分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 土地利用/覆被变化将干扰生态系统的稳定供给能力，进而对生态系统服务和可持续发展构成威胁。以乌鲁木齐市为研究区，基于斑块生成土地利用模拟（Patch-generating land use simula⁃tion，PLUS）模型，模拟了2030年多情景下乌鲁木齐市的土地利用变化，并结合当量因子法、空间自相关分析等方法估算并预测了19902030年乌鲁木齐市生态系统服务价值（Ecosystem service val⁃ue, ESV）及其权衡协同关系。结果表明：（1）19902020年乌鲁木齐市土地利用呈现两增四减变化趋势。2030年在惯性发展情景下，除林地外其他地类皆遵循历史演变规律；在生态保护情境下，建设用地面积萎缩，生态用地大幅增加；在综合开发情境下，建设用地面积有所增加的同时生态用地面积也处于上升状态；在重点开发情景下，城市建设用地扩张最为剧烈，耕地面积退化严重。（2）19902020年乌鲁木齐市ESV整体上呈现V型下降态势，共减少59.59108元。2030年在生态保护情景下和综合开发情景下ESV处于增加趋势，在惯性发展情景和重点开发情景下ESV出现减少趋势。（3）2030年4种发展情景下，乌鲁木齐市各项生态系统服务间以协同关系为主，高-高低-低协同聚集区与ESV高值、低值区域分布高度吻合，权衡关系零星分布于局部地区。研究结果可为乌鲁木齐市国土空间规划及生态安全格局构建提供科学参考。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 推动边境口岸与载体城镇协调发展是高质量发展口岸经济带的重要内容。运用熵权法和耦合协调模型对20092019年新疆陆路口岸与载体城镇耦合协调水平演进的时空特征进行度量。结果表明：（1）新疆主要陆路口岸与载体城镇综合发展水平总体稳步上升，2015年后两系统综合发展的动力由口岸先导逐渐切换到载体城镇先导，过度依赖进出口数量是口岸经济增速放缓的主要原因。（2）新疆主要陆路口岸与载体城镇的耦合协调水平整体趋于优化，耦合协调水平可以分为3类：以阿拉山口口岸代表的良好协调型口岸、以巴克图口岸代表的初级协调型口岸、以塔克什肯口岸为代表的勉强协调型口岸。（3）从空间上来看，新疆陆路口岸经济发展格局正在朝阿拉山口口岸与霍尔果斯口岸并重、南北疆多口岸均衡发展的空间格局演进，但部分载体城镇社会经济发展比较落后，限制了与口岸协调发展水平进一步提升。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 黄河流域生态保护与高质量发展已上升为国家战略。作为经济高质量发展的微观基础，在环境约束下要素效能充分发挥就显得至关重要。根据马克思主义政治经济学，要素效能由要素质量与要素效率有机构成，前者是要素效能发挥的必然前提，后者是要素效能发挥的内在要求。基于环境规制影响要素质量与要素效率的作用机理，采用面板固定效应模型与中介效应模型实证分析了20082019年黄河流域环境规制对要素效能发挥的影响。结果表明：（1）环境规制通过人口集聚实现要素质量升级，通过产业结构优化促进要素效率提高，并在二者的共同作用下促进要素效能发挥。（2）环境规制与要素质量升级、要素效率提高、要素效能发挥均呈现先抑制后促进的U型关系。（3）环境规制对要素效能发挥的促进作用存在经济发展水平与城市规模异质性。在经济发展水平高的地区，环境规制显著促进要素效能发挥；经济发展水平较低或城市规模较小的地区，环境规制先抑制后促进要素效能发挥，二者呈U型关系；在城市规模较大的地区，二者关系不显著。研究结果为黄河流域从微观要素层面促进经济高质量发展指明方向，对落实黄河流域生态保 护与高质量发展战略具有积极意义。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 乡村国土空间安全不仅是保障国家粮食安全的基础，更是实现生态文明建设和乡村振兴的重要基础。以黄土丘陵区为研究区，基于遥感数据和统计数据等数据，定量评价了临洮县18个乡镇323个行政村的国土空间安全，并借助地理探测器识别了影响乡村国土空间安全的因素。结果表明：（1）临洮县乡村国土空间安全整体处于中等水平，表现为：生活空间安全水平>生产空间安全水平>生态空间安全水平。安全水平较高的乡村（69.73%）主要分布在洮河川区灌溉农业区，而低等安全水平的乡村（30.27%）主要分布在县域北部与东部丘陵山地的旱作农业区。（2）临洮县乡村国土空间安全空间分布有较强的空间自相关性，局部空间分布以高-高（18.52%）、低-高（0.62%）、低-低（9.26%）这3种类型为主，且集聚分布特征明显。（3）地形地势、人口规模、政府投入及区位联系对临洮县的乡村国土空间安全水平具有显著影响，且对不同乡镇其影响程度有显著差异。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 中亚作为丝绸之路经济带的重要枢纽，其土地与人口城镇化间的协调发展不仅影响中亚地区社会经济的可持续发展，同时能够推动一带一路倡议的实施。