027002    Wharfe at Flint Mill Weir                                                                                1966


           Measuring authority: EA            Grid reference:     44    (SE) 422 473     Catchment area (sq km):    758.9
           First year: 1936                   Level stn. (m OD):   13.70                            Max alt. (m OD):  704



 Daily mean gauged discharges (cubic metres per second)


 
        DAY         JAN      FEB      MAR      APR      MAY      JUN      JUL      AUG      SEP      OCT      NOV      DEC

          1        49.110   15.090   30.700   26.960    9.953    6.456    8.722   15.420   10.960    6.207    8.529   94.350
          2        44.500   13.560   35.040   24.310    9.733    5.805    7.306   15.320   16.210    6.425    8.399   75.090
          3        29.350   13.600   32.080   25.020    9.291    5.069    6.230   19.500   16.470   13.260    8.198   36.250
          4        20.970   17.630   23.330   24.100    9.464    4.417    5.267   25.230   24.360   68.970    8.042   22.500
          5        26.170   92.660   18.980   28.600   13.960   21.630    6.570   19.350   21.690   30.070    7.728   19.630

          6        43.070   49.270   15.640   66.780   20.730   11.180    5.805   10.460   32.480   24.030   14.500   47.860
          7        23.800   46.830   13.680   44.210   18.330    6.768    7.042    8.586   14.710   18.680   20.620   23.850
          8        18.930  162.200   13.780   50.540   16.110    5.918    6.722    8.419   11.030   15.200   16.030   47.000
          9        16.230   59.760   15.540   63.740   19.720    6.145    6.400    7.994    9.461   12.360   12.280   45.340
         10        14.120   36.870   39.340   64.410   13.110    6.032    5.893   14.900    8.645   11.130   10.290   41.070

         11        12.450   24.430   31.460   33.310   26.060    4.304    7.074   10.160   19.460   10.160    9.226   26.580
         12        11.510   20.590   24.380   23.360   77.930    4.304    7.532   25.140   28.900    9.413   19.390   29.550
         13        10.840   18.510   17.570   20.680   27.750    4.616    9.676   54.610   44.190    9.996   55.570   30.590
         14        10.360   15.880   14.130   15.920   17.940    4.304   15.340   38.470   40.300   64.590   40.930   21.300
         15         9.877   14.090   12.300   14.460   14.230    4.616    8.809   19.050   58.210   36.970   74.260   17.230

         16         9.710   13.250   11.090   15.180   11.970    4.729    7.283   12.770   26.100   29.370   57.350   24.630
         17         9.396   12.210   10.330   14.370   11.130   12.150    6.453   10.280   16.990   20.470   26.330   69.530
         18         8.682   11.530    9.948   16.890   10.460   25.400    6.250    9.076   13.620   24.290   20.910  121.000
         19         8.209   25.280    8.815   19.730   10.680   11.530    5.915    8.113   11.660   22.730   18.700   81.330
         20         8.036  123.800    8.167   20.340   17.020    8.297    5.689    6.873    9.792   27.700   16.050   93.750

         21         8.099   96.410    8.467   22.050   11.040    7.844    5.369   48.450    8.928   20.360   13.640   39.320
         22         7.323   68.200    8.291   54.770   36.870    8.382    5.001   27.580    8.300   19.050   12.330   32.650
         23         7.748  138.100    8.206   44.460   89.400   34.550    4.500   14.910    7.875   16.210   11.860   28.280
         24         8.586  125.500    8.226   36.220   29.730   31.150    4.310   11.220    7.430   14.210   11.090   27.660
         25         9.214  141.800    7.827   25.810   30.300   24.860    7.006    9.537    7.249   12.640   11.120   20.860

         26        19.770   69.430    9.396   18.180   25.850   14.950    5.958    8.498    7.011   11.150   14.200   16.210
         27        41.400   59.080   53.140   21.520   16.370   49.840    8.240    7.309    6.765   10.440   18.810   16.870
         28        77.350   42.990   26.000   18.410   11.920   27.130    6.955    6.779    6.502   10.120   21.760   24.310
         29        46.210            14.460   14.160    9.345   13.990   14.330   19.340    6.278    9.690   21.990   50.650
         30        29.410            11.450   11.380    8.297   10.340   18.160   25.990    6.148    9.243   84.180   36.470
         31        19.540            11.100             7.504            13.880   15.370             7.221            35.400
 


