scholarly journals Provenance of Aeolian Sediments in the Ordos Deserts and Its Implication for Weathering, Sedimentary Processes

2021 ◽  
Vol 9 ◽  
Author(s):  
Guoxiang Chen ◽  
Zhibao Dong ◽  
Chao Li ◽  
Weikang Shi ◽  
Tianjie Shao ◽  
...  
Keyword(s):  
Yellow River ◽  
Grain Morphology ◽  
Heavy Minerals ◽  
The Yellow River ◽  
Sandy Land ◽  
Mu Us Sandy Land ◽  
Aeolian Sediments ◽  
Southwest Region ◽  
Semi Arid ◽  
Aeolian Sands

Identifying the provenance of aeolian deposits in semi-arid zones of China is beneficial in understanding Earth’s surface processes and helping to alleviate ecological stress. In this paper, we use grain-size, geochemical elements, heavy-minerals, and quartz grain morphology data to investigate the potential source of aeolian sands from the Ordos Deserts (Mu Us Sandy Land and Hobq Desert). Sedimentological, geochemical and geomorphological results indicate that significant provenance differences exist among various parts of the Mu Us Sandy Land, i.e., aeolian sediments from the southwest region are obviously distinct from other areas in the Mu Us Sandy Land but show the same external provenance with the Hobq Desert referring to the sorting, mineralogical maturity, geochemical characteristics, heavy-minerals, and quartz grain morphology. Comparing the samples from the Ordos Deserts with felsic rocks from potential sources via a serious of geochemical methods, we conclude that: 1) Aeolian sands from other regions of the Mu Us are a mixture of binary provenance, i.e., one originated from local lacustrine sediments and underlying sandstones, and another from the Alxa Plateau (AP) carried by northwesterly Asian winter monsoon. 2) The fluvial deposits denuded from the Qilian Orogenic Belt in the Northeastern Tibetan Plateau (NTP) and carried by the Yellow River are likely the initial material source for the southwest region of the Mu Us Sandy Land and the Hobq Desert. 3) The Yellow River plays a significant and critical role in sediment transport for sand seas in arid and semi-arid areas of northern China.

scholarly journals Study on the hydro-chemistry process after mixing between water and rocks

2018 ◽  
Vol 54 (2) ◽  
pp. 104-114
Author(s):  
Xiuyan Jing ◽  
Hongbin Yang ◽  
Na Wang
Keyword(s):  
River Water ◽  
Arid Regions ◽  
Yellow River ◽  
Dilution Effect ◽  
Northwest China ◽  
Experimental Simulation ◽  
The Yellow River ◽  
Mixing Ratio ◽  
Close Attention ◽  
Semi Arid

Abstract The chemical evolution of groundwater has received close attention from hydro-geologists. Northwest China largely consists of arid and semi-arid regions, where surface water and groundwater frequently exchange with each other, and where the mixing and water–rock interactions significantly affect the direction of water quality evolution. Based on experimental simulation, this paper investigates the interactions among the Yellow River water, groundwater and rocks in Yinchuan. The study found that when groundwater is mixed with the Yellow River water, the Yellow River water has a certain dilution effect on the hydro-chemical composition of groundwater; however, this effect is not simply diluted by proportion for no reaction between irons, but a portion of calcium, sulfur, and carbonate form precipitates. After mixing of the Yellow River water, groundwater and rocks, the pH increased, and the carbon dioxide system reached equilibrium again. In addition, CO32− was produced. While Na+ increase was mainly due to dissolution, SO42− decrease was because of precipitation. The precipitation or dissolution of Ca2+, Mg2+, and CO32− mainly depended on the mixing ratio between groundwater and river water, which suggested the reversible behavior of the dissolution-precipitation of carbonate minerals.

scholarly journals A New Application of Random Forest Algorithm to Estimate Coverage of Moss-Dominated Biological Soil Crusts in Semi-Arid Mu Us Sandy Land, China

