scholarly journals Assessment of the Effects of Climate Change on Evapotranspiration with an Improved Elasticity Method in a Nonhumid Area

2018 ◽  
Vol 10 (12) ◽  
pp. 4589 ◽  
Author(s):  
Lei Tian ◽  
Jiming Jin ◽  
Pute Wu ◽  
Guo-yue Niu
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Energy Budget ◽  
Yellow River ◽  
Rate Of Change ◽  
Climatic Variables ◽  
Accurate Estimation ◽  
Net Radiation ◽  
River Watershed ◽  
Significant Downward Trend

Climatic elasticity is a crucial metric to assess the hydrological influence of climate change. Based on the Budyko equation, this study performed an analytical derivation of the climatic elasticity of evapotranspiration (ET). With this derived elasticity, it is possible to quantitatively separate the impacts of precipitation, air temperature, net radiation, relative humidity, and wind speed on ET in a watershed. This method was applied in the Wuding River Watershed (WRW), located in the center of the Yellow River Watershed of China. The estimated rate of change in ET caused by climatic variables is −10.69 mm/decade, which is close to the rate of change in ET (−8.06 mm/decade) derived from observable data. The accurate estimation with the elasticity method demonstrates its reliability. Our analysis shows that ET in the WRW had a significant downward trend, but the ET ratio in the WRW has increased continually over the past 52 years. Decreasing precipitation is the first-order cause for the reduction of ET, and decreasing net radiation is the secondary cause. Weakening wind speed also contributed to this reduction. In contrast, regional warming led to an increase in ET that partly offset the negative contributions from other climatic variables. Moreover, reforestation can affect the energy budget of a watershed by decreasing albedo, compensating for the negative influence of global dimming. The integrated effect from precipitation and temperature can affect the energy budget of a watershed by causing a large fluctuation in winter albedo.

scholarly journals Response of LUCC on Runoff Generation Process in Middle Yellow River Basin: The Gushanchuan Basin

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1237 ◽  
Author(s):  
Caihong Hu ◽  
Li Zhang ◽  
Qiang Wu ◽  
Shan-e-hyder Soomro ◽  
Shengqi Jian
Keyword(s):  
Climate Change ◽  
Human Activities ◽  
Yellow River ◽  
Trend Test ◽  
Generation Process ◽  
Runoff Generation ◽  
Contribution Rate ◽  
Runoff Reduction ◽  
Runoff Change ◽  
Significant Downward Trend

Runoff reduction in most river basins in China has become a hotpot in recent years. The Gushanchuan river, a primary tributary of the middle Yellow river, Northern China, showed a significant downward trend in the last century. Little is known regarding the relative contributions of changing environment to the observed hydrological trends and response on the runoff generation process in its watershed. On the basis of observed hydrological and meteorological data from 1965–2010, the Mann-Kendall trend test and climate elasticity method were used to distinguish the effects of climate change and human activities on runoff in the Gushanchuan basin. The results indicate that the runoff in the Gushanchuan Basin has experienced significant declines as large as 77% from 1965 to 2010, and a mutation point occurred around 1997; the contribution rate of climate change to runoff change is 12.9–15.1%, and the contribution rate of human activities to runoff change is 84.9–87.1%. Then we divided long-term data sequence into two stages around the mutation point, and analyzed runoff generation mechanisms based on land use and cover changes (LUCC). We found that the floods in the Gushanchuan Basin were still dominated by Excess-infiltration runoff, but the proportion in 1965–1997 and 1998–2010 decreased gradually (68.46% and 45.83% in turn). The proportion of Excess-storage runoff and Mixed runoff has increased, which means that the runoff is made up of more runoff components. The variation law of the LUCC indicates that the forest area increased by 49.61%, the confluence time increased by 50.42%, and the water storage capacity of the watershed increased by 30.35%.

scholarly journals Responses of natural runoff to recent climatic variations in the Yellow River basin, China

2013 ◽  
Vol 17 (11) ◽  
pp. 4471-4480 ◽  
Author(s):  
Y. Tang ◽  
Q. Tang ◽  
F. Tian ◽  
Z. Zhang ◽  
G. Liu
Keyword(s):  
Wind Speed ◽  
Yellow River ◽  
Low Flow ◽  
The Yellow River ◽  
Net Radiation ◽  
Recent Period ◽  
Flow Phenomenon ◽  
Climatic Variations ◽  
Runoff Reduction ◽  
Zero Flow

