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Distribution,characteristics and influencing factors of fresh groundwater resources in the Loess Plateau,China

China Geology 2021年第3期4卷 509-526页

作者： Hai-xue Li Shuang-bao Han Xi Wu Sai Wang Wei-po Liu Tao Ma Meng-nan Zhang Yu-tao Wei Fu-qiang Yuan Lei Yuan Fu-cheng Li Bin Wu Yu-shan Wang Min-min Zhaoa Han-wen Yang Shi-bo Wei Center for Hydrogeology and Environmental Geology Survey China Geological SurveyBaoding 071051China Southern University of Science and Technology Shenzhen 518055China Geological Environment Monitoring Institute of Gansu Province Lanzhou 730050China China Institute for GeoEnvironmental Monitoring China Geological SurveyBeijing 100081China Xi'an Center China Geological SurveyXi'an 710100China

The fresh groundwater in the Loess Plateau serves as a major source of water required for the production and livelihood of local residents and is greatly significant for regional economic and social development and ecological protection.This paper analyzes the hydrogeological conditions and groundwater characteristics in the Loess Plateau,expatiates on the types and distribution characteristics of the fresh groundwater in the plateau,and analyzes the influencing factors and mechanisms in the formation of the fresh groundwater in the plateau as a priority.Based on this,it summarizes the impacts of human activities and climatic change on the regional fresh groundwater.The groundwater in Loess Plateau features uneven temporal-spatial distribution,with the distribution space of the fresh groundwater closely relating to precipitation.The groundwater shows a distinct zoning pattern of hydrochemical types.It is fresh water in shallow parts and is salt water in deep parts overall,while the fresh water of exploration value is distributed only in a small range.The storage space and migration pathways of fresh groundwater in the loess area feature dual voids,vertical multilayers,variable structure,poor renewability,complex recharge processes,and distinct spatial differences.In general,the total dissolved solids(TDS)of the same type of groundwater tends to gradually increase from recharge areas to discharge areas.Conditions favorable for the formation of fresh groundwater in loess tablelands include the low content of soluble salts in strata,weak evaporation,and special hydrodynamic conditions.Owing to climate change and human activities,the resource quantity of regional fresh water tends to decrease overall,and the groundwater dynamic field and the recharge-discharge relationships between groundwater and surface water have changed in local areas.Human activities have a small impact on the water quality but slightly affect the water quantity of the groundwater in loess.

关键词： Fresh groundwater Distribution pattern Climate change Human activities Hydrogeological survey engineering Loess Plateau China

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Slope spectrum critical area and its spatial variation in the Loess Plateau of China

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Journal of Geographical Sciences 2015年第12期25卷 1452-1466页

作者： TANG Guoan SONG Xiaodong LI Fayuan ZHANG Yong XION-GLiyang Key Laboratory of Virtual Geographic Environment (Nanjing Normal University) Ministry of Education Nanjing 210023 China State Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province) Nanjing 210023 China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Ap- plication Nanjing 210023 China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science CAS Nanjing 210008 China Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center China Meteorological Administration Beijing 100081 China

Slope spectrum has been proved to be a significant methodology in revealing geomorphological features in the study of Chinese loess terrain. The determination of critical areas in deriving slope spectra is an indispensable task. Along with the increase in the size of the study area, the derived spectra are becoming more and more alike, such that their dif- ferences can be ignored in favor of a standard. Subsequently, the test size is defined as the Slope Spectrum Critical Area （SSCA）. SSCA is not only the foundation of the slope spectrum calculation but also, to some extent, a reflection of geomorphological development of loess relief. High resolution DEMs are important in extracting the slope spectrum. A set of 48 DEMs with different landform areas of the Loess Plateau in northern Shaanxi province was selected for the experiment. The spatial distribution of SSCA is investigated with a geo-statistical analysis method, resulting in values ranging from 6.18 km^2 to 35.1 km^2. Primary experimental results show that the spatial distribution of SSCA is correlated with the spatial distribution of the soil erosion intensity, to a certain extent reflecting the terrain complexity. The critical area of the slope spectrum presents a spatial variation trend of weak-strong-weak from north to south. Four terrain parameters, gully density, slope skewness, terrain driving force （Td） and slope of slope （SOS）, were chosen as indicators. There exists a good exponential function relationship between SSCA and gully density, terrain driving force （Td） and SOS and a loga- rithmic function relationship between SSCA and slope skewness. Slope skewness increases, and gully density, terrain driving force and SOS decrease with increasing SSCA. SSCA can be utilized as a discriminating factor to identify loess landforms, in that spatial distributions of SSCA and the evolution of loess landforms are correlative. Following the evolution of a loess landform from tableland to gully-hilly region, this also proves that SSCA can represent the develop

