027002 Wharfe at Flint Mill Weir 1998
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 45.790 6.892 9.750 10.440 7.832 4.002 6.015 10.810 8.809 20.720 20.930 11.850
2 62.250 6.736 41.310 14.280 7.302 21.530 5.244 8.569 13.600 14.890 30.320 10.350
3 87.940 6.529 88.280 55.900 6.831 30.780 5.080 44.830 6.501 8.766 69.740 9.524
4 65.520 6.430 90.130 55.990 6.333 12.300 4.427 28.700 4.724 6.023 40.430 8.912
5 57.640 7.123 40.470 62.650 6.325 7.474 4.137 12.440 4.498 7.614 40.250 8.068
6 34.160 7.108 84.820 53.110 19.930 8.748 3.925 8.288 4.317 15.380 31.720 7.445
7 42.940 12.730 162.900 40.140 15.060 24.300 3.914 15.880 4.725 8.793 20.510 7.342
8 120.900 11.500 53.830 45.380 24.010 34.310 3.554 12.360 7.545 6.030 49.670 33.840
9 121.300 18.130 28.230 77.170 15.370 49.130 3.914 8.870 14.730 5.207 55.080 25.600
10 40.990 29.880 26.240 36.140 10.320 27.780 3.615 7.369 35.950 9.786 33.380 14.770
11 25.690 57.880 44.440 24.480 8.962 50.380 3.514 5.984 19.620 6.904 22.560 16.890
12 19.670 33.830 23.620 17.950 8.373 21.680 4.074 5.287 12.010 16.220 46.580 25.860
13 26.880 16.510 23.710 14.110 7.257 13.960 10.610 5.109 10.390 32.250 53.880 54.370
14 38.760 11.540 16.730 12.670 6.248 15.690 7.372 6.701 7.164 51.560 25.320 65.020
15 37.880 9.003 13.310 13.840 5.647 16.780 5.082 10.630 5.575 18.310 17.890 32.650
16 41.940 8.198 11.200 11.350 5.407 12.940 4.988 6.322 4.942 63.840 14.190 19.150
17 33.770 8.592 9.845 9.801 5.310 9.977 4.953 14.760 4.893 77.180 12.020 14.550
18 74.120 7.549 8.853 8.346 4.555 11.340 8.180 8.329 4.513 34.450 12.010 15.230
19 52.150 6.982 7.894 7.589 4.375 14.390 6.974 4.819 5.224 18.610 13.150 27.180
20 26.920 6.753 7.244 7.325 4.182 10.380 10.880 4.438 4.385 16.610 11.060 20.220
21 20.300 6.277 6.770 7.300 3.912 7.789 24.730 16.510 4.295 59.770 9.887 13.650
22 22.020 6.672 6.439 33.620 3.853 6.019 28.810 8.178 4.186 40.550 10.490 11.650
23 21.290 6.922 6.244 54.420 3.728 5.524 19.040 5.569 4.097 91.330 20.590 12.860
24 17.450 5.845 6.814 22.490 3.642 7.311 12.380 5.512 3.867 109.500 22.340 13.030
25 14.300 6.127 10.870 16.950 3.519 7.838 7.615 5.463 3.924 71.720 18.480 52.970
26 12.530 5.604 40.870 15.270 3.528 7.661 5.784 11.740 3.956 35.480 37.960 63.890
27 10.930 6.182 21.750 15.320 3.442 26.360 5.353 8.059 3.922 132.100 27.140 40.240
28 9.534 7.572 12.550 11.870 4.291 14.940 4.883 5.438 3.903 114.500 27.210 36.450
29 8.811 11.490 11.700 7.069 9.306 10.410 4.544 3.675 72.360 22.010 24.380
30 8.254 24.450 9.286 5.967 7.303 17.550 4.202 5.655 50.570 14.740 27.820
31 7.553 15.050 4.035 18.580 4.109 29.550 19.190
Average 39.040 11.820 30.840 25.900 7.310 16.600 8.567 9.994 7.520 40.210 27.720 24.030
Lowest 7.553 5.604 6.244 7.300 3.442 4.002 3.514 4.109 3.675 5.207 9.887 7.342
Highest 121.300 57.880 162.900 77.170 24.010 50.380 28.810 44.830 35.950 132.100 69.740 65.020
Monthly total
(million cu m) 104.60 28.61 82.61 67.12 19.58 43.02 22.95 26.77 19.49 107.70 71.84 64.36
Runoff (mm) 138 38 109 88 26 57 30 35 26 142 95 85
Rainfall (mm) 158 56 142 137 58 151 90 76 71 223 112 103
Statistics of monthly data for previous record (Oct 1955 to Dec 1997)
Mean Avg. 27.760 24.100 21.190 15.390 10.370 6.945 7.076 10.530 12.650 16.910 22.670 27.690
flows: Low 4.472 2.974 5.740 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.537 4.832
(year) 1963 1963 1993 1974 1980 1957 1976 1976 1959 1972 1995 1995
High 44.230 54.590 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1995 1966 1981 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 98 78 75 53 37 24 25 37 43 60 77 98
Low 16 9 20 15 8 5 6 4 5 11 22 17
High 156 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 117 90 91 75 74 74 81 97 100 106 112 128
Low 12 14 24 8 13 18 20 12 8 32 33 41
High 217 206 222 147 181 183 185 226 241 225 211 234
Summary statistics Factors affecting runoff
1998
For 1998 For record As % of $ Reservoir(s) in catchment.
preceding 1998 pre-1998 $ Abstraction for public water supplies.
Mean flow 20.880 16.910 123 $ Flow reduced by industrial and/or
Lowest yearly mean 10.430 1996 agricultural abstractions.
Highest yearly mean 23.300 1966 $ Augmentation from surface water and/or
Lowest monthly mean 7.310 May 0.991 Aug 1976 groundwater.
Highest monthly mean 40.210 Oct 62.090 Dec 1965
Lowest daily mean 3.442 27 May 0.425 23 Jun 1957
Highest daily mean 162.900 7 Mar 292.900 23 Feb 1991
10% exceedance 51.560 40.380 128
50% exceedance 11.850 9.167 129
95% exceedance 3.972 2.311 172
Annual total (million cu m) 658.50 533.60 123
Annual runoff (mm) 868 703 123
Annual rainfall (mm) 1377 1145 120
{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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