基于中亚五国首都20002019年城市土地和人口数据，采用城市扩张模式指数、人口集中指数、等扇分析法和空间耦合协调模型等方法，研究了城市土地扩张与人口增长的时空耦合特征。结果表明：（1）从空间演变特征看，中亚五国首都城市土地扩张模式类型主要以蔓延式为主，扩张模式指数整体呈先上升后下降趋势；人口集聚特征上，阿什哈巴德人口集中度呈上升趋势，杜尚别和努尔苏丹呈下降趋势，塔什干和比什凯克的人口集中指数在0.6~0.7之间波动变化。（2）从空间增长趋势看，比什凯克、阿什哈巴德和努尔苏丹城市土地与人口扩展方向基本相同，塔什干稍有偏差，杜尚别差异较大。（3）从耦合协调特征看，塔什干土地与人口间的耦合性和协调度都偏低，其城镇化协调发展处于起步阶段；杜尚别和比什凯克耦合性较好，但协调度变化较大，处于波动阶段；阿什哈巴德和努尔苏丹协调度较高，处于稳定阶段。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 景观多样性指数（LDI）不仅是景观生态学研究中的一个重要指标，而且也是生物多样保护中的重要层次。基于土地利用栅格数据（30 m分辨率），在ArcMap环境中采用Neighborhood和Fo⁃cal工具对宁夏沿黄绿洲LDI时空变化和尺度依赖特征进行了研究。结果表明：（1） 基本单元（正方形）边长90~6000 m 5个时期重复统计分析表明宁夏沿黄绿洲景观在空间上具有明显的尺度依赖特征，转折点在3000 m。（2）近50 a来研究区LDI 变化具有周期性，2000年是转折点。其中，19752000年LDI呈降低趋势，LDI分区分析显示以退化区斑块类型面积（CA）最大和好转区CA最小为主要特点，分别为6840 km2和1332 km2。20002020年LDI呈增加趋势，以稳定区CA最大和退化区CA最小为主要特点，分别为7848 km2和792 km2；由于此阶段初始LDI（2000年）最低，LDI后期好转程度没有达到前期水平。（3）LDI分级面积转换以前期好转区向后期稳定区流转（796km2，占好转区60.5%）和退化区分别向稳定区（3519 km2，占退化51.5%）、好转区（3036 km2，占退化区44.4%）流转为主要特征。（4）景观多样性变化格局以CA与相对分裂度指数（RSI）呈负关联为特点，这种关系机制在不同时期和不同变化类型中具有普遍性。总的来看，在区域景观变化研究中确定分析指标在时空尺度上的变化转折点既是保障研究结果具有借鉴和共享的必要条件，也是区域景观多样性可视化表达与分析的基础。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 黄土高原流域地貌系统的地貌演化特征十分复杂，尚有诸多科学问题有待进一步深入研究。以往研究大多集中在流域地貌演化的侵蚀和发育特征等某一方面，缺乏从流域地貌系统及其势能信息熵的视角深入剖析野外多岩土层黄土小流域地貌演化特征的研究。为此，基于系统论的观点和方法，构建多岩土层黄土小流域地貌系统及其势能信息熵的数学模型，并以辛店沟小流域为例，对其地貌演化特征进行研究。结果表明：（1）构建的野外多岩土层黄土小流域地貌系统的概念模型及其势能信息熵的数学模型能够有效对辛店沟小流域进行数值模拟。（2）以黄土侵蚀作用为主的辛店沟小流域从20002019年的地貌演化过程是其势能信息熵的熵减过程和黄土地貌不断侵蚀的过程。（3）辛店沟小流域的势能信息熵能较好地反映该小流域的地貌演化阶段和地貌侵蚀过程。
分类： 地球科学 >> 地理学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 通过实地考察、观测和采样，利用Google Earth遥感影像和激光粒度分析仪，研究了科尔沁沙地大型沙波纹（large-scale ripples, LSR）的空间分布、单体和群体的基本形态和粒度特征，探讨了LSR粗颗粒的来源、它同普通沙波纹和普通风成沙在颗粒组成、形态特征和内部沉积结构方面的区别。结果表明：（1）科尔沁沙地的LSR主要分布于翁牛特旗中部和北部地区。（2）LSR空间单元的空间形态具有片状、斑块状和条带状3种类型，分别发育于宽阔的丘间地、沙丘中上部、槽形低地3类地形部位。（3）LSR平均长度为6.32 m，总体走向为东北西南，平均波长为1.68 m，空间分异较为明显；单体LSR的前后坡不对称。（4）LSR的颗粒为中砂-粗砂粒级，其中粗颗粒主要来自旧河道的河流冲积层、下伏Q3河湖相地层、剥蚀残山的风化壳和山麓洪积物。（5）LSR同普通沙波纹在外观、物质组成、几何形态和内部沉积结构方面有明显差异。该项研究将有助于促进风沙地貌学的理论发展和实践。
