027002 Wharfe at Flint Mill Weir 1986
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 24.190 26.580 4.846 26.100 12.270 8.334 3.356 5.954 6.853 2.967 88.560 12.500
2 22.920 28.430 4.698 21.790 10.790 7.525 3.264 6.904 7.522 2.876 31.140 12.080
3 16.110 23.410 4.898 17.070 12.590 7.006 3.226 7.118 23.860 2.824 23.490 19.440
4 12.260 19.090 55.680 13.650 14.180 6.209 3.141 4.802 13.710 2.948 18.020 75.360
5 11.100 15.490 145.400 12.100 12.360 5.791 3.267 4.413 8.713 3.079 21.530 55.410
6 9.913 13.450 39.210 12.360 15.260 5.375 3.320 4.338 6.813 2.823 20.770 30.710
7 8.724 12.030 21.300 14.500 62.920 5.126 3.245 14.520 5.876 2.912 14.310 19.390
8 8.467 10.840 16.950 32.030 40.680 4.901 3.102 10.340 5.340 4.362 15.870 60.090
9 8.551 10.150 16.940 23.030 23.200 4.811 3.100 6.223 4.956 3.783 14.420 49.220
10 97.350 9.236 16.640 22.010 20.870 23.500 2.965 4.809 4.551 5.009 34.480 26.030
11 51.810 8.306 15.400 14.740 23.670 24.170 2.929 3.944 4.273 5.529 23.240 64.370
12 34.840 8.113 13.170 14.620 26.860 13.490 2.996 3.529 4.069 3.976 17.790 42.760
13 76.420 7.674 11.670 15.870 20.090 9.066 3.014 3.418 3.889 3.597 14.720 93.140
14 58.070 7.415 10.100 17.220 15.000 7.697 2.954 3.380 3.770 3.494 24.880 34.710
15 40.260 7.100 13.960 149.200 16.470 6.595 2.939 3.358 3.656 4.109 30.200 83.450
16 21.620 6.709 16.710 86.990 12.960 5.712 3.106 3.370 3.569 4.081 19.280 56.160
17 15.960 6.489 16.940 135.700 11.610 5.232 2.754 3.913 3.519 3.511 22.130 86.090
18 35.590 5.810 12.390 64.910 23.160 4.818 2.764 4.064 3.457 3.330 47.240 69.030
19 99.780 5.301 13.490 36.520 13.860 4.560 2.759 3.839 3.347 8.213 78.260 47.640
20 72.420 5.538 14.290 70.810 28.250 4.338 2.706 3.334 3.356 21.640 29.550 34.750
21 127.900 5.547 15.420 50.640 36.950 4.126 2.800 3.143 3.327 46.100 27.170 28.570
22 72.230 5.556 34.700 46.120 25.120 4.053 2.745 3.389 3.358 40.690 25.760 23.030
23 55.420 5.519 90.180 30.830 16.340 4.382 2.884 3.479 3.233 30.390 59.160 17.920
24 31.530 5.338 34.970 24.760 13.360 5.798 2.986 3.422 3.183 18.950 60.280 15.370
25 21.150 5.403 35.060 23.290 45.660 4.373 2.729 7.593 3.152 58.400 80.450 79.910
26 16.260 5.106 38.190 19.860 24.200 4.121 2.691 155.900 3.137 27.460 74.030 32.200
27 14.970 4.924 69.830 17.650 15.770 3.794 2.644 42.090 3.006 48.510 39.030 25.380
28 14.320 5.083 36.160 14.260 13.750 3.492 2.708 19.140 2.993 57.270 23.540 41.740
29 19.420 45.490 13.370 11.250 3.557 2.855 12.230 3.013 29.790 17.500 40.530
30 31.780 28.410 11.480 9.340 3.467 5.324 9.052 2.989 28.540 14.210 110.900
31 33.280 27.730 8.740 6.229 7.750 22.720 85.900
Average 37.570 9.987 29.700 35.120 20.570 6.847 3.145 12.020 5.216 16.250 33.700 47.540
Lowest 8.467 4.924 4.698 11.480 8.740 3.467 2.644 3.143 2.989 2.823 14.210 12.080
Highest 127.900 28.430 145.400 149.200 62.920 24.170 6.229 155.900 23.860 58.400 88.560 110.900
Monthly total
(million cu m) 100.60 24.16 79.56 91.02 55.08 17.75 8.42 32.21 13.52 43.54 87.35 127.30
Runoff (mm) 133 32 105 120 73 23 11 42 18 57 115 168
Rainfall (mm) 182 27 117 147 122 47 45 141 22 161 141 218
Statistics of monthly data for previous record (Oct 1955 to Dec 1985)
Mean Avg. 27.530 23.170 21.040 15.500 11.250 7.519 7.659 11.750 13.890 18.150 23.700 27.310
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 44.000 54.590 53.940 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1984 1966 1981 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 97 75 74 53 40 26 27 41 47 64 81 96
Low 16 9 24 15 8 5 6 4 5 11 23 36
High 155 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 113 81 88 74 77 76 84 99 107 106 113 122
Low 41 14 28 8 13 18 20 18 8 32 33 41
High 217 194 222 147 181 183 185 226 241 225 211 233
Summary statistics Factors affecting runoff
1986
For 1986 For record As % of $ Reservoir(s) in catchment.
preceding 1986 pre-1986 $ Abstraction for public water supplies.
Mean flow 21.580 17.350 124 $ 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 3.145 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 47.540 Dec 62.090 Dec 1965
Lowest daily mean 2.644 27 Jul 0.425 23 Jun 1957
Highest daily mean 155.900 26 Aug 288.400 3 Jan 1982
10% exceedance 55.790 41.230 135
50% exceedance 13.400 9.657 139
95% exceedance 2.945 2.259 130
Annual total (million cu m) 680.50 547.50 124
Annual runoff (mm) 897 721 124
Annual rainfall (mm) 1370 1140 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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