027002 Wharfe at Flint Mill Weir 1981
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 30.050 8.281 15.870 14.420 22.270 5.921 2.500 2.443 1.772 99.550 32.840 31.150
2 66.960 25.360 66.280 12.700 13.220 32.640 2.579 2.187 1.671 73.680 54.480 19.670
3 88.850 116.200 39.600 10.480 17.490 17.890 2.466 2.049 1.695 34.560 24.030 15.870
4 39.660 40.750 19.880 9.338 22.050 10.500 2.418 1.807 1.693 37.050 17.760 23.220
5 22.710 24.200 14.360 8.577 12.940 13.960 2.408 1.909 1.689 21.700 13.110 19.370
6 18.690 23.660 53.220 8.091 14.360 11.580 8.252 5.824 1.641 32.070 10.660 14.590
7 14.870 20.880 126.800 7.834 12.220 15.840 5.452 11.920 1.645 59.480 9.159 12.750
8 21.740 29.340 88.460 7.332 9.607 16.360 3.986 6.625 1.705 75.510 8.100 10.840
9 45.630 56.800 42.960 6.990 8.631 14.420 3.613 7.703 1.617 86.410 7.421 9.115
10 23.940 29.890 89.850 6.621 9.068 16.040 3.756 5.984 1.913 67.490 7.766 8.239
11 15.650 19.080 77.250 6.763 8.522 25.690 3.005 3.595 2.278 34.280 40.790 7.570
12 25.110 15.480 51.870 7.075 6.431 24.020 2.439 2.644 2.229 22.090 21.040 6.032
13 17.660 14.120 33.700 6.798 5.527 12.610 2.348 2.622 2.126 17.040 12.450 6.066
14 57.440 12.360 23.830 6.193 4.962 21.120 2.153 2.448 2.018 13.720 9.967 7.517
15 33.320 10.720 19.850 5.602 4.685 17.100 1.908 4.148 5.107 11.430 8.681 6.659
16 19.470 9.991 16.280 5.228 5.344 11.740 1.919 2.976 5.270 9.656 10.220 5.355
17 59.410 9.815 13.770 4.497 6.368 8.718 1.937 2.445 4.643 8.532 9.787 4.487
18 38.560 8.847 21.710 4.405 5.723 7.238 1.970 2.127 21.800 7.783 50.810 4.411
19 50.010 8.027 75.710 4.239 7.178 6.429 2.140 2.246 26.160 14.600 31.480 4.911
20 32.380 7.354 87.200 4.264 6.432 6.090 2.518 10.980 64.170 18.810 36.830 6.870
21 49.680 6.937 114.400 4.114 10.060 5.480 10.590 6.734 25.920 11.690 29.090 6.930
22 42.470 6.628 139.700 3.999 11.700 4.808 9.276 4.167 14.590 8.974 46.920 6.236
23 24.730 6.560 108.300 3.936 15.660 4.364 12.430 3.163 10.020 7.672 45.760 5.725
24 21.010 6.138 97.560 6.400 12.970 3.960 9.304 2.676 10.880 12.030 31.170 5.640
25 17.140 6.012 72.650 21.670 12.030 3.478 5.644 2.427 9.123 26.760 18.430 4.899
26 14.740 5.952 54.330 19.960 17.500 3.180 4.030 2.159 74.610 13.810 33.270 4.365
27 14.620 5.837 33.730 25.400 12.060 2.945 3.707 2.056 59.040 14.160 100.300 5.597
28 12.210 7.775 24.390 41.350 13.140 2.799 3.265 2.058 51.310 29.130 45.130 5.356
29 10.880 19.110 62.220 9.065 2.738 2.853 2.014 25.450 37.970 30.080 14.590
30 9.819 15.770 44.500 7.198 2.635 2.653 1.992 42.320 31.810 38.250 38.230
31 8.981 13.610 6.414 2.426 1.913 52.440 45.400
Average 30.590 19.390 53.940 12.700 10.670 11.080 4.063 3.743 15.870 32.000 27.860 11.860
Lowest 8.981 5.837 13.610 3.936 4.685 2.635 1.908 1.807 1.617 7.672 7.421 4.365
Highest 88.850 116.200 139.700 62.220 22.270 32.640 12.430 11.920 74.610 99.550 100.300 45.400
Monthly total
(million cu m) 81.94 46.91 144.50 32.92 28.58 28.71 10.88 10.03 41.14 85.70 72.21 31.77
Runoff (mm) 108 62 190 43 38 38 14 13 54 113 95 42
Rainfall (mm) 100 88 222 77 88 75 58 64 170 178 122 73
Statistics of monthly data for previous record (Oct 1955 to Dec 1980)
Mean Avg. 26.350 23.720 20.060 15.750 11.350 7.044 8.220 12.080 13.950 17.430 23.440 27.110
flows: Low 4.472 2.974 6.741 4.496 2.312 1.545 1.674 0.991 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1974 1980 1957 1976 1976 1959 1972 1958 1963
High 39.260 54.590 53.890 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1961 1966 1979 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 93 76 71 54 40 24 29 43 48 62 80 96
Low 16 9 24 15 8 5 6 4 5 11 23 36
High 139 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 109 86 82 74 77 74 90 99 104 102 110 119
Low 41 20 28 8 13 18 35 18 8 32 33 41
High 165 194 170 147 181 177 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1981
For 1981 For record As % of $ Reservoir(s) in catchment.
preceding 1981 pre-1981 $ Abstraction for public water supplies.
Mean flow 19.510 17.180 114 $ 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 3.743 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 53.940 Mar 62.090 Dec 1965
Lowest daily mean 1.617 9 Sep 0.425 23 Jun 1957
Highest daily mean 139.700 22 Mar 233.600 4 Dec 1960
10% exceedance 49.850 40.620 123
50% exceedance 10.650 9.682 110
95% exceedance 2.002 2.254 89
Annual total (million cu m) 615.30 542.20 113
Annual runoff (mm) 811 714 113
Annual rainfall (mm) 1315 1126 117
{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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