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2010, the floods caused by the continuous torrential rain [4] have nevertheless
resulted in multi-defense riverbank breaches in the Fuhe basin. In July 2009,
April 2011 and January 2012, the region had to face the extreme drought [5],
[6]. Drought and flood have become the primary natural disaster in Jiangxi
and have seriously impacted the industrial and agricultural production in this
region. Analyzing the precipitation characteristics and its evolution patterns can
provide a theoretical basis for drought and flood management and mitigation in
the context of climate change in the Fu river basin.
A large number of experiments have demonstrated that the Standard Pre-
cipitation Index (SPI) enjoys a strong sensitivity property and is capable of
accurately capturing the characteristics of the rainfall distribution with time
variations [7]-[9]. The SPI can be employed and is indeed flexible and suitable
for precipitation estimation of both dry and wet spells at different hydrological
levels and locations [10].
In this paper, a 10-days scale SPI is used to study the rainfall characteristics
in the Fuhe basin for the first-time in the literature. The objective of this study
is mainly to analyze the precipitation distribution by year, month, day and the
changes in the SPI characteristics in the Fuhe basin from the years 1970 to
2008, which can provide the basis for the prediction of droughts and floods in
this region.
The remainder of the paper is organized as follows. The study area and the
data base are introduced and described in Section 2. The basic SPI metric is
reviewed in Section 3. In Section 4, the results and discussion are provided.
Finally, concluding remarks and future work are provided in Section 5.
2 Study Area and Its Database
For this study, the historical daily precipitation (
mm
) time series data sets are
collected from the years 1970 to 2008 in 17 hydrological stations which cover a
duration of 39 years (468 months and 14244 days). Fig. 1 shows the schematic
diagram of the hydrological stations spatial distribution in the Fuhe basin where
the 17 hydrological stations are marked. Agricultural production is quite domi-
nant in the Fuhe basin. Large-scale agricultural irrigation areas are concentrated
mainly in the S2, S3, S4, S5, and S7 regions around the Fu River in the basin as
shown in Fig. 1.
3 Standard Precipitation Index Metric
The Standard Precipitation Index (SPI), which was developed by McKee et al.
in 1993, provides a metric for the degrees of wetness and aridity by evaluating
the precipitation for any period of interest (e.g., days, weeks, months, seasons,
years). In the time scale of interest, a gamma function is used as a probability
density function (pdf) to fit the distribution of the observed data, and then
the probability is calculated and the probability is transformed to an SPI index
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