Assessing spatial and temporal variability in water consumption and the maintainability oasis maximum area in an oasis region of Northwestern China     

XueXiang Chang  WenZhi Zhao  XueLi Chang  Bing Liu  Jun Du 《寒旱区科学》2020,12(4):217-233

Water consumption is a key role in improving the efficiency and sustainability of water management in arid environments.In this study, we explored an approach based on meta-analysis, MODIS NDVI products, land-use spatial distribution, and soil water physical parameters to gain insight into long-term and large scale distribution of land use and water consumption, maintain maximum Zhangye Oasis area according to Heihe River runoff, and suitable water resource management in Zhangye Oasis. This approach was initiated in order to improve the efficiency of irrigation and water resource management in arid regions. Results showed that Heihe River runoff can maintain a maximum Zhangye Oasis area of 22.49×10~4 hm~2.During the 2000-2016 growing seasons, actual oasis water consumption ranged from 11.35×10~8 m~3 to 13.73×10~8 m~3, with a mean of(12.89 ± 0.60)×10~8 m~3; if maintaining agricultural production and oasis stability was chosen, oasis water consumption ranged from 10.24×10~8 m~3 to 12.37×10~8 m~3, with a mean of(11.62 ± 0.53)×10~8 m~3. From the perspective of water resources management and ecosystem stability, it is necessary to reduce the area of Zhangye Oasis or choose the minimum water consumption method to manage the oasis, to ease the pressure of water shortage and maintain stable and sustainable development of the Zhangye Oasis. These results can provide future practical guidance for water resource management of coordinated development of the economy and the environment in an arid area.  相似文献   

Soil moisture temporal stability and spatio-temporal variability about a typical subalpine ecosystem in northwestern China     

Xi Zhu  Zhibin He  Jun Du  Longfei Chen  Pengfei Lin  Quanyan Tian 《水文研究》2020,34(11):2401-2417

Knowledge of the spatial–temporal variability of soil water content is critical for water management and restoration of vegetation in semi-arid areas. Using the temporal stability method, we investigated soil water relations and spatial–temporal variability of volumetric soil water content (VSWC) in the grassland–shrubland–forest transect at a typical semi-arid subalpine ecosystem in the Qilian Mountains, northwestern China. The VSWC was measured on 48 occasions to a depth of 70 cm at 50 locations along a 240-m transect during the 2016–2017 growing seasons. Results revealed that temporal variability in VSWC in the same soil layer in the three vegetation types and averaged across vegetation types tended to exhibit similar patterns of a decrease with increasing soil depth. Temporal stability in each vegetation type was stronger with an increase in soil depth. However, the results of temporal stability determined with standard deviation of relative difference (SDRD) disagreed with those based on the Spearman's rank correlation coefficient; the forest site had the highest Spearman rank correlation coefficient while the shrubland—the smallest SDRD in the 0–20 cm soil layer. Correlation analyses of VSWCs between two vegetation types indicated that soil water was related among all three vegetation types at the 0–20, and 0–70 cm soil layer, but in the 20–40 and 40–70 cm soil layers, significant correlation (p < .01) occurred only between adjacent vegetation types. In the upper soil layer (0–20 cm), soil water relations were mainly affected by surface runoff. In the lower soil layer (20–40 and 40–70 cm), soil water relations among the three vegetation types were highly complex, and probably resulting from a combination of root distribution and activity, interflow, and the impact of deep soil freeze–thaw dynamics. These results suggest that the factors affecting soil water are complex, and further research should address the relative importance of and interactions among different determining factors.  相似文献   

南昌市厚田剖面末次冰期风沙沉积的粒度分维特征及其揭示的古环境意义     

詹江振  李志文  王志刚  孙丽  黎武标  杜兰 《热带地理》2020,40(6):1075-1084

赣江下游阶地上断续发育着系列沙丘砂－砂质古土壤序列，有助于探讨亚热带地区粒度分维特征对古环境的指示意义。在多次综合考察的基础上，选择南昌市新建区的厚田剖面开展工作，在OSL年代和粒度测试基础上，采用分形理论中的幂指函数关系法分析了粒度分维特征，并将其与黏粒体积分数、平均粒径、冬夏季风敏感粒径、南京葫芦洞石笋氧同位素进行对比。结果表明：1）厚田剖面的沙丘砂－砂质古土壤序列主要形成于末次冰期（14.9—77.0 ka），其中沙丘砂的分维值为2.04~2.62（平均值2.34），砂质古土壤为2.24~2.70（平均值2.51）。2）分维值与夏季风强度敏感粒径呈正相关性，与冬季风强度敏感粒径呈负相关性，且与粒度分选性密切相关，标准偏差越小则分维值越小，反之则越大。3）分维值在垂向上呈现峰谷交替旋回，峰值分别对应MIS2早期、MIS3c和MIS3a阶段，该时期夏季风强盛，气候暖湿，砂质古土壤发育；谷值分别对应MIS2晚期、MIS3b和MIS4阶段，该时期冬季风强盛，气候干冷，沙丘砂发育。说明厚田沙地在末次冰期发生了3次气候冷暖旋回，其中还明显记录了H5、H6的极端寒冷事件。由此可见，鄱阳湖地区的风沙沉积序列基本同步于区域乃至全球性气候变化事件。  相似文献   

