 67.0

16.0 486 493 501 508 515 522 530 537 545 552 74.0

17.0 560 568 575 583 591 599 607 615 623 631 80.0

18.0 640 648 656 665 673 682 690 699 708 717 85.0

19.0 725 734 743 752 762 771 780 789 799 808 92.0

20.0 817 827 837 846 856 866 876 886 896 906 99.0

21.0 916 926 936 946 957 967 978 988 999 1010 104

22.0 1020 1030 1040 1050 1060 1080 1090 1100 1110 1120 110

23.0 1130 1140 1150 1170 1180 1190 1200 1210 1230 1240 120

24.0 1250 1260 1270 1290 1300 1310 1320 1340 1350 1360 120

25.0 1370 1390 1400 1410 1430 1440 1450 1470 1480 1490 140

26.0 1510 1520 1530 1550 1560 1570 1590 1600 1620 1630 130

27.0 1640 1660 1670 1690 1700 1720 1730 1740 1760 1770 150

28.0 1790 1800 1820 1830 1850 1860 1880 1890 1910 1930 150

29.0 1940 1960 1970 1990 2000 2020 2040 2050 2070 2080 160\*

30.0 2100\*