027002 Wharfe at Flint Mill Weir 1984
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 48.500 72.840 9.600 9.689 3.121 2.534 2.724 2.020 5.189 11.580 15.640 17.540
2 74.240 140.700 32.620 8.879 2.989 2.617 2.669 2.454 10.140 7.685 17.390 18.310
3 70.690 130.900 15.930 7.941 2.853 3.389 2.570 3.628 16.020 6.272 134.700 24.050
4 34.420 117.700 19.480 7.525 2.664 3.526 2.306 12.270 75.750 10.630 63.200 25.620
5 39.380 94.850 20.700 7.043 3.113 3.860 2.232 4.587 15.350 8.544 30.880 23.390
6 46.860 140.700 14.920 6.973 3.037 6.329 2.148 3.375 7.487 5.747 21.280 20.870
7 44.680 69.080 11.960 6.806 2.864 4.525 2.155 3.483 5.127 4.570 19.780 14.820
8 26.970 75.650 10.120 6.456 2.773 3.852 2.163 3.744 4.546 21.390 18.880 12.360
9 19.860 39.300 8.958 6.262 2.720 3.278 2.144 3.094 7.266 30.130 28.630 12.000
10 34.490 31.160 8.200 6.100 3.016 2.966 2.106 2.716 10.760 12.040 56.530 10.900
11 101.600 31.200 8.259 6.461 3.120 2.858 2.102 2.507 5.586 12.970 27.040 9.743
12 47.970 24.950 8.282 7.291 2.911 2.894 2.163 2.333 5.610 12.390 45.800 8.972
13 126.400 20.500 8.277 6.316 2.741 31.290 2.324 2.238 4.482 8.629 40.510 8.417
14 59.740 16.530 7.978 5.814 2.665 31.810 2.486 2.200 22.770 17.890 24.470 8.402
15 36.420 14.070 7.828 5.790 2.610 9.831 2.367 2.105 16.280 16.990 17.910 8.154
16 65.950 12.770 7.565 5.667 2.584 5.742 2.302 2.069 8.061 10.390 14.740 7.659
17 72.880 11.670 7.186 5.228 2.619 4.592 2.290 2.053 23.880 8.367 14.790 8.998
18 41.760 10.790 6.790 4.843 2.686 4.174 2.243 2.045 16.890 40.240 16.550 14.100
19 29.450 10.100 6.436 4.588 2.611 3.737 2.247 2.000 8.169 60.770 13.970 49.490
20 22.550 9.422 6.185 4.570 2.574 3.452 2.173 1.957 5.615 43.050 12.200 43.890
21 18.310 9.696 5.841 4.702 2.634 3.136 2.114 1.944 6.859 20.040 35.920 45.030
22 16.940 10.810 5.647 4.471 3.173 3.087 2.022 1.956 18.950 71.480 94.120 32.390
23 16.590 13.660 5.726 4.201 3.352 3.225 2.043 1.942 22.330 46.060 96.560 38.200
24 14.630 10.960 29.090 4.044 3.181 3.443 1.942 1.963 11.440 39.520 54.820 29.190
25 12.680 9.526 29.730 3.887 2.844 3.229 1.882 1.897 7.382 59.420 41.820 22.120
26 12.620 8.901 40.840 3.683 2.721 3.175 1.889 1.875 5.436 34.440 29.550 23.930
27 22.310 8.442 23.030 3.530 3.178 3.117 2.029 1.891 4.402 23.850 22.030 16.010
28 33.170 7.876 20.380 3.366 3.352 2.993 2.114 1.917 3.953 33.900 61.960 12.610
29 58.560 7.675 17.030 3.262 2.684 2.923 1.947 1.882 4.938 31.600 31.390 11.550
30 60.110 13.070 3.170 2.644 2.784 1.918 1.922 12.720 38.510 21.370 13.310
31 53.240 11.070 2.539 2.026 2.020 22.140 16.670
Average 44.000 40.080 13.830 5.619 2.857 5.612 2.188 2.712 12.450 24.880 37.480 19.640
Lowest 12.620 7.675 5.647 3.170 2.539 2.534 1.882 1.875 3.953 4.570 12.200 7.659
Highest 126.400 140.700 40.840 9.689 3.352 31.810 2.724 12.270 75.750 71.480 134.700 49.490
Monthly total
(million cu m) 117.80 100.40 37.04 14.56 7.65 14.55 5.86 7.26 32.26 66.63 97.15 52.59
Runoff (mm) 155 132 49 19 10 19 8 10 43 88 128 69
Rainfall (mm) 217 83 78 18 37 67 20 73 160 155 191 80
Statistics of monthly data for previous record (Oct 1955 to Dec 1983)
Mean Avg. 27.350 22.990 21.710 15.540 11.620 7.612 7.757 11.480 13.670 18.100 23.560 27.460
flows: Low 4.472 2.974 6.741 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1974 1980 1957 1976 1976 1959 1972 1958 1963
High 39.260 54.590 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1961 1966 1981 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 97 74 77 53 41 26 27 41 47 64 80 97
Low 16 9 24 15 8 5 6 4 5 11 23 36
High 139 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 110 83 89 74 78 77 85 98 105 105 111 123
Low 41 20 28 8 13 18 22 18 8 32 33 41
High 165 194 222 147 181 183 185 226 241 225 211 233
Summary statistics Factors affecting runoff
1984
For 1984 For record As % of $ Reservoir(s) in catchment.
preceding 1984 pre-1984 $ Abstraction for public water supplies.
Mean flow 17.510 17.390 101 $ 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 2.188 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 44.000 Jan 62.090 Dec 1965
Lowest daily mean 1.875 26 Aug 0.425 23 Jun 1957
Highest daily mean 140.700 2 Feb 288.400 3 Jan 1982
10% exceedance 44.400 41.400 107
50% exceedance 8.230 9.721 85
95% exceedance 2.020 2.267 89
Annual total (million cu m) 553.70 548.80 101
Annual runoff (mm) 730 723 101
Annual rainfall (mm) 1179 1138 104
{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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