027002 Wharfe at Flint Mill Weir 1999
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 14.940 15.060 57.560 8.187 7.195 4.523 5.084 2.822 3.272 65.370 12.640 19.170
2 16.460 12.880 100.300 7.399 6.649 5.801 5.131 2.902 3.178 124.000 36.820 30.200
3 35.440 11.430 138.400 7.322 6.282 7.849 6.006 2.809 3.084 55.110 21.130 148.500
4 53.870 12.540 65.370 7.079 5.934 6.346 5.727 2.714 2.991 25.750 13.070 48.300
5 62.920 17.620 35.590 6.856 6.480 8.300 5.182 2.528 2.898 15.790 20.820 26.100
6 99.710 13.460 32.480 6.786 6.013 8.209 9.285 2.387 2.861 11.550 31.610 188.400
7 47.310 11.070 37.170 7.114 8.619 16.230 6.054 3.002 2.919 9.613 14.990 100.700
8 48.410 9.231 30.560 6.321 36.840 55.010 4.725 2.598 3.154 10.530 12.670 69.440
9 26.880 7.918 36.050 6.097 24.060 26.920 4.861 2.810 3.250 17.120 11.340 80.300
10 18.510 7.487 36.090 6.606 24.280 12.530 3.896 2.953 2.967 17.000 9.341 44.700
11 14.530 7.395 25.240 8.514 29.620 8.629 3.657 2.860 3.017 18.550 8.186 89.320
12 13.300 7.261 25.130 32.430 34.240 7.492 3.543 2.857 2.917 10.050 7.485 69.920
13 13.390 7.154 23.250 18.370 32.320 6.876 3.438 2.767 2.953 7.908 7.246 43.810
14 51.710 7.151 17.040 15.210 30.130 6.102 3.349 5.268 2.994 7.953 7.062 30.630
15 110.700 7.541 13.400 13.840 16.970 5.514 3.444 7.028 2.841 6.625 6.896 22.260
16 87.510 7.250 12.100 20.990 11.760 5.079 3.027 6.059 2.824 5.970 6.879 18.940
17 37.510 7.196 11.010 18.640 9.220 5.132 3.710 4.237 2.910 5.585 6.421 87.190
18 43.290 14.980 9.743 17.170 7.942 4.414 4.868 4.199 2.965 5.296 5.859 32.350
19 57.910 52.770 8.647 16.430 7.217 4.260 6.956 5.286 3.099 4.906 5.575 19.310
20 50.110 19.650 8.063 52.950 6.614 13.470 6.989 4.560 36.770 4.789 5.578 13.860
21 31.540 18.910 27.070 48.790 6.602 7.783 12.010 3.661 17.110 4.753 5.357 13.420
22 21.030 18.140 18.090 48.250 6.223 5.277 10.320 3.284 8.311 7.442 5.141 41.210
23 16.890 11.940 13.090 27.670 5.986 4.513 5.369 3.102 16.260 20.470 4.884 46.050
24 19.500 9.562 13.270 23.490 7.426 4.126 4.549 3.035 30.270 17.990 4.908 60.140
25 73.080 8.788 20.890 16.550 8.785 3.979 3.705 3.232 17.380 37.990 10.120 62.550
26 53.520 15.150 17.350 12.800 5.874 3.709 3.422 3.526 10.570 14.530 11.740 35.040
27 42.000 12.510 11.670 10.400 5.653 4.740 3.034 3.999 11.560 9.737 17.540 29.470
28 45.980 21.280 9.247 8.924 5.368 11.850 3.412 3.786 17.470 9.699 11.460 21.710
29 26.840 9.734 8.126 7.034 10.550 2.923 3.479 17.950 8.817 9.526 15.900
30 21.560 12.570 7.501 6.018 5.772 2.817 3.324 16.990 8.327 12.220 26.870
31 17.500 9.039 5.074 2.757 3.342 16.260 31.060
Average 41.090 13.330 28.560 16.560 12.530 9.366 4.944 3.562 8.591 18.890 11.480 50.540
Lowest 13.300 7.151 8.063 6.097 5.074 3.709 2.757 2.387 2.824 4.753 4.884 13.420
Highest 110.700 52.770 138.400 52.950 36.840 55.010 12.010 7.028 36.770 124.000 36.820 188.400
Monthly total
(million cu m) 110.10 32.26 76.48 42.92 33.56 24.28 13.24 9.54 22.27 50.59 29.77 135.40
Runoff (mm) 145 43 101 57 44 32 17 13 29 67 39 178
Rainfall (mm) 169 64 112 89 91 101 37 70 117 116 62 231
Statistics of monthly data for previous record (Oct 1955 to Dec 1998)
Mean Avg. 28.020 23.820 21.410 15.630 10.300 7.169 7.110 10.510 12.530 17.440 22.790 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. 99 77 76 53 36 24 25 37 43 62 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. 117 89 93 76 73 75 81 96 99 109 112 127
Low 12 14 24 8 13 18 20 12 8 32 33 41
High 217 206 222 147 181 183 185 226 241 225 211 234
Summary statistics Factors affecting runoff
1999
For 1999 For record As % of $ Reservoir(s) in catchment.
preceding 1999 pre-1999 $ Abstraction for public water supplies.
Mean flow 18.400 17.000 108 $ 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 3.562 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 50.540 Dec 62.090 Dec 1965
Lowest daily mean 2.387 6 Aug 0.425 23 Jun 1957
Highest daily mean 188.400 6 Dec 292.900 23 Feb 1991
10% exceedance 45.690 40.630 112
50% exceedance 9.547 9.205 104
95% exceedance 2.919 2.325 126
Annual total (million cu m) 580.30 536.50 108
Annual runoff (mm) 765 707 108
Annual rainfall (mm) 1259 1147 110
{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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