London scoping - ukcip

Final Report
22
Figure 3.9 Days with River Thames flow at Teddington exceeding 250 cumecs (naturalised),
1883-2002. Anomalies are relative to 1961-1990 average.
Number of days per year
70
60
50
40
30
20
10
0
1881 1901 1921 1941 1961 1981 2001
There is no single definition of hydrological drought (Mawdsley et al., 1994), however, the
annual series of seven-day minimum dry weather flows (DWF) is widely employed.
Figure 3.10 shows the DWF for the Thames since the 1880’s. The most prominent era of low
flows occurred between the 1880’s and early 1900’s, followed by notable droughts in 1921/22,
1933/34, 1943/44, 1975/76, 1988-92 and 1995-97 (see also Jones and Lister, 1998). Using this
index of drought, 1976 is ranked 2nd and 1995 as 50th in the entire record. Although the DWF
has declined since the late 1960’s there is, again, no clear trend in the overall series for the
Thames.