Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hess-2016-588
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
25 Nov 2016
Review status
A revision of this discussion paper is under review for the journal Hydrology and Earth System Sciences (HESS).
Historical and future trends in wetting and drying in 291 catchments across China
Zhongwang Chen1,2, Huimin Lei1,2, Hanbo Yang1,2, Dawen Yang1,2, and Yongqiang Cao3 1Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084, China
2State Key Laboratory of Hydro-Science and Engineering, Tsinghua University, Beijing, 100084, China
3School of urban planning and Environmental science, Liaoning Normal University, Dalian, 116029, China
Abstract. The "dry gets drier, wet gets wetter" (DDWW) pattern is a popular catchphrase to summarize hydrologic changes under global warming. However, recent studies based on simulated data have failed to obtain a feasible DDWW pattern for runoff trends. This study tested the DDWW pattern using observed streamflow and meteorological data from 291 catchments in China from 1956 to 2000, interpreted it using a simple method derived from the Budyko hypothesis, and explored its future evolution according to the projections of five global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Similar to the DDWW pattern, the results show that catchments with an aridity index of φ < 1 become wetter and that catchments with φ > 1 become drier, with nearly 80 % of the studied catchments following this pattern. However, the pattern does not hold in glacier regions due to the effects of melting ice and snow. Based on precipitation and potential evapotranspiration changes, the first-order differential of the Budyko hypothesis can provide a good estimate of runoff changes (R2 = 0.70). Therefore, the atmospheric forcing of water and energy is the key factor in interpreting the DDWW pattern. Over 80 % of the estimated trends have signs coincident with those of the measured trends, implying that the DDWW pattern can be assessed with estimated data. Precipitation is the controlling factor that leads to the DDWW pattern in nearly 90 % of catchments where observed and estimated signs are consistent. In the three tested scenarios (RCP2.6, RCP4.5 and RCP8.5), the different models produce significantly different predicted changes, even under the same scenario, whereas a given model yields similar results under different scenarios. Based on the projected results, the DDWW pattern no longer provides a reliable prediction. However, this conclusion remains tentative due to the large uncertainty of the simulations. The considerable differences between the observed and modelled meteorological data for the same period suggest that this conclusion should be adopted with caution.

Citation: Chen, Z., Lei, H., Yang, H., Yang, D., and Cao, Y.: Historical and future trends in wetting and drying in 291 catchments across China, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-588, in review, 2016.
Zhongwang Chen et al.
Zhongwang Chen et al.
Zhongwang Chen et al.

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Short summary
The significant climate changes remind us to characterize the hydrologic response to it. Based on the long-term observed hydrologic and meteorological data in 291 catchments across China, we find a pattern of the response stating that "dry areas get drier, wet areas get wetter". We also reveal that the precipitation changes play the most significant role in it. However, the pattern won't work anymore in projection according to the simulated data.
The significant climate changes remind us to characterize the hydrologic response to it. Based...
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