027002    Wharfe at Flint Mill Weir                                                                                1972


           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        11.460   12.360   20.030   43.680    7.915   33.210    9.203    6.463    2.906    2.012    4.904   92.770
          2        10.860   13.510   24.970   79.330    7.236   19.130    8.167    6.449    2.838    2.166    3.967   45.500
          3        11.750   48.560   24.060   46.660    6.859   37.080    7.901    5.473    2.609    1.699    5.583   42.220
          4        10.520   58.790   27.200   27.660   14.340   20.830   19.790    6.121    2.931    1.699    8.758   56.080
          5         9.596   33.630   21.490   43.910    9.961   27.570   28.440    7.290    2.991    1.472    9.259   95.120

          6         8.804   38.280   21.390   48.140    8.993   17.210   13.960   24.580    2.922    1.842    8.436   75.280
          7         8.402   27.560   27.000   39.860   13.630   14.660   10.320   20.810    2.922    1.666    7.383   63.570
          8        11.420   22.300   26.490   35.370   11.030   14.520    9.636   24.190    3.268    1.695    8.611   40.590
          9        28.900   29.000   22.180   26.460   14.100   13.020    8.591   12.960    8.023    2.132   35.240   25.820
         10        30.930   23.780   17.990   43.490   13.950   26.060    7.711    9.146    7.468    3.968   69.990   25.740

         11        64.540   31.270   14.730   60.700   10.930   19.120    7.134    7.499    5.125    6.605   26.110   33.250
         12        43.040   21.170   12.290   34.390   34.990   17.620    8.048    6.627    4.131    4.097   44.120   70.050
         13        51.340   19.350   11.070   22.600   29.840   19.300    6.520    5.832    4.069    3.407   41.210   51.700
         14        34.730   17.410   10.160   17.120   16.240   13.500    5.739    5.065    3.707    3.096   28.950   29.710
         15        23.060   25.430    9.913   13.750   11.570   11.190    5.227    4.661    3.512    2.563   16.770   21.670

         16        20.250   68.100    9.755   11.980    9.505    9.571    4.946    4.709    3.146    2.640   14.010   17.440
         17        21.600   37.850    9.104   10.600    8.458    8.572    4.629    7.046    3.056    2.251   11.940   14.890
         18        20.390   25.640    8.552    9.559    7.912   26.640    4.437    5.108    3.113    2.250    9.658   13.160
         19        68.570   18.360    8.342    8.620    7.315   18.250    4.126    4.564    2.728    2.218   10.760   11.670
         20        31.410   15.030    7.972    7.986    7.075   15.290    4.004    4.295    2.870    2.254   54.140   10.590

         21        21.660   13.330    7.564    7.570    6.899   27.360    3.942    4.021    2.708    2.416   73.970    9.282
         22        29.260   12.450    7.193    7.278    6.823   18.760    4.593    3.913    2.754    2.606   38.660    8.685
         23        30.200   12.220    6.944    7.055    6.551   14.800    4.511    3.775    2.802    2.759   19.900    8.246
         24        45.780   11.150    6.755    6.806    6.251   12.100    7.972    3.562    2.544    2.374   14.050    7.989
         25        25.090   10.250    6.667    6.409    6.876   13.730   10.370    3.345    2.865    2.523   11.620    7.686

         26        50.420   11.420    7.598    6.282   32.610   26.310    6.596    3.212    2.575    2.551   10.770    7.522
         27        48.220   11.070   11.290    6.132   51.340   18.550    5.289    3.393    2.575    2.606   10.080    7.400
         28        28.940   10.180   12.720    5.920   20.810   18.930    4.485    3.214    2.691    3.107   14.120    7.377
         29        19.750    9.220   14.030    9.081   16.210   12.350    4.236    2.931    2.572    3.345   26.330    7.417
         30        16.140            68.770   10.210   39.770   10.520    4.061    3.076    2.689   10.690   50.340    6.913
         31        13.430            50.510            55.750             4.462    2.906             7.083             6.743
 


 Average           27.430   23.750   17.250   23.490   16.190   18.530    7.711    6.975    3.370    3.026   22.990   29.740
 Lowest             8.402    9.220    6.667    5.920    6.251    8.572    3.942    2.906    2.544    1.472    3.967    6.743
 Highest           68.570   68.100   68.770   79.330   55.750   37.080   28.440   24.580    8.023   10.690   73.970   95.120

 Monthly total
  (million cu m)    73.48    59.50    46.20    60.88    43.35    48.02    20.65    18.68     8.74     8.10    59.58    79.67


 Runoff   (mm)       97       78       61       80       57       63       27       25       12       11       79      105  
 Rainfall (mm)      133       87       95       83      124      109       72       50       37       34      144      109  


 Statistics of monthly data for previous record  (Oct 1955 to Dec 1971)

 Mean      Avg.    25.300   23.300   18.850   16.910   12.110    7.139    9.153   13.850   14.540   17.920   23.050   26.090
 flows:    Low      4.472    2.974    6.741    5.197    3.911    1.545    3.601    1.795    1.419    6.209    6.876   10.230
           (year)    1963     1963     1961     1957     1960     1957     1959     1959     1959     1969     1958     1963
           High    39.260   54.590   36.400   35.240   26.750   14.540   16.440   41.340   33.520   54.000   51.090   62.090
           (year)    1961     1966     1963     1970     1967     1969     1963     1956     1968     1967     1963     1965

 Runoff:   Avg.      89       75       67       58       43       24       32       49       50       63       79       92  
           Low       16        9       24       18       14        5       13        6        5       22       23       36  
           High     139      174      128      120       94       50       58      146      115      191      174      219  

 Rainfall: Avg.     101       84       77       80       77       75       93      105      100      105      108      114  
           Low       41       20       28       10       13       33       35       18        8       38       33       41  
           High     165      194      148      147      181      140      185      226      241      225      211      224  


 
 Summary statistics                                                           Factors affecting runoff
                                                                    1972
                                   For 1972       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 1972    pre-1972  $ Abstraction for public water supplies.
 Mean flow                       16.660          17.330                  96   $ Flow reduced by industrial and/or
 Lowest yearly mean                              12.390        1964             agricultural abstractions.
 Highest yearly mean                             23.300        1966           $ Augmentation from surface water and/or
 Lowest monthly mean              3.026    Oct    1.419    Sep 1959             groundwater.
 Highest monthly mean            29.740    Dec   62.090    Dec 1965
 Lowest daily mean                1.472  5 Oct    0.425 23 Jun 1957
 Highest daily mean              95.120  5 Dec  233.600  4 Dec 1960

 10% exceedance                  40.330          39.760                 101
 50% exceedance                  10.270           9.609                 107
 95% exceedance                   2.551           2.591                  98
 Annual total (million cu m)     526.80          546.90                  96
 Annual runoff (mm)               694             721                    96
 Annual rainfall (mm)            1077            1119                    96
         {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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