Effect of topography on the changes of Urumqi Glacier No. 1 in the Chinese Tianshan Mountains

Topography plays an important role in determining the glacier changes. However, topography has often been oversimplified in the studies of the glacier changes. No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features. The present study provided a detailed insight into the changes in the two branches (east branch and west branch) of Urumqi Glacier No. 1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters. This study analyzed comprehensive recently observed data (from 1992/1993 to 2018/2019), including mass balance, ice thickness, surface elevation, ice velocity, terminus, and area, and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes. We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation (SW_in) across the entire glacier, focusing on the difference in the SW_in between the two branches. The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019, and this was mainly attributed to the lower average altitude of the east branch. Compared with the west branch, the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope. The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch. The spatial variability of the SW_in across the glacier surface became much larger as altitude increased. The SW_in received by the east branch was slightly larger than that received by the west branch, and the northern aspect could receive more SW_in, leading to glacier melting. In the future, the difference of the glacier changes between the two branches will continue to exist due to their topographic differences. This work is fundamental to understanding how topographic features affect the glacier changes, and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.     

A magnetic investigation along a NE–SW transect of the Yasouj Plain,southwestern Iran

The magnetic susceptibility (χ) of soils varies with the slope position due to some factors such as texture, drainage class, and land use. Limited information is available about the magnetic susceptibility properties of semi arid regions of southwestern Iran. This study attempts to link χ and Fe oxides of the soils to landforms, soil characteristics, and land use (paddy and dryland soils) on the same parent materials. Ten representative pedons were taken along a NE–SW transect in different physiographic units in the Yasouj Plain. The results indicated that χ is determined mainly by topography and land use. In most pedons, the highest concentrations of poorly crystalline Fe (Fe_o) were observed in the top soil with different types of land use. Aquic condition in paddy soils seems the main cause for a significant decrease in the amount of Fe_d in the studied soils. Maximum concentration of pedogenic Fe (Fe_d) was noticed in more stable landforms with non-aquic moisture regime. Paddy soils exhibited higher Fe_o/Fe_d ratio values, suggesting that they have more poorly crystalline iron oxide phases than dryland soils. Magnetic measurements showed that the χ values of paddy soils were much lower (3.8 times) than those of dryland soils. The highest value of χ was found in the pedons located on plateau and piedmont plains and the lowest value of χ belongs to those that are located on hill and river lower terraces. A positive correlation was found between the frequency dependence of χ (χ_fd) and χ in paddy and dryland soils. Higher values of χ_fd were observed at soil surface than at deeper levels, suggesting a greater proportion of ultrafine grains.     

A study on historical location and evolution of Lop Nor in China with maps and DEM

Lop Sea, located at the east end of the Tarim Basin, Northwest China, dried up permanently, which is the terminal lake of the Tarim River. Lop Sea was considered as the lake basin of Lop Nor since Quaternary. However, the possibility that Lop Nor was away from the Lop Sea in historical time is crucial to be discussed to interpret the proxy records in sediment profiles. To obtain a general view of the evolution of Lop Nor and Lop Sea in a historical period, several approaches were adopted in this paper. First, the Qianlong Thirteen-Row Atlas, an ancient imperial atlas of the Qing Dynasty, which was completed around 1760, indicated that the Tarim River formed a relatively large lake at its modern upstream region. Second, a Digital Elevation Model(DEM) with a 10-m spatial resolution and a relative precision of 0.42 m was derived from TanDEM-X/Terra SAR-X satellite image pairs using the interferometry method, which was verified using ICESat-GLAS laser footprints and a local DEM acquired by a drone. Finally, based on the spatial analysis of historical documents, expedition reports, sediment profiles and archaeological evidence, it can be deduced that the lacustrine deposition was discontinued in the Lop Sea. Six episodes in the evolutionary history of the drainage system in eastern Tarim Basin were summarized. The proved depositional condition variations could be used for future interpretation of proxy records in sediment. The high-accurate DEM provided a reference for the location of further fieldwork in the Lop Sea. The method proposed in this paper may be efficient for the research of inland lakes or rivers in global arid regions.     

