027002 Wharfe at Flint Mill Weir 1994
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 23.300 33.620 33.200 69.210 6.244 3.114 3.057 3.449 12.190 4.691 33.550 7.232
2 58.220 30.450 25.760 30.820 6.079 3.319 2.911 3.283 7.397 23.460 16.350 7.300
3 86.670 29.700 59.360 26.440 5.752 3.359 2.794 3.269 5.144 29.160 19.330 10.130
4 56.510 43.100 31.930 58.550 5.716 4.821 2.718 7.848 4.401 14.170 23.540 38.500
5 38.620 30.690 27.310 29.020 6.565 4.419 2.586 6.212 6.573 8.639 47.880 40.760
6 36.490 24.250 21.360 27.960 12.290 3.708 2.668 3.720 5.817 6.521 26.230 38.880
7 23.770 21.760 54.720 26.120 7.750 3.871 2.948 3.052 12.240 6.363 15.990 36.390
8 18.310 17.230 70.260 49.590 6.300 4.060 2.939 2.812 8.677 7.729 12.490 52.450
9 26.480 30.800 44.940 41.630 5.346 3.482 2.676 2.579 7.877 7.818 47.400 28.140
10 49.370 16.990 23.290 27.610 4.795 3.346 2.502 2.464 16.440 5.576 34.680 69.240
11 26.170 13.280 20.240 21.280 4.718 3.415 2.450 2.401 27.360 5.193 21.430 42.790
12 40.680 11.320 21.540 17.140 4.486 3.244 2.534 2.470 36.600 5.108 37.030 55.850
13 45.080 9.385 64.690 15.090 4.188 3.072 2.360 2.230 34.550 4.788 76.780 42.410
14 53.940 8.764 59.900 11.840 4.225 2.916 2.312 2.037 16.280 4.525 119.000 31.740
15 35.490 8.431 35.300 9.794 5.570 2.785 2.235 1.993 38.470 4.296 69.440 20.310
16 21.050 8.585 22.330 8.344 5.000 2.705 2.182 1.989 24.100 4.168 42.290 24.210
17 15.640 8.051 20.780 7.714 4.687 2.736 2.114 2.310 11.490 4.048 31.690 18.690
18 22.040 8.135 21.620 7.712 4.179 2.624 2.140 5.562 7.799 3.914 36.830 47.160
19 36.400 7.604 24.100 7.375 3.819 2.685 2.116 3.381 7.314 3.879 62.360 33.430
20 30.580 7.062 15.800 7.450 3.677 5.793 2.068 2.858 6.819 4.289 67.370 21.410
21 27.750 6.751 12.450 8.148 4.255 10.100 2.085 2.781 9.834 6.536 33.760 15.820
22 24.040 6.454 21.440 10.280 5.265 12.730 2.069 2.448 7.211 13.030 22.420 12.460
23 79.220 6.464 82.050 25.240 6.341 4.903 1.982 2.986 5.348 52.320 17.650 10.350
24 30.280 6.285 62.330 19.270 4.607 4.252 2.760 6.837 5.371 26.030 14.770 8.926
25 98.550 7.826 37.780 12.650 3.964 4.328 3.176 30.840 19.540 34.180 12.390 16.380
26 73.450 25.060 25.230 15.430 3.665 4.059 2.603 10.860 13.440 30.990 10.580 38.650
27 103.300 76.170 16.880 10.340 3.452 4.552 2.961 7.076 8.024 17.310 10.070 56.600
28 52.000 59.040 22.230 9.417 3.375 6.098 2.507 20.410 6.278 17.390 9.237 139.000
29 46.450 17.880 10.300 3.295 3.856 2.451 9.742 5.352 13.390 8.693 102.000
30 50.060 13.860 7.394 3.208 3.274 2.304 6.095 4.754 15.100 7.472 72.470
31 26.620 14.260 3.107 3.527 6.578 35.960 55.430
Average 43.760 20.120 33.060 20.970 5.030 4.254 2.540 5.567 12.760 13.570 32.960 38.550
Lowest 15.640 6.285 12.450 7.375 3.107 2.624 1.982 1.989 4.401 3.879 7.472 7.232
Highest 103.300 76.170 82.050 69.210 12.290 12.730 3.527 30.840 38.470 52.320 119.000 139.000
Monthly total
(million cu m) 117.20 48.67 88.54 54.36 13.47 11.03 6.80 14.91 33.06 36.34 85.42 103.30
Runoff (mm) 154 64 117 72 18 15 9 20 44 48 113 136
Rainfall (mm) 174 84 155 91 40 49 55 93 111 106 150 203
Statistics of monthly data for previous record (Oct 1955 to Dec 1993)
Mean Avg. 27.900 23.170 21.300 15.960 10.690 7.182 7.441 11.190 13.150 17.680 23.020 28.060
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. 98 75 75 55 38 25 26 39 45 62 79 99
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. 117 85 91 77 74 75 83 99 101 108 111 127
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
1994
For 1994 For record As % of $ Reservoir(s) in catchment.
preceding 1994 pre-1994 $ Abstraction for public water supplies.
Mean flow 19.440 17.210 113 $ 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 2.540 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 43.760 Jan 62.090 Dec 1965
Lowest daily mean 1.982 23 Jul 0.425 23 Jun 1957
Highest daily mean 139.000 28 Dec 292.900 23 Feb 1991
10% exceedance 49.110 40.820 120
50% exceedance 10.090 9.452 107
95% exceedance 2.450 2.360 104
Annual total (million cu m) 613.10 543.10 113
Annual runoff (mm) 808 716 113
Annual rainfall (mm) 1311 1148 114
{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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