027002 Wharfe at Flint Mill Weir 1997
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 8.375 4.805 31.320 6.530 5.298 3.208 10.200 7.316 13.660 3.543 3.373 14.050
2 7.350 4.354 65.220 5.898 4.932 3.142 8.582 7.087 9.866 4.754 3.097 10.600
3 7.190 4.151 29.520 5.709 4.419 2.969 8.263 4.712 10.140 3.941 3.034 8.879
4 6.616 82.390 19.580 5.489 4.836 2.813 9.410 3.937 23.690 3.567 3.007 7.974
5 6.206 25.320 15.820 5.410 100.100 2.801 12.530 3.564 10.320 3.388 3.518 7.400
6 6.206 13.240 18.430 5.388 34.040 2.949 7.603 3.321 9.753 3.577 3.446 43.650
7 6.254 29.290 13.530 5.160 15.540 2.885 6.099 3.123 7.978 8.879 3.939 27.180
8 5.706 15.400 10.940 5.231 24.480 2.908 5.591 3.090 6.196 14.780 7.579 34.650
9 5.671 14.250 9.452 4.417 18.530 2.945 5.361 3.048 5.823 19.480 9.152 51.700
10 5.153 37.030 8.900 4.168 11.490 3.080 4.944 2.970 4.355 42.390 14.680 94.190
11 5.056 27.040 8.335 4.072 12.310 14.510 4.208 2.966 4.058 23.400 18.360 50.490
12 31.690 86.420 7.747 3.934 13.740 13.460 4.164 2.747 4.395 10.810 17.640 27.590
13 25.510 52.010 7.405 3.928 10.680 6.991 4.131 2.595 5.913 7.373 10.660 17.300
14 12.950 23.250 8.781 3.841 10.490 5.175 4.183 3.087 5.317 6.122 7.825 13.190
15 7.970 14.340 9.867 3.768 7.993 5.604 4.150 2.746 22.700 8.395 8.017 11.250
16 7.516 11.420 9.648 3.688 6.572 4.946 3.803 2.383 51.480 15.840 6.989 10.070
17 6.888 55.470 10.850 3.635 6.339 4.340 4.043 2.601 40.040 16.780 16.670 9.103
18 6.973 78.270 13.640 3.614 7.585 3.892 3.925 2.321 13.910 9.034 17.800 22.350
19 7.008 85.000 21.230 3.551 7.868 3.737 3.396 2.260 8.848 6.501 24.110 28.320
20 6.084 89.870 12.140 3.494 7.534 3.796 3.337 2.267 6.799 5.477 50.230 15.990
21 5.636 96.870 8.865 3.599 6.115 4.303 3.034 2.323 5.651 4.998 40.980 12.660
22 5.290 38.070 7.149 3.708 5.628 6.588 2.930 2.423 4.887 4.825 17.700 10.730
23 5.092 38.750 15.610 3.717 5.658 7.146 2.871 2.506 4.430 4.414 11.710 14.650
24 4.853 42.130 14.150 3.565 4.721 5.647 3.413 2.864 4.057 3.978 12.710 61.980
25 7.499 71.330 12.670 4.535 4.363 11.800 3.528 2.882 3.937 3.751 12.270 82.480
26 7.774 63.610 15.300 6.457 4.166 44.200 4.627 2.648 3.834 3.769 10.060 91.870
27 5.735 49.970 16.660 5.071 4.022 19.700 6.228 2.550 3.690 3.585 13.660 32.600
28 5.791 59.120 23.510 10.730 3.860 23.840 5.318 2.666 3.468 3.411 22.200 33.920
29 5.113 12.120 16.640 3.766 19.990 3.769 3.232 3.355 3.256 33.280 27.590
30 4.534 8.912 6.771 3.539 11.600 3.980 3.305 3.428 3.246 22.190 25.190
31 4.527 7.442 3.391 5.198 6.883 2.987 63.710
Average 7.878 43.330 15.310 5.191 11.740 8.365 5.252 3.304 10.200 8.395 14.330 31.070
Lowest 4.527 4.151 7.149 3.494 3.391 2.801 2.871 2.260 3.355 2.987 3.007 7.400
Highest 31.690 96.870 65.220 16.640 100.100 44.200 12.530 7.316 51.480 42.390 50.230 94.190
Monthly total
(million cu m) 21.10 104.80 41.02 13.45 31.45 21.68 14.07 8.85 26.44 22.49 37.14 83.23
Runoff (mm) 28 138 54 18 41 29 19 12 35 30 49 110
Rainfall (mm) 12 206 61 35 98 131 70 65 64 66 112 161
Statistics of monthly data for previous record (Oct 1955 to Dec 1996)
Mean Avg. 28.240 23.630 21.330 15.640 10.330 6.910 7.120 10.700 12.710 17.110 22.870 27.600
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. 100 76 75 53 36 24 25 38 43 60 78 97
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. 119 87 92 76 73 72 81 97 100 107 112 127
Low 41 14 24 8 13 18 20 12 8 32 33 41
High 217 201 222 147 181 183 185 226 241 225 211 234
Summary statistics Factors affecting runoff
1997
For 1997 For record As % of $ Reservoir(s) in catchment.
preceding 1997 pre-1997 $ Abstraction for public water supplies.
Mean flow 13.500 16.990 79 $ 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 3.304 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 43.330 Feb 62.090 Dec 1965
Lowest daily mean 2.260 19 Aug 0.425 23 Jun 1957
Highest daily mean 100.100 5 May 292.900 23 Feb 1991
10% exceedance 32.760 40.510 81
50% exceedance 6.785 9.227 74
95% exceedance 2.859 2.292 125
Annual total (million cu m) 425.70 536.20 79
Annual runoff (mm) 561 707 79
Annual rainfall (mm) 1081 1143 95
{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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