不同因子对玛纳斯河流域农田土壤盐分的影响

选取玛纳斯河流域内玛纳斯灌区和莫索湾灌区为研究区．利用遥感影像和GPS定位技术布设土壤盐分采样点,研究分析土壤质地、作物类型及地形因子对农田土壤盐分的影响。结果表明,研究区农田表层土壤（0～20cm层、20～40cm层）的盐分含量大小为：粘壤土〉粉壤土〉砂壤土;不同作物种植条件下农田土壤盐分状况表现为：棉花地〉葡萄地〉玉米地;不同地形部位农田土壤盐分含量表现为：冲积洪积扇下部〉冲积洪积扇中部〉沙漠边缘〉冲积洪积扇上部,各地形部位农田土壤盐渍化程度均表现为轻度盐渍化;不同海拔农田土壤盐分状况表现为：400500m〉500～700m〉400m以下,土壤盐分含量随着海拔的升高呈先增加后降低的趋势。     

Utilizing GIS Technologies in Selection of Suitable Vineyard Sites

Abstract

Geographic information system (GIS) technologies and a weighted linear indexing model were used for suitability analysis of potential vineyard sites in Illinois. The model included a macroscale climate variables layer (40 points), a mesoscale climate variables layer (40 points), a soil properties layer (10 points) and a current land use variables layer (10 points) for a possible 100 points. Macroscale climate variables, growing degree day summation for a 33-year period (1969-2002) and occurrence of -26°C were interpolated using thin plate smoothing splines over the Illinois terrain using 100 m2 resolution digital elevation models (DEM). Using the same DEMs, absolute elevation, slope, and aspect were reclassified using surface analysis of the terrain to model the effects of mesoscale climate variables in Jackson and Union Counties in Illinois (study area). Locations in the study area above 259 m in absolute elevation (above sea level), with gently rolling slopes (5 to 10%), and facing North, East, or Northeast received the most points within the mesoscale climate layer. Soils that drained well or moderately well with moderate organic matter content (2 to 3%) received the most points in the soil properties layer. Lands that promoted ease of conversion to vineyards were assigned the most points in the current land use layer. The resulting four layers were arithmetically summed and suitability maps with 760 m2 resolution were developed. In the study area, over 18,155 hectares of land highly suitable or suitable for viticulture were identified. A portion of the existing orchard and vineyard acreage (223 ha) in the study area were surveyed with a global positioning system. Of the surveyed vineyard acreage, over 81% lies within the suitable or better ranking according to the model. Of the surveyed orchard acreage, over 50% lies within the suitable or better ranking.     

基于遥测雨量数据的地形对降水特性的影响研究

以浙江省东部的宁波市鄞州区为例,采用15 min间隔的遥测降水数据,根据最小事件间隔时间对降水事件进行划分,探讨了地形对降水特性的影响在时间和空间上变化的复杂性。结果表明,不同年份年降水总量及降水频次与高程的相关关系较为显著,山区降水次数的增多对其降水量的增大有一定影响。另一方面,降水强度及历时与高程的关系比较复杂,地形对各种天气条件控制下不同类型降水的影响并不一致。降水强度小于2 mm/h以及降水历时介于2～5 h的降水频次随高程增大存在增加的趋势,且不同年份的这种增长趋势较为接近;而其它高强度、短历时或长历时的降水频次与高程的关系则比较复杂,地形对这些类型降水的影响具有较大的随机性。     