关键词： digital elevation model slope spectrum critical area spatial variation independent geomorphological unit Loess Plateau

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Solute transport characteristics of a deep soil profile in the Loess Plateau,China

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Journal of Arid Land 2018年第4期10卷 628-637页

作者： WANG Jiao SHAO Ming'an Key Laboratory of Ecosystems Network Observation and Modeling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100China

Understanding solute transport behaviors of deep soil profile in the Loess Plateau is helpful for ecological construction and agricultural production improvement. In this study, solute transport processes of a deep soil profile were measured by a conservative tracer experiment using 25 undisturbed soil cores （20 cm long and 7 cm diameter for each） continuously sampled from the surface downward to the depth of 500 cm in the Loess Plateau of China. The solute transport breakthrough curves （BTCs） were analyzed in terms of the convection-dispersion equation （CDE） and the mobile-immobile model （MIM）. Average pore-water velocity and dispersion coefficient （or effective dispersion coefficient） were calculated using the CDE and MIM. Basic soil properties and water infiltration parameters were also determined to explore their influence on the solute transport parameters. Both pore-water velocity and dispersion coefficient （or effective dispersion coefficient） generally decreased with increasing depth, and the dispersivity fluctuated along the soil profile. There was a good linear correlation between log-transformed pore-water velocity and dispersion coefficient, with a slope of about 1.0 and an average dispersivity of 0.25 for the entire soil profile. Generally speaking, the soil was more homogeneous along the soil profile. Our results also show that hydrodynamic dispersion is the dominant mechanism of solute transport of loess soils in the study area.

关键词： solute transport loess soil pore-water velocity dispersion coefficient hydraulic conductivity Loess Plateau

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Soil temperature and moisture sensitivities of soil CO_2 efflux before and after tillage in a wheat field of Loess Plateau,China

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Journal of Environmental Sciences 2011年第1期23卷 79-86页

作者： Hongxing Zhang Xiaoke Wang Zongwei Feng Junzhu Pang Fei Lu Zhiyun Ouyang Hua Zheng Wenzhao Liu Dafeng Hui State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Shaanxi 722400 China Department of Biological Sciences Tennessee State University 3500 John A. Merritt Blvd. Nashville TN 37209 USA

As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies have investigated the influences of tillage on the responses of soil CO2 efflux （SCE） to soil temperature and moisture. Using a multi-channel automated CO2 efflux chamber system, we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau, China. The changes in soil temperature and moisture sensitivities of SCE, denoted by the Q10 value and linear regression slope respectively, were compared in the same range of soil temperature and moisture before and after the tillage. The results showed that, after the tillage, SCE increased by 1.2-2.2 times; the soil temperature sensitivity increased by 36.1%-37.5%; and the soil moisture sensitivity increased by 140%-166%. Thus, the tillage-induced increase in SCE might partially be attributed to the increases in temperature and moisture sensitivity of SCE.

