027002    Wharfe at Flint Mill Weir                                                                                2004


           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        21.700   88.800    4.960    5.610    6.190    3.150   11.800    2.840    7.530    6.260   10.700    7.520
          2        32.100   67.100    4.840    6.890    5.700    2.990    7.550    3.060    6.860   14.200    9.950    7.450
          3        18.200  128.000    5.580   16.600    5.380    3.160   37.600    3.140    6.150   22.100   10.800    7.030
          4        17.500  137.000    5.470   37.100   10.700    3.110   34.500    6.560    5.680   55.800   14.200    7.710
          5        34.100   85.100    7.300   26.000   11.700    3.250   18.500    6.970    5.330   25.700   12.800    7.730

          6        56.500   38.100    6.640   20.100   15.400    3.060    9.140    4.430    5.110   42.300   11.300    7.440
          7        23.600   30.400    6.370   13.600    9.450    2.930    6.460    3.680    4.790   28.000   12.000    7.800
          8        43.400   34.500    5.670   10.300    7.650    2.950    5.340    3.230    4.770   15.900   10.400    7.400
          9        73.500   23.500    5.480    8.320    7.220    2.850    4.590   24.300    4.880   10.900    9.320    6.680
         10        35.000   22.100    5.260    7.390    6.330    2.810    5.100  168.000    4.800    8.660    8.220    6.150

         11        52.200   21.500    4.780    6.790    6.340    2.940    4.320   61.200    4.680    7.400    7.220    5.770
         12        49.900   15.000    4.900    6.860    5.600    2.830    4.080   48.300    5.020    7.250    7.490    7.390
         13        54.100   12.400    4.650    6.910    4.950    2.790    3.830   44.100   19.500    8.360    7.730    6.960
         14        35.200   10.900    4.740    5.860    4.610    2.700    3.650   19.900   10.600   11.600    7.600    6.020
         15        36.500    9.830    9.920    5.570    4.460    2.560    3.740   12.800    9.870   10.900    7.910   28.500

         16        65.800    8.900   13.200    6.930    4.220    2.590    3.840    9.780    7.250   12.500   16.600   15.200
         17        29.700    9.280    8.340   12.700    4.020    2.570    4.970   10.300    6.410   13.300   46.700   33.500
         18        20.100    8.810    6.440   41.100    3.870    2.760    9.530   18.500    8.210    9.630   26.800   24.600
         19        26.300    8.010   18.800   25.700    3.710    2.820    5.850   26.500   14.600    7.480   19.100   17.800
         20        32.200    7.490   40.200   16.500    3.690    3.010    4.840  123.000   57.100   23.800   13.000   11.100

         21        23.400    6.990   32.400   13.000    3.610    2.980    4.570   43.000   63.000   84.500   10.900    9.900
         22        16.900    6.480   23.200   29.800    3.440    3.020    3.920   23.000   22.600   95.700   46.200   69.900
         23        18.800    6.070   14.000   15.200    3.300   12.300    3.590   20.500   14.500  124.000   23.600   60.900
         24        20.100    6.070   10.200   10.400    3.210   11.300    3.320   24.800   10.300   57.600   15.200   50.600
         25        14.800    5.990    9.100    8.470    3.130    6.580    3.140   21.600    7.870   73.800   12.600   35.700

         26        12.000    5.580    8.640    7.630    3.090    5.020    5.090   13.700    6.680   39.100   16.300   18.200
         27        10.300    5.520    7.570    8.210    3.010    4.060    3.980   26.500    8.600   23.900   13.800   13.500
         28         9.520    5.390    7.420    8.000    2.960    3.760    3.210   14.400    8.100   18.400   11.600   53.900
         29         9.010    5.150    6.790    7.670    3.000    3.630    3.070   10.400   11.200   17.700    9.930   26.900
         30        15.600             6.250    6.910    3.180    5.480    3.110   13.500    7.510   16.800    8.360   28.100
         31       157.000             5.760             3.170             2.910    9.290            12.900            75.600
 


 Average           34.360   28.270    9.835   13.400    5.364    3.865    7.392   26.490   11.980   29.240   14.610   21.710
 Lowest             9.010    5.150    4.650    5.570    2.960    2.560    2.910    2.840    4.680    6.260    7.220    5.770
 Highest          157.000  137.000   40.200   41.100   15.400   12.300   37.600  168.000   63.000  124.000   46.700   75.600

 Monthly total
  (million cu m)    92.02    70.84    26.34    34.74    14.37    10.02    19.80    70.96    31.06    78.32    37.87    58.14


 Runoff   (mm)      121       93       35       46       19       13       26       94       41      103       50       77  
 Rainfall (mm)      146       96       53       99       33       79       80      225       71      173       60      101  


 Statistics of monthly data for previous record  (Oct 1955 to Dec 2003)

 Mean      Avg.    28.070   24.720   21.350   15.560   10.440    7.468    6.926   10.310   12.300   17.990   23.350   27.900
 flows:    Low      4.472    2.974    5.740    4.496    2.312    1.545    1.674    0.991    1.419    3.026    6.537    4.832
           (year)    1963     1963     1993     1974     1980     1957     1976     1976     1959     1972     1995     1995
           High    44.230   71.210   53.940   35.240   26.750   18.530   16.440   41.340   33.520   54.000   66.610   62.090
           (year)    1995     2002     1981     1970     1967     1972     1963     1956     1968     1967     2000     1965

 Runoff:   Avg.      99       79       75       53       37       26       24       36       42       64       80       98  
           Low       16        9       20       15        8        5        6        4        5       11       22       17  
           High     156      227      190      120       94       63       58      146      115      191      228      219  

 Rainfall: Avg.     117       93       91       78       74       77       80       95       99      112      113      129  
           Low       12       14       24        8       13       18       20       12        8       32       33       41  
           High     217      285      222      152      181      183      185      226      241      257      242      234  


 
 Summary statistics                                                           Factors affecting runoff
                                                                    2004
                                   For 2004       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 2004    pre-2004  $ Abstraction for public water supplies.
 Mean flow                       17.220          17.170                 100   $ Flow reduced by industrial and/or
 Lowest yearly mean                              10.430        1996             agricultural abstractions.
 Highest yearly mean                             26.320        2000           $ Augmentation from surface water and/or
 Lowest monthly mean              3.865    Jun    0.991    Aug 1976             groundwater.
 Highest monthly mean            34.360    Jan   71.210    Feb 2002
 Lowest daily mean                2.560 15 Jun    0.425 23 Jun 1957
 Highest daily mean             168.000 10 Aug  292.900 23 Feb 1991

 10% exceedance                  39.810          41.000                  97
 50% exceedance                   8.696           9.228                  94
 95% exceedance                   2.996           2.391                 125
 Annual total (million cu m)     544.50          541.80                 100
 Annual runoff (mm)               718             714                   100
 Annual rainfall (mm)            1216            1158                   105
         {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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