027002 Wharfe at Flint Mill Weir 1989
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 9.615 6.012 49.530 11.690 6.919 3.191 36.360 3.438 5.789 2.347 14.510 2.620
2 8.957 6.022 32.900 9.730 6.235 3.050 10.730 3.090 4.521 2.288 19.390 2.638
3 8.515 6.684 29.200 9.271 5.750 2.907 6.133 2.980 4.210 2.247 16.170 2.517
4 7.837 21.370 27.800 8.830 5.392 2.894 4.988 2.740 3.502 2.131 22.210 2.435
5 12.700 30.840 21.100 19.810 5.220 2.855 4.022 2.653 3.269 2.179 23.170 2.456
6 33.480 19.050 17.670 41.390 4.909 2.974 3.679 2.596 3.042 2.294 13.580 2.534
7 14.530 12.000 23.900 42.700 8.657 2.878 3.657 2.721 2.901 2.654 10.280 2.513
8 11.200 20.970 14.780 38.780 5.961 3.082 4.270 2.501 2.773 2.827 11.700 2.474
9 14.830 14.070 21.010 23.540 4.515 2.832 7.038 2.534 2.641 2.857 14.800 2.467
10 14.380 10.420 36.830 30.220 4.290 2.741 4.690 9.063 2.582 2.658 39.990 2.298
11 10.500 8.951 17.750 46.250 4.534 2.668 3.727 10.000 2.528 2.516 48.170 2.272
12 10.280 24.270 12.920 87.440 5.505 2.679 3.405 9.521 2.500 2.482 21.390 2.438
13 12.680 25.590 24.500 75.980 5.155 3.127 3.392 6.238 2.555 3.438 13.700 3.590
14 56.660 20.250 31.260 47.130 4.584 3.499 3.149 5.718 2.418 4.327 10.040 13.100
15 20.770 33.460 40.170 25.560 4.422 2.798 2.944 8.823 2.399 4.346 8.185 10.960
16 14.060 19.860 19.030 18.340 4.567 2.568 2.867 6.586 3.340 35.620 6.860 50.400
17 16.210 12.460 13.860 14.100 4.350 2.478 2.768 5.893 4.302 19.210 5.913 96.380
18 12.680 38.740 11.570 11.820 3.872 2.387 2.796 5.243 3.187 8.016 4.936 53.540
19 10.560 53.660 29.340 10.510 3.752 2.351 2.791 4.085 2.863 5.771 4.452 24.440
20 8.929 41.750 35.180 9.573 3.659 2.369 2.645 3.667 2.926 46.990 4.136 39.070
21 10.650 23.690 23.350 8.920 3.547 2.258 2.635 3.181 2.794 54.130 4.220 71.390
22 9.549 17.640 108.600 9.054 3.475 2.138 2.635 3.032 2.797 21.550 3.899 35.190
23 8.696 13.920 62.480 11.330 3.463 2.220 2.583 2.853 2.792 13.380 3.626 21.510
24 10.050 29.110 126.500 11.290 3.641 2.210 2.532 2.903 3.037 8.473 3.458 32.710
25 8.647 30.180 37.500 11.080 3.479 2.103 2.591 2.906 2.947 18.980 3.202 32.300
26 11.370 18.250 24.120 9.588 3.322 2.361 2.624 3.222 2.788 17.010 2.690 19.510
27 13.630 15.900 18.500 8.957 3.234 14.260 2.454 3.509 2.698 15.570 2.552 14.000
28 8.937 36.420 14.890 7.334 3.135 11.670 2.426 3.695 2.587 14.300 2.662 10.950
29 7.450 12.420 7.392 3.084 12.730 2.945 3.228 2.490 38.780 2.685 9.257
30 7.005 14.300 7.109 2.972 9.073 5.172 3.726 2.395 57.520 2.726 7.671
31 6.766 16.170 2.960 5.452 11.160 19.900 6.708
Average 13.290 21.840 31.260 22.490 4.470 3.912 4.842 4.629 3.052 14.090 11.510 18.790
Lowest 6.766 6.012 11.570 7.109 2.960 2.103 2.426 2.501 2.395 2.131 2.552 2.272
Highest 56.660 53.660 126.500 87.440 8.657 14.260 36.360 11.160 5.789 57.520 48.170 96.380
Monthly total
(million cu m) 35.61 52.84 83.73 58.30 11.97 10.14 12.97 12.40 7.91 37.74 29.83 50.31
Runoff (mm) 47 70 110 77 16 13 17 16 10 50 39 66
Rainfall (mm) 55 127 138 106 22 97 53 67 27 137 59 121
Statistics of monthly data for previous record (Oct 1955 to Dec 1988)
Mean Avg. 28.040 23.040 21.350 15.940 11.160 7.489 7.735 11.940 13.730 18.350 23.560 27.720
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 44.000 54.590 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1984 1966 1981 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 99 74 75 54 39 26 27 42 47 65 80 98
Low 16 9 24 15 8 5 6 4 5 11 23 36
High 155 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 115 81 91 75 77 75 86 102 104 109 112 124
Low 41 14 28 8 13 18 20 18 8 32 33 41
High 217 194 222 147 181 183 185 226 241 225 211 233
Summary statistics Factors affecting runoff
1989
For 1989 For record As % of $ Reservoir(s) in catchment.
preceding 1989 pre-1989 $ Abstraction for public water supplies.
Mean flow 12.800 17.490 73 $ 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 3.052 Sep 0.991 Aug 1976 groundwater.
Highest monthly mean 31.260 Mar 62.090 Dec 1965
Lowest daily mean 2.103 25 Jun 0.425 23 Jun 1957
Highest daily mean 126.500 24 Mar 288.400 3 Jan 1982
10% exceedance 32.780 41.460 79
50% exceedance 6.491 9.760 67
95% exceedance 2.404 2.339 103
Annual total (million cu m) 403.70 552.00 73
Annual runoff (mm) 532 727 73
Annual rainfall (mm) 1009 1151 88
{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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