『Summary
In order to predict future hydrological trends, it is important
to understand those that have occurred in the past. In this study,
the entire area of China was divided into 10 basins to analyze
the country's hydrological trends. 317 weather stations with data
from 1956 to 2005 were selected for trend analysis. Based on the
observations, we found that precipitation has decreased in the
north but has increased in the south due to weakening monsoon
winds over the past 50 years. In the same period, the pan evaporation
decreased as a whole but it was not uniform in either timing or
spatial dimension. With the stepwise regression method, we concluded
that precipitation had a greater impact on pan evaporation in
the north than in the south. Furthermore, sun duration had a more
significant impact on hydrological processes in the south than
in the north. On the assumption that water storage and water use
for irrigation has not changed, which is reasonable when the actual
evaporation is decreasing, the actual evaporation estimated by
the water balance equation showed a decreasing trend in both the
north and south. Using complementary relation curves, we concluded
that the decrease in the north was caused by the decrease in precipitation
while the decrease in the south was caused by a decrease in potential
evaporation.
Keywords: Hydrological trend; Climate change; Evaporation; Precipitation』
1. Introduction
2. Data and methodology
2.1. Basins in China
2.2. Weather and hydrological data
2.3. Spatial analysis, trend analysis and correlation analysis
2.3.1. Spatial analysis
2.3.2. Trend analysis
2.3.3. Correlation analysis
3. Results and discussion
3.1. Trends of precipitation
3.2. Trends of pan evaporation
3.3. Hydrological trends in different basins
3.4. Understanding with complementary relation curves
4. Conclusions
Acknowledgement
Reference