Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： The Hexi Region holds a dual significance in China, being both a pivotal area for ecological security and the core of the Silk Road Economic Belt. The assessment of the net primary productivity (NPP) of the region and a quantitative analysis of the driving forces behind these dynamics bears immense theoretical importance and practical implications. Based on MOD17A3 product, land use cover, and meteorological information, this study scrutinized the evolving characteristics of the vegetation- related NPP, the influence of land use cover changes, and climate fluctuations on the NPP of the Hexi Region from 2000 to 2020. This study employed R-contribution rate and biased correlation analysis methods. The results show that: (1) There was an overall increase in the area of arable land, waters, and residential land in the Hexi Region, while the grassland and unused land area was reduced. The overall dynamics of land use cover change (LUCC) after 2010 was significantly higher, with grassland, cropland, built- up land, and unused land dominating the inter- conversion of land use types. (2) The overall NPP in the Hexi Region increased, with rates of change of 0.86 and 1.29 in the periods 2000-2010 and 2010-2020, respectively. There was a significant regional variation in NPP, which decreased from southeast to northwest. (3) The influence of LUCC on NPP gradually increased from 2000 to 2020. While climate change contributed more to NPP than LUCC, their respective roles varied among land use cover types. Specifically, climate change dominated the influence factor of NPP on cropland, forested land, and grassland, whereas for unutilized land and residential construction areas, LUCC played a more significant role.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-02-27 Cooperative journals: 《干旱区地理》
Abstract： Drought is the main environmental stressor to crop growth and development and a pivotal natural constraint to high agricultural yield and harvest. Agricultural drought monitoring is typically based on meteorological observations, which, to some extent, cannot reflect the agricultural drought conditions on a regional scale. Taking the Gansu Province of China as the study area, the compositive meteorological drought index (CMDI) was constructed using a random forest regression model and the spatiotemporal pattern and change rule of drought during the crop-growing season (April to September) from 2011 to 2019 in the Gansu Province were analyzed based on MODIS, TRMM, ESA CCI, and other remote sensing data products as well as meteorological station data. The results are as follows: (1) the coefficient of determination (R2 ) of the CMDI and the measured value were all greater than 0.634 in each month; the CMDI has a high spatial correlation with the standardized precipitation evapotranspiration index, showing that the CMDI can reflect the occurrence and development of agricultural drought. (2) The agricultural drought in the Gansu Province exhibited an obvious pattern of regional differentiation, with the drought degree gradually increasing from southeast to northwest. Most parts of the Hexi region were in special and severe drought, the Longzhong region was in severe (medium) drought, and the Longdong, Longnan, and Gannan regions were in fluctuating drought. (3) From 2011 to 2019, the agricultural drought in the Gansu Province exhibited a significant fluctuating trend on both annual and monthly scales, and the drought degree was most moderate in 2012 and most severe in 2017. Agricultural drought has been reduced in the Gannan region in April-September, most areas in April and June, the Longdong region in May, and the Longnan region in September. However, the remaining regions experienced an increasing trend of drought during the crop-growing season from 2011 to 2019
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2018-11-13 Cooperative journals: 《干旱区地理》
Abstract： 冰川冰储量不仅是冰川的重要属性，而且是核算冰川水资源及预测冰川变化的基础数据，因此准确计算冰川冰储量及其变化具有重要的理论与现实意义。目前冰川储量估算的主要方法有经验公式法、冰厚模型估算法、探地雷达法；冰川储量相对变化计算方法有实地测量法和遥感监测法。本文系统分析和讨论各计算方法的原理、现状及存在的问题，以期为冰川储量估算提供方法参考。研究表明，对于冰川冰储量计算而言，经验公式法适用于区域性或全球性的冰川储量估算；模型估算法适用于个体或小范围冰川储量估算；探地雷达法适用于人类易到达区域冰川储量的估算。对于冰川冰储量相对变化计算，实地测量法适用于对精度要求高且满足实地测量条件的单条或中小型冰川，遥感监测法适用于全球性冰储量变化估算，但需改进算法和提高数据空间分辨率。目前，随着无人机技术的逐步应用，以及冰川流速等理论模型的提出，这为冰川冰储量估算方法的发展提供了新契机。
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