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2011 International Conference on Energy and Environment(ICEE 2011)

作者： Xiaona Liu Tai yuan university of science and technology

The heat-pulse technique is emerging as a useful technique for measuring soil water content（θ）, with the advantages of automated, rapid, and minimal destructive. The purpose of this study is to evaluate the performance of the Liu et al.（2008） thermo-TDR（time domain reflectometry） sensor for measuring soil water content using the heat-pulse technique. For this sensor, the root mean square errors（RMSE） of heat-pulse soil water content（θHP） estimates compared with gravimetric measures in laboratory evaluations was 0.011 m3 m-3 and was 0.018 m3 m-3 in a field evaluation. The results indicated that the sensor with a needle diameter of 2 mm, needle length of 40 mm, and needle-to-needle spacing of 8 mm can provide accurate, nondestructive, repeated estimates of soil θ.

关键词： Heat-pulse Time Domain Reflectometry TDR soil volumetric water content Thermo-TDR

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How precipitation and grazing influence the ecological functions of drought-prone grasslands on the northern slopes of the Tianshan Mountains, China?

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Journal of Arid Land 2021年第1期13卷 88-97页

作者： HUANG Xiaotao LUO Geping CHEN Chunbo PENG Jian ZHANG Chujie ZHOU Huakun YAO Buqing MA Zhen XI Xiaoyan Qinghai Provincial Key Laboratory of Restoration Ecology for Cold Regions Northwest Institute of Plateau BiologyChinese Academy of SciencesXining 810008China Key Laboratory of Adaptation and Evolution of Plateau Biota Chinese Academy of SciencesXining 810008China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Xinjiang Grassland Technical Popularization Station Urumqi 830049China Qinghai Environmental Sciences Research and Design Institute Co.Ltd. Xining 810007China

Drought-prone grasslands provide a critical resource for the millions of people who are dependent on livestock for food security.However,this ecosystem is potentially vulnerable to climate change(e.g.,precipitation)and human activity(e.g.,grazing).Despite this,the influences of precipitation and grazing on ecological functions of drought-prone grasslands in the Tianshan Mountains remain relatively unexplored.Therefore,we conducted a systematic field investigation and a clipping experiment(simulating different intensities of grazing)in a drought-prone grassland on the northern slopes of the Tianshan Mountains in China to examine the influences of precipitation and grazing on aboveground biomass(AGB),soil volumetric water content(SVWC),and precipitation use efficiency(PUE)during the period of 2014–2017.We obtained the meteorological and SVWC data using an HL20 Bowen ratio system and a PR2 soil profile hydrometer,respectively.We found that AGB was clearly affected by both the amount and seasonal pattern of precipitation,and that PUE may be relatively low in years with either low or excessive precipitation.The PUE values were generally higher in the rapid growing season(April–July)than in the entire growing season(April–October).Overall,moderate grazing can promote plant growth under water stress conditions.The SVWC value was higher in the clipped plots than in the unclipped plots in the rapid growing season(April–July),but it was lower in the clipped plots than in the unclipped plots in the slow growing season(August–October).Our findings can enhance the understanding of the ecological effects of precipitation and grazing in drought-prone grasslands and provide data that will support the effective local grassland management.

关键词： climate change human activity aboveground biomass precipitation use efficiency soil volumetric water content water stress

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Construction of Forecast and Early Warning System of Meteorological and Geological Disasters in Qinghai Province

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Meteorological and Environmental Research 2022年第3期13卷 49-55页

作者： Qingping LI Qin GUAN Aijuan BAI Jinhai LI Yujun ZHU Qinghai Provincial Key Laboratory of Disaster Prevention and Mitigation Xining 811300China Huangnanzhou Meteorological Bureau Tongren 811300China Qinghai Provincial Meteorological Observatory Xining 831100China Chengdu University of Information Engineering Chengdu 210025China

