027002 Wharfe at Flint Mill Weir 1978
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 11.390 55.340 31.840 19.560 8.833 2.794 2.218 3.930 2.441 18.350 5.357 7.148
2 19.450 58.850 28.500 34.370 8.048 2.754 2.669 3.360 2.345 13.160 5.428 6.605
3 107.700 37.810 23.210 19.230 7.018 2.626 4.327 8.664 2.181 16.530 6.199 6.602
4 41.540 39.560 18.030 14.220 9.676 2.903 3.980 18.440 2.037 11.590 5.590 21.100
5 36.640 56.580 13.310 11.330 22.770 5.168 4.239 9.512 2.213 9.881 9.326 15.900
6 31.600 42.920 11.410 9.264 23.700 3.639 3.467 22.810 7.038 10.290 7.561 10.810
7 20.470 33.080 10.160 8.378 14.620 2.903 2.713 20.400 12.140 8.358 5.869 11.960
8 15.290 23.490 18.650 7.436 10.040 2.724 2.365 12.100 6.439 7.097 5.082 65.330
9 20.100 17.620 15.890 7.065 7.980 2.537 2.142 13.960 19.310 6.276 4.473 54.240
10 23.520 14.670 11.580 6.674 6.768 2.473 2.028 8.700 73.830 5.677 4.097 32.060
11 27.950 12.510 10.460 6.260 6.235 2.421 1.968 6.210 96.710 5.251 3.907 28.920
12 19.720 11.820 9.469 6.237 6.216 2.288 1.891 5.451 33.210 4.845 3.952 42.320
13 15.340 10.680 9.607 7.458 6.407 2.212 1.866 7.508 22.520 4.486 10.880 52.070
14 24.700 9.603 27.100 8.389 6.687 2.076 1.701 9.443 32.920 3.998 43.240 30.910
15 22.090 8.740 59.630 8.893 6.605 2.170 1.659 24.870 18.610 4.067 58.190 21.160
16 17.690 7.996 28.060 8.111 7.463 2.733 1.581 34.770 12.760 4.770 60.770 15.700
17 15.350 7.611 18.870 7.460 7.300 2.210 1.559 18.440 9.584 9.201 58.600 12.310
18 12.250 7.111 14.000 6.561 5.981 1.891 1.544 10.160 7.666 6.256 57.350 10.350
19 11.340 6.751 26.550 6.075 5.238 1.802 1.589 7.123 6.461 4.968 52.240 8.900
20 10.490 6.771 39.940 6.531 4.596 1.752 1.664 5.733 5.735 4.322 29.150 8.077
21 10.600 6.353 36.980 9.464 4.223 1.802 1.684 4.590 5.018 4.096 37.250 8.297
22 48.540 8.427 42.910 7.708 3.986 1.817 1.637 5.978 4.693 3.925 23.480 9.933
23 46.580 58.670 67.930 6.806 3.296 1.834 1.651 7.315 4.205 4.758 43.270 9.470
24 58.130 68.530 49.960 6.201 2.739 1.963 1.514 4.963 4.096 4.607 66.850 33.340
25 31.260 41.230 44.320 5.745 2.610 1.968 1.554 3.933 10.330 12.990 29.650 53.570
26 21.940 41.100 32.930 5.539 2.706 2.234 2.015 3.385 6.991 9.038 19.280 39.730
27 22.940 31.190 54.710 6.434 2.996 2.119 2.161 3.102 10.460 7.419 14.280 91.600
28 109.700 31.960 34.320 6.349 2.996 2.005 2.820 2.940 26.850 5.847 10.930 148.100
29 77.580 29.180 5.971 2.975 1.923 3.041 2.828 75.860 5.006 8.887 106.200
30 46.380 20.670 6.651 2.909 1.927 3.529 2.605 32.250 4.437 8.045 49.840
31 29.970 14.200 2.833 2.669 2.626 4.153 32.890
Average 32.520 27.030 27.560 9.212 6.982 2.389 2.305 9.544 18.560 7.279 23.310 33.720
Lowest 10.490 6.353 9.469 5.539 2.610 1.752 1.514 2.605 2.037 3.925 3.907 6.602
Highest 109.700 68.530 67.930 34.370 23.700 5.168 4.327 34.770 96.710 18.350 66.850 148.100
Monthly total
(million cu m) 87.11 65.40 73.82 23.88 18.70 6.19 6.17 25.56 48.12 19.50 60.41 90.33
Runoff (mm) 115 86 97 31 25 8 8 34 63 26 80 119
Rainfall (mm) 163 77 106 54 41 50 75 86 131 32 95 218
Statistics of monthly data for previous record (Oct 1955 to Dec 1977)
Mean Avg. 26.250 23.280 17.990 16.080 11.580 7.076 8.773 11.750 13.730 17.490 22.640 25.670
flows: Low 4.472 2.974 6.741 4.496 2.794 1.545 1.674 0.991 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1974 1974 1957 1976 1976 1959 1972 1958 1963
High 39.260 54.590 36.400 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1961 1966 1963 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 93 75 64 55 41 24 31 41 47 62 77 91
Low 16 9 24 15 10 5 6 4 5 11 23 36
High 139 174 128 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 106 85 75 77 78 71 93 96 104 101 108 111
Low 41 20 28 10 13 18 35 18 8 34 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1978
For 1978 For record As % of $ Reservoir(s) in catchment.
preceding 1978 pre-1978 $ Abstraction for public water supplies.
Mean flow 16.650 16.830 99 $ 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 2.305 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 33.720 Dec 62.090 Dec 1965
Lowest daily mean 1.514 24 Jul 0.425 23 Jun 1957
Highest daily mean 148.100 28 Dec 233.600 4 Dec 1960
10% exceedance 43.170 39.500 109
50% exceedance 8.251 9.477 87
95% exceedance 1.874 2.298 82
Annual total (million cu m) 525.10 531.10 99
Annual runoff (mm) 692 700 99
Annual rainfall (mm) 1128 1105 102
{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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