027002    Wharfe at Flint Mill Weir                                                                                1964


           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        26.050   29.170    7.815    8.920   16.200    5.918    2.073    3.738    3.879    3.568    3.879    8.297
          2        15.520   18.010    7.985    9.033   13.030    5.663    2.146    3.794    3.851    3.653    4.927    6.994
          3        11.550   18.070    7.476    8.722   22.200    8.325    2.044    3.794    3.823    1.914    4.078   17.100
          4         9.231   17.470    6.201    7.221   28.090    7.532    1.790    3.568    3.823    2.313    3.710    9.798
          5         8.892   10.990    6.485    6.456   17.870   11.440    2.107    3.993    2.313    4.559    3.511    7.108

          6         7.872    8.297    6.201    6.343   12.290    8.665    3.115    4.361    2.888    3.058    3.625   14.410
          7         7.617    7.108    4.417    5.918    9.911   14.300    2.115    7.957    4.361   34.260    2.384   72.770
          8         7.504    6.683    4.304    6.485   12.690   11.130   32.850    5.493    3.256   38.790    2.735   43.040
          9         7.277    6.032    5.947    6.286   14.100    6.994   12.630    7.051    3.172   16.910    4.134  152.100
         10         6.371    6.683    7.249    6.003   19.140    6.173   16.200    6.966   12.800   10.360    3.370   47.290

         11         5.777    6.456    8.184    4.701   56.630    5.975   24.210    5.607   12.970    7.646    3.313   26.140
         12         5.522    5.692    6.400    4.871   43.330    4.871   14.040    4.871    8.778    6.513    3.370  119.500
         13         7.249    5.805    6.286    9.656   18.830    5.692    8.467    4.333    4.984    5.352    7.306  155.700
         14         8.552    5.380   52.100    7.759   12.380    5.295    5.862    3.964    4.899    5.125   20.110   49.920
         15        14.840    4.474   66.550   11.210    9.684    6.003    5.465    3.653    5.069    5.182   15.630   27.670

         16        10.870    4.474   27.350    8.014    7.646    7.362    7.079    3.511    8.382    5.182   28.880   17.870
         17         8.438    6.116   19.260    7.872    6.456    6.003    5.437    5.125   20.330    4.021   18.460   13.760
         18         6.739    5.324   15.720    7.731    5.975    6.570   27.550    8.637   10.480    4.134   11.180   11.610
         19         6.116    5.295   14.780    8.269    5.777    6.088   55.220   15.290    7.674    4.842   20.870    9.146
         20        10.510    5.040   23.280   29.170    5.805    4.955   23.500   11.500    9.090    3.370   15.830    8.722

         21        14.390    5.154   63.150   18.970    5.069    4.559   13.420    6.881    8.722    4.927    9.684    8.920
         22         9.713    3.681   38.230   17.900    6.060    3.851    9.373    4.757    6.796    5.522    7.646    9.260
         23         8.637    7.051   24.010   17.980    7.079    3.681    8.976    4.049    9.005    7.815   23.140    9.260
         24         8.212   25.340   54.940   16.480    4.871    3.058    7.306   12.040    6.428    7.193   44.740    7.844
         25         6.570   25.830  110.700   11.950    5.777    2.730    5.635    9.203    5.437    5.295   41.060    6.683

         26         6.286   14.100   37.660   10.560    4.842    2.718    6.513    6.570    3.964    5.890   17.440    5.692
         27         7.674   10.760   22.910   11.780    4.701    2.333    6.286    5.069    3.908    5.437   17.300    5.607
         28        12.800    9.458   18.520   11.950    4.531    2.498    4.955    4.559    4.842    5.239   13.220    5.833
         29        12.830    9.061   15.180   19.480    4.333    2.633    4.616    2.860    4.134    4.984   10.760    6.654
         30        47.860            13.220   18.380    2.973    2.297    4.106    3.313    4.389    4.871    9.260   50.400
         31        31.430            10.450             3.964             3.908    4.417             3.568            28.600
 


 Average           11.580   10.100   23.000   10.870   12.650    5.844   10.610    5.836    6.482    7.468   12.520   31.090
 Lowest             5.522    3.681    4.304    4.701    2.973    2.297    1.790    2.860    2.313    1.914    2.384    5.607
 Highest           47.860   29.170  110.700   29.170   56.630   14.300   55.220   15.290   20.330   38.790   44.740  155.700

 Monthly total
  (million cu m)    31.01    25.32    61.60    28.17    33.89    15.15    28.43    15.63    16.80    20.00    32.45    83.26


 Runoff   (mm)       41       33       81       37       45       20       37       21       22       26       43      110  
 Rainfall (mm)       48       38      127       74       74       71      102       66       56       54       69      127  


 Statistics of monthly data for previous record  (Oct 1955 to Dec 1963)

 Mean      Avg.    27.610   23.250   16.780   14.150    8.953    5.345    9.368   15.300   13.330   14.990   20.840   24.730
 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   22.270   25.440   51.090   40.190
           (year)    1961     1958     1963     1962     1958     1958     1963     1956     1956     1958     1963     1959

 Runoff:   Avg.      97       75       59       48       32       18       33       54       46       53       71       87  
           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      142  

 Rainfall: Avg.     110       81       60       71       63       69       95      113       92      101       97      122  
           Low       41       20       28       10       25       33       35       18        8       46       33       41  
           High     165      178      112      130      122      140      185      226      135      165      211      203  


 
 Summary statistics                                                           Factors affecting runoff
                                                                    1964
                                   For 1964       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 1964    pre-1964  $ Abstraction for public water supplies.
 Mean flow                       12.390          16.200                  76   $ Flow reduced by industrial and/or
 Lowest yearly mean                              12.470        1959             agricultural abstractions.
 Highest yearly mean                             19.290        1958           $ Augmentation from surface water and/or
 Lowest monthly mean              5.836    Aug    1.419    Sep 1959             groundwater.
 Highest monthly mean            31.090    Dec   51.090    Nov 1963
 Lowest daily mean                1.790  4 Jul    0.425 23 Jun 1957
 Highest daily mean             155.700 13 Dec  233.600  4 Dec 1960

 10% exceedance                  25.410          39.720                  64
 50% exceedance                   7.110           8.579                  83
 95% exceedance                   2.925           2.117                 138
 Annual total (million cu m)     391.80          511.20                  77
 Annual runoff (mm)               516             674                    77
 Annual rainfall (mm)             906            1074                    84
         {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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