Hydrological Variability in the Arid Region of Northwest China from 2002 to 2013

The arid region of Northwest China (ANC) has a distinct and fragile inland water cycle. This study examined the hydrological variations in ANC and its three subregions from August 2002 to December 2013 by integrating terrestrial water storage (TWS) anomaly data derived from the Gravity Recovery and Climate Experiment (GRACE) satellite, soil moisture data modeled by the Global Land Data Assimilation System, and passive microwave snow water equivalent data. The results show that the TWS in ANC increased at a rate of 1.7 mm/a over the past decade, which consisted of an increasing trend of precipitation (0.12 mm/a). Spatially, in the northern ANC, TWS exhibited a significant decreasing trend of −3.64 mm/a (p<0.05) as a result of reduced rainfall, increased glacial meltwater draining away from the mountains, and intensified human activities. The TWS in southern and eastern ANC increased at a rate of 2.14 (p=0.10) and 1.63 (p<0.01) mm/a, respectively. In addition to increasing precipitation and temperature, decreasing potential evapotranspiration in Southern Xinjiang and expanding human activities in Hexi-Alashan together led to an overall increase in TWS. Increased glacier meltwater and permafrost degradation in response to climate warming may also affect the regional TWS balance. The variations in soil moisture, groundwater, and surface water accounted for the majority of the TWS anomalies in southern and eastern ANC. The proposed remote sensing approach combining multiple data sources proved applicable and useful to understand the spatiotemporal characteristics of hydrological variability in a large area of arid land without the need for field observations.

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Intercomparison of the Surface Energy Partitioning in CMIP5 Simulations

Atmosphere ◽

10.3390/atmos10100602 ◽

2019 ◽

Vol 10 (10) ◽

pp. 602 ◽

Cited By ~ 1

Author(s):

Yang ◽

Wang ◽

Huang

Keyword(s):

Soil Moisture ◽

Surface Energy ◽

Land Surface ◽

Radiative Forcing ◽

Climate Models ◽

Water Cycle ◽

Potential Evapotranspiration ◽

Sensible Heat Flux ◽

Coupled Model ◽

Energy Partitioning

The warming climate significantly modifies the global water cycle. Global evapotranspiration has increased over the past decades, yet climate models agree on the drying trend of land surface. In this study, we conducted an intercomparison analysis of the surface energy partitioning across Coupled Model Intercomparison Phase 5 (CMIP5) simulations and evaluated its behaviour with surface temperature and soil moisture anomalies, against the theoretically derived thermodynamic formula. Different responses over land and sea surfaces to elevated greenhouse gas emissions were found. Under the Representative Concentration Pathway of +8.5 W m−2 (RCP8.5) warming scenario, the multi-model mean relative efficiency anomaly from CMIP5 simulations is 3.83 and −0.12 over global sea and land, respectively. The significant anomaly over sea was captured by the thermodynamic solution based on the principle of maximum entropy production, with a mean relative error of 14.6%. The declining trend over land was also reproduced, but an accurate prediction of its small anomaly will require the inclusions of complex physical processes in future work. Despite increased potential evapotranspiration under rising temperatures, both CMIP5 simulations and thermodynamic principles suggest that the soil moisture-temperature feedback cannot support long-term enhanced evapotranspiration at the global scale. The dissipation of radiative forcing eventually shifts towards sensible heat flux and accelerates the warming over land, especially over South America and Europe.

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High-resolution simulation and validation of soil moisture in the arid region of Northwest China

Scientific Reports ◽

10.1038/s41598-019-52923-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Xianyong Meng ◽

Hao Wang ◽

Ji Chen ◽

Mingxiang Yang ◽

Zhihua Pan

Keyword(s):

