Ejina Desert Oasis: A Fragile "Ecological Screen" in Inland Region of Northwest China

2008 ◽  
Author(s):  
Jianhua Si ◽  
Qi Feng ◽  
Haiyang Xi ◽  
Zongqiang Chang ◽  
Yonghong Su
Keyword(s):  
Northwest China ◽  
Desert Oasis

scholarly journals Analysis of land cover change and its driving forces in a desert oasis landscape of Xinjiang, northwest China

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1071-1085 ◽  
Author(s):  
T. Amuti ◽  
G. Luo
Keyword(s):  
Land Cover ◽  
Land Degradation ◽  
Driving Forces ◽  
Northwest China ◽  
Landsat Images ◽  
Desert Oasis ◽  
Standard Classification ◽  
Effects Of Drought ◽  
Arid Desert ◽  
Southern Xinjiang

Abstract. The combined effects of drought, warming and the changes in land cover have caused severe land degradation for several decades in the extremely arid desert oases of southern Xinjiang, northwest China. Land cover classifications of Landsat images in 1990, 2000 and 2008 were performed based on the multistage supervised classification scheme using the maximum likelihood classifier integrated with conventional vegetation and soil indexes, which improved overall accuracies by 4–5% compared to the standard classification method. Based on the detection of changes in land cover during 1990–2008 using remote sensing (RS) and a geographic information system (GIS), it can be found that the oasis significantly (+35%) increased, while the area of ecotone decreased (−43%). The major trends of the land cover changes were the notable growth of the oasis and the reduction of the desert–oasis ecotone. These changes were mainly a result of the intensified human activities such as land and water exploitation as well as overgrazing. The results of this study indicate that the oasis environment will be deteriorated by increase in potential areas of land degradation if the trend of desert moving further inward and the shrinking of the ecotone continues over the next decades.

Soil Susceptibility to Macropore Flow Across a Desert-Oasis Ecotone of the Hexi Corridor, Northwest China

2018 ◽  
Vol 54 (2) ◽  
pp. 1281-1294 ◽  
Author(s):  
Yongyong Zhang ◽  
Wenzhi Zhao ◽  
Jianhua He ◽  
Li Fu
Keyword(s):  
Northwest China ◽  
Hexi Corridor ◽  
Macropore Flow ◽  
Desert Oasis

Declining Singapore — a 21st Century Dunhuang in the Making?

2018 ◽  
Vol 01 (02) ◽  
pp. 1850012
Author(s):  
Vincent F. Yip
Keyword(s):  
21St Century ◽  
Conflicts Of Interest ◽  
Northwest China ◽  
Silk Road ◽  
Belt And Road Initiative ◽  
Strategic Response ◽  
Existential Crisis ◽  
Desert Oasis ◽  
Belt And Road

Singapore is currently facing economic realities and geo-political headwinds that bear many similarities to those that brought about the decline and eventual obsolescence of Dunhuang, the desert oasis city in northwest China that once served as the strategic fulcrum of the prosperous Silk Road, connecting East and West for more than a thousand years. Ideological differences and practical conflicts of interest with an emerging China threaten to sideline Singapore and even render it irrelevant as China continues to pursue its ambitious Belt and Road Initiative. Singapore is experiencing an existential crisis unlike any it has encountered in its past 53 years of independence. A prudent strategic response would be for Singapore to emulate the Swiss model of political balance among nations, maintain its traditional neutrality and rely on its unique strategic/economic strengths in order to ensure the small republic’s survival and long-term prosperity in a region facing tumultuous upheavals in the remainder of the 21st century.

scholarly journals Daily Evapotranspiration Estimation Using HJ-1 Data for Irrigation Water Management in a Desert-Oasis Irrigation District, Northwest China

2018 ◽  
Vol 246 ◽  
pp. 02006
Author(s):  
Zhenyan Yi ◽  
Yunzhong Jiang ◽  
Hongli Zhao ◽  
Haichen Li ◽  
Rong Wang ◽  
...  
Keyword(s):  
Water Management ◽  
Time Series ◽  
Irrigation Water ◽  
Agricultural Land ◽  
Northwest China ◽  
Field Scale ◽  
Irrigation Water Management ◽  
Vegetation Fraction ◽  
Desert Oasis ◽  
Daily Evapotranspiration

Irrigation of agricultural land is the main water consumer in the arid and semiarid regions. The accurate time series of daily evapotranspiration (ET) at the field scale is crucial for irrigation water management. Here, we presented an integrated approach to field-scale ET mapping by combing METRIC (Mapping Evapotranspiration at High Resolution with Internalized Calibration) with trapezoidal framework of vegetation fraction and land surface temperature (fv-Trad). This approach fed with Chinese satellite HJ-1 (environmental and disaster monitoring and forecasting with a small satellite constellation) images was used to map daily ET over the desert-oasis irrigation fields in the middle of the Heihe River Basin, Northwest China. The results showed that time series of daily ET derived from HJ-1 were well consistent with the in situ measurements (coefficient of determination (R2) of 0.95, root mean square error (RMSE) of 0.31 mmd–1, mean absolute percentage error (MAPE) of 12.0% at Daman station; R2 of 0.89, RMSE of 0.16 mmd–1, and MAPE of 13.2% at Huazhaizi station). The rapid variation of ET could be precisely captured by HJ-1, especially when rainfall or irrigation events occurred between successive acquisitions of satellite data. Meanwhile, the spatiotemporal variation of monthly ET is closely related to crop growth. Daily ET at field scale will support a variety of local interests in water use and irrigation management for both planning and regulatory purposes.