Monitoring of water surface temperature of Eurasian large lakes using MODIS land surface temperature product     

Jia Du  Pierre-Andre Jacinthe  Haohao Zhou  Xiaoyun Xiang  Boyu Zhao  Min Wang  Kaishan Song 《水文研究》2020,34(16):3582-3595

In this study, data from MODIS land surface temperature product level 3 (MOD11A2) were used to investigate the spatiotemporal variation of Eurasian lakes water surface temperature (LSWT) from 2001 to 2015, and to examine the most influencing factors of that variation. The temperature of most lakes in the dry climate zone and in the equatorial climatic zone varied from 17 to 31°C and from 23 to 27°C, respectively. LSWTs in the warm temperate and cold climatic zones were in the range of 20 to 27°C and −0.6 and 17°C, respectively. The average day time LSWT in the polar climate zone was −0.71°C in the summer. Lakes in high latitude and in the Tibetan Plateau displayed low LSWT, ranging from −11 to 26°C during the night time. Large spatial variations of diurnal temperature difference (DTD) were observed in lakes across Eurasia. However, variations in DTDs were small in lakes located in high latitude and in tropical rainforest regions. The shallow lakes showed a rapid response of LSWT to solar and atmospheric forcing, while in the large and deep lakes, that response was sluggish. Results of this study demonstrated the applicability of remote sensing and MODIS LST products to capture the spatial–temporal variability of LSWT across continental scales, in particular for the vast wilderness areas and protected environment in high latitude regions of the world. The approach can be used in future studies examining processes and factors controlling large scale variability of LSWT.  相似文献   

Genome-wide identification and transcriptome-based expression analysis of sox gene family in the Japanese flounder Paralichthys olivaceus     

Yu  Haiyang  Du  Xinxin  Li  Xiaojing  Qu  Jiangbo  Zhu  He  Zhang  Quanqi  Wang  Xubo 《中国海洋湖沼学报》2018,36(5):1731-1745

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Gravitational Waves and Gravitational-wave Sourcestwo     

Zhao Wen  Zhang Xing  Liu Xiao-jin  Zhang Yang  Wang Yun-yong  Zhang Fan  Zhao Yu-hang  Guo Yue-fan  Chen Yi-kang  Ai Shun-ke  Zhu Zong-hong  Wang Xiao-ge  Lebigot Eric  Du Zhi-hui  Cao Jun-wei  Qian Jin  Yin Cong  Wang Jian-bo  Wen Lin-qing 《Chinese Astronomy and Astrophysics》2018,42(4):487-526

The recent discovery of gravitational-wave burst GW150914 marks the coming of a new era of gravitational-wave astronomy, which provides a new window to study the physics of strong gravitational field, extremely massive stars, extremely high energy processes, and extremely early universe. In this article, we introduce the basic characters of gravitational waves in the Einstein's general relativity, their observational effects and main generation mechanisms, including the rotation of neutron stars, evolution of binary systems, and spontaneous generation in the inflation universe. Different sources produce the gravitational waves at quite different frequencies, which can be detected by different methods. In the lowest frequency range (f < 10^?15 Hz), the detection is mainly dependent of the observation of B-mode polarization of cosmic microwave background radiation. In the middle frequency range (10^?9 < f < 10^?6 Hz), the gravitational waves are detected by analyzing the timing residuals of millisecond pulsars. And in the high frequency range (10 ? 4 < f < 10⁴ Hz), they can be detected by the space-based and ground-based laser interferometers. In particular, we focus on the main features, detection methods, detection status, and the future prospects for several important sources, including the continuous sources (e.g., the spinning neutron stars, and stable binary systems), the burst sources (e.g., the supernovae, and the merge of binary system), and the stochastic backgrounds generated by the astrophysical and cosmological process. In addition, we forecast the potential breakthroughs in gravitational-wave astronomy in the near future, and the Chinese projects which might involve in these discoveries.  相似文献   