 Average           21.290   54.590   17.830   29.330   20.720   12.890    7.732   17.250   16.920   19.430   22.480   41.840
 Lowest             7.323   11.530    7.827   11.380    7.504    4.304    4.310    6.779    6.148    6.207    7.728   16.210
 Highest           77.350  162.200   53.140   66.780   89.400   49.840   18.160   54.610   58.210   68.970   84.180  121.000

 Monthly total
  (million cu m)    57.02   132.10    47.77    76.02    55.49    33.41    20.71    46.20    43.87    52.04    58.26   112.10


 Runoff   (mm)       75      174       63      100       73       44       27       61       58       69       77      148  
 Rainfall (mm)       67      194       61      123      116      107       78      149       77      111      111      143  


 Statistics of monthly data for previous record  (Oct 1955 to Dec 1965)

 Mean      Avg.    26.660   20.330   17.360   13.980    9.382    5.550    9.420   13.940   13.550   14.300   20.440   28.700
 flows:    Low      4.472    2.974    6.741    5.197    3.911    1.545    3.601    1.795    1.419    6.597    6.876   10.230
           (year)    1963     1963     1961     1957     1960     1957     1959     1959     1959     1955     1958     1963
           High    39.260   47.220   36.400   22.280   17.780   14.450   16.440   41.340   22.320   25.440   51.090   62.090
           (year)    1961     1958     1963     1962     1958     1958     1963     1956     1965     1958     1963     1965

 Runoff:   Avg.      94       65       61       48       33       19       33       49       46       50       70      101  
           Low       16        9       24       18       14        5       13        6        5       23       23       36  
           High     139      151      128       76       63       49       58      146       76       90      174      219  

 Rainfall: Avg.     107       72       69       73       64       69       96      107       97       93       99      132  
           Low       41       20       28       10       25       33       35       18        8       46       33       41  
           High     165      178      127      130      122      140      185      226      184      165      211      224  


 
 Summary statistics                                                           Factors affecting runoff
                                                                    1966
                                   For 1966       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 1966    pre-1966  $ Abstraction for public water supplies.
 Mean flow                       23.300          16.130                 144   $ Flow reduced by industrial and/or
 Lowest yearly mean                              12.390        1964             agricultural abstractions.
 Highest yearly mean                             19.610        1965           $ Augmentation from surface water and/or
 Lowest monthly mean              7.732    Jul    1.419    Sep 1959             groundwater.
 Highest monthly mean            54.590    Feb   62.090    Dec 1965
 Lowest daily mean                4.304 11 Jun    0.425 23 Jun 1957
 Highest daily mean             162.200  8 Feb  233.600  4 Dec 1960

 10% exceedance                  49.530          39.000                 127
 50% exceedance                  15.310           8.448                 181
 95% exceedance                   5.933           2.192                 271
 Annual total (million cu m)     734.80          509.10                 144
 Annual runoff (mm)               968             671                   144
 Annual rainfall (mm)            1337            1078                   124
         {1961-90 rainfall average (mm)          1161} 


 Station and catchment description

 
  Broad-crested masonry weir 47m wide; c/m cableway originally 1.5km u/s then moved to new ultrasonic station at Tadcaster
  in 1990. Insensitive at low flows. Does not drown at high flows, though small amount of bypassing on the right bank.
  Level data: 1936-1955. Recalibration (from 1965) completed but flows reprocessed from 1982 only. Pre-1965 data less
  reliable. Mill race opened in early 1990s (not rated) so flows not reliable. Regulation effect of headwater reservoirs
  evident at low flows. Small net export of water (inc. Bradford supply).
  Mixed geology of moderate permeability - mainly Carboniferous Limestone, grits and Coal Measures with over 40%
  superficial deposits. Predominantly mixed rural catchment, 60% grassland, with moorland headwaters.


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