Water exchange process and water uptake for irrigated maize cropland in a desert-oasis transition area, Northwest China

2020 ◽  
Author(s):  
Yongyong Zhang ◽  
Wenzhi Zhao ◽  
Chun Zhao
Keyword(s):  
Soil Moisture ◽  
Stable Isotope ◽  
Water Potential ◽  
Soil Water ◽  
Water Exchange ◽  
Exchange Process ◽  
Northwest China ◽  
Transition Area ◽  
Desert Oasis ◽  
Water Stable Isotope

<p>Soil water and groundwater convert frequently under cropland in a desert-oasis transition area, Northwest China. Crops variedly utilize soil water and groundwater during different growth periods under the cropland with shallow groundwater. The study of water exchange process under irrigated cropland has important significance for regulating the contradiction between water saving and groundwater recharge in the desert-oasis transition area. Soil moisture and soil matric potential at depths ranging from 0 to 70 cm were measured using HydraProbe II and TEROS-21 soil sensors in maize (Zea mays L.) fields in 2019. Stable isotope (δ<sup>2</sup>H、δ<sup>18</sup>O) in different water sources (precipitation, irrigation water, soil water, crop stem, and groundwater) was also measured. The results showed that the groundwater depth varied between 0.57-1.07 m during the maize growth periods. The groundwater depth increased in summer due to the influence of pumped well, while the depth decreased in autumn resulting from the irrigation return water. In the maize growing season, soil moisture and water potential at depths from 10 cm to 30 cm responded to three irrigation times, while soil moisture and water potential below the depth of 50 cm were greater and kept a steady state, which were affected by upward capillary rise of groundwater. The relationship of soil water stable isotope values ​​was δ<sup>2</sup>H=2.45δ<sup>18</sup>O-31.41, which was lower than the slope of the local atmospheric precipitation line due to the evaporation effect. The soil water stable isotope values at depth of 10 cm varied, while the variation of soil water stable isotope values decreased with the increase of soil depth. The soil water stable isotope values at the depths from 70 to 90cm were close to the groundwater isotope values, which were affected by the groundwater. The stable isotope values in crop stem water were relatively scattered, indicating that the maize used multiple water sources and the water use strategy changed during the growth periods.</p>

Non‐destructive dry matter estimation of Alhagi sparsifolia vegetation in a desert oasis of Northwest China

2004 ◽  
Vol 15 (3) ◽  
pp. 365-372
Author(s):  
S. Siebert ◽  
D. Gries ◽  
X. Zhang ◽  
M. Runge ◽  
A. Buerkert
Keyword(s):  
Dry Matter ◽  
Northwest China ◽  
Alhagi Sparsifolia ◽  
Desert Oasis ◽  
Non Destructive

scholarly journals Dynamics of Soil Water Content Across Different Landscapes in a Typical Desert-Oasis Ecotone

2020 ◽  
Vol 8 ◽  
Author(s):  
Guohua Wang ◽  
Qianqian Gou ◽  
Yulian Hao ◽  
Huimin Zhao ◽  
Xiafang Zhang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Groundwater Resources ◽  
Time Lag ◽  
Northwest China ◽  
Deep Soil ◽  
Deep Layers ◽  
Desert Oasis

An understanding of soil water content dynamics is important for vegetation restoration in an arid desert-oasis ecotone under different landscapes. In this study, the dynamics of soil water content under three typical landscapes (i.e., desert, sand-binding shrubland, and farmland shelter woodland) were investigated in the Hexi Corridor, northwest China, during the growing season from 2002 to 2013. The results showed that the soil water content in the deep layers decreased from 20–30% to a stable low level of 3–5% in the desert and shrubland. For the farmland shelter woodland, the soil water content at the deep layers also decreased, but the decrease rate was much smaller than the desert and shrubland. The decrease of soil water content in the deep soil layers among desert–shrubland–woodland was strongly associated with the increase of groundwater depths. The greatest increase of groundwater depths mainly occurred during 2008–2011, while the largest decrease of soil water content took place during the years 2009–2011, with a time-lag in response to increase in groundwater depths. This study provides new insight into the long-term dynamics of soil water content in a typical desert oasis ecotone under different landscape components from the influence of overexploiting groundwater that cannot be inferred from a short-term study. The findings demonstrate that the sharp increase of groundwater depths could be the main reason behind the reduction of soil water content in the clay interlayers, and sustainable development of groundwater resources exploitation is very important for the management of desert-oasis ecotone from a long-term perspective.

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