Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： In this article, using the parameters of hydrological, water resources, and the desertification area of theShiyang River basin in different periods, the basin hydrology, water resources, desertification, and its changes inthe relationship between them were quantitatively studied. It provides the data and the theoretical basis forhydrological, water resource features, and land desertification in this area. The research showed that although theprecipitation in the Shiyang River basin had increased from 2005 to 2021, the variability was large and remainedat a low level, with an average annual precipitation of only 234.70 mm. From 1993-2004, the annual precipitationat the Caiqi hydrological station reduced, whereas the annual sediment transport increased. The annualprecipitation at the Zamusi hydrological station increased from 1999 to 2021, whereas the annual sedimentdischarge decreased. From 2005 to 2021, the total amount of water resources in the Shiyang River basindecreased by 0.24×108 m3 ·a-1, but water consumption and water consumption remained at high levels of 24.70×108 m3 and 17.07 × 108 m3, with high water consumption and consumption in agriculture, forestry, and fruitindustries, exacerbating the irrationality of water resource utilization in the basin. From 1975 to 2014, the totalarea of desertified land in the basin reduced, but the land changes in different periods and desertification typesremained quite different, and the situation of desertification prevention and control in the basin was still grim.
Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： The dynamic wind environment characteristics on the east and west sides of the Shashangou Bridgeused by the Dunge Railway were investigated using field observations, indoor analysis, and CFD numericalsimulations. The results show that the sand-driving winds on the east and west sides of Shashangou Bridge weremainly NW and WNW winds in the spring and summer, and SE and S winds in the autumn and winter. Theannual sand transport potential on the west side of Shashangou Bridge is 284.19 VU, which indicates a mediumwind energy environment. The sand transport potential was determined to be 27.4 VU, and the sand transportwith the wind direction was 124° . The directional variability index is 0.10, which indicates a small ratio andvariable wind direction. The sediment transport potential on the east side of Shashangou Bridge is 31.24 VU,indicating a low wind energy environment. The results of the sediment transport potential were 8.97 VU, whilethe results of the sediment transport wind direction were 91° , and the directional variability index was 0.29,indicating a medium ratio. The average wind speed, frequency of sand-driving wind, sand transport potential, andresultant sand transport potential on the west side of Shashangou Bridge were larger, indicating that themonitoring and control of sand damage on the west side of the bridge should be improved. According to thecharacteristics of the wind dynamic environment on the west side of the bridge when combined with the flowingdune, the numerical simulation analysis results show that the wind speed in the overhead area and bridge deck isgreater than the sand- driving wind speed, and the sand transport capacity was strong, indicating that sandaccumulation does not readily occur. However, with the advance of sand dunes, the possibility of sandaccumulation at the bottom of the bridge and wind sand on the rail increases.
Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Debris-covered glaciers are widely distributed in Western China. Their ablation areas are covered byvarying degrees of rock debris, and consequently, their melting statuses differ greatly when compared to debrisfreeglaciers. There is currently a need for melting simulations to better understand debris- covered glaciers. Inthis paper, driven by field meteorological data, an energy balance model for debris- covered glaciers has beenused to simulate the energy and ablation in debris-covered areas of Qingbingtan Glacier No. 72 in Mt. Tomor,Tianshan. Based on the heat conduction process and the energy balance equation, the model calculates the debrissurface temperature and the internal temperature of the debris, then estimates the subdebris melt using the internaldebris temperature. The results showed that the modeled ablation was 0.39 m w.e. in the summer of 2008, and thesimulation accuracy (R2 = 0.92, RMSE = ± 0.03 m w.e.) was higher when compared with the field data. Thesimulated debris temperatures at the surface and a depth of 10 cm inside the debris were also found to fit wellwith the measured data (R2 = 0.91 and 0.60, respectively). During energy exchange in the debris area, netshortwave radiation was the only energy income item, and sensible heat flux was the largest energy expenditureitem (49.7%), followed by the heat conduction flux (ablation heat consumption) (25.8%), net longwave radiation(19.8%), and latent heat flux (4.6%), while precipitation heat was <1%. Cloud cover had a significant impact onthe meteorological and energy characteristics of the debris area. Under overcast conditions, the incomingshortwave radiation in the debris area decreased from 854 W·m- 2 on sunny days to 587 W·m− 2, while thedownward longwave radiation and relative humidity increased, and the average ablation decreased by 12%, whencompared with sunny days. In addition, the sensitivity analysis of the key parameters for debris shows that thesimulated ablation is most sensitive to the changes in thermal conductivity, and the changes in albedo and surfaceroughness cannot be ignored.
Subjects: Biology >> Botany >> Applied botany submitted time 2024-02-07 Cooperative journals: 《广西植物》
Abstract： Investigating the variation patterns of hydraulic traits of trees with different diameters at breast height (DBH) grades has important physiological significance for understanding the water transport mechanism in plants. We focused a dominant tree species (Lannea coromandelica) in the dry and hot ecosystem of the Yuanjiang River, and measured the distribution patterns of hydraulic traits including shoot- (leaves and stems), leaf-, and stem hydraulic conductance, and morphological properties (diameter at breast height, leaf area/petiole length, leaf area/mass of petiole, mass of leaf/mass of petiole, average petiole length, bark density, wood density, Huber value and leaf mass per area) for 56 L. coromandelica individuals with different DBH (0 < DBH ≤ 9 cm), and then discussed the variation patterns of these traits among these three DBH levels (0 < DBH ≤ 3, 3 < DBH ≤ 6 and 6 < DBH ≤ 9 cm). The results were as follows: (1) the stem hydraulic conductance was significantly greater than leaf hydraulic conductance in three DBH grades, indicating that there was a hydraulic segmentation between the stem and leaves, whereas the degree of hydraulic segmentation had a similar pattern. (2) Among the three different diameter grades, there were significant differences in morphological traits such as average petiole length, bark density, wood density, Huber value and leaf mass per area, but there were no significant differences in the hydraulic conductance of the shoot, stem, and leaf. (3) Among the three diameter grades, the shoot hydraulic conductance was positively correlated with leaf and stem hydraulic conductance, indicating there was a coordination between leaf and stem hydraulic conductance. The shoot hydraulic conductance was negatively correlated with bark density and wood density, and leaf hydraulic conductance was significantly negatively correlated with the Huber value, indicating these leaf and stem morphological properties may impact shoot and leaf hydraulic conductance. Overall, this study suggest that there are similar hydraulic distribution patterns between leaves and the stem of L. coromandelica at different growth stages, although some morphological traits differ significantly among different diameter grades. These results improve our understanding for the intra-specific variation in leaf and stem hydraulic traits of valley savanna plants.
Subjects: Astronomy >> Astrophysical processes submitted time 2017-10-11 Cooperative journals: 《天文研究与技术》
Abstract：时域脉冲机制雷达广泛应用于地球探测、月球与深空探测等领域，研究雷达的探测深度有利于分析目标是否在雷达探测范围内。传统的计算方法大多基于经典雷达传输方程，在实际计算时，需要对地下介质结构以及介质特性做先验性假设，进而给出理论的穿透深度。为了克服传统计算探测深度方法的局限性，给出了一种新的计算方法，该方法不需要对探测介质做先验假设，直接从雷达实测数据出发，通过计算雷达数据间的相关性，给出雷达的探测深度。给出了两种具体的计算方法，一种为结合子波形式，另一种是利用道相关形式。分别对两种方法进行了介绍，并通过仿真验证了两种方法在计算雷达穿透深度时的有效性，同时分析了两种计算方法存在的局限性，该研究为后期处理时域脉冲雷达穿透深度问题提供了解决方法。
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