028026 Anker at Polesworth 1997
Measuring authority: EA Grid reference: 43 (SK) 263 034 Catchment area (sq km): 368.0
First year: 1966 Level stn. (m OD): 60.40 Max alt. (m OD): 278
Daily mean gauged discharges (cubic metres per second)
DAY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1 1.244 1.342 3.158 1.161 0.981 0.807 2.322 1.044 3.027 0.906 1.031 4.779
2 1.278 1.351 3.045 1.152 0.969 0.778 2.645 1.118 2.046 0.891 1.020 3.538
3 1.275 1.331 2.471 1.185 0.954 0.767 2.239 0.963 1.581 0.886 1.011 2.799
4 1.253 1.395 2.317 1.166 1.131 0.780 2.128 0.860 1.349 0.890 1.102 2.378
5 1.262 1.347 2.371 1.276 2.013 0.847 1.802 0.872 1.247 0.843 1.356 2.149
6 1.280 1.272 2.313 1.328 2.330 0.889 1.433 0.887 1.159 0.849 1.187 1.996
7 1.236 1.272 2.074 1.088 1.582 1.218 1.249 0.839 1.067 1.006 1.133 1.933
8 1.245 1.226 1.884 1.072 2.350 0.989 1.239 0.820 1.002 2.028 1.909 2.042
9 1.210 1.219 1.765 1.052 3.594 0.916 1.184 0.800 1.009 4.595 1.813 2.019
10 1.169 1.447 1.716 1.058 2.311 0.958 1.221 0.779 1.008 2.704 1.696 2.450
11 1.227 1.486 1.632 1.046 1.945 3.068 1.096 0.718 0.958 2.226 1.500 2.504
12 1.293 1.920 1.599 1.027 1.605 3.498 1.018 0.737 1.075 2.336 1.296 2.218
13 1.559 2.105 1.544 1.004 1.334 2.251 1.109 0.971 1.030 1.659 1.204 1.919
14 1.574 1.920 1.557 1.005 1.247 2.130 1.144 1.978 1.016 1.613 1.121 1.783
15 1.453 1.607 1.470 1.001 1.190 1.792 1.096 1.076 0.954 2.274 1.076 1.713
16 1.389 1.701 1.394 0.995 1.184 1.455 1.088 0.944 0.901 2.001 1.098 1.670
17 1.360 1.973 1.369 1.029 1.510 1.231 2.311 0.812 0.889 1.768 1.143 1.739
18 1.345 3.675 1.537 1.026 1.477 1.036 1.793 0.762 0.992 1.536 1.371 3.255
19 2.078 4.317 1.486 1.023 1.297 1.103 1.272 0.827 1.523 1.300 1.809 4.240
20 2.278 5.360 1.352 0.995 1.888 1.614 1.083 1.985 1.383 1.214 5.204 3.261
21 2.078 3.749 1.300 1.016 2.418 2.325 0.950 1.117 1.091 1.164 6.012 2.682
22 2.317 3.078 1.270 1.050 1.593 3.257 0.918 1.035 0.955 1.130 3.336 2.663
23 2.463 3.106 1.298 1.048 1.246 3.870 0.898 1.442 0.927 1.111 2.383 4.250
24 2.274 5.794 1.332 1.008 1.069 2.189 1.078 2.955 0.895 1.062 2.247 8.291
25 1.990 7.067 1.290 2.408 0.994 2.598 1.523 4.306 0.908 1.067 2.082 12.350
26 1.786 6.263 1.268 2.287 0.939 5.751 1.165 2.877 0.900 1.018 1.943 9.391
27 1.654 5.064 1.260 1.560 0.936 8.146 1.017 2.019 0.927 1.022 2.072 5.717
28 1.562 3.897 1.271 1.333 0.915 4.203 0.942 1.930 0.927 1.003 9.096 6.811
29 1.502 1.188 1.311 0.903 2.797 0.912 1.721 0.919 0.994 14.010 7.622
30 1.458 1.151 1.067 0.823 2.247 0.900 2.269 0.898 1.008 9.042 5.618
31 1.379 1.136 0.822 0.907 4.110 1.030 5.535
Average 1.564 2.760 1.672 1.193 1.469 2.184 1.345 1.470 1.152 1.456 2.743 3.913
Lowest 1.169 1.219 1.136 0.995 0.822 0.767 0.898 0.718 0.889 0.843 1.011 1.670
Highest 2.463 7.067 3.158 2.408 3.594 8.146 2.645 4.306 3.027 4.595 14.010 12.350
Monthly total
(million cu m) 4.19 6.68 4.48 3.09 3.94 5.66 3.60 3.94 2.99 3.90 7.11 10.48
Runoff (mm) 11 18 12 8 11 15 10 11 8 11 19 28
Rainfall (mm) 16 54 16 27 67 116 43 78 15 52 75 54
Statistics of monthly data for previous record (Sep 1966 to Dec 1996----incomplete or missing months total 0.2 years)
Mean Avg. 5.471 5.103 4.010 2.930 2.188 1.827 1.322 1.348 1.416 2.016 2.945 4.498
flows: Low 1.299 0.953 0.813 0.657 0.685 0.484 0.343 0.405 0.711 0.729 0.855 1.174
(year) 1976 1976 1976 1976 1976 1976 1976 1976 1977 1970 1978 1975
High 9.572 16.200 9.233 6.628 8.389 4.650 5.580 4.173 3.363 8.109 7.309 9.474
(year) 1988 1977 1979 1987 1969 1973 1968 1980 1992 1993 1992 1978
Runoff: Avg. 40 34 29 21 16 13 10 10 10 15 21 33
Low 9 6 6 5 5 3 3 3 5 5 6 9
High 70 106 67 47 61 33 41 30 24 59 51 69
Rainfall: Avg. 58 50 48 48 56 55 52 59 57 56 59 63
Low 20 9 14 7 11 9 12 15 10 7 28 20
High 103 138 92 100 141 132 111 110 118 127 129 148
Summary statistics Factors affecting runoff
1997
For 1997 For record As % of $ Flow influenced by groundwater abstraction
preceding 1997 pre-1997 and/or recharge.
Mean flow 1.904 2.914 65 $ Augmentation from effluent returns.
Lowest yearly mean 1.213 1976
Highest yearly mean 4.114 1993
Lowest monthly mean 1.152 Sep 0.343 Jul 1976
Highest monthly mean 3.913 Dec 16.200 Feb 1977
Lowest daily mean 0.718 11 Aug 0.234 26 Aug 1976
Highest daily mean 14.010 29 Nov 56.720 24 Jan 1988
10% exceedance 3.296 5.959 55
50% exceedance 1.331 1.643 81
95% exceedance 0.855 0.656 130
Annual total (million cu m) 60.04 91.96 65
Annual runoff (mm) 163 250 65
Annual rainfall (mm) 613 661 93
{1961-90 rainfall average (mm) 653}
Station and catchment description
Crump profile weir with flanking floodbanks to contain out-of-channel flows. Cableway and d/s recorder. Low modular limit
and prone to weed growth, causing variable drowning and uncertainty with high flows. Substantial modification owing to
PWS imports to the catchment. Quite responsive.
Predominantly agricultural catchment (although containing Nuneaton and Hinkley). Lower reaches drain sandstone of the
Coal Measures. Sherwood sandstone and Mercia Mudstone over the remainder of the catchment are widely blanketed with
Boulder Clay.
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