027002 Wharfe at Flint Mill Weir 1977
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 20.510 13.860 18.650 44.030 20.270 3.336 14.440 2.498 6.399 49.980 28.670 8.647
2 13.800 17.460 48.720 40.490 23.640 3.089 17.310 2.257 7.725 23.510 37.420 8.376
3 9.570 92.480 48.990 26.600 62.070 3.017 8.040 2.173 6.378 12.420 35.900 7.460
4 9.158 49.230 29.290 21.770 44.730 2.966 5.395 2.049 4.663 62.930 41.390 6.942
5 43.790 55.180 20.400 16.440 26.190 3.126 4.113 6.952 5.185 30.440 39.580 6.775
6 33.980 45.070 15.300 12.550 19.620 3.827 3.199 6.591 7.612 17.690 37.760 7.073
7 19.530 68.790 12.800 10.750 16.660 4.048 2.777 3.377 10.740 14.500 25.060 7.996
8 17.800 48.650 11.910 9.647 18.190 4.679 2.536 3.024 6.333 14.680 55.900 19.030
9 24.510 30.720 11.290 8.663 14.890 4.509 2.358 2.525 4.513 11.320 56.840 22.820
10 19.670 83.820 10.930 8.261 12.060 4.626 2.265 2.155 27.630 14.070 48.480 31.260
11 14.090 58.010 11.030 7.833 10.960 16.310 2.182 1.998 30.520 10.720 40.070 68.010
12 10.960 33.590 12.990 7.601 12.410 15.420 2.138 2.078 14.350 9.760 74.140 52.220
13 9.745 24.360 12.560 15.170 25.150 25.270 2.077 1.731 8.331 9.059 39.340 33.070
14 12.960 20.280 14.290 11.390 19.170 28.440 2.015 1.857 6.053 7.173 51.350 24.170
15 18.080 17.360 18.070 8.604 12.660 12.940 1.937 2.161 5.025 6.051 39.030 17.950
16 13.780 20.530 35.740 7.197 14.320 8.321 1.884 2.102 4.291 5.608 24.290 13.760
17 11.020 28.420 22.540 7.097 9.999 6.575 1.947 1.702 3.628 4.739 17.940 11.530
18 9.365 56.560 17.140 6.595 8.448 5.547 2.304 1.812 3.347 4.420 13.350 10.730
19 8.970 35.340 25.310 6.267 7.737 5.067 3.265 1.812 3.101 4.027 21.240 10.220
20 11.060 30.510 33.560 6.296 7.076 4.623 3.300 1.605 2.889 6.465 47.110 9.141
21 40.600 27.880 33.060 37.140 6.684 3.756 5.253 2.136 2.770 21.390 24.870 8.594
22 70.510 47.490 24.430 78.650 6.301 3.513 3.278 2.783 2.525 12.670 18.970 8.587
23 47.390 77.040 21.780 30.500 5.985 3.233 3.675 2.644 2.345 12.700 54.970 84.280
24 40.610 57.490 22.070 22.160 5.716 3.067 22.930 3.932 2.241 24.370 51.500 90.280
25 113.400 47.960 16.950 20.410 5.321 2.994 11.470 12.480 2.529 18.650 25.640 54.410
26 101.500 31.760 16.520 32.020 4.948 2.901 9.048 29.620 3.059 10.530 18.390 32.600
27 50.860 24.710 22.350 22.590 4.586 2.931 6.630 19.800 3.669 8.210 14.380 42.320
28 33.870 19.380 18.490 20.310 4.271 4.994 4.275 11.680 2.884 6.957 12.270 28.070
29 23.730 13.270 45.100 3.967 4.772 3.334 6.638 4.110 6.303 10.620 20.300
30 18.820 11.200 33.710 3.749 3.470 2.811 5.605 32.740 5.899 9.102 17.360
31 16.310 39.650 3.535 2.630 7.558 23.090 12.870
Average 28.710 41.570 21.650 20.860 14.240 6.712 5.188 5.075 7.586 15.170 33.850 25.060
Lowest 8.970 13.860 10.930 6.267 3.535 2.901 1.884 1.605 2.241 4.027 9.102 6.775
Highest 113.400 92.480 48.990 78.650 62.070 28.440 22.930 29.620 32.740 62.930 74.140 90.280
Monthly total
(million cu m) 76.89 100.60 58.00 54.07 38.13 17.40 13.89 13.59 19.66 40.64 87.75 67.12
Runoff (mm) 101 133 76 71 50 23 18 18 26 54 116 88
Rainfall (mm) 103 165 91 90 56 102 41 82 71 95 149 111
Statistics of monthly data for previous record (Oct 1955 to Dec 1976)
Mean Avg. 26.130 22.410 17.820 15.860 11.450 7.094 8.943 12.070 14.030 17.590 22.130 25.700
flows: Low 4.472 2.974 6.741 4.496 2.794 1.545 1.674 0.991 1.419 3.026 6.876 10.230
(year) 1963 1963 1961 1974 1974 1957 1976 1976 1959 1972 1958 1963
High 39.260 54.590 36.400 35.240 26.750 18.530 16.440 41.340 33.520 54.000 51.090 62.090
(year) 1961 1966 1963 1970 1967 1972 1963 1956 1968 1967 1963 1965
Runoff: Avg. 92 72 63 54 40 24 32 43 48 62 76 91
Low 16 9 24 15 10 5 6 4 5 11 23 36
High 139 174 128 120 94 63 58 146 115 191 174 219
Rainfall: Avg. 106 82 75 76 79 70 95 96 106 102 106 111
Low 41 20 28 10 13 18 35 18 8 34 33 41
High 165 194 148 147 181 140 185 226 241 225 211 224
Summary statistics Factors affecting runoff
1977
For 1977 For record As % of $ Reservoir(s) in catchment.
preceding 1977 pre-1977 $ Abstraction for public water supplies.
Mean flow 18.640 16.750 111 $ 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 5.075 Aug 0.991 Aug 1976 groundwater.
Highest monthly mean 41.570 Feb 62.090 Dec 1965
Lowest daily mean 1.605 20 Aug 0.425 23 Jun 1957
Highest daily mean 113.400 25 Jan 233.600 4 Dec 1960
10% exceedance 46.450 39.110 119
50% exceedance 12.340 9.394 131
95% exceedance 2.173 2.303 94
Annual total (million cu m) 587.80 528.60 111
Annual runoff (mm) 775 697 111
Annual rainfall (mm) 1156 1104 105
{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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