scholarly journals Evolutional Characteristics of Regional Meteorological Drought and Their Linkages with Southern Oscillation Index across the Loess Plateau of China during 1962–2017

2020 ◽  
Vol 12 (18) ◽  
pp. 7237
Author(s):  
Ming Li ◽  
Fuqiang Cao ◽  
Guiwen Wang ◽  
Xurong Chai ◽  
Lianzhi Zhang
Keyword(s):  
Loess Plateau ◽  
Southern Oscillation Index ◽  
Temporal Evolution ◽  
Southern Oscillation ◽  
Arid Area ◽  
The Loess Plateau ◽  
Drought Period ◽  
Humid Area ◽  
Semi Arid ◽  
Meteorological Droughts

The Loess Plateau of China (CLP) is located in the transition zone from a semi-humid climate zone to semi-arid and arid climate zones. It is influenced by the westerly circulation, plateau monsoon, and East Asian monsoon circulation, and the drought disasters across the CLP have obvious regional characteristics. In this study, climate regionalization was performed by a spatial hierarchical cluster approach based on the gridded datasets of monthly precipitation across the CLP from 1961 to 2017. Then, the standardized precipitation index (SPI) was used to explore the temporal evolution of regional meteorological droughts. Finally, wavelet methods were used to investigate the drought cycles in each homogeneous subregion and the linkages between SPI and the Southern Oscillation Index (SOI). The results show that: (1) Spatially, the CLP can be divided into four homogeneous regions, namely, Ordos Plateau semi-arid area (Region I), Northern Shanxi hilly semi-humid area (Region II), Longzhong plateau cold-arid area (Region III), and Fenwei Plain and Shaanxi-Shanxi hilly semi-humid area (Region IV). (2) There are apparent differences in the temporal evolution of meteorological droughts in different subregions, but two wet periods from the 1960s to 1980s and 2010s, and a drought period in the 1990s, can be found in each subregion. (3) There is a significant drought cycle of 3–8 years in the four subregions, and the first main cycles of drought variation are not completely consistent. (4) The linkages between SPI and SOI are time- and space-dependent and the phase differences are dominated by in-phase. The strongest correlations between the two time series occur in the 1980s in the four subregions. The results of this research have important implications for the establishment of drought monitoring programs in homogeneous climate regions, and informed decision making in water resource management.

scholarly journals Spatial–Temporal Evolution of Vegetation NDVI in Association with Climatic, Environmental and Anthropogenic Factors in the Loess Plateau, China during 2000–2015: Quantitative Analysis Based on Geographical Detector Model

2021 ◽  
Vol 13 (21) ◽  
pp. 4380
Author(s):  
Yi Dong ◽  
Dongqin Yin ◽  
Xiang Li ◽  
Jianxi Huang ◽  
Wei Su ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Temporal Evolution ◽  
Driving Forces ◽  
Arid Area ◽  
Anthropogenic Factors ◽  
The Loess Plateau ◽  
Geographical Detector ◽  
Humid Area ◽  
Detector Model ◽  
Semi Arid

In the Loess Plateau (LP) of China, the vegetation degradation and soil erosion problems have been shown to be curbed after the implementation of the Grain for Green program. In this study, the LP is divided into the northwestern semi-arid area and the southeastern semi-humid area using the 400 mm isohyet. The spatial–temporal evolution of the vegetation NDVI during 2000–2015 are analyzed, and the driving forces (including factors of climate, environment, and human activities) of the evolution are quantitatively identified using the geographical detector model (GDM). The results showed that the annual mean NDVI in the entire LP was 0.529, and it decreased from the semi-humid area (0.619) to the semi-arid area (0.346). The mean value of the coefficient of variation of the NDVI was 0.1406, and it increased from the semi-humid area (0.1165) to the semi-arid area (0.1926). The annual NDVI growth rate in the entire LP was 0.0079, with the NDVI growing faster in the semi-humid area (0.0093) than in the semi-arid area (0.0049). The largest increments of the NDVI were from grassland, farmland, and woodland. The GDM results revealed that changes in the spatial distribution of the NDVI could be primarily explained by the climatic and environmental factors in the semi-arid area, such as precipitation, soil type, and vegetation type, while the changes were mainly explained by the anthropogenic factors in the semi-humid area, such as the GDP density, land-use type, and population density. The interactive analysis showed that interactions between factors strengthened the impacts on the vegetation change compared with an individual factor. Furthermore, the ranges/types of factors suitable for vegetation growth were determined. The conclusions of this study have important implications for the formulation and implementation of ecological conservation and restoration strategies in different regions of the LP.

