Regional differences in gully network connectivity based on graph theory:a case study on the Loess Plateau,China

Material exchange frequently occurs in gullies,and thus the relationship between a gullynetwork structure and sediment transport potential has attracted considerable interest.However,previous researches ignored the difficulty of material transport from sources to sinks,and did not quantify the connectivity of a network structure.In this study,we used a graph model structure to model gully networks of six typical sample areas in the Loess Plateau of China and quantified gully network connectivity using four indexes:average node strength,accessibility from sources to sinks,potential flow,and network structural connectivity index.Results show that:(1)Reflected by different quantitative indexes,the trends of gully network connectivity in different regions are similar.From north to south,the connectivity of a sample area first increases and then decreases.(2)The more mature gullies have stronger network connectivity.Small resistance is conducive to material transport in the gullies.(3)The node connectivity index of the gully network shows a significant aggregation distribution in space,and node connectivity on the main channel is often stronger than that on the branch trench.These results not only deepen the understanding of the process and mechanism of loess gully geomorphic development and evolution but also provide a reference for geomorphic studies.

Study on Rural Domestic Waste Treatment in Loess Plateau Region——Taking Longfang Town in Shaanxi Province as Example

With the continuous development of economy and changes in people’s lifestyle,rural domestic waste brought about serious harm to water,air,human health,ecological landscape and so forth.In this paper,taking Longfang Town in Loess Plateau region as example,the source,amount and harms of rural domestic waste were analyzed firstly,as well as the current situation and existing problems of treatment,and then a suitable waste disposal technology for the town was chosen,finally the reasonable treatment methods combining new countryside and non-new countryside with township was summed up,so as to realize the reduction,harmless and resource treatment of rural domestic waste.

Study on the Climate Changes Characteristics in the Hilly Region of the Loess Plateau and Its Influence on Agricultural Production

[Objective] The aim was to study the climate changes characteristics in the hilly region of the loess plateau and its influence on agricultural production.[Method] Taking Yan’an City as an example,and by dint of temperature and precipitation in nine meteorological stations from 1957 to 2007 and accumulated anomaly curve,linear regression and relevant analysis,the climate changes characteristics in 51 years in Yan’an were expounded.The climate changes in the hilly region of the loess plateau were studied and its influences on agricultural production were concluded.[Result] The characteristics of climate changes in the hilly region were as follow:high temperature in winter and warm winter trend was clearly;the temperature in spring enhanced fast and the drought disaster was increasing worse;rainy days occurred now and then in autumn.The climate changes had different levels of influences on agricultural production in Yan’an City.Because of rising temperature in winter,facility agriculture was vigorously developed and the apple range expanded;in the meantime,because of rising temperature in spring,drought was worsen and sowing in spring can not proceed;constant rain in autumn damaged the quality of date.[Conclusion] The study provided theoretical basis for the regional agricultural production and agricultural structure adjustment.

A GIS-based Modeling Approach for Fast Assessment of Soil Erosion by Water at Regional Scale, Loess Plateau of China

The objective of this study is to develop a unique modeling approach for fast assessment of massive soil erosion by water at a regional scale in the Loess Plateau, China. This approach relies on an understanding of both regional patterns of soil loss and its impact factors in the plateau area. Based on the regional characteristics of precipitation, vegetation and land form, and with the use of Landsat TM and ground investigation data, the entire Loess Plateau was first divided into 3 380 Fundamental Assessment Units （FAUs） to adapt to this regional modeling and fast assessment. A set of easily available parameters reflecting relevant water erosion factors at a regional scale was then developed, in which dynamic and static factors were discriminated. Arclnfo GIS was used to integrate all essential data into a central database. A resulting mathematical model was established to link the sediment yields and the selected variables on the basis of FAUs through overlay in GIS and multiple regression analyses. The sensitivity analyses and validation results show that this approach works effectively in assessing large area soil erosion, and also helps to understand the regional associations of erosion and its impact factors, and thus might significantly contribute to planning and policymaking for a large area erosion control in the Loess Plateau.

Land-use changes in the small watershed of the Loess Plateau,hilly-gully region, China

As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.

Dynamic Land Use /Cover Change and Analysis of Landscape Pattern in the Hilly and Gully Region of Loess Plateau: A Case Study of Pengyang County in Southern Ningxia

The quantitative evaluation on land use /cover change as well as its influence on landscape pattern under the background of returning grain plots to forestry is significant to the sustainable utilization of land resources and ecological environment reconstruction in the southern Ningxia.Based on multi-temporal remote sensing data from four periods of Landsat TM /ETM,and combination of ecological quantity analytical method with GIS,the change of land use /cover and landscape pattern in Pengyang County of Ningxia Province were analyzed.The conclusions showed that the amount of each land use type was changed with different degrees,the area of forest /grass land increased,while farmland and unused land decreased.The change of landscape pattern was characterized as that the degree of landscape fragmentation,mixed distribution of patches,diversity index and evenness index increased gradually and then decreased,the connectivity between patches decreased gradually and then increased,and landscape shape presented irregular.