分类： 地球科学 >> 大气科学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 提高太阳辐射短时临近预报（<6 h）的准确率是确保电网调度的重要举措，也是极具挑战性的技术瓶颈之一。基于云-辐射关系，利用地面观测的太阳辐照度反演的云相对辐射强迫比值，构建了太阳辐射短时临近预报模型（R模型），并用美国南部大平原中心站16 a的辐照度观测数据，对R模型的预报性能进行了评估。结果表明：（1）有云存在的个例中，R模型较传统的简单持续性模型（Simple模型）的预报性能有很大提升，相比于预报性能较高的智能持续性模型（Smart模型或RCRF模型）仍有2%~25%的改进。（2）在16 a包含2.9105个8类云状个例的总体检验中，当预报时效超过1 h时，R模型的预报性能显著优于Simple模型和RCRF模型。相对于RCRF模型，R模型在6 h预报时效下，对总辐射和直接辐射的预报性能可分别提高25%和19%，预报时效分别延长了1.5 h和1 h。（3）R模型为太阳辐射短时临近预报提供了准确率更高的基准模型。同时，该模型可仅依靠地面短期的辐照度观测资料即可预报，为缺少同期气象要素观测的光伏电厂的辐射预报提供了新的途径或新的可能。
分类： 地球科学 >> 大气科学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 太阳辐射是地球系统的主要能源，与人类的生活密切相关。通过选取青海高原50个气象观测站点19612020年逐月日照时数数据，分析了青海高原整体、不同纬度地区、不同海拔高度地区日照时数时空变化特征。结果表明：（1）19612020年青海高原年日照时数呈显著降低趋势，且在2004年发生突变降低。从空间分布来看，除南部个别站点日照时数持平或略微增加外，其余地区年日照时数均呈显著降低趋势，其中柴达木地区和东部农业区降低趋势最显著。（2）青海高原高纬度地区年日照时数降低趋势显著大于低纬度地区。春季不同纬度地区日照时数变化趋势均较小，夏季和冬季纬度相对较高地区日照时数减少趋势显著大于纬度较低地区，秋季纬度较低和纬度较高地区日照时数减少趋势显著大于中纬度地区。（3）青海高原海拔相对较低地区年日照时数降低趋势显著大于海拔相对较高地区。春季不同海拔高度地区日照时数变化趋势均较小，基本持平或略微减少，夏季和冬季海拔相对较低地区日照时数减少趋势显著大于海拔较高地区，秋季不同海拔高度日照时数均呈减少趋势，但是减少趋势显著性状况差异较大。
分类： 地球科学 >> 大气科学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 新一代区域气候模式RegCM4.6引进了Mix积云参数化方案，可以将之前版本中的Emanuel和Grell方案结合在一起，以弥补单个参数化方案的不足。利用2016年MODIS（Moderate-resolutionimaging spectroradiometer）数据对RegCM4.6 中Mix 和Emanuel 积云参数化方案模拟的东亚云量（Cloud fraction，CF）、冰水柱含量（Ice water path，IWP）和液水柱含量（Liquid water path，LWP）进行初步评估，计算了相关系数（r）、平均绝对误差（Mean absolute error，MAE）、平均偏差（Mean bias er⁃ror，MBE）和均方根误差（Root mean square error，RMSE），以便为相关研究选取积云参数化方案提供参考依据。结果表明：（1）模拟的CF的MBE大致以胡焕庸线为界，西北部为轻微高估，东南部通常为低估。2种方案在夏季的模拟效果最好，冬季最差。Mix方案的MAE、MBE和RMSE的绝对值在四季普遍小于Emanuel方案。（2）模式明显低估了东亚的IWP，除夏季外，2种方案模拟的IWP与MODIS的都呈显著负相关，表明模式难以准确模拟出云中冰晶相关的物理过程。（3）2种方案模拟的LWP在青藏高原和东部海域均为低估，在中国南部、中部和北部为高估，但Mix方案的偏差更接近于0。冬季，2种方案的评估参数相近，其他季节Mix方案的MAE、MBE和RMSE的绝对值均小于Emanuel方案，其中MAE相差21~39 gm-2。因此，Mix方案更适用于在东亚进行云水资源方面的模拟研究。
分类： 地球科学 >> 大气科学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 干旱是农作物生长发育的主要环境胁迫因子，也是制约农业丰产丰收的关键自然要素。农业干旱监测通常基于气象站点观测数据，这在一定程度上难以反映区域尺度的农业干旱状况。以甘肃省为研究区，基于MODIS、TRMM、ESA CCI等遥感数据产品和气象站点数据，利用随机森林回归模型构建综合气象干旱指数（CMDI），并对甘肃省20112019年农作物生长季（49月）旱情时空格局及变化规律进行分析。结果表明：（1）CMDI与实测值的决定系数（R2）在各月均高于0.634，且与标准化降水蒸散发指数（SPEI）在空间上具有一定的相关性，表明该指数可反映农业干旱的发生发展过程。（2）甘肃省农业干旱呈现明显的地域分异规律，干旱程度由东南向西北逐渐加重，其中河西地区多为特旱区和重旱区，陇中地区为重（中）旱区，陇南、陇东、甘南地区为干旱-无旱波动变化区。（3）20112019年甘肃省农业干旱在年、月尺度上均呈现较大的波动趋势，其中2012年干旱程度最轻，2017年则最为严重；甘肃省大部分地区在4月和6月，陇东、陇南地区分别在5月和9月以及甘南地区49月农业旱情有所减轻外，其余地区在农作物生长季的旱情呈加重趋势。
