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Hydrological processes depend directly on climate conditions [e.g., precipitation, potential evapotranspiration ( PE)] based on the water balance. This paper examines streamflow datasets at four hydrological stations and meteorological observations at 79 weather stations to reveal the streamflow changes and underlying drivers in four typical watersheds (Meigang, Saitang, Gaosha, and Xiashan) within Poyang Lake Basin from 1961 to 2000. Most of the less than 90th percentile of daily streamflow in each watershed increases significantly at different rates. As an important indicator of the seasonal changes in the streamflow, CT (the timing of the mass center of the streamflow) in each watershed shows a negligible change. The annual streamflow in each watershed increases at different rates, with a statistically significant trend (at the 5 % level) of 9.87 and 7.72 mm year, respectively, in Meigang and Gaosha watersheds. Given the existence of interactions between precipitation and PE, the original climate elasticity of streamflow can not reflect the relationship of streamflow with precipitation and PE effectively. We modify this method and find the modified climate elasticity to be more accurate and reasonable using the correlation analysis. The analyses from the modified climate elasticity in the four watersheds show that a 10 % increase (decrease) in precipitation will increase (decrease) the annual streamflow by 14.1-16.3 %, while a 10 % increase (decrease) in PE will decrease (increase) the annual streamflow by −10.2 to −2.1 %. In addition, the modified climate elasticity is applied to estimate the contribution of annual precipitation and PE to the increasing annual streamflow in each watershed over the past 40 years. Our result suggests that the percentage attribution of the increasing precipitation is more than 59 % and the decreasing in PE is less than 41 %, indicating that the increasing precipitation is the major driving factor for the annual streamflow increase for each watershed. [ABSTRACT FROM AUTHOR]

Vegetation and land-surface hydrology are intrinsically linked under long-term climate change. This paper aims to evaluate the dynamics of potential natural vegetation arising from 21st century climate change and its possible impact on the water budget of the Hanjiang River basin in China. Based on predictions of the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC-SRES) A1 scenario from the PRECIS (Providing Regional Climates for Impact Studies) regional climate model, changes in plant functional types (PFTs) and leaf area index (LAI) were simulated via the Lund-Potsdam-Jena dynamic global vegetation model. Subsequently, predicted PFTs and LAIs were employed in the Xinanjiang vegetation-hydrology model for rainfall-runoff simulations. Results reveal that future long-term changes in precipitation, air temperature and atmospheric CO2 concentration would remarkably affect the spatiotemporal distribution of PFTS and LAIS. These climate-driven vegetation changes would further influence regional water balance. With the decrease in forest cover in the 21st century, plant transpiration and evaporative loss of intercepted canopy water will tend to fall while soil evaporation may rise considerably. As a result, total evapotranspiration may increase moderately with a slight increase in annual runoff depth. This indicates that, for long-term hydrological prediction, climate-induced changes in terrestrial vegetation cannot be neglected as the terrestrial biosphere plays an important role in land-surface hydrological responses. [ABSTRACT FROM AUTHOR]

Abstract: Evapotranspiration is an important flux term in the water cycle that integrates atmospheric demands and surface conditions. Thus, analysis of the temporal variation of reference evapotranspiration (ET0) will help us to understand climate change and its effect on hydrology. In this paper, we present an analysis of the monthly ET0 at 15 stations during 1961–2005 in the Taoer River basin in China, calculated by the FAO Penman–Monteith method. We derived the growing season and annual total ET0 time series and using the Mann–Kendall method, moving t test and Morlet wavelet conducted comprehensive time series analysis to characterize significance test, abrupt change and period in the ET0 data sets. The results present that: (i) in terms of the seasonal cycle, monthly ET0 reaches its peak in May and growing season ET0 accounts for 60.7% of annual total. Long term growing season ET0 fluctuates in accordance with annual ET0, both having turning points in 1982 and 1993; (ii) with respect to the long term persistence, the trends for growing season and annual ET0 show the same spatial patterns: high positive values in the west study area in the upper reach and negative values in the Southeast study area in the lower reach. The spatial distribution of annual tendencies suggests an influence from the altitude and latitude; (iii) for individual station, abrupt changes in annual ET0 are more pronounced than those in growing season ET0. The timings for the abrupt changes in ET0 series at individual stations are consistent with those in regional ET0. Abrupt changes detected in the early 1980s are all increasing changes, while those in earlier 1990 are all decreasing changes; and (iv) based on the Morlet wavelet analysis, there exist significant periods of 1, 3 and 7.3 years in annual ET0 series and significant 1 year period and 7.3 years period in growing season ET0 series. Maximum air temperature, mean air temperature, relative humidity and bright sunshine hours are main climate variables responsible for the periodicity in ET0. [Copyright &y& Elsevier]

Evapotranspiration is an important component and key link of river basin water cycles and plant hydrological processes, and is a core issue in global climate change research. It is not only an important way to understand the energy and water consumption of permafrost regions, but also is an important channel to master the water cycle and energy balance in cold regions. In this paper, multiple linear regression analysis method and weighted comprehensive analysis of major factors method were used to investigate the variation characteristics and impact factors of evapotranspiration in the Genhe River Basin. The results showed the following: (1) The monthly average evapotranspiration in the Genhe River Basin during the freezing-thawing periods in 1980–2017 was 28.29 mm. Compared with the freezing-thawing periods, the total evapotranspiration in the growing seasons was much higher than that in the freezing-thawing periods, with monthly average evapotranspiration of 67.71 mm; (2) The main factors affecting evapotranspiration in the Genhe River Basin were precipitation and temperature. During the freezing-thawing periods, the variation in evapotranspiration in May was mainly determined by temperature. In the growing season, precipitation was the main factors affecting evapotranspiration in June. This will lay a foundation for clarifying the relationship between permafrost–climate change–hydrologic cycle in the permafrost active layer during the land surface process, so as to provide some basic data and important scientific basis for the comprehensive study of the hydrologic process and its impact on climate, ecology, water resources and environment in the permafrost area. • Evapotranspiration variability in permafrost zone have been analyzed in growing season and freezing and thawing period. • The influencing factors of evapotranspiration in a long term have been explored. • This study enriches the data of eco-hydrology research in data-deficient areas. [ABSTRACT FROM AUTHOR]