Autumn Daily Characteristics of Land Surface Heat and Water Exchange over the Loess Plateau Mesa in China

The Loess Plateau, located in northern China, has a significant impact on the climate and ecosystem evolvement over the East Asian continent. In this paper, the preliminary autumn daily characteristics of land surface energy and water exchange over the Chinese Loess Plateau mesa region are evaluated by using data collected during the Loess Plateau land-atmosphere interaction pilot experiment （LOPEX04）, which was conducted from 25 August to 12 September 2004 near Pingliang city, Gansu Province of China. The experiment was carried out in a region with a typical landscape of the Chinese Loess Plateau, known as ＂loess mesa＂. The experiment＇s field land utilizations were cornfield and fallow farmland, with the fallow field later used for rotating winter wheat. The autumn daily characteristics of heat and water exchange evidently differed between the mesa cornfield and fallow, and the imbalance term of the surface energy was large. This is discussed in terms of sampling errors in the flux observations-footprint; energy storage terms of soil and vegetation layers; contribution from air advections; and low and high frequency loss of turbulent fluxes and instruments bias. Comparison of energy components between the mesa cornfield and the lowland cornfield did not reveal any obvious difference. Inadequacies of the field observation equipment and experimental design emerged during the study, and some new research topics have emerged from this pilot experiment for future investigation.

Vegetation and environmental changes in western Chinese Loess Plateau since 13.0 ka BP

Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate （12.1-11.0 ka BP）. The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP. After a brief episode of a cool and wet climate （9.8-9.6 ka BP）, a relatively mild and dry condition prevailed during the early Holocene （9.6-7.6 ka BP）. The most favourable climate of warm and humid period occurred during mid-Holocene （7.6-4.0 ka BP） marked by forest-steppe landscape and vegetation alternatively changed between steppe and desert-steppe from -4.0 to -1.0 ka BP.

Quantitative analysis of the dynamic change and spatial differences of the ecological security: a case study of Loess Plateau in northern Shaanxi Province

Using the theory and method of the ecological footprint, and combining the changes of regional land use, resource environment, population, society and economy, this paper calculated the ecological footprint, ecological carrying capacity and ecological surplus/loss in 1986-2002 on the Loess Plateau in northern Shaanxi Province. What is more, this paper has put forward the concept of ecological pressure index, set up ecological pressure index models, and ecological security grading systems, and the prediction models of different ecological footprints, ecological carrying capacity, ecological surplus and ecological safety change, and also has assessed the ecological footprint demands of 10,000 yuan GDE The results of this study are as follows： （1） the ecological carrying capacity in northern Shaanxi shows a decreasing trend, the difference of reducing range is the fastest; （2） the ecological footprint appears an increasing trend; （3） ecological pressure index rose to 0.91 from 0.44 during 1986-2002 on the Loess Plateau of northern Shaanxi with an increase of 47%; and （4） the ecological security in the study area is in a critical state, and the ecological oressure index has been increasing rapidlv.

Dynamic Simulation of Land Use in the Southern Loess Plateau

To study the dynamic changes of land use and predict the future land use scenarios based on the current land use,this paper uses Cellular Automata- Markov( CA- Markov) model to simulate the landscape pattern in 2030. The results show that in the study area during the period 1980- 2005,grassland and construction land increased,and woodland increased slightly; waters and unused land decreased,and arable land underwent dramatic changes. The simulation precision of CA- Markov model is 87. 28%,indicating that the use of it for simulation is reliable. The land use of the study area will be changed greatly in the future. This method provides a reference for the regions to carry out land prediction,and the research results can provide a basis for the study of optimization of land.

THE SYSTEMATIC DYNAMIC EMULATION ON THE AGRICULTURAL DEVELOPMENT ON THE LOESS PLATEAU

The Loess Plateau, covered with thick loess, lies in the middle reaches of the YellowRiver to the west of the Taihangshan Mountains, east of the Wuqiao Mountains south ofYinshan Mountains and north of the Qinling Mountains with a total area of 56×10~4km^2.The plateau is 1000--2500m above sea level and has loess as thick as 100--200 metres, be-

Review on Regional Climate Change Induced by Qinghai-Tibet Plateau Uplift

[Objective]The aim was to study the influence of Qinghai-Tibet Plateau uplift on regional climate in China.[Method] Trough relevant study of Qinghai-Tibet Plateau and its surrounding movement,the tectonic movement of the Qinghai-Tibet Plateau and its surrounding areas,especially the case of the impact caused by plateau phased uplift were studied based on paleomagnetic measurements.[Result]The increasing Qinghai-Tibet Plateau led to obvious transition from dry to cold in northwest China and it became dry quickly,which led to loess accumulation,replacement of vegetation types and human activity.Meanwhile,it was dry,and there was certain degree of climate changes in the area.[Conclusion] Qinghai-Tibet Plateau had far-reaching significance on basic climate characteristics in northwest China.