2019 ◽  
Vol 11 (11) ◽  
pp. 1286 ◽  
Author(s):  
Xiang Chen ◽  
Tao Wang ◽  
Shulin Liu ◽  
Fei Peng ◽  
Atsushi Tsunekawa ◽  
...  
Keyword(s):  
Random Forest ◽  
Biological Soil Crusts ◽  
Data Availability ◽  
Sandy Land ◽  
Desert Ecosystems ◽  
Mu Us Sandy Land ◽  
Soil Crusts ◽  
Band Combinations ◽  
Semi Arid ◽  
Sentinel 2

Biological soil crusts (BSCs) play an essential role in desert ecosystems. Knowledge of the distribution and disappearance of BSCs is vital for the management of ecosystems and for desertification researches. However, the major remote sensing approaches used to extract BSCs are multispectral indices, which lack accuracy, and hyperspectral indices, which have lower data availability and require a higher computational effort. This study employs random forest (RF) models to optimize the extraction of BSCs using band combinations similar to the two multispectral BSC indices (Crust Index-CI; Biological Soil Crust Index-BSCI), but covering all possible band combinations. Simulated multispectral datasets resampled from in-situ hyperspectral data were used to extract BSC information. Multispectral datasets (Landsat-8 and Sentinel-2 datasets) were then used to detect BSC coverage in Mu Us Sandy Land, located in northern China, where BSCs dominated by moss are widely distributed. The results show that (i) the spectral curves of moss-dominated BSCs are different from those of other typical land surfaces, (ii) the BSC coverage can be predicted using the simulated multispectral data (mean square error (MSE) < 0.01), (iii) Sentinel-2 satellite datasets with CI-based band combinations provided a reliable RF model for detecting moss-dominated BSCs (10-fold validation, R2 = 0.947; ground validation, R2 = 0.906). In conclusion, application of the RF algorithm to the Sentinel-2 dataset can precisely and effectively map BSCs dominated by moss. This new application can be used as a theoretical basis for detecting BSCs in other arid and semi-arid lands within desert ecosystems.

Effects of check dams on runoff and sediment load in a semi-arid river basin of the Yellow River

2016 ◽  
Vol 31 (7) ◽  
pp. 1791-1803 ◽  
Author(s):  
Erhui Li ◽  
Xingmin Mu ◽  
Guangju Zhao ◽  
Peng Gao ◽  
Wenyi Sun
Keyword(s):  
River Basin ◽  
Sediment Load ◽  
Yellow River ◽  
The Yellow River ◽  
Check Dams ◽  
Semi Arid

Water transport properties of seven woody species from the semi-arid Mu Us Sandy Land, China

2016 ◽  
Vol 12 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Y. Murakami ◽  
N. H. Miki ◽  
L. Yang ◽  
G. Zhang ◽  
L. H. Wang ◽  
...  
Keyword(s):  
Transport Properties ◽  
Water Transport ◽  
Woody Species ◽  
Sandy Land ◽  
Mu Us Sandy Land ◽  
Water Transport Properties ◽  
Semi Arid

scholarly journals Can the Pinus sylvestris var. mongolica sand-fixing forest develop sustainably in a semi-arid region?

2019 ◽  
Author(s):  
Yiben Cheng ◽  
Hongbin Zhan ◽  
Mingchang Shi
Keyword(s):  
Pinus Sylvestris ◽  
Arid Region ◽  
Arid Regions ◽  
Moisture Distribution ◽  
Water Infiltration ◽  
Accurate Estimation ◽  
Sandy Land ◽  
Mu Us Sandy Land ◽  
Semi Arid Region ◽  
Semi Arid