Abstract. The zero-flow phenomenon appeared frequently in the lower reaches of the Yellow River in China in the 1990s, whereas it has almost disappeared in recent years. The disappearance of the zero-flow phenomenon should be mainly attributed to the recent water management practices. However, little is known about the effects of recent climatic variations on natural runoff. In this study, we investigated the impacts of climatic variations on natural runoff above the Huayuankou station. The results indicate that there was little increase in precipitation, but substantial recovery of natural runoff in the recent period (2003–2011) compared with the low-flow period (1991–2002). The recent precipitation was slightly greater (∼2% of the baseline precipitation in 1960–1990) than precipitation in the low-flow period. However, the recent natural runoff was much larger (∼14% baseline runoff) than runoff in the low-flow period. The runoff reduction in the low-flow period was mainly caused by precipitation decrease. In the recent period, precipitation accounted for a runoff reduction (∼21% baseline runoff), whereas net radiation, wind speed, air temperature, and relative humidity accounted for a runoff increase (∼7.5% baseline runoff). The spatial pattern of the climatic variation is a factor influencing the response of runoff to climatic variations. The reduction in runoff induced by precipitation change was offset up to half by the impacts of changes in net radiation and wind speed at most sub-basins in the recent period.

scholarly journals Energy budget comparison of snowmelt rates in a deciduous forest and an open site

1993 ◽  
Vol 18 ◽  
pp. 53-59 ◽  
Author(s):  
T. Ohta ◽  
T. Hashimoto ◽  
H. Ishibashi
Keyword(s):  
Wind Speed ◽  
Energy Budget ◽  
Deciduous Forest ◽  
Meteorological Conditions ◽  
Turbulent Heat ◽  
Forest Site ◽  
Strong Wind ◽  
Net Radiation ◽  
Open Site ◽  
Turbulent Heat Exchange

Daily snowmelt rates at a leafless deciduous forest site were 40–85% of those at an open site. Reduced snowmelt rates were caused by a difference in meteorological conditions at the forested site. Solar radiation, net radiation and wind speed were especially reduced in the forest, and relationships between them at the two sites were represented by linear functions. Snowmelt rates at the two sites could be predicted by an energy budget method, and net radiation was the major component in the snowmelt energy at both sites. Differences between snowmelt rates at the two sites were due to net radiation differences over many days, but dependency on net radiation at both sites was reduced under particular meteorological conditions. Parameteric analysis under fixed meteorological conditions indicates that this dependency is changed by wind speed, temperature and humidity, because wind speed is reduced in the forest and decrease of turbulent heat exchange in the forest will be notable under strong wind conditions.

scholarly journals Four Decades of Surface Temperature, Precipitation, and Wind Speed Trends over Lakes of Greece

2021 ◽  
Vol 13 (17) ◽  
pp. 9908
Author(s):  
Konstantinos Stefanidis ◽  
George Varlas ◽  
Anastasios Papadopoulos ◽  
Elias Dimitriou
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Surface Temperature ◽  
Average Rate ◽  
Generalized Additive Models ◽  
Climatic Changes ◽  
Rate Of Change ◽  
Additive Models ◽  
Freshwater Bodies ◽  
Of Greece

Climate change is known to affect world’s lakes in many ways. Lake warming is perhaps the most prominent impact of climate change but there is evidence that changes of precipitation and wind speed over the surface of the lakes may also have a significant effect on key limnological processes. With this study we explored the interannual trends of surface temperature, precipitation, and wind speed over 18 lakes of Greece using ERA5-Land data spanning over a period of almost four decades. We used generalized additive models (GAMs) to conduct time-series analysis in order to identify significant trends of change. Our results showed that surface temperature has significantly increased in all lakes with an average rate of change for annual temperature of 0.43 °C decade−1. With regard to precipitation, we identified significant trends for most lakes and particularly we found that precipitation decreased during the first two decades (1981–2000), but since 2000 it increased notably. Finally, wind speed did not show any significant change over the examined period with the exception for one lake. In summary, our work highlights the major climatic changes that have occurred in several freshwater bodies of Greece. Thus, it improves our understanding on how climate change may have impacted the ecology of these important ecosystems and may aid us to identify systems that are more vulnerable to future changes.

scholarly journals Energy budget comparison of snowmelt rates in a deciduous forest and an open site