关键词： soil CO2 efflux Loess Plateau moisture sensitivity temperature sensitivity tillage wheat field

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Responses of nighttime sap flow to atmospheric and soil dryness and its potential roles for shrubs on the Loess Plateau of China

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Journal of Plant Ecology 2018年第5期11卷 717-729页

作者： Weiwei Fang Nan Lu Yu Zhang Lei Jiao Bojie Fu State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China College of Tourism and Environment Shaanxi Normal UniversityShaanxi 710119China

Aims Nocturnal sap flow(E_(night))has been observed in a variety of plant species and environmental conditions.In water-limited environ-ments,E_(night) is important in the regulation of plant water’s physi-ology.This study was designed to evaluate the way in which E_(night)(defined as sap flow from 20:30 to 06:00)responded to changes in the atmospheric vapor pressure deficit(VPD)and the soil water con-tent(SWC),and explored its potential physiological significance for different plant species in a semi-arid area.Methods We selected three shrub species:Vitex negundo L.(VN),Hippophae rhamnoides L.(HR)and Spiraea pubescens Turcz(SP)in the semi-arid Loess Plateau of China.The plots of the three communities dominated by each of three species were on the same hill slope.Half-hourly sap flow density was measured in six to seven sample stems for each species during the main grow-ing season(June to August 2015).VPD,SWC,leaf water potential(Ψleaf)and stomatal conductance(G_(s))were measured at the same time.Regression analyses were conducted to determine the rela-tionships between E_(night),E_(day),E_(night)/E_(daily),VPD and SWC at half-hourly and daily time scales,as well as between E_(night),E_(day) andΨleaf.Important Findings The mean values of E_(night) and E_(day) were higher,but E_(night)/E_(daily) val-ues were lower for VN compared to HR and SP.The responses of sap flow density to VPD and SWC varied at different temporal scales.VPD was the dominant factor that affected E_(night) and E_(day) at the half-hourly scale for all three species.In contrast,SWC was the key factor that influenced E_(day) at the daily time scale.The values of E_(day) and E_(night)/E_(daily) correlated negatively with SWC because the effect of SWC was stronger on E_(day) than on E_(night).Although the low fraction of E_(night)/E_(daily)(4%-7%)may indicate a minor short-term effect of E_(night) on the standing water balance,E_(night) had eco-physiologically significance to the plants.The discrepancy inΨleaf between sunset and the following day’s

关键词： nocturnal sap flow stem refilling stomatal conductance leaf water potential Loess Plateau

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Physiological responses of artificial moss biocrusts to dehydration-rehydration process and heat stress on the Loess Plateau, China

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Journal of Arid Land 2017年第3期9卷 419-431页

作者： BU Chongfeng WANG Chun YANG Yongsheng ZHANG Li Matthew A BOWKER Institute of Soil and Water Conservation Northwest A&F University Yangling 712100 China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling 712100 China Northwest Institute of plateau Biology Chinese Academy of Sciences Xining 810001 China Qinghai Remote Sensing Monitoring Center of Eco-Environment Xining 810001 China School of Forestry Northern Arizona University Flagstaff 86011 USA

Ex-situ cultivation of biological soil crusts （biocrusts） is a promising technology to produce materials that can induce the recovery of biocrusts in the field for the purposes of preventing soil erosion and improving hydrological function in degraded ecosystems. However, the ability of artificially cultivated biocrusts to survive under adverse field conditions, including drought and heat stresses, is still relatively unknown. Mosses can bolster biocrust resistance to the stresses （e.g., drought and heat） and the resistance may be introduced prior to field cultivation. In this study, we subjected the well-developed artificial moss biocrusts （dominant species of Didjmodon vinealis （Brid.） Zand.） that we cultivated in the phytotron to a dehydration-rehydration experiment and also a heat stress experiment and measured the activities of protective enzymes （including peroxidase （POD）, superoxide dismutase （SOD）, and catalase （CAT）） and the contents of osmoregulatory substances （including soluble proteins and soluble sugars） and malondialdehyde （MDA, an indicator of oxidative stress） in the stem and leaf fragments of mosses. The results showed that, during the dehydration process, the activities of protective enzymes and the contents of osmoregulatory substances and MDA gradually increased with increasing duration of drought stress （over 13 days）. During the rehydration process, values of these parameters decreased rapidly after 1 d of rehydration. The values then showed a gradual decrease for 5 days, approaching to the control levels. Under heat stress （45℃）, the activities of protective enzymes and the content of soluble proteins increased rapidly within 2 h of heat exposure and then decreased gradually with increasing duration of heat exposure. In contrast, the contents of soluble sugars and MDA always increased gradually with increasing duration of heat exposure. This study indicates that artificial moss biocrusts possess a strong drought resistance and this resistance can be enhanced after a gradual dehydration tr