黄河口埕岛海域粉土波致孔压现场监测     

杜星  孙永福  宋玉鹏  赵晓龙  周其坤 《海洋学报》2019,41(7):116-122

波浪会对海床产生反复的作用力，由此引起的土体颗粒间孔隙水压力变化是造成土体液化的主要原因。使用自行研发的孔压监测设备，对黄河口埕岛海域易液化区海底孔压进行了长时间、高精度的观测，并对孔隙水压力、波高以及潮位间的关系进行分析。监测结果显示，本次监测条件下波浪最大作用深度介于0.5～1.5 m之间，超过该作用深度后孔压无明显变化。土体内部孔隙水压力的变化主要由潮位和波高决定，潮位的作用可使孔压缓慢平滑的变化且对超孔压无影响；波高的作用可使孔压快速、剧烈地振荡并导致超孔压的出现。  相似文献   

Validation of Global Evapotranspiration Product (MOD16) Using Flux Tower Data from Panjin Coastal Wetland,Northeast China     

Jia Du  Kaishan Song 《中国地理科学(英文版)》2018,28(3):420-429

Recent advances in remote sensing technology and methods have resulted in the development of an evapotranspiration(ET) product from the Moderate Resolution Imaging Spectrometer(MOD16). The accuracy of this product however has not been tested for coastal wetland ecosystems. The objective of this study therefore is to validate the MOD16 ET product using data from one eddy covariance flux tower situated in the Panjin coastal wetland ecosystem within the Liaohe River Delta, Northeast China. Cumulative ET data over an eight-day period in 2005 from the flux tower was calculated to coincide with the MOD16 products across the same period. Results showed that data from the flux tower were inconsistent with that gained form the MOD16 ET. In general, results from Panjin showed that there was an underestimation of MOD16 ET in the spring and fall, with Biases of -2.27 and -3.53 mm/8 d, respectively(–40.58% and -49.13% of the observed mean). Results for Bias during the summer had a range of 1.77 mm/8 d(7.82% of the observed mean), indicating an overestimation of MOD16 ET. According to the RMSE, summer(6.14 mm/8 d) achieved the lowest value, indicating low accuracy of the MOD16 ET product. However, RMSE(2.09 mm/8 d) in spring was the same as that in the fall. Relationship between ET and its relevant meteorological parameters were analyzed. Results indicated a very good relationship between surface air temperature and ET. Meanwhile a significant relationship between wind speed and ET also existed. The inconsistent comparison of MOD16 and flux tower-based ET are mainly attributed to the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs. MODIS pixels.  相似文献   

A simple assessment approach for winter wheat loss risk impacted by water stress     

Xin Du  Hongyan Wang  Jilei Liu  Longcai Zhao  Huanxue Zhang 《国际地球制图》2019,34(5):473-489

In this study, an empirical assessment approach for the risk of crop loss due to water stress was developed and used to evaluate the risk of winter wheat loss in China, the United States, Germany, France and the United Kingdom. We combined statistical and remote sensing data on crop yields with climate data and cropland distribution to model the effect of water stress from 1982 to 2011. The average value of winter wheat loss due to water stress for the three European countries was about ?931 kg/ha, which was higher than that in China (?570 kg/ha) and the United States (?367 kg/ha). Our study has important implications for the operational assessment of crop loss risk at a country or regional scale. Future studies should focus on using higher spatial resolution remote sensing data, combining actual evapotranspiration to estimate water stress, improving the method for downscaling of statistical crop yield data and establishing more sophisticated zoning methods.  相似文献   

三沙永乐龙洞洞底沉积速率变化及其影响因素     

李建坤  李铁刚  丰爱平  杜军  邹欣庆  刘世昊  于晓晓  段佰川 《海洋学报》2019,41(5):107-117

三沙永乐龙洞位于西沙永乐环礁，是目前世界范围内已探明的最深蓝洞，其内部沉积动力环境相对单一，是研究沉积速率变化的天然实验室。龙洞洞底约24 cm以浅沉积物粒度分析结果显示，洞底浅埋沉积物以砂质组分为主，平均粒径多介于22.9~123.9 μm之间，在表层、4 cm、9.5 cm以及21 cm深度分别出现了沉积物变粗、砂含量增多的现象；利用210Pb的CRS定年模式计算得到底层沉积物沉积时间为1896年，平均沉积速率为0.19 cm/a，在4 cm和9.5 cm深度沉积速率急剧增加。柱状样顶部沉积速率显著增加，与近年来西沙地区人类活动加剧吻合。沉积物粒度变粗以及沉积速率骤然加快现象，与西沙地区台风活动频繁相关，通过对比历史台风记录，验证了沉积物在1999-2001年以及2010-2011年所记录的6次台风事件:199902、199915、200110、201002、201005以及201118。推测龙洞洞底沉积物沉积速率主要受台风活动影响，近期有人类活动影响的痕迹。  相似文献