027002 Wharfe at Flint Mill Weir 1990
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 7.431 38.060 37.980 4.993 4.347 2.874 6.881 2.386 4.656 7.693 17.820 5.796
2 12.180 32.490 26.930 5.379 4.024 2.848 6.841 2.322 5.013 4.158 12.090 5.090
3 26.750 27.590 29.460 6.083 3.768 2.904 6.431 2.239 3.632 10.890 8.684 4.894
4 14.400 40.330 53.520 5.429 3.778 2.807 9.149 2.165 3.345 11.610 7.025 4.444
5 10.760 37.570 46.460 5.164 3.709 2.912 50.470 2.119 3.258 57.410 5.966 4.196
6 13.280 20.300 25.770 4.886 3.595 3.036 14.070 2.119 3.055 46.360 5.226 4.001
7 17.200 67.150 20.720 5.101 3.523 3.160 9.771 2.398 5.264 24.930 4.858 10.520
8 28.180 73.180 16.440 4.781 3.783 3.642 26.620 2.279 4.795 10.980 4.498 24.650
9 18.280 43.370 16.210 4.565 5.463 5.726 11.660 2.231 2.946 11.510 3.781 25.640
10 20.670 39.930 30.180 4.414 20.060 3.898 7.296 2.160 2.435 17.620 3.465 37.010
11 105.000 37.510 19.600 4.570 9.418 3.377 5.507 2.203 2.161 48.730 3.497 56.000
12 36.200 37.540 13.340 4.539 6.027 3.251 5.396 2.255 2.085 25.970 6.635 53.030
13 22.480 44.470 16.250 4.514 5.317 3.072 4.727 2.260 2.044 12.400 8.767 22.310
14 17.020 61.370 21.150 4.533 4.695 2.989 4.043 2.167 2.033 8.432 10.820 15.430
15 39.620 35.020 13.450 4.877 5.295 2.957 4.073 2.325 2.044 6.501 12.030 11.680
16 41.880 23.340 11.200 7.210 8.858 2.793 3.965 2.818 2.034 6.598 73.990 16.120
17 52.620 42.390 9.119 6.898 8.259 2.701 3.684 5.214 2.151 9.054 58.890 15.650
18 22.280 34.220 7.797 7.962 5.570 2.756 3.539 6.963 2.039 9.922 40.360 11.320
19 32.290 79.130 7.287 9.155 4.941 2.801 3.412 7.925 13.180 11.950 39.510 9.212
20 25.310 96.800 6.873 8.492 4.303 2.731 3.268 10.420 7.233 14.340 21.490 46.300
21 19.120 39.810 6.699 6.620 4.007 3.250 3.157 4.678 17.190 9.821 13.570 33.800
22 27.910 24.450 6.738 5.567 3.619 5.549 3.011 3.845 6.492 7.278 10.430 56.970
23 61.900 18.030 6.130 4.720 3.579 4.156 2.816 3.626 4.030 5.620 8.713 32.470
24 41.070 17.650 7.538 4.699 3.403 3.562 2.665 3.618 3.333 4.692 10.990 21.750
25 115.200 33.670 10.870 4.272 3.261 4.345 2.510 4.056 2.740 4.656 17.520 49.840
26 62.270 104.400 11.150 6.237 3.187 4.360 2.462 3.974 2.383 15.090 17.490 95.930
27 39.300 58.370 8.124 11.560 3.105 4.078 2.502 3.238 2.217 12.200 15.680 51.730
28 43.180 54.240 7.097 5.999 3.106 5.031 2.561 2.996 1.988 27.060 10.420 56.430
29 78.900 6.446 5.347 3.054 4.421 2.494 2.887 2.038 45.000 8.069 49.220
30 79.530 5.897 4.765 3.014 4.074 2.474 3.431 3.959 53.560 7.031 25.620
31 71.060 4.982 2.933 2.391 2.672 27.350 27.810
Average 38.820 45.090 16.500 5.778 5.000 3.535 7.092 3.419 4.059 18.370 15.640 28.540
Lowest 7.431 17.650 4.982 4.272 2.933 2.701 2.391 2.119 1.988 4.158 3.465 4.001
Highest 115.200 104.400 53.520 11.560 20.060 5.726 50.470 10.420 17.190 57.410 73.990 95.930
Monthly total
(million cu m) 104.00 109.10 44.19 14.98 13.39 9.16 18.99 9.16 10.52 49.19 40.55 76.45
Runoff (mm) 137 144 58 20 18 12 25 12 14 65 53 101
Rainfall (mm) 208 201 54 45 39 84 52 72 61 146 83 152
Statistics of monthly data for previous record (Oct 1955 to Dec 1989)
Mean Avg. 27.600 23.010 21.640 16.140 10.960 7.384 7.649 11.720 13.410 18.230 23.220 27.470
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. 97 74 76 55 39 25 27 41 46 64 79 97
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. 113 82 93 75 76 76 85 101 102 110 110 124
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
1990
For 1990 For record As % of $ Reservoir(s) in catchment.
preceding 1990 pre-1990 $ Abstraction for public water supplies.
Mean flow 15.840 17.350 91 $ 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 3.419 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 45.090 Feb 62.090 Dec 1965
Lowest daily mean 1.988 28 Sep 0.425 23 Jun 1957
Highest daily mean 115.200 25 Jan 288.400 3 Jan 1982
10% exceedance 43.380 41.060 106
50% exceedance 6.700 9.675 69
95% exceedance 2.241 2.349 95
Annual total (million cu m) 499.50 547.50 91
Annual runoff (mm) 658 721 91
Annual rainfall (mm) 1197 1147 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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