基于GIS和改进型土地生态适宜性评价模型的茶叶适宜性综合评价

Tea(Camellia sinensis) is one of the most valuable cash crops in southern China;however,the planting distribution of tea crops is not optimal and the production and cultivation regions of tea crops are restricted by law and custom.In order to evaluate the suitability of tea crops in Zhejiang Province,the annual mean temperature,the annual accumulated temperature above 10 C,the frequency of extremely low temperature below 13 C,the mean humidity from April to October,slope,aspect,altitude,soil type,and soil texture were selected from climate,topography,and soil factors as factors for land ecological evaluation by the Delphi method based on the ecological characteristics of tea crops.These nine factors were quantitatively analyzed using a geographic information system(GIS).The grey relational analysis(GRA) was combined with the analytic hierarchy process(AHP) to address the uncertainties during the process of evaluating the traditional land ecological suitability,and a modified land ecological suitability evaluation(LESE) model was built.Based on the land-use map of Zhejiang Province,the regions that were completely unsuitable for tea cultivation in the province were eliminated and then the spatial distribution of the ecological suitability of tea crops was generated using the modified LESE model and GIS.The results demonstrated that the highly,moderately,and non-suitable regions for the cultivation of tea crops in Zhejiang Province were 27 552.66,42 724.64,and 26 507.97 km 2,and accounted for 28.47%,44.14%,and 27.39% of the total evaluation area,respectively.Validation of the method showed a high degree of coincidence with the current planting distribution of tea crops in Zhejiang Province.The modified LESE model combined with GIS could be useful in quickly and accurately evaluating the land ecological suitability of tea crops,providing a scientific basis for the rational distribution of tea crops and acting as a reference to land policy makers and land use planners.     

浅谈地理和地形影响下的我国区域气温空间分布情况

我国国土广阔,属季风性气候区,地形复杂多样。全国多山地,自西向东来看,呈现出西高东低、分三级阶梯逐级递减的主要特征。随着科学和经济的发展,对气温空间分布作进行一步分析具有重要的现实价值和意义。     

地形因子和物理保护对张广才岭次生林土壤有机碳密度的影响

在张广才岭西部典型低山丘陵次生林区,按坡位、坡向差异对等设置36块样地,采集1 m深度剖面内不同发生层土样,研究了地形因子(坡位、坡向、坡度)对土壤有机碳含量、有机碳密度的影响,以及土壤有机碳与物理保护因子(黏粒、团聚体)的关系,并借助逐步回归分析量化各地形因子对土壤有机碳密度变异的相对贡献。结果表明,本地区土壤有机碳具有较大的空间变异性,土壤剖面的有机碳密度范围为8.9～31.3 kg/m。土壤有机碳的表聚特征明显,平均而言腐殖质层(A1层)集中了全剖面总有机碳的55.2%。坡位和坡向显著影响土壤有机碳的分布:下坡A1层有机碳密度是上坡的1.83倍,其1 m剖面有机碳密度是上坡的1.67倍, 阴坡A1层有机碳密度是阳坡的1.37倍,其1 m剖面有机碳密度是阳坡的1.17倍。坡度对上、下坡土壤有机碳含量和密度均无显著影响。排除坡位和坡积埋藏层等影响因子后,土壤有机碳含量、有机碳密度与黏粒、团聚体均无显著相关性,因此黏粒保护和团聚体保护并非土壤有机碳积累的控制因子。逐步回归显示,坡位是土壤有机碳数量分异的主控因子,可独立解释A1层有机碳密度空间变异的57.4%与1 m剖面有机碳空间变异的63.2%, 下层土壤埋藏层则是主控因子,可独立解释沉积层(B层)有机碳密度空间变异的63.4%, 黏粒和团聚体作为公认的土壤有机碳物理保护因子,却因贡献较小而在逐步回归过程中被剔除。研究结果可为区域森林土壤碳储量准确估算和碳汇林立地选择提供参考。      

山地城市土地利用地形分异特征及功能分区研究

采集北碚区2014年的土地利用变更数据、土地利用现状图和DEM数据,运用GIS技术,从坡度和高程角度,引入分布指数、洛伦兹曲线以及基尼系数,研究北碚区土地利用的地形分异规律。结果发现,研究区土地利用类型分布特征与高程、坡度联系紧密。林地和未利用地的优势位主要分布在较高地形等级区间,建设用地、耕地、园地等受人为干扰较大的地类优势则随地形等级的减少逐渐显现。坡度对各地类空间分布影响显著,高程在300~400 m、坡度在6~15°之间的区域是城市扩展和耕地保护的主要空间。耕地和园地在地形上的分布相差不大,建设用地、林地以及其他农用地则表现出一定的区域差异。从优势度来看,土地利用类型分布呈现明显的层级性,地形优势等级由低到高依次为水域层、城镇层、耕地层、园地层、林地层。基于该地形分异规律,将研究区划分为核心水体区、城镇发展区、现代农业发展区、生态农业发展区和生态屏障区等5个功能区,并提出各区土地利用发展建议。