027002 Wharfe at Flint Mill Weir 1961
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 59.180 45.870 13.450 10.450 14.950 3.172 1.971 2.829 4.021 19.030 45.870 41.340
2 76.740 35.110 15.290 46.440 43.610 3.087 1.985 3.115 3.596 9.005 39.640 21.750
3 56.070 27.010 15.600 17.640 43.040 2.602 3.002 3.087 19.790 7.646 26.360 17.640
4 40.490 37.660 10.220 11.070 30.580 2.591 2.141 58.050 13.880 6.400 15.380 19.340
5 30.870 75.610 8.495 33.410 111.300 6.173 4.871 18.210 7.617 5.154 11.410 107.600
6 56.070 81.550 8.297 46.160 39.930 6.485 2.945 9.911 7.164 6.145 9.996 37.100
7 35.960 86.650 7.221 23.450 28.600 4.672 2.178 8.750 9.515 4.955 10.990 21.520
8 30.300 50.120 7.306 14.530 29.730 3.766 2.141 17.270 7.249 3.993 10.870 16.990
9 35.110 94.580 7.108 11.300 38.510 2.727 2.163 25.800 5.097 4.955 11.840 21.290
10 32.280 49.270 6.881 10.990 19.790 2.704 3.568 12.350 4.474 24.980 8.920 64.560
11 20.670 58.900 5.154 9.373 13.990 14.220 3.143 9.373 4.417 19.680 7.108 174.700
12 20.870 37.100 5.069 12.260 11.070 11.040 3.285 11.360 4.672 14.530 6.456 65.410
13 128.800 27.130 6.145 36.250 9.033 6.400 50.400 8.212 15.380 8.835 7.221 67.390
14 47.290 19.680 5.069 31.720 7.532 4.672 27.070 8.665 13.510 6.456 9.260 64.000
15 25.830 15.070 4.191 15.070 7.221 4.333 40.210 6.032 21.290 4.955 8.297 28.600
16 18.830 13.760 4.616 10.220 6.145 3.172 21.720 4.871 31.430 4.955 7.108 19.790
17 15.380 12.150 4.078 8.297 6.343 3.200 10.960 4.276 13.590 51.250 6.230 15.490
18 13.450 11.070 3.681 7.419 5.493 19.230 7.844 3.964 9.005 27.330 4.955 13.030
19 13.680 10.220 3.681 6.881 5.493 8.552 5.890 15.090 7.532 14.640 4.616 10.650
20 17.300 9.798 4.729 7.108 4.304 5.692 5.097 8.665 7.023 10.340 5.380 10.530
21 23.250 9.033 3.879 8.184 4.304 4.219 4.531 61.170 6.003 12.150 5.380 10.110
22 35.680 8.382 3.681 14.840 4.304 3.058 3.908 34.830 5.522 12.490 5.267 8.920
23 24.980 8.070 3.341 31.430 4.191 3.115 3.710 16.400 5.663 31.720 5.069 7.957
24 18.830 7.957 3.228 21.630 5.918 2.574 3.794 11.640 5.380 43.330 7.646 7.306
25 14.530 9.260 1.829 15.910 7.108 2.594 3.426 9.939 4.955 27.550 16.790 6.230
26 12.260 17.220 2.260 37.950 4.729 3.087 5.097 31.430 4.417 20.760 11.070 5.918
27 48.990 17.220 3.879 35.680 2.475 2.534 6.626 16.000 4.729 15.180 9.033 6.768
28 52.390 12.380 2.917 26.050 3.030 2.415 4.786 9.571 4.927 15.380 7.759 6.343
29 83.820 3.115 18.290 3.993 2.107 3.936 6.711 9.061 13.990 9.260 6.683
30 74.470 17.760 14.410 2.152 2.112 3.370 5.267 29.170 9.798 92.600 5.918
31 52.670 16.790 2.583 3.256 3.936 56.070 5.069
Average 39.260 31.710 6.741 19.810 16.820 4.877 8.033 14.410 9.669 16.570 14.260 29.550
Lowest 12.260 7.957 1.829 6.881 2.152 2.107 1.971 2.829 3.596 3.993 4.616 5.069
Highest 128.800 94.580 17.760 46.440 111.300 19.230 50.400 61.170 31.430 56.070 92.600 174.700
Monthly total
(million cu m) 105.20 76.71 18.05 51.36 45.05 12.64 21.52 38.60 25.06 44.38 36.96 79.14
Runoff (mm) 139 101 24 68 59 17 28 51 33 58 49 104
Rainfall (mm) 165 94 28 130 61 51 99 114 97 130 71 124
Statistics of monthly data for previous record (Oct 1955 to Dec 1960)
Mean Avg. 28.890 25.080 16.450 10.010 7.442 5.131 9.285 15.540 13.780 15.950 18.380 27.660
flows: Low 24.320 7.996 10.600 5.197 3.911 1.545 3.601 1.795 1.419 6.597 6.876 18.930
(year) 1956 1959 1959 1957 1960 1957 1959 1959 1959 1955 1958 1957
High 32.960 47.220 22.520 16.750 17.780 14.450 14.000 41.340 22.270 25.440 45.900 40.190
(year) 1958 1958 1957 1959 1958 1958 1960 1956 1956 1958 1960 1959
Runoff: Avg. 102 81 58 34 26 18 33 55 47 56 63 98
Low 86 25 37 18 14 5 13 6 5 23 23 67
High 116 151 79 57 63 49 49 146 76 90 157 142
Rainfall: Avg. 111 85 60 52 63 67 102 103 89 108 89 142
Low 77 20 46 10 25 41 35 18 8 61 33 112
High 157 178 86 104 122 112 185 226 135 165 198 203
Summary statistics Factors affecting runoff
1961
For 1961 For record As % of $ Reservoir(s) in catchment.
preceding 1961 pre-1961 $ Abstraction for public water supplies.
Mean flow 17.590 16.120 109 $ Flow reduced by industrial and/or
Lowest yearly mean 12.470 1959 agricultural abstractions.
Highest yearly mean 19.290 1958 $ Augmentation from surface water and/or
Lowest monthly mean 4.877 Jun 1.419 Sep 1959 groundwater.
Highest monthly mean 39.260 Jan 47.220 Feb 1958
Lowest daily mean 1.829 25 Mar 0.425 23 Jun 1957
Highest daily mean 174.700 11 Dec 233.600 4 Dec 1960
10% exceedance 43.660 39.750 110
50% exceedance 9.380 8.752 107
95% exceedance 2.617 1.747 150
Annual total (million cu m) 554.70 508.80 109
Annual runoff (mm) 731 670 109
Annual rainfall (mm) 1164 1071 109
{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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