Abstract. Desertification is a global environmental and societal concern at present, and China is one of the countries that face the most severe damage of desertification. China’s so-called Three North shelterbelt Program (3NSP) has produced a vast area of lined forest in the semi-arid regions with the purpose of battling desertification. Such a wind-breaking and sand-fixing forest has successfully slowed down the incursion of desert. However, the vast artificial forestry consumes a large amount of water resources, which profoundly affect the fragile ecological environment in the semi-arid regions. In turn, a large amount of water loss also causes a great number of vegetation deaths or defects. To understand the water balance and sustainable development of artificial forest in semi-arid region, this study uses the 30-year-old lined Pinus sylvestris var. mongolica sand-fixing forest in the eastern part of Mu Us Sandy land in Northwestern China as an example. Specifically, this investigation studies the redistribution of water in soil under existing precipitation conditions, so as to evaluate whether the rain-feed forestry can develop sustainably or not. Rain gauge, newly designed lysimeter and soil moisture sensor are used to monitor precipitation, deep soil recharge (DSR) and soil water content, resulting in an accurate estimation of annual moisture distribution of the rain-feed Pinus sylvestris var. mongolica. The study shows that there are two obvious moisture recharge processes in an annual base for the Pinus sylvestris var. mongolica forest soil in Mu Us Sandy land: 1) the snow melted water infiltration-recharge process in the spring, and 2) the precipitation-recharge process in the summer. The recharge depth of the first process is 160 cm. The second process results in DSR (referring to recharge that can reach a depth more than 200 cm and may eventually replenish the groundwater reservoir). The DSR of 2016–2018 is 1.4 mm, 0.2 mm, 1.2 mm, respectively. To reach the recharge depths of 20 cm, 40 cm, 80 cm, 120 cm, 160 cm, and 200 cm, the corresponding precipitation intensities have to be 2.6 mm/d, 3.2 mm/d, 3.4 mm/d, 8.2 mm/d, 8.2 mm/d, and 13.2 mm/d, respectively. The annual evaporation amount in the Mu Us Sandyland Pinus sylvestris var. mongolica forest is 426.96 mm in 2016, 324.6 mm in 2017, 416.253 mm in 2018. This study concludes that under the current precipitation conditions, very small but observable DSR happened, thus the groundwater system underneath the forest may be replenished, meaning that the artificial Pinus forestry can probably develop sustainably. This study confirms that developing limited amount forestry in semi-arid regions is likely in a sustainable fashion. The widely variable annual precipitation in semi-arid areas may affect this conclusion and should be investigated in the future.

scholarly journals Redistribution process of precipitation in ecological restoration activity of Pinus sylvestris  var. mongolica in Mu Us Sandy Land, China

2021 ◽  
Author(s):  
Yiben Cheng ◽  
Hongbin Zhan ◽  
Wenbin Yang ◽  
Yunqi Wang ◽  
Qunou Jiang ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Soil Water ◽  
Sap Flow ◽  
Arid Regions ◽  
Moisture Distribution ◽  
Sandy Land ◽  
Mu Us Sandy Land ◽  
Shallow Soil ◽  
Semi Arid ◽  
Horizontal Area

Abstract. Precipitation was the most important water resource in semi-arid regions of China. The redistribution of precipitation among atmospheric water, soil water and groundwater are related to the land surface ecological system sustainability. The study took widely replanted Pinus sylvestris var. mongolica (PSM) in Mu Us Sandy Land (MUSL) as a research object and monitored precipitation, soil moisture, sap flow, and deep soil recharge (DSR) to find out moisture distribution in shallow soil layer. Results showed that the restoration process of PSM in MUSL changed the distribution of precipitation. Precipitation was intercepted in shallow soil, evapotranspiration increased, and DSR significantly decreased, resulting in up to 466.94 mm of precipitation returning to the atmosphere through evapotranspiration in 2016. Vegetation increased soil water storage (SWS) capacity, with maximum SWS in PSM plot and bare sandy land (BSL) being 260 mm and 197 mm per unit horizontal area, respectively in 2016. DSR decreased from 54.03 % of precipitation in BSL to 0.2 % of precipitation in PSM in 2016. Infiltration was not only intercepted by PSM ecosystem, resulting in a time lag, but was also affected by soil temperature, and the infiltration rate in the BSL plot was 11 times of that in the PSM plot from August to September in an annual base. SWS decreased 16 mm and 7.58 mm per unit horizontal area over a one-year period (from March to October) in 2017 and 2019, respectively. The PSM annual sap flow was maintained at a relatively constant level of 153.98 mm/yr. This study helps understand the role of precipitation-induced groundwater recharge in the process of vegetation restoration in semi-arid regions and explains the possible causes of PSM forest degradation. It is necessary to reduce PSM density to allow adaptation to extreme drought in the future.

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