027002 Wharfe at Flint Mill Weir 2003
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 66.750 11.990 19.640 6.100 22.060 6.502 35.210 5.616 2.672 5.300 4.566 30.570
2 66.160 15.710 24.960 9.049 24.390 6.055 14.410 5.146 2.633 3.825 20.020 51.810
3 43.210 18.700 13.280 6.297 26.530 5.535 9.742 4.141 2.632 3.358 19.450 22.910
4 27.490 13.650 11.160 5.761 27.640 5.245 6.049 3.865 2.598 3.085 12.920 15.150
5 20.980 11.330 13.620 5.495 13.980 5.355 5.453 3.455 2.591 2.970 7.596 11.170
6 17.460 10.730 10.760 5.299 10.840 5.309 4.147 3.136 2.684 3.768 5.713 9.081
7 14.930 25.910 10.280 5.365 8.356 4.996 3.745 3.015 2.626 10.830 4.662 7.730
8 13.130 23.630 73.220 5.197 8.067 5.578 3.516 2.914 2.751 6.686 4.264 7.481
9 12.340 34.750 65.820 4.961 7.209 5.351 3.382 2.821 2.724 7.348 4.016 6.782
10 12.710 22.460 32.740 5.193 6.714 5.598 3.224 2.759 3.090 31.060 3.834 6.110
11 12.120 35.420 48.270 4.756 6.436 4.785 3.103 8.471 3.210 9.775 3.757 8.013
12 11.750 20.000 29.720 4.677 8.226 4.550 2.990 4.296 3.124 5.861 5.186 10.400
13 28.900 15.520 18.320 4.593 9.885 4.409 2.878 4.178 2.725 4.752 8.565 75.110
14 87.580 12.830 14.190 4.573 12.320 4.205 2.822 3.182 2.552 4.118 12.630 38.670
15 56.210 11.000 12.050 4.511 8.857 4.058 2.738 2.910 2.587 3.675 22.640 18.380
16 28.570 10.240 10.680 4.379 9.908 3.956 2.689 2.817 2.451 3.411 11.190 12.490
17 20.140 9.595 10.030 4.310 32.550 4.071 3.399 2.747 2.395 3.265 8.719 10.050
18 20.470 9.050 9.266 4.212 61.870 4.794 3.369 2.850 2.348 3.259 39.320 8.533
19 32.690 8.588 8.199 4.173 33.550 4.304 3.042 2.679 2.621 3.094 35.000 7.421
20 58.720 8.251 7.781 4.182 47.030 4.245 2.731 2.641 21.800 3.193 69.710 8.158
21 42.820 7.956 7.634 4.382 22.550 4.117 2.800 3.075 16.890 26.500 15.410
22 31.280 7.705 7.419 4.144 34.890 4.103 2.869 8.245 9.238 13.720 10.130
23 20.270 7.524 7.086 3.940 31.800 3.859 2.717 5.656 9.654 9.834 18.120
24 15.890 7.426 6.818 4.191 19.100 3.586 3.104 3.845 5.544 8.724 15.740
25 31.680 7.578 6.518 4.611 15.930 3.495 6.714 3.349 4.370 7.706 21.320
26 23.460 7.479 5.635 4.627 12.070 3.538 9.616 3.112 3.791 38.250 50.820
27 28.750 6.856 6.483 4.816 9.885 4.243 5.034 2.930 3.581 34.810 44.620
28 40.350 7.542 5.973 19.990 8.507 4.601 3.837 2.908 3.536 3.090 24.220 23.610
29 29.110 5.759 17.100 8.113 3.713 3.843 2.905 3.333 3.163 34.770 14.400
30 17.830 5.625 16.810 7.523 11.770 12.020 2.712 5.082 5.187 31.290 10.640
31 13.050 5.518 6.967 9.582 2.678 4.231 9.043
Average 30.540 13.910 16.600 6.256 18.190 4.864 5.831 3.711 4.594 17.790 19.350
Lowest 11.750 6.856 5.518 3.940 6.436 3.495 2.689 2.641 2.348 3.757 6.110
Highest 87.580 35.420 73.220 19.990 61.870 11.770 35.210 8.471 21.800 69.710 75.110
Monthly total
(million cu m) 81.80 33.65 44.45 16.22 48.71 12.61 15.62 9.94 11.91 46.10 51.83
Runoff (mm) 108 44 59 21 64 17 21 13 16 61 68
Rainfall (mm) 90 44 64 60 114 86 68 35 60 46 114 116
Statistics of monthly data for previous record (Oct 1955 to Dec 2002)
Mean Avg. 28.020 24.950 21.450 15.760 10.280 7.523 6.950 10.450 12.460 18.240 23.460 28.070
flows: Low 4.472 2.974 5.740 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.537 4.832
(year) 1963 1963 1993 1974 1980 1957 1976 1976 1959 1972 1995 1995
High 44.230 71.210 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 66.610 62.090
(year) 1995 2002 1981 1970 1967 1972 1963 1956 1968 1967 2000 1965
Runoff: Avg. 99 80 76 54 36 26 25 37 43 64 80 99
Low 16 9 20 15 8 5 6 4 5 11 22 17
High 156 227 190 120 94 63 58 146 115 191 228 219
Rainfall: Avg. 118 94 92 79 73 77 80 96 100 114 113 129
Low 12 14 24 8 13 18 20 12 8 32 33 41
High 217 285 222 152 181 183 185 226 241 257 242 234
Summary statistics Factors affecting runoff
2003
For 2003 For record As % of $ Reservoir(s) in catchment.
preceding 2003 pre-2003 $ Abstraction for public water supplies.
Mean flow 17.270 $ Flow reduced by industrial and/or
Lowest yearly mean 10.430 1996 agricultural abstractions.
Highest yearly mean 26.320 2000 $ Augmentation from surface water and/or
Lowest monthly mean 3.711 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 30.540 Jan 71.210 Feb 2002
Lowest daily mean 2.348 18 Sep 0.425 23 Jun 1957
Highest daily mean 87.580 14 Jan 292.900 23 Feb 1991
10% exceedance 41.230
50% exceedance 9.264
95% exceedance 2.376
Annual total (million cu m) 545.00
Annual runoff (mm) 718
Annual rainfall (mm) 897 1165 77
{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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