1993 ◽  
Vol 18 ◽  
pp. 53-59 ◽  
Author(s):  
T. Ohta ◽  
T. Hashimoto ◽  
H. Ishibashi
Keyword(s):  
Wind Speed ◽  
Energy Budget ◽  
Deciduous Forest ◽  
Meteorological Conditions ◽  
Turbulent Heat ◽  
Forest Site ◽  
Strong Wind ◽  
Net Radiation ◽  
Open Site ◽  
Turbulent Heat Exchange

Daily snowmelt rates at a leafless deciduous forest site were 40–85% of those at an open site. Reduced snowmelt rates were caused by a difference in meteorological conditions at the forested site. Solar radiation, net radiation and wind speed were especially reduced in the forest, and relationships between them at the two sites were represented by linear functions. Snowmelt rates at the two sites could be predicted by an energy budget method, and net radiation was the major component in the snowmelt energy at both sites. Differences between snowmelt rates at the two sites were due to net radiation differences over many days, but dependency on net radiation at both sites was reduced under particular meteorological conditions. Parameteric analysis under fixed meteorological conditions indicates that this dependency is changed by wind speed, temperature and humidity, because wind speed is reduced in the forest and decrease of turbulent heat exchange in the forest will be notable under strong wind conditions.

scholarly journals Responses of natural runoff to recent climatic changes in the Yellow River basin, China

2013 ◽  
Vol 10 (4) ◽  
pp. 4489-4514 ◽  
Author(s):  
Y. Tang ◽  
Q. Tang ◽  
F. Tian ◽  
Z. Zhang ◽  
G. Liu
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Yellow River ◽  
Climatic Changes ◽  
Low Flow ◽  
Mean Annual Precipitation ◽  
The Yellow River ◽  
Net Radiation ◽  
Recent Period ◽  
Zero Flow

Abstract. The Yellow River, the second longest river in China, experienced frequent zero flow in the lower reaches of the mainstream in the 1990s. In recent years, the zero-flow phenomenon has almost disappeared. Besides engineering measures implemented to maintain ecological flows, the changes in natural runoff might have contributed to replenish the river. In this study, we used the Soil and Water Assessment Tool (SWAT) model and runoff elasticity analyses to assess the impacts of climatic changes on the natural streamflow at the Huayuankou station. The results show that there was little increase of precipitation but substantial recovery of natural runoff in the recent period (2003–2011) compared with the low flow period (1991–2002). The recent precipitation was slightly greater (~2% of the mean annual precipitation in the baseline period of 1960–1990) than precipitation in the low flow period. However, the natural runoff in the recent period was much larger (~14% baseline runoff) than runoff in the low flow period. The decreasing runoff in the low flow period was mainly caused by the decline in precipitation while the runoff recovery in the recent period was largely affected by the contributions from the climatic variables other than the precipitation. In the recent period, precipitation could account for a reduction of 21% baseline runoff whereas the others – net radiation, wind speed, air temperature, and relative humidity – accounted for an increase of 7.5% baseline runoff. The runoff reduction (~10.4% baseline runoff) caused by the changes in temperature and relative humidity was offset by the contribution from the decreasing net radiation and wind speed which resulted in an increase of ~17.9% baseline runoff.

التغير المناخي واثره في المقنن المائي لمحصول العنب في محافظة ديالى

2019 ◽  
Vol 1 (34) ◽  
pp. 391-422
Author(s):  
اشواق حسن حميد صالح
Keyword(s):  
Climate Change ◽  
Statistical Analysis ◽  
Wind Speed ◽  
Extreme Temperature ◽  
Solar Brightness ◽  
The Subject ◽  
Climate Station ◽  
The Times ◽  
High Level ◽  
Very High

Climate change and its impact on water resources is the problem of the times. Therefore, this study is concerned with the subject of climate change and its impact on the water ration of the grape harvest in Diyala Governorate. The study was based on the data of the Khanaqin climate station for the period 1973-2017, (1986-2017) due to lack of data at governorate level. The general trend of the elements of the climate and its effect on the water formula was extracted. The equation of change was extracted for the duration of the study. The statistical analysis was also used between the elements of the climate (actual brightness, normal temperature, micro and maximum degrees Celsius, wind speed m / s, relative humidity% The results of the statistical analysis confirm that the water ration for the study area is based mainly on the X7 evaporation / netting variable, which is affected by a set of independent variables X1 Solar Brightness X4 X5 Extreme Temperature Wind Speed ​​3X Minimal Temperature and Very High Level .

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