027002 Wharfe at Flint Mill Weir 1971
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 8.789 14.840 9.035 9.240 7.575 6.910 7.128 12.580 15.400 7.567 6.735 9.834
2 7.751 12.810 10.670 8.787 6.925 5.691 6.194 7.258 10.750 5.085 6.441 9.208
3 7.191 14.410 11.510 7.618 6.930 5.405 5.391 7.162 19.710 4.177 6.497 8.628
4 7.411 13.340 9.976 7.417 6.695 4.977 4.745 43.970 14.350 3.729 6.627 8.246
5 7.083 10.780 9.035 7.581 6.525 4.621 4.737 37.090 10.960 3.387 6.667 8.954
6 7.021 8.951 7.938 7.442 6.610 4.247 4.624 14.630 8.597 3.398 6.970 8.639
7 55.760 8.526 7.641 7.165 11.050 4.363 4.361 10.820 7.417 2.994 16.050 8.082
8 28.200 8.470 14.650 6.905 13.280 4.372 4.188 7.989 6.848 2.999 27.150 7.273
9 16.470 8.209 18.210 6.732 8.789 4.185 4.044 12.390 6.409 5.094 16.240 6.851
10 12.600 7.867 13.440 6.146 7.929 4.018 3.874 15.390 6.084 8.532 9.822 6.523
11 10.570 7.629 10.240 5.750 7.230 4.550 3.226 52.100 5.725 41.550 8.187 6.172
12 9.146 73.530 9.544 5.606 6.916 5.911 3.254 19.940 5.552 17.570 7.493 5.928
13 8.436 99.050 8.228 5.348 7.035 8.795 3.234 39.710 5.439 9.766 7.185 8.065
14 8.130 45.500 7.896 5.592 6.825 7.154 3.415 70.230 5.207 8.113 7.278 10.220
15 7.881 53.300 7.669 5.600 6.217 5.948 3.087 31.530 5.068 7.227 6.409 8.195
16 7.570 26.300 7.117 5.657 5.130 5.263 2.747 16.660 5.000 17.390 13.350 7.403
17 7.247 19.710 7.025 5.294 5.671 4.694 2.677 12.030 4.856 16.060 11.870 6.882
18 7.264 37.380 25.890 4.876 5.866 4.553 2.394 9.497 4.910 54.910 38.310 6.492
19 14.530 29.900 38.940 5.088 5.586 9.868 2.699 8.215 4.873 150.700 15.760 8.538
20 22.070 36.950 35.140 5.283 5.348 18.020 2.626 7.420 4.743 64.030 11.370 30.030
21 38.200 30.810 23.960 5.068 5.320 13.540 2.278 6.206 4.513 42.810 94.490 20.940
22 21.180 19.240 15.580 5.011 5.150 27.010 2.136 5.725 4.329 29.330 30.730 13.030
23 37.330 14.930 12.460 7.292 7.004 11.030 3.186 5.750 4.259 20.260 18.610 14.550
24 34.720 12.930 24.500 79.680 17.810 8.014 4.689 5.965 4.117 14.580 15.080 14.920
25 33.760 14.320 35.430 32.990 11.370 6.783 14.700 5.793 3.800 11.840 15.700 16.430
26 22.080 10.240 23.930 17.000 8.359 8.487 11.270 5.473 3.571 9.845 18.020 12.340
27 16.740 8.766 18.970 12.490 7.437 10.730 7.609 5.221 3.834 8.801 14.550 10.690
28 16.620 8.433 13.230 10.070 6.616 10.140 6.407 5.147 3.421 8.178 18.370 14.070
29 16.110 11.840 8.696 6.078 11.110 5.102 59.250 3.347 7.833 13.090 11.420
30 15.580 10.510 8.424 5.730 8.444 4.327 45.890 7.007 7.358 10.910 9.788
31 17.440 9.431 6.540 4.530 30.630 6.992 9.087
Average 17.130 23.470 15.150 10.530 7.469 7.961 4.674 19.920 6.670 19.420 16.200 10.560
Lowest 7.021 7.629 7.025 4.876 5.130 4.018 2.136 5.147 3.347 2.994 6.409 5.928
Highest 55.760 99.050 38.940 79.680 17.810 27.010 14.700 70.230 19.710 150.700 94.490 30.030
Monthly total
(million cu m) 45.87 56.78 40.58 27.29 20.01 20.64 12.52 53.37 17.29 52.02 41.99 28.29
Runoff (mm) 60 75 53 36 26 27 16 70 23 69 55 37
Rainfall (mm) 72 77 77 74 67 88 67 61 35 117 89 45
Statistics of monthly data for previous record (Oct 1955 to Dec 1970)
Mean Avg. 25.840 23.290 19.100 17.340 12.420 7.084 9.451 13.440 15.060 17.820 23.480 27.070
flows: Low 4.472 2.974 6.741 5.197 3.911 1.545 3.601 1.795 1.419 6.209 6.876 10.230
(year) 1963 1963 1961 1957 1960 1957 1959 1959 1959 1969 1958 1963
High 39.260 54.590 36.400 35.240 26.750 14.540 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1961 1966 1963 1970 1967 1969 1963 1956 1968 1967 1963 1965
Runoff: Avg. 91 75 67 59 44 24 33 47 51 63 80 96
Low 16 9 24 18 14 5 13 6 5 22 23 36
High 139 174 128 120 94 50 58 146 115 191 174 219
Rainfall: Avg. 103 85 77 81 78 74 94 108 105 104 109 118
Low 41 20 28 10 13 33 35 18 8 38 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1971
For 1971 For record As % of $ Reservoir(s) in catchment.
preceding 1971 pre-1971 $ Abstraction for public water supplies.
Mean flow 13.210 17.590 75 $ Flow reduced by industrial and/or
Lowest yearly mean 12.390 1964 agricultural abstractions.
Highest yearly mean 23.300 1966 $ Augmentation from surface water and/or
Lowest monthly mean 4.674 Jul 1.419 Sep 1959 groundwater.
Highest monthly mean 23.470 Feb 62.090 Dec 1965
Lowest daily mean 2.136 22 Jul 0.425 23 Jun 1957
Highest daily mean 150.700 19 Oct 233.600 4 Dec 1960
10% exceedance 29.240 40.540 72
50% exceedance 8.159 9.785 83
95% exceedance 3.517 2.520 140
Annual total (million cu m) 416.60 555.10 75
Annual runoff (mm) 549 731 75
Annual rainfall (mm) 869 1136 76
{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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