027002 Wharfe at Flint Mill Weir 1991
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 58.830 5.705 24.830 39.730 6.168 2.847 4.778 2.736 2.522 4.899 39.790 7.347
2 93.450 4.925 17.940 112.500 4.819 2.989 4.808 2.528 2.468 9.967 55.820 6.550
3 36.960 4.563 17.860 41.990 4.519 3.116 4.235 2.626 2.426 9.739 72.690 6.027
4 28.340 4.754 46.040 25.670 4.719 2.928 3.804 2.617 2.336 7.906 40.170 5.366
5 36.480 4.600 61.480 35.350 4.609 2.875 3.765 2.715 2.276 7.226 25.990 4.923
6 106.800 4.422 26.930 29.740 4.508 2.864 3.553 2.732 2.226 9.192 18.060 4.712
7 38.960 4.489 21.730 32.820 4.458 2.841 3.412 9.347 2.181 6.151 99.240 4.232
8 32.980 4.342 25.590 17.950 4.217 2.858 3.267 4.342 2.186 45.950 61.820 3.809
9 35.380 4.244 21.520 13.190 4.218 3.302 7.261 3.450 2.189 15.570 23.230 3.554
10 48.410 4.083 24.550 10.710 3.950 15.750 8.041 12.110 2.116 8.263 31.330 3.509
11 36.220 3.773 17.580 9.262 3.790 8.283 4.661 13.390 2.108 5.913 85.480 3.321
12 36.720 4.095 14.230 7.796 3.746 9.336 3.830 6.262 2.219 5.554 28.450 3.510
13 20.840 4.058 12.110 7.131 3.712 9.733 4.549 4.531 2.098 4.812 36.340 3.158
14 15.550 4.058 10.970 6.377 3.697 15.070 6.513 3.993 2.126 4.908 33.190 3.058
15 12.900 8.927 9.393 6.375 4.215 9.309 5.424 3.541 2.381 4.442 30.580 3.040
16 11.040 13.830 10.820 6.239 3.914 8.083 10.610 3.351 2.392 13.650 21.990 2.935
17 10.220 10.530 26.970 5.851 3.638 6.681 7.811 3.262 5.099 16.560 15.510 3.194
18 23.560 8.904 23.260 6.022 3.708 6.968 4.718 3.488 3.295 20.970 37.110 21.120
19 35.950 7.914 113.900 6.191 3.652 6.948 9.956 3.241 2.745 8.482 89.920 142.800
20 34.460 9.772 57.110 5.692 3.477 10.900 7.628 3.036 2.628 5.392 30.970 44.470
21 27.000 58.350 48.490 5.456 3.322 7.159 4.985 2.963 2.501 4.171 24.850 149.400
22 15.760 70.760 26.620 5.215 3.156 13.800 4.269 2.837 4.276 3.789 32.920 141.700
23 11.860 292.900 17.820 5.199 3.086 23.830 4.124 2.782 4.952 3.241 17.910 72.750
24 10.760 162.000 13.690 4.989 3.064 11.740 4.229 6.115 19.700 2.856 12.970 37.620
25 9.865 49.210 11.690 4.660 3.002 8.163 4.183 5.040 9.882 2.884 10.900 23.130
26 7.942 28.640 10.150 4.283 3.012 7.876 4.947 3.531 8.139 2.622 10.740 24.190
27 7.126 25.160 8.900 4.464 3.150 7.462 3.852 3.243 10.020 2.645 8.909 17.630
28 7.077 39.130 7.983 4.309 2.967 13.450 3.513 3.026 6.717 2.563 8.784 13.240
29 6.686 7.386 4.931 2.909 7.133 3.477 2.888 7.141 2.593 11.020 11.180
30 6.197 7.585 6.951 2.899 4.783 2.976 2.775 6.398 18.000 8.734 10.240
31 5.823 7.004 2.892 2.955 2.633 54.070 9.173
Average 28.070 30.290 24.260 15.900 3.780 7.969 5.037 4.230 4.325 10.160 34.180 25.510
Lowest 5.823 3.773 7.004 4.283 2.892 2.841 2.955 2.528 2.098 2.563 8.734 2.935
Highest 106.800 292.900 113.900 112.500 6.168 23.830 10.610 13.390 19.700 54.070 99.240 149.400
Monthly total
(million cu m) 75.18 73.28 64.98 41.22 10.13 20.66 13.49 11.33 11.21 27.21 88.60 68.33
Runoff (mm) 99 97 86 54 13 27 18 15 15 36 117 90
Rainfall (mm) 115 131 99 78 17 118 51 42 62 97 174 125
Statistics of monthly data for previous record (Oct 1955 to Dec 1990)
Mean Avg. 27.920 23.640 21.490 15.840 10.790 7.274 7.634 11.480 13.140 18.230 23.000 27.500
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 76 76 54 38 25 27 41 45 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. 116 85 91 75 75 76 84 100 100 111 110 125
Low 41 14 28 8 13 18 20 18 8 32 33 41
High 217 201 222 147 181 183 185 226 241 225 211 233
Summary statistics Factors affecting runoff
1991
For 1991 For record As % of $ Reservoir(s) in catchment.
preceding 1991 pre-1991 $ Abstraction for public water supplies.
Mean flow 16.030 17.310 93 $ 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 3.780 May 0.991 Aug 1976 groundwater.
Highest monthly mean 34.180 Nov 62.090 Dec 1965
Lowest daily mean 2.098 13 Sep 0.425 23 Jun 1957
Highest daily mean 292.900 23 Feb 288.400 3 Jan 1982
10% exceedance 36.940 41.150 90
50% exceedance 6.569 9.607 68
95% exceedance 2.549 2.342 109
Annual total (million cu m) 505.50 546.30 93
Annual runoff (mm) 666 720 93
Annual rainfall (mm) 1109 1148 97
{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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