Geoscience Reference
In-Depth Information
INDIA DROUGHT
JAVA DROUGHT
A
m
+1
0
-1
1740
1760
1780
1800
Nile: Lyons, 1906
Java drought: Berlage, 1931
Java drought
B
m
+1
0
-1
1840
1860
1880
1900
Nile: Lyons, 1906
Java tree rings: Berlage, 1931
Narrow tree rings - JAVA
Figure 23.6. Nile River flood height at the Roda Gauge (1737-1903) showing cor-
relation between droughts and/or years of narrow Tectona grandis (teak) tree rings
in Java and years of below-average flow in the Nile. (Unpublished compilation by
the late Dr Donald Adamson sent to the author in 1985, based on data obtained from
Berlage, 1931 , and Lyons, 1906 , pl. XLIII, verified by the present author.) Variation
from the mean values of maximum annual flood height readings at Roda is averaged
for (a) the 1737-1800 period and (b) the 1825-1903 period.
north-east China, as we saw above, the incidence of wet and dry years is strongly
influenced by the incidence of ENSO events (Kane, 1997 ; Peel et al., 2002 ). Many of
the rivers in these areas are sensitive to small changes in rainfall, and ENSO events will
amplify their already highly variable flow regimes (Adamson et al., 1987b ; Kuhnel
et al., 1990 ; Simpson et al., 1993a ; Simpson et al., 1993b ). The sensitive hydrological
response of desert rivers to global sea surface temperature anomalies is an integral
part of global environmental change, and it is likely to remain so in the future.
El Ni no-Southern Oscillation (ENSO) events are a major source of rainfall vari-
ability both today and in centuries past, accounting for up to 50 per cent of rainfall
variance in regions as widely dispersed as north-east Brazil, India, eastern China, east-
ern Australia, Indonesia, Thailand, the Nile Basin and southern Africa. The regions of
 
Search WWH ::




Custom Search