Physical controls of regional distribution patterns of precipitation and
flow duration curves in the middle and lower reaches of the Yangtze
River
Abstract
The flow duration curve (FDC) is the cumulative distribution function,
which represents the relationship between the frequency and magnitude of
streamflow,and the precipitation duration curves (PDC) follows the same
principle. Nowadays, the correlation between the shape of PDC and FDC
curves, their respective physical control factors, and their fitting
conditions in unmeasured catchments across China have not been fully
understood. In this paper, daily precipitation from 698 weather stations
across China and streamflow from more than 200 hydrological stations in
the middle and lower Yangtze River basin were chosen to analyze the
relationship, similarity, regional pattern and response mechanism of
fitting parameters between PDC and FDCs. Framework was proposed for
modeling FDC, decomposing the Streamflow time series into fast flow and
slow flow time series and attributing the shapes of PDC and FDCs to
catchment meteorological and geographical characteristics and physical
processes. Results indicate that the parameters of PDC and certain FDCs
(TFDC, FFDC, SFDC) share similar spatial patterns but the value of
parameters and shape of curves varies for the different duration and
interactions of the processes. The climate and catchment characteristics
such as extreme properties of precipitation, base flow index (
BFI), Pmax*αp and concentration ratio index based on
monthly precipitation ( CIM) will influence the shape of
normalized PDC and FDCs, which provides a way to predict unmeasured
catchments for PDC and FDCs, diagnose catchment rainfall-runoff
responses, including similarity and differences between catchments, and
can be applied to more future research about processes based on physical
controls.