分类： 地球科学 >> 大气科学 提交时间： 2023-02-27 合作期刊: 《干旱区地理》
摘要： 在全球陆地大气水分亏缺（VPD）已经增加、并将持续增强的背景下，新疆大气环境是否趋于干旱化值得探讨。利用19612020年地面气象观测资料，采用线性趋势分析、Mann-Kendall检验等方法，研究了新疆VPD的分布及时空演变特征。结果表明：（1）近60 a来新疆VPD整体呈现显著增加趋势，增幅为0.015 kPa(10a)-1。VPD在2005年发生突变，突变前为弱波动变化，突变后呈增加趋势。（2）各季节VPD均以增势为主，其中春、夏季增幅较大，冬季增幅最小。春、秋季VPD突变特征与年变化较为一致，夏季略晚（2006年出现突变）。（3）空间分布上，VPD呈现山区低、盆地高的鲜明格局。时空演变分析表明，全疆大范围地区（近83.65%的气象站点）VPD呈增势变化，而VPD呈下降趋势的站点多分布在天山山脉东段的北麓以及南疆盆地的北、西北缘。季节尺度上，春季VPD呈增势变化的站点数占比最高（96.15%），是新疆大气水分胁迫范围最广的时段，而冬季大气水汽含量相较稳定。
分类： 地球科学 >> 地理学 提交时间： 2023-02-15 合作期刊: 《干旱区科学》
摘要： Visible and near-infrared (vis-NIR) spectroscopy technique allows for fast and efficient determination of soil organic matter (SOM). However, a prior requirement for the vis-NIR spectroscopy technique to predict SOM is the effective removal of redundant information. Therefore, this study aims to select three wavelength selection strategies for obtaining the spectral response characteristics of SOM. The SOM content and spectral information of 110 soil samples from the Ogan-Kuqa River Oasis were measured under laboratory conditions in July 2017. Pearson correlation analysis was introduced to preselect spectral wavelengths from the preprocessed spectra that passed the 0.01 level significance test. The successive projection algorithm (SPA), competitive adaptive reweighted sampling (CARS), and Boruta algorithm were used to detect the optimal variables from the preselected wavelengths. Finally, partial least squares regression (PLSR) and random forest (RF) models combined with the optimal wavelengths were applied to develop a quantitative estimation model of the SOM content. The results demonstrate that the optimal variables selected were mainly located near the range of spectral absorption features (i.e., 1400.0, 1900.0, and 2200.0 nm), and the CARS and Boruta algorithm also selected a few visible wavelengths located in the range of 480.0510.0 nm. Both models can achieve a more satisfactory prediction of the SOM content, and the RF model had better