关键词： dehydration-rehydration heat stress Didymodon vinealis （Brid.） Zand. resistance Loess Plateau

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Effects of land-use types on the vertical distribution of fractions of oxidizable organic carbon on the Loess Plateau, China

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Journal of Arid Land 2016年第2期8卷 221-231页

作者： SUN Caili XUE Sha CHAI Zongzheng ZHANG Chao LIU Guobin Institute of Soil and Water Conservation Northwest A&F University Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources College of Forestry Northwest A&F University

The oxidizability of soil organic carbon （SOC） influences soil quality and carbon sequestration. Four fractions of oxidizable organic carbon （very labile （C1）, labile （C2）, less labile （C3） and non-labile （C4）） reflect the status and composition of SOC and have implications for the change and retention of SOC. Studies of the fractions of oxidizable organic carbon （OC） have been limited to shallow soil depths and agroecosystems. How these fractions respond at deep soil depths and in other types of land-use is not clear. In this study, we evaluated the vertical distributions of the fractions of oxidizable organic carbon to a soil depth of 5.0 m in 10 land-use types in the Zhifanggou Watershed on the Loess Plateau, China. Along the soil profile, C1 contents were highly variable in the natural grassland and shrubland I （Caragana microphylla）, C2 and C4 contents were highly variable in the natural grassland and two terraced croplands, respectively, and C3 contents varied little. Among the land-use types, natural grassland had the highest C1 and C2 contents in the 0-0.4 m layers, followed by shrubland I in the 0-0.1 m layer. Natural grassland had the highest C4 contents in the 1.0-4.5 m layers. Natural grassland and shrubland I thus contributed to improve the oxidizability of SOC in shallow soil, and the deep soil of natural grassland has a large potential to sequester SOC on the Loess Plateau.

关键词： Iand-use types deep soil oxidizable organic-carbon fractions Loess Plateau

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Effects of long-term fertilization on oxidizable organic carbon fractions on the Loess Plateau,China

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Journal of Arid Land 2016年第4期8卷 579-590页

作者： DING Shaonan XUE Sha LIU Guobin College of Natural Resources and Environment Northwest A&F University Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources

The effects of long-term fertilization on pools of soil organic carbon （SOC） have been well studied, but limited information is available on the oxidizable organic carbon （OOC） fractions, especially for the Loess Plateau in China. We evaluated the effects of a 15-year fertilization on the OOC fractions （F1, F2, F3 and F4） in the 0-20 and 20-40 cm soil layers in flat farmland under nine treatments （N （nitrogen, urea）, P （phosphorus, monocalcium phosphate）, M （organic fertilizer, composted sheep manure）, N＋P （NP）, M＋N （MN）, M＋P （MP）, M＋N＋P （MNP）, CK （control, no fertilizer） and bare land （BL, no crops or fertilizer））. SOC content increased more markedly in the treatment containing manure than in those with inorganic fertilizers alone. F1, F2, F4 and F3 accounted for 47%, 27%, 18% and 8% of total organic carbon, respectively. F1 was a more sensitive index than the other C fractions in the sensitivity index （SI） analysis. F1 and F2 were highly correlated with total nitrogen （TN） and available nitrogen （AN）, F3 was negatively correlated with pH and F4 was correlated with TN. A cluster analysis showed that the treatments containing manure formed one group, and the other treatments formed another group, which indicated the different effects of fertilization on soil properties. Long-term fertilization with inorganic fertilizer increased the F4 fraction while manure fertilizer not only increased labile fractions （F1） in a short time, but also increased passive fraction （F4） over a longer term. The mixed fertilizer mainly affected F3 fraction. The study demonstrated that manure fertilizer was recommended to use in the farmland on the Loess Plateau for the long-term sustainability of agriculture.

