055013 Arrow at Titley Mill 1999
Measuring authority: EA Grid reference: 32 (SO) 328 585 Catchment area (sq km): 126.4
First year: 1966 Level stn. (m OD): 129.00 Max alt. (m OD): 542
Daily mean gauged discharges (cubic metres per second)
DAY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1 5.036 3.234 9.241 1.053 2.422 0.991 0.548 0.295 0.337 7.897 3.567 2.613
2 6.252 2.976 11.330 1.009 2.101 2.434 0.689 0.327 0.327 12.060 3.263 2.401
3 9.842 2.770 19.660 0.964 1.856 1.530 0.619 0.518 0.321 8.401 2.965 2.665
4 9.222 2.590 11.570 0.991 1.698 1.299 0.512 0.369 0.303 5.699 2.841 2.305
5 8.690 2.429 7.657 0.991 1.565 1.579 0.650 0.464 0.291 4.461 8.591 2.084
6 10.310 2.629 5.777 1.038 1.476 1.411 0.478 0.654 0.286 3.637 6.305 2.427
7 11.540 2.366 4.713 0.966 1.503 1.307 0.433 0.958 0.317 3.114 4.960 2.788
8 11.660 2.333 4.119 0.897 1.862 1.200 0.404 0.524 0.302 2.730 4.047 5.110
9 7.941 2.075 3.500 0.859 1.848 1.135 0.404 0.450 0.296 2.364 3.360 4.715
10 6.230 1.920 3.042 0.834 1.719 1.105 0.379 0.390 0.282 2.112 2.896 4.944
11 5.049 1.876 2.815 1.096 1.770 1.068 0.361 0.356 0.315 1.859 2.578 10.470
12 6.679 1.811 2.594 1.731 2.079 1.181 0.354 0.338 0.275 1.681 2.374 10.600
13 6.976 1.765 2.309 1.546 2.009 1.033 0.366 0.331 0.253 1.544 2.155 9.804
14 6.443 1.711 2.083 1.528 2.445 0.965 0.362 0.321 0.247 1.446 1.974 7.141
15 16.690 1.668 1.930 1.595 2.071 0.910 0.342 0.305 0.247 1.366 1.820 5.316
16 17.150 1.616 1.819 1.488 1.972 0.859 0.338 0.300 0.252 1.279 1.726 5.390
17 11.920 1.555 1.719 1.368 1.845 0.825 0.323 0.364 0.327 1.200 1.597 8.091
18 10.480 1.611 1.615 1.298 1.773 0.773 0.320 0.363 3.856 1.131 1.531 6.285
19 11.040 1.914 1.523 1.306 1.668 0.770 0.349 0.303 11.260 1.075 1.378 5.035
20 9.587 1.665 1.473 3.317 1.506 0.757 0.393 0.288 7.663 1.048 1.305 4.302
21 7.433 2.480 1.580 4.602 1.439 0.703 0.321 0.284 4.700 1.371 1.256 5.479
22 6.094 2.386 1.409 4.242 1.328 0.679 0.301 0.286 3.547 3.081 1.215 6.573
23 5.380 2.375 1.339 3.987 1.259 0.679 0.293 0.286 4.653 3.713 1.158 12.530
24 5.297 2.684 1.285 3.255 1.226 0.638 0.282 0.619 15.090 10.140 2.330 22.920
25 5.571 2.473 1.404 3.672 1.136 0.604 0.280 1.321 9.567 7.652 2.839 18.270
26 6.958 3.345 1.279 6.797 1.091 0.604 0.274 0.679 9.165 5.088 2.845 14.300
27 5.540 2.994 1.182 5.267 1.064 0.685 0.275 0.502 9.915 3.977 2.702 9.614
28 4.940 3.070 1.110 4.227 1.073 0.602 0.277 0.431 6.964 3.447 3.181 7.220
29 4.269 1.285 3.479 1.212 0.576 0.289 0.402 6.111 3.165 3.040 5.560
30 3.929 1.149 2.862 1.050 0.533 0.294 0.376 4.815 3.897 2.840 6.882
31 3.615 1.106 0.965 0.295 0.359 3.210 5.482
Average 7.992 2.297 3.697 2.276 1.614 0.981 0.381 0.444 3.409 3.705 2.821 7.075
Lowest 3.615 1.555 1.106 0.834 0.965 0.533 0.274 0.284 0.247 1.048 1.158 2.084
Highest 17.150 3.345 19.660 6.797 2.445 2.434 0.689 1.321 15.090 12.060 8.591 22.920
Monthly total
(million cu m) 21.41 5.56 9.90 5.90 4.32 2.54 1.02 1.19 8.84 9.92 7.31 18.95
Runoff (mm) 169 44 78 47 34 20 8 9 70 79 58 150
Rainfall (mm) 187 70 69 106 70 71 30 115 200 119 82 185
Statistics of monthly data for previous record (Oct 1966 to Dec 1998)
Mean Avg. 4.803 3.974 3.321 2.262 1.582 1.072 0.664 0.592 0.808 1.999 3.079 4.311
flows: Low 0.565 1.064 0.666 0.600 0.355 0.257 0.210 0.112 0.135 0.204 0.662 1.369
(year) 1997 1998 1993 1997 1990 1990 1976 1995 1990 1995 1978 1988
High 9.004 8.767 8.940 5.028 5.001 2.559 3.842 2.220 2.643 8.651 6.625 8.477
(year) 1982 1990 1981 1987 1983 1972 1968 1992 1992 1998 1986 1989
Runoff: Avg. 102 77 70 46 34 22 14 13 17 42 63 91
Low 12 20 14 12 8 5 4 2 3 4 14 29
High 191 168 189 103 106 52 81 47 54 183 136 180
Rainfall: Avg. 112 84 83 63 71 67 56 74 87 100 100 111
Low 10 8 17 7 13 11 13 7 14 16 34 36
High 206 206 203 160 173 173 134 215 226 251 187 213
Summary statistics Factors affecting runoff
1999
For 1999 For record As % of
preceding 1999 pre-1999 $ Natural to within 10% at 95 percentile flow.
Mean flow 3.071 2.366 130
Lowest yearly mean 1.309 1973
Highest yearly mean 3.418 1982
Lowest monthly mean 0.381 Jul 0.112 Aug 1995
Highest monthly mean 7.992 Jan 9.004 Jan 1982
Lowest daily mean 0.247 14 Sep 0.090 28 Sep 1990
Highest daily mean 22.920 24 Dec 44.080 27 Oct 1998
10% exceedance 7.833 5.463 143
50% exceedance 1.723 1.424 121
95% exceedance 0.292 0.259 113
Annual total (million cu m) 96.85 74.66 130
Annual runoff (mm) 766 591 130
Annual rainfall (mm) 1304 1008 129
{1961-90 rainfall average (mm) 962}
Station and catchment description
Velocity-area station. Low flow control is a stable riffle; otherwise a three-bay road bridge 50m d/s is the control.
Gets out of bank but not bypassed. Intake pipes silted up during summer of 1994, treat data with caution. 1995 summer
flows suspect and under investigation by EA. Natural catchment.
Headwaters of moderate relief, draining durable Silurian slates and shales; otherwise, catchment underlain by ORS marls.
Station is in a transition zone between upland plateau supporting sheep grazing and the more productive lowlands.
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