Based on the meteorological and geological disaster data, ground observation data set, CLDAS grid point data set, and EC, BJ and other model product data during 2008-2020, the temporal and spatial distribution characteristics of meteorological and geological disasters and precipitation were analyzed, and the causes of the occurrence of meteorological geological disasters and the deviation of model precipitation forecast were revealed. Besides, an objective precipitation forecast system and a forecast and early warning system of meteorological and geological disasters were established. The results show that meteorological and geological disasters and precipitation were mainly concentrated from May to October, of which continuous precipitation appeared frequently in June and September, and convective precipitation was mainly distributed in July-August;the occurrence frequency of meteorological and geological disasters was basically consistent with the distribution of accumulated precipitation and short-term heavy precipitation, and they were mainly concentrated in the southern and eastern parts of Qinghai. Meteorological and geological disasters were basically caused by heavy rain and above, and meteorological and geological disasters were divided into three types: continuous precipitation(type I), short-term heavy precipitation(type II) and mixed precipitation(type III). For type I, the early warning conditions of meteorological and geological disasters in Qinghai are as follows: if the soil volumetric water content difference between 0-10 and 10-40 cm is ≤0.03 mm^(3)/mm^(3), or the soil volumetric water content at one of the depths is ≥0.25 mm^(3)/mm^(3), the future effective precipitation reaches 8.4 mm in 1 h, 10.2 mm in 2 h, 11.5 mm in 3 h, 14.2 mm in 6 h, 17.7 mm in 12 h, and 18.2 mm in 24 h, and such warning conditions are mainly used in Yushu, Guoluo, southern Hainan, southern Huangnan and other places. For type II, when the future effective precipitation is up to 11.5 mm in 1 h, 14.9 mm in 2 h, 16.2 mm in

关键词： Meteorological and geological disasters Precipitation threshold soil volumetric water content Continuous precipitation Short-term heavy precipitation Forecast and early warning

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Evaluating Reflected GPS Signal as a Potential Tool for Cotton Irrigation Scheduling

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Advances in Remote Sensing 2016年第3期5卷 157-167页

作者： Xin Qiao Ahmad Khalilian Jose O. Payero Joe Mari Maja Charles V. Privette Young J. Han Department of Agricultural and Environmental Sciences Clemson University Clemson SC USA Edisto REC Clemson University Blackville SC USA

Accurate soil moisture content measurements are vital to precision irrigation management. Remote sensing using the microwave spectrum (such as GPS signals) has been used for measuring large area soil moisture contents. In our previous work, we estimated surface soil moisture contents for bare soil using a GPS Delay Mapping Receiver (DMR) developed by NASA. However, the effect of vegetation was not considered in these studies. Hence the objectives of this study were to: 1) investigate the feasibility of using DMR to determine soil moisture content in cotton production fields;2) evaluate the attenuation effect of vegetation (cotton) on reflected GPS signal. Field experiments were conducted during the 2013 and 2014 growing seasons in South Carolina. GPS antennas were mounted at three heights (1.6, 2.7, and 4.2 m) over cotton fields to measure reflected GPS signals (DMR readings). DMR readings, soil core samples, and plant measurements were collected about once a week and attenuation effect of plant canopy was calculated. Results showed that DMR was able to detect soil moisture changes within one week after precipitation events that were larger than 25 mm per day. However, the DMR readings were poorly correlated with soil volumetric water content during dry periods. Attenuation effect of plant canopy was not significant. For irrigation purpose, the results suggested that the sensitivity of reflected GPS signals to soil moisture changes needed to be further studied before this technology could be utilized for irrigation scheduling in cotton production. Refinement of this technology will expand the use of advanced remote sensing technology for site-specific and timely irrigation scheduling. This would eliminate the need to install moisture sensors in production fields, which can interfere with farming operations and increase production costs.

关键词： Remote Sensing GPS soil volumetric water content Cotton Irrigation

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Variation of Surface soil water contentin two types of land use in Nanjing suburb

Variation of Surface Soil Water Contentin two types of land ...

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2015海峡两岸水土保持学术研讨会

作者： Zhuang Jiayao Wu Huqiang Shao Yongchang Lab of water and soil conservation Nanjing forestry university

Oak forest and grassland in the Tongshan forestry farm in Nanjing,China were selected,within which,4 sets EM50 was used to measure soil volumetric water content（DASVWC）at depths of 5cm,15cm,30cm respectively and air humidity was measured at the height of 2 m.All these data were recorded continuously for every 15 minutes during June,2010 to May,2011.Precipitation was measured in both two types of land use with a far distance transportation system for each mm precipitation.By analyzing the vertical-temporal variable quantity,variations of DASVWC and their correlation with meteorological factors,it was found that they were affected by precipitation,air temperature and humidity and DASVWC.Quite different from the variability law of DASVWC in the Yellow River watershed,where variability of DASVWC in the 5cm layer was lower than those in the 15 cm and 30 cm soil layer,in this research variability of DASVWC in the 0-5 layer was higher than those in the 15 cm and 30 cm soil layer in the two types of land use.DASVWC in oak forest in the 0-30 soil layer was lower compared with those in the grass land,showing decrease of DASVWC in the surface soil layer with increase of plant coverage.In the same type of land use,values of DASVWC at three layers showed linear regression outstandingly.During rain intervals indifferent seasons,DASVWC showed exponential correlation with time very significantly.

关键词： Oak forest Grass land soil volumetric water content Land use type

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