关键词： long-term fertilization oxidizable organic carbon fractions farmland soil Loess Plateau

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HIGH QUALITY DEVELOPMENTAL APPROACH FOR SOIL AND WATER CONSERVATION AND ECOLOGICAL PROTECTION ON THE Loess Plateau

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Frontiers of Agricultural Science and Engineering 2021年第4期8卷 501-511页

作者： Lei DENG Zhouping SHANGGUAN State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China

The Loess Plateau is the core area in the Yellow River basin for implementing environmental protection and high-quality development strategies. A series of ecological projects has implemented aimed at soil and water conservation and ecological management on the Loess Plateau over the past 70 years. The effects of the ecological projects are apparent mainly through a marked increase in vegetation cover, controlled soil erosion and reduced flow of sediment into the Yellow River, continual optimization of the industrial structure and increased production from arable land, poverty alleviation and greater prosperity, and optimal allocation of space for biological organisms.Major problems have also been analyzed in ecological management including the fragile ecosystem of the region, maintaining the stability of vegetation,lower agricultural productivity and continued risk from natural disasters. Some suitable schemes and models have been developed for the coordinated development of the region through research and demonstration, striking the optimum balance between rural industry and ecology, and increased regionalcapacity to supply high-quality ecological products. Countermeasures to address the problems are suggested to guide ecological management and high-quality development in the future.

关键词： ecological management high quality development industrial structure soil erosion soil and water conservation Loess Plateau

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Soil hydraulic conductivity as affected by vegetation restoration age on the Loess Plateau,China

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Journal of Arid Land 2016年第4期8卷 546-555页

作者： REN Zongping ZHU Liangjun WANG Bing CHENG Shengdong State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area Xi'an University of Technology State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau Institute of Soil and Water ConservationChinese Academy of Science State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences

The Loess Plateau of China has experienced extensive vegetation restoration in the past several decades, which leads to great changes in soil properties such as soil bulk, porosity, and organic matter with the vegetation restoration age. And these soil properties have great effect on the soil infiltration and soil hydraulic conductivity. However, the potential changes in soil hydraulic conductivity caused by vegetation restoration age have not been well understood. This study was conducted to investigate the changes in soil hydraulic conductivity under five grasslands with different vegetation restoration ages （3, 10, 18, 28 and 37 years） compared to a slope farmland, and further to identify the factors responsible for these changes on the Loess Plateau of China. At each site, accumulative infiltration amount and soil hydraulic conductivity were determined using a disc permeameter with a water supply pressure of -20 mm. Soil properties were measured for analyzing their potential factors influencing soil hydraulic conductivity. The results showed that the soil bulk had no significant changes over the initial 20 years of restoration （P〉0.05）; the total porosity, capillary porosity and field capacity decreased significantly in the grass land with 28 and 37 restoration ages compared to the slope farmland; accumulative infiltration amount and soil hydraulic conductivity were significantly enhanced after 18 years of vegetation restoration. However, accumulative infiltration amount and soil hydraulic conductivity fluctuated over the initial 10 years of restoration. The increase in soil hydraulic conductivity with vegetation restoration was closely related to the changes in soil texture and structure. Soil sand and clay contents were the most influential factors on soil hydraulic conductivity, followed by bulk density, soil porosity, root density and crust thickness. The Pearson correlation coefficients indicated that the soil hydraulic conductivity was affected by multiply factors. These results are helpful to understan

关键词： disc permeameter effect factors soil infiltration vegetation restoration Loess Plateau

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