accuracy than the PLSR model. The SOM content prediction model established by Boruta algorithm combined with the RF model performed best with 23 variables and the model achieved the coefficient of determination (R2) of 0.78 and the residual prediction deviation (RPD) of 2.38. The Boruta algorithm effectively removed redundant information and optimized the optimal wavelengths to improve the prediction accuracy of the estimated SOM content. Therefore, combining vis-NIR spectroscopy with machine learning to estimate SOM content is an important method to improve the accuracy of SOM prediction in arid land.
分类： 地球科学 >> 地理学 提交时间： 2023-02-15 合作期刊: 《干旱区科学》
摘要： Investigating the effect of geocells on the erosion and deposition distribution of ephemeral gullies in the black soil area of Northeast China can provide a scientific basis for the allocation of soil and water conservation measures in ephemeral gullies. In this study, an artificial simulated confluence test and stereoscopic photogrammetry were used to analyze the distribution characteristics of erosion and deposition in ephemeral gullies protected by geocells and the effect of different confluence flows on the erosion process of ephemeral gullies. Results showed that when the confluence flow was larger, the effect of geocell was more evident, and the protection against ephemeral gully erosion was stronger. When the confluence flow rates were 0.6, 1.8, 2.4, and 3.0 m3/h, ephemeral gully erosion decreased by 37.84%, 26.09%, 21.40%, and 35.45%. When the confluence flow rates were 2.4 and 3.0 m3/h, the average sediment yield rate of the ephemeral gully was close to 2.14 kg/(m2min), and the protective effect of ephemeral gully erosion was enhanced. When the flow rate was higher, the surface fracture of the ephemeral gully was more serious. With an increase in confluence flow rate, the ratio of erosion to deposition increased gradually, the erosion area of ephemeral gullies was expanded, and erosion depth changed minimally. In conclusion, geocell measures changed erosion patterns by altering the rill erosion/deposition ratio, converting erosion from rill erosion to sheet erosion.
