027002 Wharfe at Flint Mill Weir 1987
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 75.860 5.065 14.450 51.330 4.660 3.263 9.662 7.885 4.639 5.117 9.826 8.886
2 64.380 6.388 29.670 33.630 5.080 3.828 6.998 6.579 4.281 5.021 8.547 8.201
3 31.120 8.422 16.150 21.310 5.207 10.300 5.607 5.589 3.626 4.922 7.673 7.774
4 72.540 8.453 11.340 18.060 5.047 10.380 4.807 6.136 3.497 5.008 7.182 7.395
5 63.380 11.300 11.780 29.910 4.506 7.620 4.065 5.269 3.923 4.965 6.635 6.887
6 40.320 28.670 20.660 22.180 4.252 46.390 3.843 4.438 17.550 6.959 6.224 6.561
7 23.880 17.020 17.200 52.860 4.320 35.940 3.849 4.130 12.530 9.500 6.080 6.213
8 17.880 23.620 14.300 49.940 4.147 16.480 3.614 3.809 8.370 13.480 5.919 5.845
9 14.680 57.740 11.880 31.640 4.049 10.460 3.588 3.848 6.230 35.110 5.683 5.720
10 12.720 62.650 10.480 29.200 3.961 12.500 4.022 3.650 19.200 33.450 5.788 5.583
11 10.700 30.750 10.080 43.220 3.947 21.840 15.610 3.574 11.110 16.570 15.220 5.552
12 8.635 20.360 9.705 23.810 4.114 14.680 9.873 3.782 76.040 10.820 45.500 5.318
13 8.858 14.970 9.336 17.300 4.376 10.640 5.769 15.940 25.360 11.550 53.550 5.128
14 8.439 12.280 9.074 14.470 5.177 9.564 4.369 9.836 13.730 29.510 21.000 4.986
15 8.141 10.470 9.146 12.410 7.117 8.104 4.003 5.836 9.979 23.910 32.400 4.963
16 7.387 9.201 11.990 11.000 5.711 6.917 3.688 4.569 8.470 75.700 62.060 9.012
17 6.929 8.210 24.680 9.869 5.213 6.202 3.748 4.181 10.620 33.970 38.360 18.090
18 6.726 7.587 24.200 8.987 6.080 5.491 25.390 6.174 9.967 38.170 23.940 35.720
19 6.464 7.271 14.640 8.378 5.638 5.128 34.950 5.580 17.120 61.140 35.910 19.040
20 7.624 6.908 10.760 11.270 4.283 4.368 16.240 4.329 50.480 32.890 24.950 25.500
21 15.420 6.585 8.846 9.941 3.581 4.174 9.072 3.985 16.690 56.670 16.700 25.840
22 16.210 6.427 8.062 7.866 3.928 4.272 6.946 55.500 16.700 36.950 14.430 24.440
23 12.280 6.267 8.828 6.969 4.009 3.957 5.794 28.420 12.520 21.750 22.310 13.800
24 10.840 6.110 12.290 6.262 3.716 3.872 5.336 14.710 13.740 15.510 39.210 10.970
25 10.050 5.721 30.540 5.775 3.643 4.628 4.922 9.393 17.950 12.540 24.890 11.650
26 8.893 6.391 29.970 5.405 3.440 11.200 4.764 7.756 11.730 10.570 18.230 26.150
27 7.862 9.775 123.300 5.110 3.399 8.019 9.678 7.864 8.768 27.830 14.080 45.110
28 7.245 17.170 96.270 5.429 3.402 9.969 6.948 6.222 7.190 34.060 11.470 55.620
29 6.583 36.740 5.120 3.250 28.830 5.612 5.532 6.139 16.800 10.220 107.400
30 6.083 22.460 5.226 3.253 20.050 10.710 5.068 5.399 12.890 9.559 50.230
31 5.254 17.940 3.376 7.614 4.490 11.240 35.780
Average 19.460 15.060 22.150 18.800 4.383 11.640 8.100 8.519 14.450 23.050 20.120 19.660
Lowest 5.254 5.065 8.062 5.110 3.250 3.263 3.588 3.574 3.497 4.922 5.683 4.963
Highest 75.860 62.650 123.300 52.860 7.117 46.390 34.950 55.500 76.040 75.700 62.060 107.400
Monthly total
(million cu m) 52.13 36.44 59.34 48.72 11.74 30.16 21.69 22.82 37.46 61.74 52.15 52.65
Runoff (mm) 69 48 78 64 15 40 29 30 49 81 69 69
Rainfall (mm) 49 72 123 68 44 121 91 86 105 140 95 101
Statistics of monthly data for previous record (Oct 1955 to Dec 1986)
Mean Avg. 27.860 22.740 21.320 16.130 11.550 7.498 7.513 11.750 13.610 18.090 24.020 27.950
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. 98 73 75 55 41 26 27 41 46 64 82 99
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 79 89 76 79 75 83 101 104 107 114 125
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
1987
For 1987 For record As % of $ Reservoir(s) in catchment.
preceding 1987 pre-1987 $ Abstraction for public water supplies.
Mean flow 15.440 17.490 88 $ 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 4.383 May 0.991 Aug 1976 groundwater.
Highest monthly mean 23.050 Oct 62.090 Dec 1965
Lowest daily mean 3.250 29 May 0.425 23 Jun 1957
Highest daily mean 123.300 27 Mar 288.400 3 Jan 1982
10% exceedance 35.170 41.640 84
50% exceedance 9.252 9.739 95
95% exceedance 3.770 2.279 165
Annual total (million cu m) 486.90 551.90 88
Annual runoff (mm) 642 727 88
Annual rainfall (mm) 1095 1147 95
{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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