027002 Wharfe at Flint Mill Weir 1996
Measuring authority: EA Grid reference: 44 (SE) 422 473 Catchment area (sq km): 758.9
First year: 1936 Level stn. (m OD): 13.70 Max alt. (m OD): 704
Daily mean gauged discharges (cubic metres per second)
DAY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1 2.653 2.508 7.940 3.243 32.940 6.228 2.609 2.993 3.482 8.955 20.420 40.180
2 2.744 2.727 8.495 3.214 40.880 4.393 2.501 2.154 3.156 5.105 15.040 35.610
3 2.988 2.816 9.261 3.035 17.230 3.491 10.290 2.127 3.853 4.632 14.500 55.250
4 4.075 2.666 9.106 2.942 9.997 2.974 20.300 1.992 3.559 20.090 25.180 47.850
5 9.550 2.558 7.649 2.688 7.340 2.828 11.990 1.956 3.246 14.340 53.030 28.390
6 17.130 2.675 5.183 2.888 5.552 2.754 5.204 2.162 3.027 6.458 87.470 17.370
7 21.230 2.642 4.786 2.753 4.503 3.353 3.360 2.643 2.855 4.604 31.960 12.590
8 32.980 2.558 4.801 2.685 3.821 4.207 3.839 2.345 2.711 4.662 17.480 10.300
9 30.150 3.352 4.468 2.626 3.497 2.826 2.903 2.436 2.642 4.797 20.910 10.220
10 13.830 22.470 3.949 2.826 3.205 2.935 2.573 6.319 2.555 4.085 15.990 9.346
11 9.954 69.260 4.129 2.711 3.421 3.126 2.543 9.895 2.508 3.627 11.860 7.997
12 15.380 71.910 5.928 2.800 3.704 5.584 2.417 4.042 2.369 3.161 35.480 6.740
13 37.130 43.020 5.765 2.637 3.489 3.949 2.580 2.788 2.368 3.133 18.740 6.626
14 20.430 22.570 4.700 2.432 3.045 3.057 2.538 2.494 2.430 3.011 11.220 6.424
15 12.810 15.000 4.413 2.686 3.172 2.915 2.726 2.399 2.359 3.412 8.966 6.536
16 8.877 38.670 5.811 2.666 2.906 2.764 2.308 2.384 2.333 5.433 7.620 8.235
17 6.956 28.310 7.185 2.840 2.921 2.759 2.472 2.407 2.252 4.900 10.570 8.106
18 5.700 79.980 7.185 6.788 2.836 2.569 2.538 2.406 2.201 5.537 11.880 12.920
19 4.862 29.580 8.435 14.270 2.587 2.558 2.668 2.291 2.220 11.950 9.535 101.700
20 4.465 16.960 9.291 6.215 3.036 2.315 2.431 2.569 2.257 23.080 19.510 92.920
21 4.300 12.920 8.050 3.981 6.674 2.342 2.282 2.532 2.079 31.010 11.380 35.640
22 3.814 11.670 9.272 3.005 3.668 2.280 2.388 2.762 1.980 10.980 12.230 20.700
23 3.420 10.880 8.853 13.020 12.940 2.116 2.408 3.291 1.945 7.311 12.030 16.310
24 3.121 33.960 10.440 19.500 9.159 2.170 2.386 10.480 1.911 5.956 10.600 13.360
25 3.077 25.410 8.632 22.180 6.343 2.219 2.038 15.380 1.945 6.249 34.200 11.320
26 2.879 14.620 6.975 10.120 4.160 2.382 2.053 17.530 1.986 29.810 39.250 9.913
27 3.148 10.920 5.599 9.050 15.350 2.130 1.836 36.280 2.162 35.000 18.210 9.171
28 2.770 9.155 5.068 7.180 8.351 2.584 1.823 15.840 2.433 23.990 12.370 8.468
29 2.574 7.919 4.318 5.004 15.650 2.089 2.668 13.910 62.540 20.930 48.090 7.886
30 2.516 3.703 9.378 14.160 2.039 4.231 7.262 25.740 10.930 50.780 9.081
31 2.450 3.417 11.140 2.475 4.783 14.220 9.750
Average 9.612 20.680 6.542 5.912 8.635 2.998 3.786 6.157 5.303 11.010 23.220 21.840
Lowest 2.450 2.508 3.417 2.432 2.587 2.039 1.823 1.956 1.911 3.011 7.620 6.424
Highest 37.130 79.980 10.440 22.180 40.880 6.228 20.300 36.280 62.540 35.000 87.470 101.700
Monthly total
(million cu m) 25.74 51.81 17.52 15.32 23.13 7.77 10.14 16.49 13.75 29.49 60.18 58.48
Runoff (mm) 34 68 23 20 30 10 13 22 18 39 79 77
Rainfall (mm) 67 107 41 71 82 48 77 109 54 101 150 116
Statistics of monthly data for previous record (Oct 1955 to Dec 1995)
Mean Avg. 28.710 23.710 21.700 15.880 10.380 7.008 7.203 10.820 12.890 17.260 22.860 27.750
flows: Low 4.472 2.974 5.740 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.537 4.832
(year) 1963 1963 1993 1974 1980 1957 1976 1976 1959 1972 1995 1995
High 44.230 54.590 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1995 1966 1981 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 101 76 77 54 37 24 25 38 44 61 78 98
Low 16 9 20 15 8 5 6 4 5 11 22 17
High 156 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 120 87 93 76 73 73 81 97 101 107 111 127
Low 41 14 24 8 13 18 20 12 8 32 33 41
High 217 201 222 147 181 183 185 226 241 225 211 234
Summary statistics Factors affecting runoff
1996
For 1996 For record As % of $ Reservoir(s) in catchment.
preceding 1996 pre-1996 $ Abstraction for public water supplies.
Mean flow 10.430 17.160 61 $ Flow reduced by industrial and/or
Lowest yearly mean 11.420 1975 agricultural abstractions.
Highest yearly mean 23.300 1966 $ Augmentation from surface water and/or
Lowest monthly mean 2.998 Jun 0.991 Aug 1976 groundwater.
Highest monthly mean 23.220 Nov 62.090 Dec 1965
Lowest daily mean 1.823 28 Jul 0.425 23 Jun 1957
Highest daily mean 101.700 19 Dec 292.900 23 Feb 1991
10% exceedance 25.130 40.890 61
50% exceedance 4.812 9.339 52
95% exceedance 2.154 2.300 94
Annual total (million cu m) 329.80 541.50 61
Annual runoff (mm) 435 714 61
Annual rainfall (mm) 1023 1146 89
{1961-90 rainfall average (mm) 1161}
Station and catchment description
Broad-crested masonry weir 47m wide; c/m cableway originally 1.5km u/s then moved to new ultrasonic station at Tadcaster
in 1990. Insensitive at low flows. Does not drown at high flows, though small amount of bypassing on the right bank.
Level data: 1936-1955. Recalibration (from 1965) completed but flows reprocessed from 1982 only. Pre-1965 data less
reliable. Mill race opened in early 1990s (not rated) so flows not reliable. Regulation effect of headwater reservoirs
evident at low flows. Small net export of water (inc. Bradford supply).
Mixed geology of moderate permeability - mainly Carboniferous Limestone, grits and Coal Measures with over 40%
superficial deposits. Predominantly mixed rural catchment, 60% grassland, with moorland headwaters.
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