THE ATMOSPHERIC WATER BALANCE AND THE HYDROLOGY OF LARGE RIVER BASINS

Abstract. The partitioning of water and energy, governed by the controlling parameter in the Budyko framework (i.e., n parameter in the Choudhury and Yang equation), is critical to assess the water balance at global scale. It is widely acknowledged that the spatial variation of this controlling parameter is affected by landscape characteristics, but characterizing its temporal variation remains yet to be done. Considering effective precipitation (Pe), the Budyko framework was extended to the annual water balance analysis. To reflect the mismatch between water supply (precipitation, P) and energy (potential evapotranspiration, E0), a climate seasonality and asynchrony index (SAI) were proposed in terms of both phase and amplitude mismatch between P and E0. Considering streamflow changes in 26 large river basins as a case study, SAI was found to the key factor explaining 46 % of the annual variance of parameter n. Furthermore, the vegetation dynamics (M) remarkably impacted the temporal variation of n, explaining 67 % of the variance. With SAI and M, a semi-empirical formula for parameter n was developed at the annual scale to describe annual runoff (R) and evapotranspiration (E). The impacts of climate variability (Pe, E0 and SAI) and M on R and E changes were then quantified. Results showed that R and E changes were controlled mainly by the Pe variations in most river basins over the globe, while SAI acted as the controlling factor modifying R and E changes in the East Asian subtropical monsoon zone, E0 in the temperate maritime climate of Europe, and M in the temperate grassland zone of South America.

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Hydrological effects of climate variability and vegetation dynamics on annual fluvial water balance in global large river basins

Hydrology and Earth System Sciences ◽

10.5194/hess-22-4047-2018 ◽

2018 ◽

Vol 22 (7) ◽

pp. 4047-4060 ◽

Cited By ~ 14

Author(s):

Jianyu Liu ◽

Qiang Zhang ◽

Vijay P. Singh ◽

Changqing Song ◽

Yongqiang Zhang ◽

...

Keyword(s):

Water Balance ◽

Climate Variability ◽

Temporal Variation ◽

Vegetation Dynamics ◽

Potential Evapotranspiration ◽

River Basins ◽

Large River ◽

Landscape Characteristics ◽

Controlling Parameter ◽

Large River Basins

Abstract. The partitioning of precipitation into runoff (R) and evapotranspiration (E), governed by the controlling parameter in the Budyko framework (i.e., n parameter in the Choudhury and Yang equation), is critical to assessing the water balance at global scale. It is widely acknowledged that the spatial variation in this controlling parameter is affected by landscape characteristics, but characterizing its temporal variation remains yet to be done. Considering effective precipitation (Pe), the Budyko framework was extended to the annual water balance analysis. To reflect the mismatch between water supply (precipitation, P) and energy (potential evapotranspiration, E0), we proposed a climate seasonality and asynchrony index (SAI) in terms of both phase and amplitude mismatch between P and E0. Considering streamflow changes in 26 large river basins as a case study, SAI was found to the key factor explaining 51 % of the annual variance of parameter n. Furthermore, the vegetation dynamics (M) remarkably impacted the temporal variation in n, explaining 67 % of the variance. With SAI and M, a semi-empirical formula for parameter n was developed at the annual scale to describe annual runoff (R) and evapotranspiration (E). The impacts of climate variability (Pe, E0 and SAI) and M on R and E changes were then quantified. Results showed that R and E changes were controlled mainly by the Pe variations in most river basins over the globe, while SAI acted as the controlling factor modifying R and E changes in the East Asian subtropical monsoon zone. SAI, M and E0 have larger impacts on E than on R, whereas Pe has larger impacts on R.

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Comments on “Hydrological effects of climate variability and vegetation dynamics on annual fluvial water balance at global large river basins”

10.5194/hess-2018-200-rc2 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Water Balance ◽

Climate Variability ◽

Vegetation Dynamics ◽

River Basins ◽

Large River ◽

Hydrological Effects ◽

Large River Basins

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The Water Balance Change of Large River Basins of the European Russia

Water sector of Russia: problems, technologies, management - Методы оценки и механизмы регулирования водопользования в современных условиях ◽

10.35567/1999-4508-2018-4-3 ◽

2018 ◽

Author(s):

Keyword(s):

Water Balance ◽

River Flow ◽

Potential Evapotranspiration ◽

Aridity Index ◽

River Basins ◽

Large River ◽

European Russia ◽

Runoff Coefficient ◽

The Third ◽

Large River Basins

For a number of large river basins of the European Russia (total area 1, 88 million km2), the analysis of average annual river flow, precipitation, evaporation, potential evaporation, runoff coefficient, and aridity index for 3 periods was carried out: 1945–1977, 1978–2002, 2003–2015. It was found that on average the second period, compared with the first, is characterized by high precipitation (+4,3 %), evapotranspiration (+3,2 %), river flow (+6,1 %), runoff coefficient (+1,8 %). The potential evapotranspiration is almost not increased (+0.09%), resulting in a increase in the aridity index (+4,2 %). The third period is characterized by high values of the basic water balance characteristics in comparison with the first period, but smaller in comparison with the second. A positive anomaly of precipitation (+2,4 %) and potential evapotranspiration (+5,8 %), have led that the third period, unlike the second, was more arid than the first (index of aridity -3,2 %).

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