027002 Wharfe at Flint Mill Weir 2002
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 7.093 74.860 41.160 5.462 21.200 12.080 9.550 44.370 5.851 2.896 24.600 35.270
2 5.643 84.990 29.620 6.141 14.050 8.874 19.430 197.200 4.719 2.880 55.240 82.080
3 6.931 60.620 29.170 5.994 10.880 28.470 11.970 55.540 4.687 2.857 66.670 39.150
4 5.896 58.270 25.710 5.410 8.456 13.830 11.280 30.170 4.023 2.855 28.700 31.510
5 6.172 58.440 18.040 4.865 6.482 9.475 25.780 21.290 3.875 2.888 19.800 23.810
6 6.454 54.740 26.880 4.325 6.002 8.621 13.760 22.850 4.205 2.854 41.970 16.790
7 6.753 53.380 23.940 4.133 5.856 6.977 7.981 26.250 6.291 2.838 25.590 15.330
8 7.017 71.980 14.960 4.102 5.259 6.464 6.110 17.710 8.172 2.789 60.310 14.040
9 6.481 88.770 16.900 4.555 4.761 8.948 6.077 20.840 11.580 2.780 44.530 11.630
10 5.821 107.700 37.210 4.049 4.394 35.720 5.359 57.790 27.410 2.693 33.820 9.971
11 5.715 262.800 32.010 3.965 4.089 22.130 4.807 24.560 11.090 2.714 43.460 8.754
12 8.880 79.540 17.370 3.881 3.947 12.380 5.463 18.940 6.744 4.046 39.310 8.302
13 8.416 54.840 13.580 3.775 4.553 14.920 4.423 15.250 5.743 5.163 33.240 8.010
14 8.784 35.050 13.900 3.721 8.691 64.160 3.858 11.710 4.911 5.083 77.920 8.736
15 11.510 24.790 20.880 3.702 20.970 59.760 3.718 9.485 4.486 6.150 50.810 17.570
16 8.576 19.310 24.730 3.575 18.650 23.930 3.562 7.533 4.208 4.904 31.220 22.130
17 30.890 15.860 20.140 3.523 8.157 14.430 3.464 7.176 3.992 5.800 24.880 15.550
18 16.720 13.920 17.780 3.468 8.467 9.793 3.251 6.859 3.897 3.727 20.740 11.190
19 21.450 64.330 14.240 3.402 9.245 7.645 3.914 6.395 3.731 3.391 16.380 9.562
20 41.690 91.390 13.130 3.329 6.980 6.574 5.716 5.621 3.576 5.150 15.890 9.032
21 28.130 48.350 14.440 3.468 15.700 5.839 8.009 5.330 3.406 73.800 20.800 13.170
22 26.640 135.000 11.800 3.504 19.410 5.195 5.387 5.027 3.310 41.580 25.890 41.050
23 35.910 47.570 9.705 3.838 13.970 4.917 9.585 5.025 2.761 19.640 17.900 39.340
24 41.520 30.630 8.554 3.553 24.530 4.532 13.730 5.014 2.936 14.510 14.200 49.390
25 32.960 111.200 7.825 3.487 46.300 4.258 6.684 6.133 2.873 66.390 11.880 29.890
26 68.360 131.800 7.519 3.534 22.670 3.831 6.022 5.589 2.824 65.980 10.450 31.750
27 35.550 56.710 6.967 6.178 17.880 3.842 4.865 5.618 2.797 78.550 9.736 60.190
28 42.500 56.850 6.614 25.360 11.210 3.768 4.090 4.628 2.762 36.000 16.560 34.110
29 49.060 6.202 35.680 23.890 3.442 3.717 4.594 2.711 29.380 14.660 53.500
30 33.330 5.857 43.360 27.990 3.574 17.370 4.772 3.384 24.810 13.350 122.700
31 46.160 5.627 20.610 57.600 7.678 15.810 44.520
Average 21.520 71.200 17.500 7.245 13.720 13.950 9.566 21.510 5.432 17.450 30.350 29.610
Lowest 5.643 13.920 5.627 3.329 3.947 3.442 3.251 4.594 2.711 2.693 9.736 8.010
Highest 68.360 262.800 41.160 43.360 46.300 64.160 57.600 197.200 27.410 78.550 77.920 122.700
Monthly total
(million cu m) 57.63 172.30 46.87 18.78 36.74 36.15 25.62 57.62 14.08 46.73 78.67 79.32
Runoff (mm) 76 227 62 25 48 48 34 76 19 62 104 105
Rainfall (mm) 118 285 54 71 109 91 127 120 37 148 141 148
Statistics of monthly data for previous record (Oct 1955 to Dec 2001)
Mean Avg. 28.160 23.940 21.540 15.950 10.200 7.383 6.893 10.210 12.610 18.260 23.320 28.040
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. 99 77 76 54 36 25 24 36 43 64 80 99
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. 118 90 92 79 73 76 79 96 101 113 113 129
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
2002
For 2002 For record As % of $ Reservoir(s) in catchment.
preceding 2002 pre-2002 $ Abstraction for public water supplies.
Mean flow 21.260 17.180 124 $ 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 5.432 Sep 0.991 Aug 1976 groundwater.
Highest monthly mean 71.200 Feb 66.610 Nov 2000
Lowest daily mean 2.693 10 Oct 0.425 23 Jun 1957
Highest daily mean 262.800 11 Feb 292.900 23 Feb 1991
10% exceedance 54.800 41.000 134
50% exceedance 11.030 9.264 119
95% exceedance 3.237 2.361 137
Annual total (million cu m) 670.50 542.20 124
Annual runoff (mm) 883 714 124
Annual rainfall (mm) 1449 1159 125
{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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