043005 Avon at Amesbury 1997
Measuring authority: EA Grid reference: 41 (SU) 151 413 Catchment area (sq km): 323.7
First year: 1965 Level stn. (m OD): 67.10 Max alt. (m OD): 294
Daily mean gauged discharges (cubic metres per second)
DAY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1 1.486 1.512 2.651 2.557 2.004 1.363 1.417 0.907 1.133 0.735 0.842 2.098
2 1.497 1.500 2.620 2.546 1.921 1.335 1.392 0.907 1.069 0.735 0.879 2.438
3 1.505 1.525 2.647 2.542 1.915 1.345 1.384 0.986 1.033 0.735 0.887 2.382
4 1.507 1.582 2.860 2.560 1.943 1.332 1.369 1.071 0.995 0.735 0.931 2.118
5 1.504 1.605 2.940 2.520 1.964 1.331 1.299 1.076 0.968 0.734 1.128 2.045
6 1.550 1.607 2.812 2.508 1.931 1.387 1.263 0.996 0.955 0.757 1.276 1.984
7 1.567 1.619 2.774 2.480 1.905 1.411 1.210 1.142 0.934 0.777 1.272 2.013
8 1.575 1.551 2.718 2.472 1.939 1.401 1.167 1.070 0.929 0.830 1.289 2.099
9 1.575 1.527 2.685 2.444 1.985 1.396 1.134 1.025 0.934 1.029 1.341 2.156
10 1.590 1.651 2.688 2.389 1.962 1.410 1.093 0.964 0.916 1.082 1.297 2.406
11 1.615 1.742 2.657 2.421 1.986 1.418 1.076 0.962 0.914 1.139 1.206 2.437
12 1.655 1.852 2.659 2.395 2.017 1.425 1.055 0.932 0.908 1.126 1.161 2.271
13 1.691 2.333 2.652 2.373 1.933 1.405 1.062 0.909 0.890 1.053 1.127 2.180
14 1.702 2.237 2.664 2.347 1.872 1.384 1.073 0.868 0.895 1.022 1.117 2.155
15 1.696 2.064 2.653 2.328 1.827 1.369 1.067 0.855 0.898 1.027 1.098 2.040
16 1.691 2.034 2.642 2.298 1.822 1.343 1.061 0.836 0.903 1.025 1.100 2.012
17 1.730 2.318 2.635 2.297 1.806 1.316 1.091 0.867 0.885 1.013 1.107 2.058
18 1.696 2.764 2.669 2.268 1.792 1.279 1.079 0.826 0.866 1.011 1.276 2.433
19 1.646 2.676 2.674 2.253 1.793 1.284 1.035 0.816 0.911 0.995 1.565 2.842
20 1.610 3.157 2.673 2.220 1.824 1.331 0.976 0.815 0.906 0.974 2.315 2.555
21 1.602 2.824 2.693 2.184 1.820 1.360 1.010 0.803 0.867 0.971 2.607 2.479
22 1.625 2.746 2.604 2.170 1.800 1.423 0.946 0.807 0.856 0.956 2.363 2.485
23 1.635 2.734 2.689 2.142 1.767 1.428 0.894 0.806 0.825 0.940 2.051 2.650
24 1.612 3.021 2.729 2.119 1.741 1.364 0.900 0.814 0.857 0.937 1.920 3.093
25 1.608 3.411 2.723 2.101 1.695 1.440 0.896 0.967 0.853 0.933 1.841 3.813
26 1.584 3.134 2.690 2.243 1.635 1.540 0.952 1.186 0.818 0.902 1.804 4.156
27 1.576 2.884 2.665 2.238 1.595 1.558 0.965 1.064 0.761 0.902 1.788 4.103
28 1.557 2.788 2.649 2.143 1.515 1.529 0.970 1.020 0.758 0.898 2.224 3.635
29 1.530 2.607 2.079 1.471 1.474 0.942 1.027 0.764 0.898 2.439 3.447
30 1.512 2.581 2.038 1.418 1.431 0.924 1.165 0.759 0.927 2.124 3.410
31 1.516 2.553 1.395 0.934 1.221 0.907 3.671
Average 1.595 2.229 2.682 2.323 1.806 1.394 1.085 0.958 0.899 0.926 1.513 2.634
Lowest 1.486 1.500 2.553 2.038 1.395 1.279 0.894 0.803 0.758 0.734 0.842 1.984
Highest 1.730 3.411 2.940 2.560 2.017 1.558 1.417 1.221 1.133 1.139 2.607 4.156
Monthly total
(million cu m) 4.27 5.39 7.19 6.02 4.84 3.61 2.91 2.57 2.33 2.48 3.92 7.06
Runoff (mm) 13 17 22 19 15 11 9 8 7 8 12 22
Rainfall (mm) 12 85 15 16 57 84 32 93 14 55 123 86
Statistics of monthly data for previous record (Feb 1965 to Dec 1996)
Mean Avg. 5.545 6.281 5.534 4.656 3.541 2.692 1.997 1.661 1.584 1.909 2.585 3.984
flows: Low 1.249 1.237 1.207 1.083 0.871 0.652 0.492 0.388 0.670 1.014 1.137 1.421
(year) 1976 1976 1976 1976 1976 1976 1976 1976 1976 1989 1973 1990
High 10.630 13.860 9.208 7.571 5.249 4.345 3.104 2.438 2.598 3.681 6.395 9.427
(year) 1994 1990 1995 1979 1979 1979 1971 1979 1974 1993 1974 1992
Runoff: Avg. 46 47 46 37 29 22 17 14 13 16 21 33
Low 10 10 10 9 7 5 4 3 5 8 9 12
High 88 104 76 61 43 35 26 20 21 30 51 78
Rainfall: Avg. 82 56 64 48 55 55 49 59 68 70 76 85
Low 14 5 14 1 8 3 15 7 11 4 31 17
High 169 147 150 100 121 143 113 152 179 161 185 160
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 1.667 3.483 48
Lowest yearly mean 1.475 1976
Highest yearly mean 4.580 1994
Lowest monthly mean 0.899 Sep 0.388 Aug 1976
Highest monthly mean 2.682 Mar 13.860 Feb 1990
Lowest daily mean 0.734 5 Oct 0.183 22 Aug 1976
Highest daily mean 4.156 26 Dec 22.210 4 Feb 1990
10% exceedance 2.667 6.681 40
50% exceedance 1.528 2.822 54
95% exceedance 0.823 1.148 72
Annual total (million cu m) 52.57 109.90 48
Annual runoff (mm) 162 340 48
Annual rainfall (mm) 672 767 88
{1961-90 rainfall average (mm) 745}
Station and catchment description
Crump profile weir (crest 9.14m broad) flanked by broad-crested weirs. Small bypass channel approx. 2m u/s of weir -
included in rating. Full range station. During summer, flows are naturally augmented from gw draining from northern half
of R. Bourne catchment. May go non-modular at low flow in exceptional summers. Some gw pumping also takes place within
the catchment. Data reprocessed in 2001, resulting in decrease in high flows.
Predominantly permeable (Chalk) catchment with a small inlier of Upper Greensand and Gault. Land use: rural.
Topographical and gw catchments do not coincide.
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