027002 Wharfe at Flint Mill Weir 1974
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 11.900 23.310 9.623 6.385 3.713 1.969 1.992 25.050 2.875 6.899 5.060 32.010
2 10.030 49.190 9.629 6.219 3.627 1.914 2.640 12.060 4.733 19.310 5.166 32.140
3 8.949 53.870 9.377 5.921 3.316 2.058 23.620 7.667 31.600 28.490 6.288 21.730
4 9.998 27.650 9.769 5.624 3.252 2.187 10.350 5.636 39.170 22.230 10.730 18.570
5 35.210 23.300 10.970 5.480 3.099 1.955 28.270 5.096 39.410 20.080 8.431 20.900
6 30.110 25.370 11.550 5.247 3.009 7.101 15.710 4.321 40.670 13.330 6.499 18.400
7 68.480 19.520 59.150 5.070 2.935 14.890 8.301 3.754 85.610 20.190 9.740 19.280
8 73.200 37.210 29.410 4.921 2.890 11.340 5.998 7.569 80.940 16.450 27.230 32.900
9 49.400 67.340 17.060 4.733 2.810 24.850 4.774 8.996 63.710 16.730 25.870 33.850
10 64.490 46.330 13.270 4.572 2.869 15.310 3.844 8.192 34.670 14.110 25.050 54.530
11 58.840 79.980 18.340 4.883 3.058 9.308 3.848 8.579 21.430 15.340 90.880 52.180
12 39.890 61.200 16.490 5.238 3.026 6.479 4.582 24.580 17.010 11.650 38.200 35.590
13 42.090 37.050 15.990 4.902 2.938 4.771 3.881 15.210 29.310 9.178 67.490 33.480
14 46.010 30.090 16.420 4.524 2.808 3.550 4.587 9.493 22.960 7.817 62.850 49.680
15 94.620 76.960 32.800 4.145 2.930 2.993 9.250 17.980 13.800 7.030 55.430 28.140
16 66.240 42.370 89.240 3.963 2.825 2.763 40.550 10.050 10.770 10.580 27.490 42.300
17 64.810 31.020 38.940 3.860 2.630 8.159 23.340 7.945 9.060 19.660 17.870 52.870
18 51.030 22.110 53.870 3.834 2.545 6.781 10.240 5.849 8.364 43.180 13.820 44.350
19 49.880 17.780 34.580 3.813 2.402 4.415 6.814 5.048 7.075 34.900 11.500 34.690
20 29.370 17.440 26.070 3.782 2.345 3.212 5.283 4.257 6.209 19.340 10.210 37.020
21 21.160 15.470 18.850 3.713 2.033 2.620 4.207 3.681 6.212 13.530 15.130 54.020
22 17.190 13.580 14.810 3.627 2.106 2.281 3.698 3.493 9.676 11.690 23.400 59.990
23 19.630 12.170 12.590 3.747 2.196 2.033 7.663 3.209 46.590 10.730 20.120 30.060
24 25.880 10.630 11.050 3.692 3.358 2.051 6.261 3.028 41.110 8.887 47.540 21.390
25 20.560 9.915 10.440 3.524 3.874 2.034 4.079 3.141 31.910 7.840 90.750 34.340
26 17.430 9.344 9.894 3.524 2.938 1.921 3.150 3.185 21.060 7.209 45.680 83.570
27 31.420 8.841 9.019 3.524 2.517 1.938 4.080 3.672 14.180 6.786 53.520 47.820
28 40.270 8.677 8.246 3.808 2.295 1.947 4.850 3.343 10.890 7.274 53.110 44.690
29 23.980 7.569 3.983 2.137 1.956 11.950 2.889 8.775 6.670 33.840 48.970
30 32.180 7.049 4.620 2.065 1.917 23.550 2.648 7.442 5.921 32.930 30.810
31 43.130 6.678 2.065 22.800 2.435 5.592 24.480
Average 38.630 31.350 20.600 4.496 2.794 5.223 10.130 7.486 25.570 14.470 31.390 37.900
Lowest 8.949 8.677 6.678 3.524 2.033 1.914 1.992 2.435 2.875 5.592 5.060 18.400
Highest 94.620 79.980 89.240 6.385 3.874 24.850 40.550 25.050 85.610 43.180 90.880 83.570
Monthly total
(million cu m) 103.50 75.83 55.19 11.65 7.48 13.54 27.14 20.05 66.29 38.76 81.37 101.50
Runoff (mm) 136 100 73 15 10 18 36 26 87 51 107 134
Rainfall (mm) 165 114 76 16 38 75 131 82 153 86 152 147
Statistics of monthly data for previous record (Oct 1955 to Dec 1973)
Mean Avg. 24.820 22.980 18.500 17.190 12.240 7.651 9.358 13.270 13.650 16.960 22.650 26.070
flows: Low 4.472 2.974 6.741 5.197 3.911 1.545 3.601 1.795 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1957 1960 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. 88 74 65 59 43 26 33 47 47 60 77 92
Low 16 9 24 18 14 5 13 6 5 11 23 36
High 139 174 128 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 100 84 76 81 80 75 95 102 97 99 108 113
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
1974
For 1974 For record As % of $ Reservoir(s) in catchment.
preceding 1974 pre-1974 $ Abstraction for public water supplies.
Mean flow 19.100 17.090 112 $ 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 2.794 May 1.419 Sep 1959 groundwater.
Highest monthly mean 38.630 Jan 62.090 Dec 1965
Lowest daily mean 1.914 2 Jun 0.425 23 Jun 1957
Highest daily mean 94.620 15 Jan 233.600 4 Dec 1960
10% exceedance 48.520 39.390 123
50% exceedance 10.430 9.594 109
95% exceedance 2.155 2.622 82
Annual total (million cu m) 602.30 539.30 112
Annual runoff (mm) 794 711 112
Annual rainfall (mm) 1235 1110 111
{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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