027002 Wharfe at Flint Mill Weir 1975
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 25.000 34.730 6.220 5.153 41.080 2.474 1.644 2.653 5.054 34.120 2.710 51.460
2 22.790 23.910 6.502 5.172 23.760 2.887 1.589 2.364 3.897 40.480 2.959 92.340
3 16.960 17.760 7.560 4.913 12.670 2.955 1.674 2.139 3.437 53.890 12.820 36.470
4 14.900 14.220 8.008 4.697 9.360 3.300 1.675 1.998 2.906 55.240 8.079 22.460
5 13.590 12.160 7.258 4.520 7.732 2.916 1.620 1.971 2.310 45.830 11.410 16.660
6 20.040 10.790 10.720 4.871 6.708 2.674 1.407 1.948 2.137 25.360 10.860 12.570
7 30.930 9.711 17.210 5.968 6.124 2.926 1.516 1.872 2.235 15.930 8.288 10.300
8 19.350 8.931 12.960 9.785 6.344 2.626 1.394 2.057 2.056 11.040 6.092 8.835
9 14.650 8.402 9.916 6.310 7.469 2.415 1.056 2.380 8.154 9.171 5.234 7.719
10 12.410 8.017 8.865 5.525 7.231 2.091 1.210 2.342 29.350 17.580 4.805 7.053
11 24.090 8.595 22.810 5.487 6.739 2.077 2.179 2.039 26.020 12.370 5.041 6.503
12 30.020 9.935 22.850 6.104 6.470 2.046 1.710 1.808 21.990 9.132 4.838 6.087
13 25.700 12.760 14.230 6.079 6.538 1.896 1.622 1.617 12.420 7.767 4.288 5.735
14 19.450 15.680 10.440 11.720 7.996 1.783 8.059 18.610 8.508 6.911 3.960 4.925
15 17.690 13.000 8.613 20.280 8.155 1.768 7.162 7.457 6.079 6.207 5.895 4.562
16 21.710 10.970 7.535 11.630 6.444 1.799 7.188 34.910 4.532 5.637 25.350 4.131
17 16.460 29.370 6.989 17.070 5.699 1.782 3.739 19.670 3.745 5.114 11.060 3.913
18 18.270 19.520 6.398 20.990 5.387 1.838 4.115 9.602 3.575 4.666 8.011 3.792
19 15.240 12.420 6.010 20.320 4.486 1.977 3.996 7.125 3.761 4.389 6.555 3.736
20 55.120 10.020 5.685 16.150 4.075 2.099 2.698 15.850 3.591 4.115 10.110 3.666
21 25.560 8.927 5.647 29.120 3.826 1.953 2.369 9.106 5.018 3.803 7.243 3.525
22 116.400 8.147 8.582 21.860 3.287 1.843 22.410 6.758 4.017 3.634 5.852 3.387
23 71.730 7.646 10.680 13.530 3.095 1.831 82.520 4.537 4.551 3.218 5.461 3.200
24 58.950 8.137 7.749 10.070 2.909 1.720 22.510 3.890 6.777 3.301 14.090 3.051
25 91.460 7.857 6.695 8.453 2.879 1.699 15.460 3.408 62.360 3.198 18.480 2.996
26 45.620 7.259 8.031 7.490 2.852 1.620 8.840 3.160 34.700 3.160 21.950 3.537
27 42.320 6.622 7.977 6.843 2.755 1.707 6.857 2.867 34.400 3.072 27.270 4.977
28 35.520 6.310 6.532 6.464 2.679 1.643 5.380 2.633 39.110 2.949 24.320 4.326
29 28.910 5.947 6.354 2.647 1.631 4.167 2.475 18.530 2.737 14.050 4.298
30 56.000 5.594 7.086 2.759 1.715 3.419 4.993 13.500 2.784 9.993 4.331
31 44.840 5.285 2.530 2.968 7.716 2.648 9.737
Average 33.930 12.560 9.210 10.330 7.183 2.123 7.553 6.192 12.620 13.210 10.240 11.620
Lowest 12.410 6.310 5.285 4.520 2.530 1.620 1.056 1.617 2.056 2.648 2.710 2.996
Highest 116.400 34.730 22.850 29.120 41.080 3.300 82.520 34.910 62.360 55.240 27.270 92.340
Monthly total
(million cu m) 90.87 30.40 24.67 26.79 19.24 5.50 20.23 16.58 32.72 35.38 26.53 31.13
Runoff (mm) 120 40 33 35 25 7 27 22 43 47 35 41
Rainfall (mm) 133 31 55 83 37 25 117 82 117 61 68 64
Statistics of monthly data for previous record (Oct 1955 to Dec 1974)
Mean Avg. 25.550 23.420 18.610 16.520 11.740 7.524 9.399 12.960 14.280 16.840 23.090 26.660
flows: Low 4.472 2.974 6.741 4.496 2.794 1.545 3.601 1.795 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1974 1974 1957 1959 1959 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. 90 75 66 56 41 26 33 46 49 59 79 94
Low 16 9 24 15 10 5 13 6 5 11 23 36
High 139 174 128 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 104 85 76 78 78 75 97 101 100 99 110 114
Low 41 20 28 10 13 33 35 18 8 34 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1975
For 1975 For record As % of $ Reservoir(s) in catchment.
preceding 1975 pre-1975 $ Abstraction for public water supplies.
Mean flow 11.420 17.190 66 $ Flow reduced by industrial and/or
Lowest yearly mean 12.390 1964 agricultural abstractions.
Highest yearly mean 23.300 1966 $ Augmentation from surface water and/or
Lowest monthly mean 2.123 Jun 1.419 Sep 1959 groundwater.
Highest monthly mean 33.930 Jan 62.090 Dec 1965
Lowest daily mean 1.056 9 Jul 0.425 23 Jun 1957
Highest daily mean 116.400 22 Jan 233.600 4 Dec 1960
10% exceedance 25.460 40.060 64
50% exceedance 6.522 9.633 68
95% exceedance 1.715 2.599 66
Annual total (million cu m) 360.10 542.50 66
Annual runoff (mm) 475 715 66
Annual rainfall (mm) 873 1117 78
{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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