028026 Anker at Polesworth 1999
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 5.029 5.058 7.042 2.703 2.497 1.827 1.478 0.863 1.014 3.799 2.445 2.621
2 6.606 4.528 12.780 2.760 2.194 10.780 1.623 1.014 0.998 20.930 2.616 2.402
3 14.260 4.169 15.310 2.449 2.032 22.780 1.530 1.187 0.998 18.670 2.125 2.491
4 20.230 3.925 16.180 2.377 1.966 15.780 1.414 1.206 0.991 5.857 2.081 2.360
5 9.872 3.708 7.191 2.357 1.926 6.770 1.298 1.795 0.979 3.163 6.867 2.175
6 12.060 4.070 8.481 2.332 1.932 6.730 1.484 1.741 0.971 2.532 9.851 2.096
7 19.490 3.897 15.510 2.270 3.209 16.160 1.416 1.554 1.035 2.265 4.529 2.459
8 13.470 3.746 14.840 2.174 3.998 17.510 1.249 3.969 1.074 2.209 3.380 2.521
9 8.093 3.537 8.913 2.092 2.773 5.736 1.176 10.680 1.103 1.967 2.912 2.642
10 6.116 3.140 9.270 2.073 2.860 3.556 1.146 4.769 1.096 1.800 2.565 2.654
11 5.030 2.855 6.699 2.137 2.493 2.953 1.090 2.107 1.016 1.684 2.399 14.190
12 6.234 2.834 6.686 2.871 2.296 3.839 1.043 1.950 0.996 1.571 3.009 16.440
13 8.081 2.836 9.241 2.427 2.088 3.945 1.040 1.696 0.967 1.561 2.904 11.340
14 7.799 3.026 5.934 2.276 1.921 2.921 1.052 1.602 0.987 1.566 2.688 9.706
15 10.170 3.179 4.811 2.170 1.840 2.430 1.094 1.575 1.025 1.530 2.552 5.779
16 49.740 3.172 4.212 3.229 1.695 2.162 1.058 1.371 1.270 1.518 2.514 4.564
17 18.560 2.993 3.846 4.174 1.597 1.898 1.025 1.285 1.456 1.443 2.360 4.603
18 8.570 2.999 3.519 5.698 1.576 1.740 0.990 1.276 1.275 1.468 2.545 4.182
19 9.140 2.881 3.220 5.353 1.573 1.660 1.002 1.344 1.303 1.427 2.231 3.519
20 19.300 2.731 3.072 8.028 1.551 1.791 1.066 1.267 3.832 1.411 2.050 3.042
21 10.560 6.291 3.610 10.460 1.483 1.599 1.145 1.211 2.798 2.324 2.002 3.810
22 6.730 6.230 3.211 5.565 1.490 1.503 1.052 1.152 1.699 3.655 2.001 6.089
23 5.815 4.281 2.989 9.144 1.383 1.474 1.010 1.109 1.935 6.614 1.950 7.885
24 5.353 4.355 2.825 11.500 1.527 1.483 0.958 1.142 2.663 5.265 2.075 19.230
25 7.419 3.826 4.131 5.570 1.533 1.451 0.942 1.595 3.171 13.180 3.940 32.560
26 8.896 6.388 4.590 4.429 1.399 1.422 0.918 1.952 5.454 8.615 3.456 16.320
27 8.732 8.169 3.953 3.709 1.404 1.586 0.903 1.466 4.419 4.136 3.505 7.659
28 17.700 5.564 3.381 3.201 1.758 1.746 0.876 1.220 3.259 3.114 3.104 5.541
29 9.240 3.300 2.939 2.447 1.670 0.877 1.106 2.473 2.652 3.139 4.433
30 6.859 3.068 2.696 4.086 1.523 0.890 1.066 2.396 2.604 2.761 4.786
31 5.804 2.877 2.460 0.893 1.049 2.424 5.525
Average 11.320 4.085 6.603 4.039 2.096 4.948 1.121 1.881 1.822 4.289 3.085 6.956
Lowest 5.029 2.731 2.825 2.073 1.383 1.422 0.876 0.863 0.967 1.411 1.950 2.096
Highest 49.740 8.169 16.180 11.500 4.086 22.780 1.623 10.680 5.454 20.930 9.851 32.560
Monthly total
(million cu m) 30.32 9.88 17.69 10.47 5.62 12.82 3.00 5.04 4.72 11.49 8.00 18.63
Runoff (mm) 82 27 48 28 15 35 8 14 13 31 22 51
Rainfall (mm) 106 42 65 63 60 92 11 77 78 81 43 75
Statistics of monthly data for previous record (Sep 1966 to Dec 1998----incomplete or missing months total 0.2 years)
Mean Avg. 5.452 4.926 3.927 3.041 2.147 1.881 1.322 1.346 1.417 2.121 2.997 4.560
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 8.230 8.389 4.650 5.580 4.173 3.363 8.109 7.309 9.474
(year) 1988 1977 1979 1998 1969 1973 1968 1980 1992 1993 1992 1978
Runoff: Avg. 40 33 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 58 61 33 41 30 24 59 51 69
Rainfall: Avg. 57 49 48 49 55 60 50 59 57 58 59 63
Low 16 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
1999
For 1999 For record As % of $ Flow influenced by groundwater abstraction
preceding 1999 pre-1999 and/or recharge.
Mean flow 4.366 2.919 150 $ Augmentation from effluent returns.
Lowest yearly mean 1.213 1976
Highest yearly mean 4.132 1998
Lowest monthly mean 1.121 Jul 0.343 Jul 1976
Highest monthly mean 11.320 Jan 16.200 Feb 1977
Lowest daily mean 0.863 1 Aug 0.234 26 Aug 1976
Highest daily mean 49.740 16 Jan 56.720 24 Jan 1988
10% exceedance 9.505 5.972 159
50% exceedance 2.673 1.651 162
95% exceedance 1.001 0.664 151
Annual total (million cu m) 137.70 92.11 149
Annual runoff (mm) 374 250 149
Annual rainfall (mm) 793 664 119
{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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