scholarly journals Precipitation Changes in Semi-arid Regions in East Asia Under Global Warming

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaodan Guan ◽  
Kaiwei Zhu ◽  
Xiaoqian Huang ◽  
Xinrui Zeng ◽  
Yongli He
Keyword(s):  
East Asia ◽  
Loess Plateau ◽  
Arid Regions ◽  
Southern Oscillation ◽  
The Loess Plateau ◽  
Westward Expansion ◽  
Westerly Winds ◽  
Negative Effect ◽  
Precipitation Changes ◽  
Semi Arid

The semi-arid regions of East Asia are located in the transition area between regions dominated by the monsoon system and by westerly winds; their interaction is the key to understand precipitation changes, especially in the summer. Our results show that the enhancement of both the monsoon and westerly winds occurs in wet years, leading to stronger convergence and more rainfall. Weakening of both the monsoon and westerly winds occurs in dry years and results in less rainfall. Such interaction between the monsoon and westerlies is not constant; the boundary of their effects is changing all the time. As the monsoon strengthens, it shifts to the west in wet years and covers most of the semi-arid regions, and the negative effect of the El Niño-Southern Oscillation (ENSO) system on precipitation in the semi-arid regions becomes obvious. However, westward expansion has not been evident over the past 70 years in historic data. In the future, the monsoon will obviously expand westward, and the precipitation over the Loess Plateau will gradually increase as the monsoon boundary expand westward until the end of the 21st century. This change indicates that more rainfall will occur in the semi-arid regions of East Asia, which could dramatically change the ecological environment, especially over the Loess Plateau.

scholarly journals Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China

2011 ◽  
Vol 15 (8) ◽  
pp. 2519-2530 ◽  
Author(s):  
T. T. Jin ◽  
B. J. Fu ◽  
G. H. Liu ◽  
Z. Wang
Keyword(s):  
Loess Plateau ◽  
Large Scale ◽  
Regional Scale ◽  
Negative Relationship ◽  
Northern Region ◽  
Shaanxi Province ◽  
Stand Age ◽  
Mean Annual Precipitation ◽  
The Loess Plateau ◽  
Semi Arid

Abstract. Hydrologic viability, in terms of moisture availability, is fundamental to ecosystem sustainability in arid and semi-arid regions. In this study, we examine the spatial distribution and after-planting variations of soil moisture content (SMC) in black locust tree (Robinia pseudoacacia L.) plantings in the Loess Plateau of China at a regional scale. Thirty sites (5 to 45 yr old) were selected, spanning an area of 300 km by 190 km in the northern region of the Shaanxi Province. The SMC was measured to a depth of 100 cm at intervals of 10 cm. Geographical, topographic and vegetation information was recorded, and soil organic matter was evaluated. The results show that, at the regional scale, SMC spatial variability was most highly correlated with rainfall. The negative relationship between the SMC at a depth of 20–50 cm and the stand age was stronger than at other depths, although this relationship was not significant at a 5 % level. Watershed analysis shows that the after-planting SMC variation differed depending upon precipitation. The SMC of plantings in areas receiving sufficient precipitation (e.g., mean annual precipitation (MAP) of 617 mm) may increase with stand age due to improvements in soil water-holding capacity and water-retention abilities after planting. For areas experiencing water shortages (e.g., MAP = 509 mm), evapotranspiration may cause planting soils to dry within the first 20 yr of growth. It is expected that, as arid and semi-arid plantings age, evapotranspiration will decrease, and the soil profile may gradually recover. In extremely dry areas (e.g., MAP = 352 mm), the variation in after-planting SMC with stand age was found to be negligible. The MAP can be used as an index to divide the study area into different ecological regions. Afforestation may sequentially exert positive, negative and negligible effects on SMCs with a decrease in the MAP. Therefore, future restoration measures should correspond to the local climate conditions, and the MAP should be a major consideration for the Loess Plateau. Large-scale and long-term research on the effects of restoration projects on SMCs is needed to support more effective restoration policies. The interaction between afforestation and local environmental conditions, particularly water availability to plants, should be taken into account in afforestation campaigns in arid and semi-arid areas.

