027002    Wharfe at Flint Mill Weir                                                                                2005


           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        35.600    7.140   10.700    6.680   10.500    5.770    3.440    2.780    7.980   34.400   12.300    7.530
          2        40.200    6.640   14.500    6.370    9.050   11.900    3.400    2.800    5.780   14.800   42.800   36.700
          3        26.200    6.330   10.500    5.990   23.900   13.800    3.260    2.890    3.340    8.110   55.900   39.900
          4        26.700    6.030   13.700    5.930   17.100    8.650    3.570    2.840    2.370    6.680   93.400   31.700
          5        29.600    5.820   15.300    6.940   10.500   11.800    4.200    2.830    1.710    5.520   33.400   27.800

          6        32.500    5.780   10.700   29.600    8.740    9.510    5.360    2.880    3.190    5.040   48.000   17.000
          7       151.000    6.050    8.970   30.800    8.010    6.950    4.800    2.950    2.650    4.510   28.600   14.500
          8       187.000    5.770    9.390   16.600    9.090    5.780    3.620    2.770    3.160    4.210   67.100   11.700
          9        58.100    5.830   11.400    9.810   10.100    5.190    3.280    2.710   15.600    4.200   45.000   10.200
         10        40.800   28.500   12.000    8.210    7.780    5.070    2.960    3.070   12.300    4.380   28.500    9.900

         11        26.600   13.200   22.800    7.100    6.670    4.820    2.790    2.850    6.640    4.190   38.800   13.800
         12        22.400   99.900   17.800    6.540    6.090    4.900    2.740    3.270    4.630    8.930   35.600   11.500
         13        24.000   32.400    9.810    7.950    5.690    4.910    3.280    5.280    4.210   14.900   22.200    9.650
         14        18.500   17.400    7.880   12.900    5.390    4.860    2.980    7.230    5.770    7.640   15.900    8.600
         15        14.900   12.500   47.500   26.800    5.120    5.680    2.660    4.780    8.630    5.760   14.500    7.990

         16        13.600   10.100   24.900   42.500    5.170    6.590    2.530    3.820   15.300    4.910   12.600    7.580
         17        35.400    9.100   17.600   24.400    4.990   11.900    2.480    3.420    7.560    4.560   10.300    7.420
         18        39.300    8.400   25.800   57.700    4.860    8.970    2.470    3.200    5.310    4.480    9.290    6.640
         19        40.200    7.820   18.400   28.600    5.190    7.260    2.520    3.080    4.490    4.460    8.340    6.710
         20        51.500    6.920   11.600   30.000    5.200    6.430    2.400    2.950    4.040    5.600    7.740    7.090

         21        32.800    7.020    9.160   19.000    5.780    4.820    2.310    2.850    3.990    9.910    7.320    7.240
         22        18.800    7.260   10.900   12.900    6.900    4.630    2.330    2.950    3.780   18.700    6.840    9.660
         23        13.700    6.650   12.500   10.900    6.700    4.250    2.330    2.870    3.730   13.800    6.540    8.930
         24        11.400    8.880    9.570    9.340   18.800    4.070    2.310    5.440    4.390   97.600    6.730   11.600
         25        10.200    8.910    8.010    7.750   19.400    3.860    2.340   12.700    4.200   79.700    6.650    8.190

         26        10.100   10.500    7.480    9.110   11.500    3.630    2.280    7.550    4.000   62.000    6.510    7.240
         27        10.100   10.300    6.990   11.400    7.320    3.490    2.250    7.010    5.480   39.800    7.860    7.160
         28         9.600    9.190   12.600    9.240    6.260    3.430    4.550    6.020    9.000   19.600    8.230    6.370
         29         8.660            10.400   10.600    5.710    3.700    4.810    4.620   22.700   14.000    6.860    6.160
         30         7.780             7.840    9.280    4.770    3.650    4.580    6.780   19.000   14.100    6.080    7.170
         31         7.280             6.970             4.950             3.390    5.640            16.300            56.700
 


 Average           34.020   13.230   13.670   16.030    8.620    6.342    3.168    4.285    6.831   17.510   23.330   13.880
 Lowest             7.280    5.770    6.970    5.930    4.770    3.430    2.250    2.710    1.710    4.190    6.080    6.160
 Highest          187.000   99.900   47.500   57.700   23.900   13.800    5.360   12.700   22.700   97.600   93.400   56.700

 Monthly total
  (million cu m)    91.11    32.00    36.61    41.55    23.09    16.44     8.49    11.48    17.71    46.90    60.47    37.18


 Runoff   (mm)      120       42       48       55       30       22       11       15       23       62       80       49  
 Rainfall (mm)      132       73       54      112       65       51       59       80       90      123      109       71  


 Statistics of monthly data for previous record  (Oct 1955 to Dec 2004)

 Mean      Avg.    28.200   24.790   21.120   15.520   10.340    7.394    6.936   10.640   12.290   18.220   23.170   27.770
 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.     100       80       75       53       36       25       24       38       42       64       79       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.     118       93       90       79       73       77       80       97       99      114      112      128  
           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
                                                                    2005
                                   For 2005       For record        As % of   $ Reservoir(s) in catchment.
                                                  preceding 2005    pre-2005  $ Abstraction for public water supplies.
 Mean flow                       13.410          17.170                  78   $ 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              3.168    Jul    0.991    Aug 1976             groundwater.
 Highest monthly mean            34.020    Jan   71.210    Feb 2002
 Lowest daily mean                1.710  5 Sep    0.425 23 Jun 1957
 Highest daily mean             187.000  8 Jan  292.900 23 Feb 1991

 10% exceedance                  30.490          40.980                  74
 50% exceedance                   7.697           9.221                  83
 95% exceedance                   2.756           2.406                 115
 Annual total (million cu m)     422.90          541.90                  78
 Annual runoff (mm)               557             714                    78
 Annual rainfall (mm)            1019            1160                    88
         {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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