043005 Avon at Amesbury 2001
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 11.690 8.527 8.356 9.811 7.229 4.442 2.971 2.116 1.800 1.794 2.397 2.706
2 12.370 9.281 8.053 9.661 7.149 4.392 2.902 2.149 1.796 1.910 2.337 2.867
3 13.360 9.485 7.884 9.970 6.982 4.275 2.860 2.169 1.832 1.872 2.300 2.693
4 13.000 11.150 7.662 11.420 6.813 4.215 2.842 2.270 1.804 1.776 2.311 2.786
5 15.330 13.270 7.381 10.970 6.623 4.183 2.825 2.187 1.792 1.736 2.278 2.947
6 12.760 12.630 7.519 10.900 6.479 4.174 2.835 2.159 1.795 1.707 2.287 3.086
7 11.070 12.130 8.345 10.680 6.389 4.231 2.852 2.156 1.799 2.046 2.383 2.823
8 10.660 11.630 7.700 10.400 6.211 4.099 2.921 2.143 1.791 2.791 2.459 2.711
9 10.460 11.120 7.505 11.650 6.166 4.057 2.825 2.317 1.769 2.452 2.384 2.631
10 10.360 10.620 7.780 10.660 6.223 4.005 2.828 2.998 1.750 2.090 2.301 2.591
11 10.050 10.560 8.136 9.906 6.113 3.954 2.926 2.856 1.736 1.973 2.281 2.555
12 9.793 11.730 8.973 9.483 5.969 3.893 2.796 2.566 1.725 1.900 2.286 2.540
13 9.565 14.110 8.280 9.420 5.848 3.867 2.743 2.483 1.743 1.858 2.317 2.529
14 9.326 11.590 7.843 9.336 5.744 3.834 2.817 2.376 1.738 1.830 2.283 2.498
15 9.213 10.990 7.590 9.256 5.669 3.897 2.637 2.234 1.712 2.089 2.233 2.464
16 9.021 10.670 7.674 8.873 5.994 4.742 2.593 2.221 1.688 2.258 2.234 2.469
17 8.828 10.340 9.564 8.617 6.426 4.253 2.640 2.163 1.672 2.052 2.238 2.459
18 8.645 10.170 9.762 8.560 6.605 4.005 2.842 2.148 1.674 2.057 2.213 2.464
19 8.403 10.070 8.528 8.379 5.912 3.821 2.817 2.284 1.699 2.114 2.210 2.472
20 8.186 9.913 8.535 8.124 5.648 3.702 2.637 2.315 1.708 2.369 2.174 2.478
21 9.109 9.746 11.140 8.022 5.503 3.633 2.615 2.134 1.696 2.479 2.152 2.477
22 9.280 9.632 11.280 8.356 5.374 3.565 2.577 2.072 1.676 2.373 2.161 2.467
23 9.765 9.487 10.550 9.178 5.209 3.396 2.531 2.059 1.655 2.680 2.148 2.432
24 9.801 9.110 10.750 8.754 5.054 3.287 2.488 2.041 1.637 2.753 2.169 2.444
25 9.125 8.834 10.020 9.048 4.939 3.229 2.412 1.999 1.646 2.914 2.207 2.458
26 9.633 9.214 9.613 8.835 4.898 3.104 2.351 1.956 1.674 3.221 2.288 2.436
27 12.620 9.543 10.050 8.116 4.893 3.019 2.297 1.912 1.682 3.273 2.241 2.404
28 10.170 8.755 10.950 7.948 4.781 2.998 2.248 1.854 1.659 2.978 2.246 2.399
29 9.180 11.330 7.899 4.673 3.043 2.184 1.837 1.630 2.760 2.283 2.430
30 8.896 10.450 7.501 4.497 3.010 2.159 1.813 1.784 2.591 2.364 2.422
31 8.816 10.140 4.456 2.119 1.819 2.489 2.374
Average 10.270 10.510 9.011 9.324 5.822 3.811 2.648 2.187 1.725 2.296 2.272 2.565
Lowest 8.186 8.527 7.381 7.501 4.456 2.998 2.119 1.813 1.630 1.707 2.148 2.374
Highest 15.330 14.110 11.330 11.650 7.229 4.742 2.971 2.998 1.832 3.273 2.459 3.086
Monthly total
(million cu m) 27.52 25.43 24.14 24.17 15.59 9.88 7.09 5.86 4.47 6.15 5.89 6.87
Runoff (mm) 85 79 75 75 48 31 22 18 14 19 18 21
Rainfall (mm) 87 82 116 90 33 31 51 76 43 128 43 20
Statistics of monthly data for previous record (Feb 1965 to Dec 2000)
Mean Avg. 5.649 6.130 5.402 4.643 3.583 2.721 2.022 1.672 1.592 1.957 2.839 4.314
flows: Low 1.249 1.237 1.207 1.083 0.871 0.652 0.492 0.388 0.670 0.926 1.137 1.421
(year) 1976 1976 1976 1976 1976 1976 1976 1976 1976 1997 1973 1990
High 10.630 13.860 9.208 7.571 6.948 4.358 3.398 2.438 2.598 3.773 10.200 14.590
(year) 1994 1990 1995 1979 2000 2000 2000 1979 1974 2000 2000 2000
Runoff: Avg. 47 46 45 37 30 22 17 14 13 16 23 36
Low 10 10 10 9 7 5 4 3 5 8 9 12
High 88 104 76 61 57 35 28 20 21 31 82 121
Rainfall: Avg. 80 56 61 52 55 57 48 61 69 74 77 87
Low 12 5 14 1 8 3 13 7 11 4 31 17
High 169 147 150 160 121 143 113 152 179 161 185 160
Summary statistics Factors affecting runoff
2001
For 2001 For record As % of $ Flow influenced by groundwater abstraction
preceding 2001 pre-2001 and/or recharge.
Mean flow 5.170 3.531 146
Lowest yearly mean 1.475 1976
Highest yearly mean 6.143 2000
Lowest monthly mean 1.725 Sep 0.388 Aug 1976
Highest monthly mean 10.510 Feb 14.590 Dec 2000
Lowest daily mean 1.630 29 Sep 0.183 22 Aug 1976
Highest daily mean 15.330 5 Jan 23.580 9 Dec 2000
10% exceedance 10.410 6.754 154
50% exceedance 3.015 2.831 106
95% exceedance 1.728 1.135 152
Annual total (million cu m) 163.00 111.40 146
Annual runoff (mm) 504 344 146
Annual rainfall (mm) 800 777 103
{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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