分类： 地球科学 >> 地理学 提交时间： 2023-02-15 合作期刊: 《干旱区科学》
REN Xiaohui
YU Ruihong
LIU Xinyu
SUN Heyang
GENG Yue
QI Zhen
ZHANG Zhuangzhuang
LI Xiangwei
WANG Jun
ZHU Penghang
GUO Zhiwei
WANG Lixin
XU Jifei
摘要： Lakes play important roles in sustaining the ecosystem and economic development in Inner Mongolia Autonomous Region of China, but the spatial patterns and driving mechanisms of water quality in lakes so far remain unclear. This study aimed to identify the spatial changes in water quality and the driving factors of seven lakes (Juyanhai Lake, Ulansuhai Lake, Hongjiannao Lake, Daihai Lake, Chagannaoer Lake, Hulun Lake, and Wulannuoer Lake) across the longitudinal axis (from the west to the east) of Inner Mongolia. Large-scale research was conducted using the comprehensive trophic level index (TLI ()), multivariate statistics, and spatial analysis methods. The results showed that most lakes in Inner Mongolia were weakly alkaline. Total dissolved solids and salinity of lake water showed obvious zonation characteristics. Nitrogen and phosphorus were identified as the main pollutants in lakes, with high average concentrations of total nitrogen and total phosphorus being of 4.05 and 0.21 mg/L, respectively. The values of TLI () ranged from 49.14 to 71.77, indicating varying degrees of lake eutrophication, and phosphorus was the main driver of lake eutrophication. The lakes of Inner Mongolia could be categorized into lakes to the west of Daihai Lake and lakes to the east of Daihai Lake in terms of salinity and TLI (). The salinity levels of lakes to the west of Daihai Lake exceeded those of lakes to the east of Daihai Lake, whereas the opposite trend was observed for lake trophic level. The intensity and mode of anthropogenic activities were the driving factors of the spatial patterns of lake water quality. It is recommended to control the impact of anthropogenic activities on the water quality of lakes in Inner Mongolia to improve lake ecological environment. These findings provide a more thorough understanding of the driving mechanism of the spatial patterns of water quality in lakes of Inner Mongolia, which can be used to develop strategies for lake ecosystem protection and water resources management in this region.
分类： 地球科学 >> 地理学 提交时间： 2023-02-07 合作期刊: 《干旱区科学》
摘要： Under the combined influence of climate change and human activities, vegetation ecosystem has undergone profound changes. It can be seen that there are obvious differences in the evolution patterns and driving mechanisms of vegetation ecosystem in different historical periods. Therefore, it is urgent to identify and reveal the dominant factors and their contribution rates in the vegetation change cycle. Based on the data of climate elements (sunshine hours, precipitation and temperature), human activities (population intensity and GDP intensity) and other natural factors (altitude, slope and aspect), this study explored the spatial and temporal evolution patterns of vegetation NDVI in the Yellow River Basin of China from 1989 to 2019 through a residual method, a trend analysis, and a gravity center model, and quantitatively distinguished the relative actions of climate change and human activities on vegetation evolution based on Geodetector model. The results showed that the spatial distribution of vegetation NDVI in the Yellow River Basin showed a decreasing trend from southeast to northwest. During 19812019, the temporal variation of vegetation NDVI showed an overall increasing trend. The gravity centers of average vegetation NDVI during the study period was distributed in Zhenyuan County, Gansu Province, and the center moved northeastwards from 1981 to 2019. During 19812000 and 20012019, the proportion of vegetation restoration areas promoted by the combined action of climate change and human activities was the largest. During the study period (19812019), the dominant factors influencing vegetation NDVI shifted from natural factors to human activities. These results could provide decision support for the protection and restoration of vegetation ecosystem in the Yellow River Basin.
