027002 Wharfe at Flint Mill Weir 2000
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 27.630 54.580 20.090 5.290 11.950 6.340 3.448 4.649 6.103 15.400 187.600 45.090
2 17.330 29.990 82.830 7.107 10.180 14.840 7.414 3.896 7.531 13.360 179.700 31.610
3 25.310 18.800 112.600 20.710 9.182 61.990 5.606 4.685 6.726 11.070 151.900 20.780
4 17.750 78.820 34.430 12.210 8.483 179.100 4.499 4.031 5.119 13.350 69.010 53.160
5 15.890 44.580 21.400 10.220 7.798 46.190 4.057 3.180 4.580 22.370 57.620 52.560
6 17.050 26.500 40.750 10.140 7.360 25.110 3.650 2.798 6.585 15.100 232.600 37.450
7 15.020 24.290 72.260 8.786 6.831 18.480 3.438 3.202 17.440 38.110 131.300 34.350
8 21.810 29.240 128.000 8.417 6.337 13.700 3.304 2.720 18.970 42.430 71.360 105.900
9 16.420 24.370 74.620 7.772 6.124 11.160 4.422 2.669 8.437 63.720 42.160 77.590
10 14.320 31.910 33.370 7.377 5.742 9.766 6.680 3.044 19.140 80.030 30.400 68.690
11 58.650 23.060 26.480 7.490 5.564 8.522 6.204 3.871 18.380 55.070 38.930 78.250
12 108.300 54.450 18.630 29.340 5.307 7.686 4.355 2.960 23.140 28.480 56.600 57.100
13 62.570 34.890 14.840 75.740 5.101 6.947 3.791 2.762 11.670 18.620 72.610 109.100
14 35.690 26.990 12.930 40.780 4.930 6.531 3.529 6.832 8.214 15.150 43.260 54.080
15 28.070 28.010 11.810 20.530 4.801 5.987 3.255 9.879 7.536 18.830 29.950 30.670
16 19.820 29.680 10.320 15.960 4.522 5.453 3.110 17.690 8.330 13.710 43.290 21.890
17 15.940 22.390 9.432 15.160 4.890 5.193 3.065 15.740 6.690 10.820 30.850 17.790
18 14.260 46.850 8.395 18.340 5.753 4.863 2.924 9.407 35.750 24.320 31.630 15.170
19 15.390 35.820 9.561 35.430 6.439 4.670 2.906 7.175 34.940 16.520 44.760 18.260
20 12.670 19.920 8.654 51.240 6.021 4.798 2.876 5.162 106.900 14.110 26.990 44.100
21 11.300 23.890 7.097 28.300 8.073 4.513 2.766 4.330 37.060 15.020 21.780 24.470
22 10.030 18.680 6.734 52.960 8.900 5.064 2.687 4.244 27.880 10.810 38.560 18.230
23 8.992 14.180 6.850 35.720 7.194 5.644 2.640 3.716 19.070 10.600 37.730 15.540
24 8.385 19.340 9.764 28.810 14.750 4.923 2.672 3.400 32.310 25.200 24.120 30.320
25 7.948 14.030 8.584 58.350 10.490 4.492 2.681 3.350 47.380 69.940 38.510 24.660
26 7.526 12.370 7.355 51.440 12.330 4.244 2.780 3.642 32.060 25.690 59.580 17.090
27 7.182 31.960 6.938 39.230 36.970 3.996 2.917 5.916 45.880 25.550 41.600 13.540
28 18.850 39.300 6.667 24.250 15.140 3.585 2.843 5.374 56.700 56.660 91.340 11.480
29 128.700 28.070 6.197 17.500 10.550 3.515 2.933 6.190 25.140 89.630 44.690 10.090
30 75.670 5.744 14.160 8.025 3.535 2.687 5.163 19.690 237.700 27.850 9.471
31 76.680 5.479 6.687 3.907 4.668 232.800 9.782
Average 29.710 30.580 26.740 25.290 8.788 16.360 3.679 5.366 23.510 42.910 66.610 37.360
Lowest 7.182 12.370 5.479 5.290 4.522 3.515 2.640 2.669 4.580 10.600 21.780 9.471
Highest 128.700 78.820 128.000 75.740 36.970 179.100 7.414 17.690 106.900 237.700 232.600 109.100
Monthly total
(million cu m) 79.59 76.63 71.61 65.56 23.54 42.41 9.85 14.37 60.94 114.90 172.70 100.10
Runoff (mm) 105 101 94 86 31 56 13 19 80 151 228 132
Rainfall (mm) 125 122 97 152 71 102 56 79 176 257 242 150
Statistics of monthly data for previous record (Oct 1955 to Dec 1999)
Mean Avg. 28.320 23.580 21.570 15.650 10.350 7.219 7.061 10.360 12.440 17.470 22.540 28.110
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 76 53 37 25 25 37 42 62 77 99
Low 16 9 20 15 8 5 6 4 5 11 22 17
High 156 174 190 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 119 89 93 76 74 76 80 96 99 109 111 130
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
2000
For 2000 For record As % of $ Reservoir(s) in catchment.
preceding 2000 pre-2000 $ Abstraction for public water supplies.
Mean flow 26.320 17.030 155 $ 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 3.679 Jul 0.991 Aug 1976 groundwater.
Highest monthly mean 66.610 Nov 62.090 Dec 1965
Lowest daily mean 2.640 23 Jul 0.425 23 Jun 1957
Highest daily mean 237.700 30 Oct 292.900 23 Feb 1991
10% exceedance 58.640 40.740 144
50% exceedance 14.970 9.208 163
95% exceedance 3.032 2.342 129
Annual total (million cu m) 832.30 537.40 155
Annual runoff (mm) 1097 708 155
Annual rainfall (mm) 1629 1152 141
{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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