Soil Moisture ◽

High Resolution ◽

Spatial Resolution ◽

Arid Region ◽

Arid Regions ◽

Northwest China ◽

Agricultural Drought ◽

Data Set ◽

Study Region ◽

Community Land Model

AbstractSoil moisture plays an important role in land-atmosphere interactions, agricultural drought monitoring, and water resource management, particularly across arid regions. However, it is challenging to simulate soil moisture of high spatial resolution and to evaluate soil moisture at fine spatial resolution in arid regions in Northwest China due to considerable uncertainties in forcing data and limited in situ measurements. Then, the data set was used to produce the 1 km high-resolution atmospheric forcing datasets and to drive the Community Land Model version 3.5 (CLM3.5) for simulating spatiotemporally continuous surface soil moisture. The capabilities of soil moisture simulation using CLM3.5 forced by the XJLDAS-driven field were validated against data obtained at three soil layers (0–10, 0–20, and 0–50 cm) from 54 soil moisture stations in Xinjiang. Results show that the simulated soil moisture agreed well with the observations [CORR > 0.952], and the intra-annual soil moisture in Xinjiang gradually increased during May through August. The main factors that affect changes in soil moisture across the study region were precipitation and snowmelt. The overall finding of this study is that an XJLDAS, high-resolution forcing data driven CLM3.5 can be used to generate accurate and continuous soil moisture of high resolution (1km) in Xinjiang. This study can help understand the spatiotemporal features of the soil moisture, and provide important input for hydrological studies and agricultural water resources management over the arid region.

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The impacts of human activities on the water–land environment of the Shiyang River basin, an arid region in northwest China / Les impacts des activités humaines sur l’environnement pédo-hydrologique du bassin de la Rivière Shiyang, une région aride du nord-ouest de la Chine

Hydrological Sciences Journal ◽

10.1623/hysj.49.3.413.54347 ◽

2004 ◽

Vol 49 (3) ◽

Cited By ~ 82

Author(s):

Shaozhong Kang ◽

Xiaoling Su ◽

Ling Tong ◽

Peize Shi ◽

Xiuying Yang ◽

...

Keyword(s):

River Basin ◽

Human Activities ◽

Arid Region ◽

Northwest China ◽

Shiyang River Basin

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A Comprehensive Approach to Assess the Hydrological Drought of Inland River Basin in Northwest China

Atmosphere ◽

10.3390/atmos9100370 ◽

2018 ◽

Vol 9 (10) ◽

pp. 370 ◽

Cited By ~ 7

Author(s):

Nina Zhu ◽

Jianhua Xu ◽

Weihong Li ◽

Kaiming Li ◽

Cheng Zhou

Keyword(s):

Soil Moisture ◽

River Basin ◽

Potential Evapotranspiration ◽

Warning System ◽

Northwest China ◽

Reanalysis Data ◽

Hydrological Drought ◽

Comprehensive Approach ◽

Inland River ◽

Inland River Basin

How to measure and quantitatively assess hydrological drought (HD) in the inland river basins of Northwest China is a difficult problem because of the complicated geographical environment and climatic processes. To address this problem, we conducted a comprehensive approach and selected the Aksu River Basin (ARB) as a typical inland river basin to quantitatively assess the hydrological drought based on the observed data and reanalysis data during the period of 1980–2010. We used two mutual complementing indicators, i.e., the standardized runoff index (SRI) and standardized terrestrial water storage index (SWSI), to quantitatively measure the spatio-temporal pattern of HD, where the SRI calculated from the observed runoff data indicate the time trend of HD of the whole basin, while SWSI extracted from the reanalysis data indicate the spatial pattern of HD. We also used the auto-regressive distribution lag model (ARDL) to show the autocorrelation of HD and its dependence on precipitation, potential evapotranspiration (PET), and soil moisture. The main conclusions are as follows: (a) the western and eastern regions of the ARB were prone to drought, whereas the frequency of drought in the middle of the ARB is relatively lower; (b) HD presents significant autocorrelation with two months’ lag, and soil moisture is correlated with SWSI with two months’ lag, whereas PET and precipitation are correlated with SWSI with 1 month’ lag; (c) the thresholds of HD for annual PET, annual precipitation, and annual average soil moisture are greater than 844.05 mm, less than 134.52 mm, and less than 411.07 kg/m2, respectively. A drought early warning system that is based on the thresholds was designed.

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