87
Tecnología y Ciencias del Agua
, vol. VIII, núm. 2, marzo-abril de 2017, pp. 77-91
Mao
et al.
,
The runoff variation characteristics of Dongting Lake in China
ISSN 2007-2422
•
with dry years. From 1986 on, its runoff was
low and exhibited an obvious duration till 2011.
Ouchikou, in particular, with the maximum dry
percentage, faces the severe risk of shrinking up.
The increasing percentage of dry years of three
bayous has posed a threat to the water utiliza-
tion in the lake. At the same period, the outflow
runoff in Chenlingji is evenly distributed. Its
normal flow percentage is 37.7%, semi-wet and
semi-dry portion are both 16.39%, wet and dry
ratio are both 14.74%, which demonstrate the
stability of outflow.
To further identify the characteristics of
inflow and outflow, this paper curves Dongting
Lake’s runoff by calculating its annual anoma-
lies.
As can be seen from figure 6, since 21 century,
four rivers have entered into a low flow period.
The anomaly percentage of that period is the
lowest in the past 61 years. Four rivers annual
average discharge is 594 × 10
8
m
3
, 198 × 10
8
m
3
,
548 × 10
8
m
3
, 139 × 10
8
m
3
, respectively. Judging
from the descending slope of that stage, the ab-
solute value of 4 stations indicated a consistent
Figure 6. Percentage of runoff cumulative anomaly in Dongting Lake.