An integrated simulation model for a semi-arid agroecosystem in the Loess Plateau of northwestern China

1996 ◽  
Vol 52 (1) ◽  
pp. 83-111 ◽  
Author(s):  
Hsin-i Wu ◽  
W.Michael Childress ◽  
Yang Li ◽  
Richard D. Spence ◽  
Jizhou Ren
Keyword(s):  
Simulation Model ◽  
Loess Plateau ◽  
Northwestern China ◽  
The Loess Plateau ◽  
Integrated Simulation ◽  
Semi Arid

scholarly journals Screening of Weeds for Vegetation Recovery in a Pasture in the Semi-arid Region of the Loess Plateau in China.

1993 ◽  
Vol 38 (3) ◽  
pp. 182-189 ◽  
Author(s):  
Nobumasa Ichizen ◽  
Masaru Ogasawara ◽  
Hitoshi Kuramochi ◽  
Makoto Konnai ◽  
Wataru Sunohara ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Arid Region ◽  
Vegetation Recovery ◽  
The Loess Plateau ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Spatial and Temporal Variations of Potential Evapotranspiration in the Loess Plateau of China During 1960–2017

2020 ◽  
Vol 12 (1) ◽  
pp. 354 ◽  
Author(s):  
Congjian Sun ◽  
Zhenjing Zheng ◽  
Wei Chen ◽  
Yuyang Wang
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Hydrological Cycle ◽  
Climatic Factors ◽  
Potential Evapotranspiration ◽  
Southern Oscillation ◽  
Chinese Loess Plateau ◽  
Future Climate Change ◽  
Strong Positive Correlation ◽  
The Loess Plateau

Potential evapotranspiration (ET0) is an integral component of the hydrological cycle and the global energy balance, and its long-term variation is of much concern in climate change studies. The Loess Plateau is an important area of agricultural civilization and water resources research. This study analyzed the spatial and temporal evolution processes and influential parameters of ET0 at 70 stations in different topographical areas of the Chinese Loess Plateau (CLP). Using the Mann–Kendall trend, Cross wavelet transform, and the ArcGIS platform, the ET0 of each station was quantified using the Penman–Monteith equation, and the effects of climatic factors on ET0 were assessed by analyzing the correlation coefficients and contribution rates of the climatic factors. The results showed that: (1) the overall trend of the ET0 in different terrains of the Loess Plateau is consistent, however, the ET0 values differ; the hill region (HR) has the highest ET0, followed by the valley region (VR), and the mountain region (MR) has the lowest, and ET0 changes differ between seasons. (2) Spatial distribution characteristics of multiyear mean ET0 in the study are as follows: the ET0 values in mountain and hilly areas are decreasing from west to east, and the higher mean annual ET0 value in the VR is mainly concentrated in the eastern CLP. (3) In the past 58 years, the annual mean and the seasonal ET0 of the region showed increasing trends, however, differences in different terrains were obvious. (4) ET0 has significant correlations with El Niño–Southern Oscillation (ENSO), Pacific–North American teleconnection (PNA), and Atlantic Multidecadal Oscillation (AMO). The resonance period of ET0 and ENSO was 3–6 a, mainly in 1976–1985. The mean coherence phase angle was close to 360°, indicating that ET0 lags behind PNA by approximately 2–6 a; ET0 has a very strong positive correlation with AMO. (5) Relative humidity (RH) is the main influencing factor of ET0 change in the Loess Plateau. Temperature (T) variation has the highest contribution rate (42%) to the regional ET0 variation in the entire CLP. We should pay more attention to the variation of evaporation under future climate change, especially temperature change.

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