027002    Wharfe at Flint Mill Weir                                                                                1956


           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        18.380   19.710   67.960    4.163    5.267    3.426    1.835   49.270   13.420   10.590    8.722    7.815
          2        19.260   15.180  131.400    4.163    4.955    2.138    3.115   88.920   14.530    9.345    7.646   11.550
          3        12.710   11.980   38.510    3.879    4.814    1.996    3.115   27.780   62.580    8.212    6.428   14.040
          4        11.470   11.550   27.640    5.097    4.531    3.879    6.570   20.670   23.420    8.665    6.145   10.140
          5        10.340   16.570   31.720    4.021    4.842    2.917   31.150   15.940   20.080   18.800    6.711   66.550

          6         9.231   18.800   26.790    4.049    3.738    3.851   14.920   11.840   73.910   11.160    5.409   36.530
          7         8.070   13.900   27.070    2.784    3.710    4.191    8.410   10.560  101.100    8.523    5.522   16.710
          8         7.929   11.380   18.350    3.256    6.116    4.163    8.523    8.410   74.760    7.929    5.239   13.650
          9         7.561    9.968   13.820    4.531    7.277    2.888    6.994    6.994   30.300    6.853    5.380   12.400
         10         6.711    8.948   11.040    3.993   24.070    2.747    4.955    6.145   19.820    6.570    5.239   11.920

         11         8.014    8.070    9.599   10.390   10.990    3.879    4.333   15.010   16.370    5.833    7.079   13.620
         12         9.373    7.815    8.637    8.835   19.480    5.380    3.568   17.560   18.580    5.692    7.532   29.450
         13         8.835    9.090    7.674   10.480   10.280    6.145    3.426   26.450   17.810    4.672    6.145   30.300
         14        16.790    8.552    7.532   13.930    7.731    4.474    3.058   28.030   16.310    4.871    5.833   48.990
         15        17.560    7.532    6.966    9.203    7.561    3.738   15.940   15.350   13.170    5.720    7.249   39.080

         16        24.720    6.966    6.683    8.297    6.258    2.302   11.920   92.880   10.620    4.446    6.428   24.350
         17        53.800    6.570    5.862    6.428    6.116    4.021    7.872  122.600    9.345    4.955    5.097   18.750
         18        32.570    5.720    6.003    5.692    5.097    7.929    5.720   90.050    8.155    7.646    5.154   18.100
         19        16.480    6.003    6.711    5.239    4.021    7.051    5.409   74.190    7.277    6.711    6.145   14.300
         20        49.270    5.833    5.833    4.757    4.163    8.552    4.955   41.060    6.570   56.350    4.955   11.840

         21        56.920    5.663    6.116    3.540    4.163    5.437    2.917   26.190    6.145   20.670    4.814   10.340
         22        75.040    5.522    6.683    3.596    4.163    3.879    2.747   16.740    5.975   11.890    4.474    9.939
         23        28.320    5.097    6.286    4.814    4.531    2.444    3.596   12.740    6.570   16.230    4.304   18.040
         24        20.190    5.692    5.097    3.568    3.596    2.161    2.917   45.310    6.570   16.710    3.540   20.420
         25        15.570    4.474    5.295    3.426    4.049    3.256    3.398  101.900    5.522   14.440    3.738   14.330

         26        15.570    5.012    6.145   12.540    3.879    2.302    3.087   85.520    5.550   12.120    6.881   11.720
         27        33.410    6.428    4.955   13.250    3.256    2.458    2.761   71.360    5.692    8.863   25.970   10.340
         28        33.700   26.080    4.814    9.401    3.058    2.458   13.760   78.160   29.170    7.929   23.390   15.520
         29        58.050  109.900    5.097    6.428    3.256    2.600   27.350   35.400   24.920   11.470   12.260   54.940
         30        39.930             4.616    6.286    3.879    1.821   22.290   22.030   13.900    9.118    8.835   81.840
         31        28.260             3.568             3.596            13.590   16.370             9.769            56.630
 


 Average           24.320   13.240   16.920    6.335    6.208    3.816    8.200   41.340   22.270   11.060    7.409   24.330
 Lowest             6.711    4.474    3.568    2.784    3.058    1.821    1.835    6.145    5.522    4.446    3.540    7.815
 Highest           75.040  109.900  131.400   13.930   24.070    8.552   31.150  122.600  101.100   56.350   25.970   81.840

 Monthly total
  (million cu m)    65.15    33.18    45.31    16.42    16.63     9.89    21.96   110.70    57.73    29.61    19.20    65.16


 Runoff   (mm)       86       44       60       22       22       13       29      146       76       39       25       86  
 Rainfall (mm)      123       51       46       58       41       76      124      226      112       61       33      117  


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

 Mean      Avg.                                                                                      6.597    9.180   27.390
 flows:    Low                                                                                       6.597    9.180   27.390
           (year)                                                                                     1955     1955     1955
           High                                                                                      6.597    9.180   27.390
           (year)                                                                                     1955     1955     1955

 Runoff:   Avg.                                                                                       23       31       97  
           Low                                                                                        23       31       97  
           High                                                                                       23       31       97  

 Rainfall: Avg.      77       72       65       43      108       78       35       38       68       74       64      155  
           Low       77       72       65       43      108       78       35       38       68       74       64      155  
           High      77       72       65       43      108       78       35       38       68       74       64      155  


 
 Summary statistics                                                           Factors affecting runoff
                                                                    1956
                                   For 1956       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 1956    pre-1956  $ Abstraction for public water supplies.
 Mean flow                       15.530                                       $ Flow reduced by industrial and/or
 Lowest yearly mean                                                             agricultural abstractions.
 Highest yearly mean                                                          $ Augmentation from surface water and/or
 Lowest monthly mean              3.816    Jun    6.597    Oct 1955             groundwater.
 Highest monthly mean            41.340    Aug   27.390    Dec 1955
 Lowest daily mean                1.821 30 Jun    1.048  2 Oct 1955
 Highest daily mean             131.400  2 Mar   98.540 10 Dec 1955

 10% exceedance                  33.500
 50% exceedance                   7.936
 95% exceedance                   2.997
 Annual total (million cu m)     491.10
 Annual runoff (mm)               647  
 Annual rainfall (mm)            1068             877                   122
         {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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