027002 Wharfe at Flint Mill Weir 2001
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 20.050 8.891 8.210 12.470 10.690 3.488 2.926 2.161 3.466 62.360 9.862 30.140
2 74.590 10.100 7.614 9.191 8.747 3.438 2.850 2.206 3.341 34.690 8.026 17.410
3 47.760 31.550 7.167 10.520 8.161 3.539 2.708 2.227 3.138 20.230 7.813 12.930
4 37.560 31.070 6.844 34.700 7.398 3.421 2.637 2.394 2.843 30.800 7.528 38.910
5 24.610 33.910 6.478 41.340 6.786 3.207 2.533 2.347 2.883 28.980 7.064 47.020
6 18.950 102.700 8.557 82.970 6.277 3.320 2.486 2.693 2.806 46.450 12.380 30.610
7 25.150 155.800 60.180 74.890 6.005 19.260 2.468 3.786 2.701 21.710 9.796 27.430
8 31.640 54.040 33.360 36.160 5.635 10.520 2.799 8.378 2.627 103.300 16.470 24.090
9 18.650 25.880 24.410 22.190 5.286 6.181 2.604 8.141 2.618 63.120 11.000 15.330
10 14.310 31.520 23.940 31.430 4.933 6.250 2.625 5.595 2.546 40.580 8.629 12.040
11 11.880 149.400 22.150 18.600 4.650 5.780 3.187 3.802 2.470 28.260 8.550 10.200
12 10.310 92.060 23.120 13.550 4.425 4.428 4.842 35.600 2.557 17.940 9.069 9.517
13 9.430 36.550 16.840 11.090 4.234 3.960 4.207 50.240 16.330 12.870 11.320 8.367
14 9.088 24.340 11.650 10.050 4.688 4.250 3.676 16.470 13.810 10.450 8.104 7.590
15 8.613 18.100 9.286 9.520 5.522 10.160 3.049 8.438 7.056 12.460 7.368 7.013
16 8.708 14.620 8.431 8.683 5.187 20.670 2.753 8.406 5.617 13.490 6.709 6.615
17 7.938 12.330 7.930 8.146 5.832 9.006 2.671 7.388 4.905 9.905 6.173 6.433
18 7.145 11.480 7.331 8.205 5.551 6.229 2.747 6.272 3.892 25.480 5.850 6.188
19 6.795 10.410 6.881 7.960 4.672 4.880 2.570 13.020 3.646 19.040 5.673 6.632
20 6.598 9.677 6.562 7.304 4.265 4.299 2.474 20.080 3.452 22.420 5.779 6.128
21 6.729 9.214 6.732 6.756 4.020 4.093 2.491 9.097 3.485 20.510 39.190 6.659
22 9.167 8.894 10.820 6.792 3.894 3.784 2.406 6.597 3.243 48.780 34.420 10.740
23 41.810 8.535 19.600 12.300 3.725 3.503 2.388 5.238 3.102 46.840 13.240 7.304
24 54.220 7.754 19.220 12.810 3.505 3.320 2.558 5.480 3.509 31.430 9.953 14.290
25 22.770 7.414 12.390 17.220 3.487 3.175 2.357 4.766 8.531 21.640 21.800 16.140
26 19.350 7.682 10.660 13.280 3.349 3.104 2.283 4.424 7.807 26.310 16.400 9.559
27 18.430 8.756 10.720 12.480 3.338 3.319 2.212 4.126 65.760 25.400 15.520 17.790
28 14.180 9.269 22.160 13.780 3.811 2.912 2.140 3.980 62.200 18.490 22.850 35.150
29 11.030 15.610 16.730 4.584 2.870 2.092 3.927 20.730 13.250 66.150 15.920
30 9.741 10.960 15.500 4.301 2.907 2.076 3.758 13.580 10.790 38.670 10.370
31 9.294 10.820 3.718 2.117 3.624 10.760 8.197
Average 19.890 33.280 14.730 19.550 5.183 5.642 2.707 8.537 9.488 28.990 15.050 15.570
Lowest 6.598 7.414 6.478 6.756 3.338 2.870 2.076 2.161 2.470 9.905 5.673 6.128
Highest 74.590 155.800 60.180 82.970 10.690 20.670 4.842 50.240 65.760 103.300 66.150 47.020
Monthly total
(million cu m) 53.27 80.52 39.45 50.68 13.88 14.63 7.25 22.87 24.59 77.65 39.00 41.71
Runoff (mm) 70 106 52 67 18 19 10 30 32 102 51 55
Rainfall (mm) 66 135 61 104 35 57 42 109 122 166 76 63
Statistics of monthly data for previous record (Oct 1955 to Dec 2000)
Mean Avg. 28.350 23.740 21.690 15.870 10.310 7.422 6.986 10.250 12.680 18.020 23.490 28.310
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 66.610 62.090
(year) 1995 1966 1981 1970 1967 1972 1963 1956 1968 1967 2000 1965
Runoff: Avg. 100 76 77 54 36 25 25 36 43 64 80 100
Low 16 9 20 15 8 5 6 4 5 11 22 17
High 156 174 190 120 94 63 58 146 115 191 228 219
Rainfall: Avg. 119 89 93 78 74 77 80 95 101 112 114 130
Low 12 14 24 8 13 18 20 12 8 32 33 41
High 217 206 222 152 181 183 185 226 241 257 242 234
Summary statistics Factors affecting runoff
2001
For 2001 For record As % of $ Reservoir(s) in catchment.
preceding 2001 pre-2001 $ Abstraction for public water supplies.
Mean flow 14.760 17.240 86 $ Flow reduced by industrial and/or
Lowest yearly mean 10.430 1996 agricultural abstractions.
Highest yearly mean 26.320 2000 $ Augmentation from surface water and/or
Lowest monthly mean 2.707 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 33.280 Feb 66.610 Nov 2000
Lowest daily mean 2.076 30 Jul 0.425 23 Jun 1957
Highest daily mean 155.800 7 Feb 292.900 23 Feb 1991
10% exceedance 34.010 41.110 83
50% exceedance 8.564 9.269 92
95% exceedance 2.499 2.354 106
Annual total (million cu m) 465.50 544.10 86
Annual runoff (mm) 613 717 86
Annual rainfall (mm) 1036 1162 89
{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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