黄土高原河谷城镇“川—沟”融合单元发展路径研究

通过分析黄土高原河谷城镇独特的城乡关系与发展困境,认为川道与次沟空间结构一体化、功能结构差异化发展是振兴黄土高原丘陵沟壑区的重要突破口,由此提出“川—沟”融合单元的概念内涵与划定方法。以榆林市绥德县为例,打破镇域行政边界和小流域镇村体系,基于川道城镇和次沟乡镇的空间关联关系划定10个融合单元,并从用地形态结构、产业经济地理、服务设施配置等方面对融合单元的空间构型、功能类型和服务水平进行剖析,探讨川道与次沟协同视角下以融合单元为抓手推动黄土高原河谷城镇高效发展和管控治理的新路径。

文化保护与乡村振兴协同的杨家沟建设规划研究

以杨家沟为代表的一类特殊乡村具有红色文化资源丰富但地处偏远、对外交通不便、产业基础薄弱、土地资源紧缺等特征,长期面临红色文化资源保护与乡村振兴的双重压力.基于乡村地域系统理论与评估框架,诊断杨家沟乡村子系统发展水平及问题,结果表明:杨家沟乡村子系统呈两极化发展水平,虽然红色文化资源丰富、历史文化底蕴深厚,但在生态环境脆弱、土地资源紧缺、遗产保护要求约束的影响下,该村农业和旅游业难以充分发展,导致人口外流、产业空心化、经济发展缓慢,进一步加剧遗址维护人员及资金短缺、遗址保护管理不善等问题.对此,规划提出“红色文化+X”的发展模式,形成文化遗产带动红色旅游、红色旅游反哺遗产保护、促进乡村振兴的良性循环,并采用“枝状网络分形”的空间布局,解决遗址环境保护与旅游产业发展、移民搬迁安置的潜在用地冲突.

2005-2019年陕西长武农田生态系统国家野外科学观测研究站气象数据集

陕西长武农田生态系统国家野外科学观测研究站(长武站)所在区域代表了黄土高塬沟壑区的典型农田,在研究站内设置气象自动观测系统对气象要素进行长期定位观测,对该区气候变化背景下农田生态系统水、土、气、生过程研究具有重要意义。本数据集对2005–2019年长武站的原始气象数据进行处理、质量控制和评估,对大气温度、相对湿度、降水量、大气压、总辐射、反射辐射、紫外辐射、净辐射、光合有效辐射、日照时数和各土层土壤温度(0 cm、5 cm、10 cm、15 cm、20 cm、40 cm、60 cm和100 cm)18项气象观测指标,以180条月尺度和15条年尺度的格式进行信息公开,以期为黄土高原沟壑区农业生态研究、天气灾害预警和气候生产潜力模拟等提供基础数据支撑。

1970—2020年黄土高原水蚀风蚀交错区极端降水时空变化研究及驱动因素分析

黄土高原水蚀风蚀交错区作为中国北方典型的生态脆弱区,因其独特地形和气候条件,极端降雨事件对其环境和生态系统的影响更加突出。选取水蚀风蚀交错区28个气象站点,结合RClimDex模型计算11个极端降水指数,采用线性相关分析法、Mann-Kendall趋势检验法和小波交叉法,分析了1970—2020年黄土高原水蚀风蚀交错区极端降水事件时空分布特征,探讨了极端降水事件的驱动因素。结果表明:(1)1970—2020年水蚀风蚀交错区持续干燥日数(CDD)呈下降趋势,其余10个指数呈上升趋势,反映出近50a研究区极端降水事件的频率、量级和强度不断增加。交错区年降水量增加和极端降水事件增加具有密切关系,且极端降水事件增加主要是由中雨日数(R10)和大雨日数(R20)引起。(2)1970—2020年极端降水事件在全区整体为增加趋势,交错区中部和西南部极端降水事件显著发生,陕西段极端降水量和强度呈显著增加趋势且极端化程度更显著。(3)湿日总降水量(PRCPTOT)、暴雨日数(R25)、5d最大降水量(R5d)3个极端降水指数,与影响因子厄尔尼诺-南方涛动(ENSO)、东亚夏季风(EASM)和太阳黑子(SN)具有不同的功率,与SN的交叉小波变换功率最大,说明影响因子中SN和极端降水指数的相关性最高,SN对极端降水事件的影响最大。

