027002 Wharfe at Flint Mill Weir 1976
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 15.430 6.021 6.366 18.670 2.573 11.950 1.493 1.060 1.217 78.470 14.610 22.360
2 80.030 5.775 6.080 18.440 3.569 11.630 1.512 1.126 0.899 109.800 32.250 18.020
3 72.620 5.647 5.533 16.910 10.720 9.547 1.454 1.198 0.880 57.870 35.720 13.780
4 30.870 6.480 5.218 21.040 15.130 7.335 1.438 1.146 0.900 35.980 22.220 11.170
5 44.420 7.117 4.917 14.150 8.681 6.273 1.482 1.211 0.921 39.200 22.730 9.125
6 37.410 6.976 4.442 17.450 8.269 5.404 1.374 1.218 0.794 57.920 20.680 14.020
7 29.830 12.120 4.195 12.670 9.132 4.747 1.243 1.140 1.083 28.070 18.700 20.850
8 19.750 17.080 3.971 10.140 13.790 4.210 1.137 1.133 0.847 18.670 14.150 51.770
9 50.410 17.670 3.808 8.450 9.304 3.494 1.150 1.020 0.875 17.030 11.750 35.430
10 39.690 30.210 3.729 7.293 6.609 3.157 1.140 1.072 1.310 15.150 10.160 20.630
11 41.160 18.100 3.621 6.616 5.010 2.934 1.132 1.143 44.750 23.210 9.143 15.280
12 27.310 42.200 3.835 6.438 7.749 2.823 1.353 1.072 44.240 43.280 8.218 13.670
13 20.770 32.430 4.896 7.224 18.560 2.711 1.952 1.103 15.850 34.470 7.534 14.670
14 20.990 17.730 5.189 18.140 9.375 2.605 1.609 1.103 13.120 64.570 6.929 19.550
15 18.720 13.180 4.714 12.920 7.167 2.414 1.626 1.077 10.230 107.300 7.046 19.020
16 13.400 11.450 4.763 8.710 14.670 2.380 3.618 1.143 6.585 51.220 9.877 19.230
17 11.050 10.320 5.870 6.949 9.151 2.542 2.997 1.020 5.072 27.810 11.330 20.840
18 9.844 9.730 5.928 6.115 6.987 2.505 2.025 0.806 3.893 39.010 10.730 16.570
19 21.850 8.435 5.774 5.615 6.439 4.579 1.659 0.703 3.315 30.430 10.590 16.610
20 85.010 7.431 5.272 5.165 11.090 4.190 5.221 0.762 2.640 23.250 8.989 22.490
21 41.820 7.134 6.945 4.587 10.670 3.059 2.595 0.708 2.479 30.100 8.033 32.110
22 49.330 11.990 11.500 4.284 7.463 2.603 1.989 0.646 2.145 37.060 7.333 35.090
23 44.680 12.700 9.029 3.691 6.596 2.372 1.605 0.620 2.022 34.440 6.579 37.210
24 21.750 17.420 11.520 3.549 5.212 2.025 1.358 0.621 1.996 29.100 6.172 36.720
25 14.490 12.180 70.070 3.406 7.575 1.813 1.237 0.815 24.390 22.920 6.513 23.710
26 11.570 9.135 43.360 3.287 17.050 1.579 1.114 0.827 55.190 22.100 6.450 18.030
27 10.320 7.881 27.480 3.191 10.760 1.509 1.081 0.810 25.770 16.650 11.370 15.180
28 9.035 7.100 18.330 3.124 7.969 1.464 0.957 0.907 15.730 13.250 23.060 13.510
29 8.098 6.580 19.310 2.814 21.290 1.445 1.076 0.975 11.600 11.870 39.340 11.520
30 6.936 15.900 2.617 19.570 1.578 1.024 0.983 17.690 14.820 34.380 10.350
31 6.320 20.780 18.920 1.244 1.556 13.250 10.180
Average 29.510 13.040 11.370 8.789 10.230 3.896 1.674 0.991 10.610 37.040 14.750 20.600
Lowest 6.320 5.647 3.621 2.617 2.573 1.445 0.957 0.620 0.794 11.870 6.172 9.125
Highest 85.010 42.200 70.070 21.040 21.290 11.950 5.221 1.556 55.190 109.800 39.340 51.770
Monthly total
(million cu m) 79.05 32.68 30.44 22.78 27.39 10.10 4.48 2.66 27.51 99.21 38.24 55.18
Runoff (mm) 104 43 40 30 36 13 6 4 36 131 50 73
Rainfall (mm) 127 59 67 28 139 18 50 20 203 204 72 88
Statistics of monthly data for previous record (Oct 1955 to Dec 1975)
Mean Avg. 25.970 22.880 18.140 16.210 11.510 7.254 9.307 12.630 14.200 16.670 22.480 25.940
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. 92 73 64 55 41 25 33 45 48 59 77 92
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. 105 83 75 78 76 72 98 100 101 97 108 112
Low 41 20 28 10 13 25 35 18 8 34 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1976
For 1976 For record As % of $ Reservoir(s) in catchment.
preceding 1976 pre-1976 $ Abstraction for public water supplies.
Mean flow 13.590 16.910 80 $ 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 0.991 Aug 1.419 Sep 1959 groundwater.
Highest monthly mean 37.040 Oct 62.090 Dec 1965
Lowest daily mean 0.620 23 Aug 0.425 23 Jun 1957
Highest daily mean 109.800 2 Oct 233.600 4 Dec 1960
10% exceedance 34.770 39.470 88
50% exceedance 8.188 9.449 87
95% exceedance 0.947 2.497 38
Annual total (million cu m) 429.70 533.60 81
Annual runoff (mm) 566 703 81
Annual rainfall (mm) 1075 1105 97
{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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