027002 Wharfe at Flint Mill Weir 1995
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 29.950 165.600 69.160 29.350 4.270 3.880 2.207 2.095 1.741 2.571 2.014 3.469
2 19.990 54.640 35.670 17.690 4.107 3.499 2.203 2.025 1.931 3.946 1.994 3.058
3 16.070 36.150 25.350 12.640 4.041 3.609 2.229 1.981 1.757 3.370 1.968 3.430
4 14.240 27.760 19.570 10.430 3.856 5.134 2.241 1.996 1.748 7.479 2.061 6.553
5 62.450 21.630 41.210 9.040 3.663 5.442 2.264 2.007 1.758 9.068 1.997 5.836
6 40.920 21.170 36.830 8.096 3.526 4.002 2.223 1.997 1.809 13.940 2.143 4.500
7 23.390 18.060 24.700 7.390 3.405 3.566 2.225 1.999 3.951 17.420 2.197 4.064
8 32.080 21.420 21.140 6.718 3.288 3.222 2.210 1.905 4.749 9.331 2.219 3.509
9 35.120 17.630 17.640 6.800 3.267 2.946 2.359 1.843 3.035 6.476 2.192 3.021
10 56.290 20.680 27.560 6.584 3.202 2.837 2.346 1.807 2.466 4.287 2.251 4.029
11 48.550 84.670 55.140 6.159 3.078 2.786 2.372 1.802 3.011 3.402 3.140 9.123
12 23.350 73.500 33.000 5.702 3.053 2.711 3.145 1.854 3.696 2.969 18.440 5.459
13 18.330 64.100 20.490 5.399 2.969 2.658 3.035 1.880 3.527 2.619 6.417 4.284
14 21.950 41.540 19.220 5.047 2.913 2.592 2.715 1.943 2.863 2.363 3.902 3.703
15 24.590 39.010 17.060 4.915 3.070 2.521 2.501 1.951 2.494 2.311 3.996 3.385
16 18.030 50.210 13.900 5.084 3.111 2.488 2.399 1.912 2.273 2.359 32.620 3.130
17 25.450 67.900 23.510 5.164 3.907 2.479 2.681 1.876 2.183 2.560 12.730 2.820
18 32.020 43.760 30.280 6.078 3.374 2.665 7.899 1.900 2.174 4.464 6.406 2.564
19 22.750 68.010 21.500 5.636 3.398 2.814 7.788 1.901 2.166 3.676 4.334 2.404
20 28.020 42.190 16.520 5.399 3.155 3.634 4.205 1.877 2.044 3.224 3.457 2.551
21 50.350 48.620 13.190 5.118 3.156 5.700 3.379 1.921 1.967 3.786 3.193 2.410
22 50.900 93.770 11.790 5.933 2.930 3.541 2.911 1.870 1.892 2.984 4.852 15.120
23 42.630 74.390 11.100 10.600 2.854 2.877 2.690 1.754 1.836 2.532 5.026 19.400
24 43.930 41.030 10.400 7.214 3.197 2.613 2.522 1.744 1.933 2.495 14.480 8.805
25 29.800 27.840 23.380 5.516 3.343 2.506 2.384 1.746 3.771 3.530 22.730 5.515
26 28.720 19.860 29.060 5.250 3.261 2.445 2.312 1.873 17.530 4.845 9.173 3.802
27 22.820 21.150 45.400 4.740 3.508 2.322 2.190 1.813 7.168 3.280 6.663 2.748
28 147.700 26.980 19.510 4.382 5.684 2.297 2.094 1.802 5.056 3.440 5.056 3.098
29 117.500 14.790 4.493 7.117 2.234 1.971 1.847 3.782 3.125 4.457 2.707
30 48.910 18.210 4.381 4.973 2.180 2.075 1.792 2.998 2.502 4.015 2.172
31 194.300 30.140 4.395 2.296 1.741 2.177 3.132
Average 44.230 47.620 25.690 7.565 3.647 3.140 2.841 1.886 3.310 4.598 6.537 4.832
Lowest 14.240 17.630 10.400 4.381 2.854 2.180 1.971 1.741 1.741 2.177 1.968 2.172
Highest 194.300 165.600 69.160 29.350 7.117 5.700 7.899 2.095 17.530 17.420 32.620 19.400
Monthly total
(million cu m) 118.50 115.20 68.81 19.61 9.77 8.14 7.61 5.05 8.58 12.31 16.95 12.94
Runoff (mm) 156 152 91 26 13 11 10 7 11 16 22 17
Rainfall (mm) 206 162 106 27 54 23 41 12 96 50 66 61
Statistics of monthly data for previous record (Oct 1955 to Dec 1994)
Mean Avg. 28.310 23.100 21.600 16.090 10.550 7.107 7.315 11.050 13.140 17.580 23.270 28.320
flows: Low 4.472 2.974 5.740 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.876 10.230
(year) 1963 1963 1993 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. 100 74 76 55 37 24 26 39 45 62 79 100
Low 16 9 20 15 8 5 6 4 5 11 23 36
High 155 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 118 85 93 77 73 74 82 99 102 108 112 129
Low 41 14 24 8 13 18 20 18 8 32 33 41
High 217 201 222 147 181 183 185 226 241 225 211 234
Summary statistics Factors affecting runoff
1995
For 1995 For record As % of $ Reservoir(s) in catchment.
preceding 1995 pre-1995 $ Abstraction for public water supplies.
Mean flow 12.790 17.270 74 $ 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 1.886 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 47.620 Feb 62.090 Dec 1965
Lowest daily mean 1.741 31 Aug 0.425 23 Jun 1957
Highest daily mean 194.300 31 Jan 292.900 23 Feb 1991
10% exceedance 33.640 40.980 82
50% exceedance 3.808 9.453 40
95% exceedance 1.858 2.364 79
Annual total (million cu m) 403.30 545.00 74
Annual runoff (mm) 531 718 74
Annual rainfall (mm) 904 1152 78
{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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