027002 Wharfe at Flint Mill Weir 1979
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 24.580 25.010 35.770 36.090 8.700 20.380 2.254 10.060 4.008 6.687 20.680 24.100
2 20.350 18.970 164.100 29.120 7.590 15.330 2.252 25.490 4.679 6.133 14.680 29.250
3 16.760 28.790 167.600 22.810 7.282 12.930 1.963 11.250 28.120 5.984 51.130 44.900
4 13.760 34.750 62.650 21.680 7.164 11.000 2.435 19.510 15.380 10.210 46.980 48.270
5 11.900 21.560 37.690 20.230 6.939 9.203 2.401 8.584 9.731 12.550 35.750 95.040
6 11.480 15.810 36.040 16.190 6.843 8.536 2.372 5.512 7.763 8.240 30.410 37.640
7 143.700 13.140 37.110 17.130 20.210 14.460 2.354 4.584 5.906 6.457 22.280 30.300
8 70.870 11.370 70.400 67.240 20.430 16.870 2.391 7.558 5.177 5.853 30.640 68.580
9 42.840 10.270 149.100 63.730 34.240 10.860 2.383 23.320 4.940 5.405 27.570 72.800
10 30.910 9.289 51.590 63.010 15.130 8.849 2.237 14.680 4.397 5.675 18.650 103.900
11 22.540 8.742 99.700 56.250 17.530 7.609 2.218 7.601 3.932 6.026 31.840 78.730
12 18.050 8.751 49.270 40.380 14.600 6.980 2.224 5.398 3.820 5.336 44.570 51.060
13 13.370 11.380 31.090 36.520 10.970 8.702 2.091 5.919 4.607 12.520 21.280 68.760
14 12.960 10.210 23.630 26.390 9.254 8.765 2.016 55.310 4.418 18.560 16.590 76.650
15 11.540 7.386 19.640 21.940 8.173 16.090 1.963 29.410 3.979 12.490 20.350 80.310
16 21.170 8.103 16.700 17.610 7.693 10.640 2.165 18.110 3.732 9.983 29.910 44.350
17 27.830 7.614 14.110 14.810 7.565 8.059 2.130 40.070 13.490 7.871 24.070 56.070
18 22.130 7.243 14.310 12.160 21.680 6.935 2.046 24.510 37.490 9.820 31.300 69.900
19 16.510 6.809 16.310 11.360 18.600 6.235 2.673 14.220 13.830 9.060 23.430 36.120
20 14.210 6.651 17.790 11.940 13.230 5.850 2.748 10.230 11.800 12.850 15.240 24.910
21 12.590 6.569 18.420 11.950 33.210 5.501 2.410 8.037 17.420 8.356 11.540 19.970
22 11.720 8.995 16.300 12.290 21.800 4.888 2.047 9.118 10.940 6.874 10.530 16.720
23 10.920 12.430 16.080 18.890 28.140 4.757 2.246 35.550 7.745 5.837 47.700 14.120
24 10.690 12.220 20.300 15.890 22.430 5.977 2.215 24.920 7.173 5.350 26.070 12.110
25 12.280 11.530 107.400 12.190 15.910 5.015 1.995 12.860 12.710 5.502 81.870 10.710
26 10.410 14.760 70.530 10.450 18.180 3.604 1.967 9.199 56.100 24.280 117.000 29.370
27 8.704 71.480 55.090 9.129 37.040 2.839 2.011 7.382 35.310 14.710 45.650 149.000
28 8.197 66.990 58.750 8.611 42.780 2.626 2.008 6.200 15.820 9.257 29.130 59.450
29 8.357 83.650 9.847 57.710 2.673 1.877 5.448 10.430 7.352 20.870 38.120
30 7.556 63.600 10.470 40.980 2.401 1.847 4.777 7.688 6.553 17.260 26.410
31 7.629 46.010 31.520 5.390 4.364 22.070 19.810
Average 21.820 17.030 53.890 24.210 19.790 8.485 2.301 15.130 12.420 9.479 32.170 49.590
Lowest 7.556 6.569 14.110 8.611 6.843 2.401 1.847 4.364 3.732 5.336 10.530 10.710
Highest 143.700 71.480 167.600 67.240 57.710 20.380 5.390 55.310 56.100 24.280 117.000 149.000
Monthly total
(million cu m) 58.45 41.20 144.40 62.75 53.01 21.99 6.16 40.54 32.19 25.39 83.37 132.80
Runoff (mm) 77 54 190 83 70 29 8 53 42 33 110 175
Rainfall (mm) 101 70 170 90 135 51 45 142 69 85 140 214
Statistics of monthly data for previous record (Oct 1955 to Dec 1978)
Mean Avg. 26.520 23.440 18.410 15.780 11.380 6.873 8.491 11.660 13.940 17.060 22.670 26.010
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. 94 75 65 54 40 23 30 41 48 60 77 92
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. 108 85 77 76 76 70 92 95 105 99 108 115
Low 41 20 28 10 13 18 35 18 8 32 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1979
For 1979 For record As % of $ Reservoir(s) in catchment.
preceding 1979 pre-1979 $ Abstraction for public water supplies.
Mean flow 22.270 16.830 132 $ 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 2.301 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 53.890 Mar 62.090 Dec 1965
Lowest daily mean 1.847 30 Jul 0.425 23 Jun 1957
Highest daily mean 167.600 3 Mar 233.600 4 Dec 1960
10% exceedance 54.970 39.780 138
50% exceedance 13.160 9.421 140
95% exceedance 2.261 2.252 100
Annual total (million cu m) 702.30 531.10 132
Annual runoff (mm) 925 700 132
Annual rainfall (mm) 1312 1106 119
{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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