分类： 地球科学 >> 地理学 提交时间： 2023-02-07 合作期刊: 《干旱区科学》
摘要： Maintaining the stability of exotic sand-binding shrub has become a large challenge in arid and semi-arid grassland ecosystems in northern China. We investigated two kinds of shrublands with different BSCs (biological soil crusts) cover in desert steppe in Northwest China to characterize the water sources of shrub (Caragana intermedia Kuang et H. C. Fu) and grass (Artemisia scoparia Waldst. et Kit.) by stable 18O isotopic. Our results showed that both shrublands were subject to persistent soil water deficiency from 2012 to 2017, the minimum soil depth with CV (coefficient of variation) C. intermedia, a considerable proportion of water sources pointed to the surface soil. Water from BSCs contributed to averages 22.9% and 17.6% of the total for C. intermedia and A. scoparia, respectively. C. intermedia might use more water from BSCs in rainy season than dry season, in contrast to A. scoparia. The relationship between shrub (or grass) and soil water by 18O shown significant differences in months, which partly verified the potential trends and relations covered by the high variability of the water source at seasonal scale. More fine roots at 05 cm soil layer could be found in the surface soil layer covered by BSCs (8000 cm/m3) than without BSCs (3200 cm/m3), which ensured the possibility of using the surface soil water by C. intermedia. The result implies that even under serious soil water deficiency, C. intermedia can use the surface soil water, leading to the coexistence between C. intermedia and A. scoparia. Different with the result from BSCs in desert areas, the natural withdrawal of artificial C. intermedia from desert steppe will be a long-term process, and the highly competitive relationship between shrubs and grasses also determines that its habitat will be maintained in serious drought state for a long time.
分类： 地球科学 >> 地理学 提交时间： 2023-02-07 合作期刊: 《干旱区科学》
摘要： Soil water content is a key controlling factor for vegetation restoration in sand dunes. The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand dune ecosystems. To determine the influence of vegetation on the hydrological regulation function of sand dunes, we examined the deep seepage and lateral migration of dune water with different vegetation coverages during the growing season in the Horqin Sandy Land, China. The results showed that the deep seepage and lateral migration of water decreased with the increase in vegetation coverage on the dunes. The accumulated deep seepage water of mobile dunes (vegetation coverage13.75%) should be retained as a water resource reservoir to maintain the water balance of artificial fixed dune ecosystems. These findings provide reliable evidence for the accurate assessment of water resources within the sand dune ecosystem and guide the construction of desertification control projects.
分类： 地球科学 >> 地理学 提交时间： 2023-02-07 合作期刊: 《干旱区科学》
摘要： Check dams are widely used on the Loess Plateau in China to control soil and water losses, develop agricultural land, and improve watershed ecology. Detailed information on the number and spatial distribution of check dams is critical for quantitatively evaluating hydrological and ecological effects and planning the construction of new dams. Thus, this study developed a check dam detection framework for broad areas from high-resolution remote sensing images using an ensemble approach of deep learning and geospatial analysis. First, we made a sample dataset of check dams using GaoFen-2 (GF-2) and Google Earth images. Next, we evaluated five popular deep-learning-based object detectors, including Faster R-CNN, You Only Look Once (version 3) (YOLOv3), Cascade R-CNN, YOLOX, and VarifocalNet (VFNet), to identify the best one for check dam detection. Finally, we analyzed the location characteristics of the check dams and used geographical constraints to optimize the detection results. Precision, recall, average precision at intersection over union (IoU) threshold of 0.50 (AP50), IoU threshold of 0.75 (AP75), and average value for 10 IoU thresholds ranging from 0.500.95 with a 0.05 step (AP5095), and inference time were used to evaluate model performance. All the five deep learning networks could identify check dams quickly and accurately, with AP5095, AP50, and AP75 values higher than 60.0%, 90.0%, and 70.0%, respectively, except for YOLOv3. The VFNet had the best performance, followed by YOLOX. The proposed framework was tested in the Yanhe River Basin and yielded promising results, with a recall rate of 87.0% for 521 check dams. Furthermore, the geographic analysis deleted about 50% of the false detection boxes, increasing the identification accuracy of check dams from 78.6% to 87.6%. Simultaneously, this framework recognized 568 recently constructed check dams and small check dams not recorded in the known check dam survey datasets. The extraction results will support efficient watershed management and guide future studies on soil erosion in the Loess Plateau.
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