Investigation of hydrological time series using copulas for detecting catchment characteristics and anthropogenic impacts
Global climate change can have impacts on characteristics of rainfall–runoff events and subsequently on the hydrological regime. Meanwhile, the catchment itself changes due to anthropogenic influences. However, it is not easy to prove the link between the hydrology and the forcings. In this context,...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | http://www.hydrol-earth-syst-sci.net/20/2705/2016/hess-20-2705-2016.pdf |
| Summary: | Global climate change can have impacts on characteristics of rainfall–runoff
events and subsequently on the hydrological regime. Meanwhile, the catchment
itself changes due to anthropogenic influences. However, it is not easy to
prove the link between the hydrology and the forcings. In this context, it
might be meaningful to detect the temporal changes of catchments independent
from climate change by investigating existing long-term discharge records.
For this purpose, a new stochastic system based on copulas for time series
analysis is introduced in this study.<br><br>A statistical tool like copula has the advantage to scrutinize the dependence
structure of the data and, thus, can be used to attribute the catchment
behavior by focusing on the following aspects of the statistics defined in
the copula domain: (1) copula asymmetry, which can capture the nonsymmetric
property of discharge data, differs from one catchment to another due to the
intrinsic nature of both runoff and catchment; and (2) copula distances can
assist in identifying catchment change by revealing the variability and
interdependency of dependence structures.<br><br>These measures were calculated for 100 years of daily discharges for the
Rhine River and these analyses detected epochs of change in the flow
sequences. In a follow-up study, we compared the results of copula asymmetry
and copula distance applied to two flow models: (i) antecedent precipitation
index (API) and (ii) simulated discharge time series generated by a
hydrological model. The results of copula-based analysis of hydrological time
series seem to support the assumption that the Neckar catchment had started
to change around 1976 and stayed unusual until 1990. |
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| ISSN: | 1027-5606 1607-7938 |