黄土高原近30年降水集中度分析及时空演变特征

选取近30年的黄土高原地区58个气象站点的降水数据,分析了黄土高原年降水以及降水集中度(PCD)和集中期(PCP)的时空变化特征,结果表明:(1)黄土高原地区年均降水量在50~900 mm,空间分布上东南高西北低。降水高值区分布在三门峡站与武功站附近以及五台山站,年均降水量为900 mm;低值区位于临河站附近,年均降水量为50 mm;(2)黄土高原地区的降水集中度分布于0.43~0.76,自东南向西北递增;而降水集中期的变化则不太明显,多集中于夏季的7-8月份。因此在降水集中的7-8月份,水土流失会比较加重,应加强水土流失防治工程,在降水量大的月份做好灾害防护,为工农业生产提供预警,减少工农业生产损失与经济损失。

黄土丘陵沟壑区典型小流域沟道类型和坡面组成对重力侵蚀的影响

重力侵蚀是黄土丘陵沟壑区小流域发生水土流失和地质灾害的重要原因之一,但对其存在和发生环境的研究仍不充分。为探究沟道形态和坡面组成对重力侵蚀的影响,基于无人机摄影测量、遥感解译、现场调查等方法,系统研究山西省吕梁市王家沟流域内78处滑坡、26处崩塌和108处泻溜的空间分布、侵蚀数量特征及与沟坡的关系。结果表明:1)沟道类型影响重力侵蚀危害程度。沟道分类有助于识别重力侵蚀活跃区域,冲沟和干沟的重力侵蚀量及面积分别占研究区总量的88.5%和81.4%。2)重力侵蚀与沟道坡度存在紧密关系,在不同类型沟道中的表现差异显著。坡度30°~60°区域分别是切沟和冲沟中重力侵蚀最严重区域,发生率约是其他区域的2.57倍和1.19倍;干沟和河沟的重力侵蚀主要发生在坡度0~30°区域。3)坡面组成方式对重力侵蚀危害程度和发生类型存在显著影响,土壤类型及其空间分布特征是重要影响因素。该研究可为黄土丘陵沟壑区重力侵蚀精准防治提供理论依据。

残塬沟壑区苹果园生态服务功能综合评价研究

为评价黄土高原残塬沟壑区典型林果经济林生态系统服务功能综合服务状况,以陕西省永寿县苹果园为研究对象,采用专家咨询、频度分析等方法构建了包含涵养水源、抗侵蚀性等10个方面17个生态服务指标评价体系,并应用层次分析法和模糊评价法构建生态系统服务综合评价模型,对苹果园生态系统服务功能进行综合评价。评价可得,生态功能、生活功能和生产功能权重分别为0.6753、0.0715、0.2532,生态功能和生产功能是影响果园生态系统服务状况的关键因素。度隶属度评价矩阵表明,林田灌水量、土壤侵蚀强度、Shannon-Wiener指数和苹果产是影响果园生态功能服务状况主要影响因子。残塬沟壑区苹果园生态系统服务功能综合评价指数0.5535,评价结果为Ⅲ等级。主要原因是人为干扰所致,导致林田施肥量过高,不合理经营导致土壤养分较低,根系土壤层含水率低,林分结构单一负离子浓度较低,导致了隶属度评价值较低。研究结果为残塬沟壑区林果经济林生态服务功能评价和可持续利用提供数据支持。

双螺孔型重建板前路双关节融合术治疗黄土高原地区晚期踝大骨节病

目的探讨双螺孔型重建板前路双关节融合术治疗黄土高原地区晚期踝大骨节病的疗效。方法采用双螺孔型重建板前路双关节融合术治疗36例黄土高原地区晚期踝大骨节病患者。记录手术情况、疼痛VAS评分、AOFAS踝-后足评分以及并发症发生情况。结果患者均获得随访,时间6~20(9.4±2.2)个月。手术时间50~60(55.0±5.0)min。切口均一期愈合,术后未发生断钉、断板等并发症。疼痛VAS评分及AOFAS踝-后足评分:术后6个月、末次随访时均较术前改善(P<0.05)。末次随访时,X线片显示踝关节植骨均融合,患侧外观正常,患肢行走无明显不适感;采用AOFAS踝-后足评分评价疗效:优30例、良6例,优良率100%。结论采用双螺孔型重建板前路双关节融合术治疗黄土高原地区晚期踝大骨节病,术中能够充分处理关节面,实现坚强固定,术后能够较好地恢复和维持踝关节的矫形位置,并发症少,疗效满意。