Testing the Universal Soil Loss Equation‐MB equation in plots in Central and South Italy

Planning soil conservation strategies requires predictive techniques at event scale because a large percentage of soil loss over a long‐time period is due to relatively few large storms. Considering runoff is expected to improve soil loss predictions and allows relation of the process‐oriented approach with the empirical one, furthermore, the effects of detachment and transport on soil erosion processes can be distinguished by a runoff component. In this paper, the empirical model USLE‐MB (USLE‐M based), including a rainfall‐runoff erosivity factor in which the event rainfall erosivity index EI₃₀ of the Universal Soil Loss Equation (USLE) multiplies the runoff coefficient Q_R raised to an exponent b₁ > 1 is tested by the measurements carried out for the Masse (10 plots) and Sparacia (22 plots) experimental stations in Italy. For the Masse experimental station, an exponent b₁ > 1 was also estimated by tests carried out by a nozzle‐type rainfall simulator. For each experimental site in fallow conditions, the effect of the sample size of the plot soil loss measurements on the estimate of the b₁ coefficient was also studied by the extraction of a fixed number N of randomly obtained pairs of the normalized soil loss and runoff coefficient. The analysis showed that the variability of b₁ with N is low and that 350 pairs are sufficient to obtain a stable estimate of b₁. A total of 1,262 soil loss data were used to parameterize the model both locally and considering the two sites simultaneously. The b₁ exponent varied between the two sites (1.298–1.520), but using a common exponent (1.386) was possible. Using a common b₁ exponent for the two experimental areas increases the practical interest for the model and allows the estimation of a baseline component of the soil erodibility factor, which is representative of the at‐site soil intrinsic and quasi‐static properties. Development of a single USLE‐MB model appears possible, and sampling other sites is advisable to develop a single USLE‐MB model for general use.     

Comparing flow resistance law for fixed and mobile bed rills

Rills caused by run‐off concentration on erodible hillslopes have very irregular profiles and cross‐section shapes. Rill erosion directly depends on the hydraulics of flow in the rills, which may differ greatly from hydraulics of flow in larger and regular channels. In this paper, a recently theoretically deduced rill flow resistance equation, based on a power–velocity profile, was tested experimentally on plots of varying slopes (ranging from 9% to 26%) in which mobile and fixed bed rills were incised. Initially, measurements of flow velocity, water depth, cross‐section area, wetted perimeter, and bed slope, carried out in 320 reaches of mobile bed rills and in 165 reaches of fixed rills, were used for calibrating the theoretical flow resistance equation. Then the relationship between the velocity profile parameter Γ, the channel slope, and the flow Froude number was separately calibrated for the mobile bed rills and for the fixed ones. The measurements carried out in both conditions (fixed and mobile bed rills) confirmed that the Darcy–Weisbach friction factor can be accurately estimated using the proposed theoretical approach. For mobile bed rills, the data were supportive of the slope independence hypothesis of velocity, due to the feedback mechanism, stated by Govers. The feedback mechanism was able to produce quasicritical flow conditions. For fixed bed rills, obtained by fixing the rill channel, by a glue, at the end of the experimental run with a mobile bed rill, the slope independence of the flow velocity measurements was also detected. Therefore, an experimental run carried out by a rill bed fixed after modelling flow action is useful to detect the feedback mechanism. Finally, the analysis showed that, for the investigated conditions, the effect of sediment transport on the flow resistance law can be considered negligible respect to the grain roughness effect.     

辽宁区域旅游竞争力比较研究

通过构建包括旅游资源实力、旅游基础、旅游市场实力、旅游环境实力、经济实力和旅游发展活力6个方向、21个指标、36个具体因子的区域旅游竞争力评价指标体系,从区域、地区2个层面分析了辽宁省旅游竞争力的格局.辽宁省三大区域旅游竞争力格局为:辽宁沿海经济带(7.98)＞全省平均(7.32)＞沈阳经济圈(7.03)＞辽西北(5.48).从空间来看,辽宁区域旅游竞争力格局是“东强西弱,南强北弱”.进一步的研究显示:地区产业结构对辽宁地区旅游竞争力具有明显的影响作用,第三产业发达的地区,作为第三产业组成部分的旅游业发展优势明显,而第一产业比重较大的地区对旅游业支撑作用明显不足.     

南京城市户籍贫困人口的时空分异格局

以城市居民最低生活保障统计数据为基础,运用ESDA的方法,探讨2000—2017年南京城市户籍贫困人口的时空分异格局,并从居住空间分异的视角出发,归纳总结出南京城市户籍贫困空间格局的演化过程与机制。研究表明：① 贫困人口的空间分布沿袭了2000年“大分散,小集中”的特点,且分布状态进一步趋于分散,空间集聚则呈现出“核心-边缘”结构,“核心”即热点区域基本都位于绕城公路以内;② 未成年、无业、有就业能力（尚未正式就业）和刑释解教的贫困群体,尤其是刑释解教且无业的贫困群体,是当下城市贫困空间治理重点关注对象;③ 相比于2000年,目前南京城市户籍人口的贫困地域产生了明显分异,可划分为隐蔽型、安置型和复合型三种类型贫困人口聚居区;④ 在政府职能、市场机制和社会行为的交织作用下,南京城市户籍贫困空间重构的同时,也经历了从显性到隐性的转向。     

《中国大百科全书•中国地理卷》西南区编撰对区域地理学研究的启示

《中国大百科全书》是中国文化遗产的宝库,地理卷作为其重要分册之一,是地理学的工具用书,更是普通大众了解地学知识的一个窗口,也是以书为鉴,明得失、知兴替的“铜镜”。基于《中国大百科全书·中国地理卷》第三版的编写,聚焦西南区,分析地理词条的构成与特征,探讨区域地理学研究的特色。梳理出西南区旅游与地理学协同发展,资源与生态保护地位凸现,地质灾害研究成效显著,地缘与经济战略优势突出等特点。并在浅析西南区地理学研究不足基础上,提出区内地理学发展的展望,即加强西南区地理学的基础性与综合性研究,提升地域系统对全球变化的动态响应研究,拓展新时期地理学的量化与应用性研究,重视地理科学知识科普的人才队伍建设等。     

基于标准化降水指数的中国冬季干旱分区及气候特征

利用中国614个气象台站1951—2006年历年月平均降水资料,计算各站的标准化降水指数及其干旱等级序列,采用REOF等方法进行气候分区,分析各区域近55 a干旱等级的时空变化,并着重讨论了黄淮—华北冬小麦种植区冬季干旱的大气环流特征。结果表明,我国冬季降水具有显著的年代际变化,西北的新疆地区,华北及黄淮地区自进入21世纪以来,冬季降水量增加十分明显,而西南,青藏高原及华南地区冬季降水量有所减少。根据标准化降水指数的旋转载荷向量可将中国划分为13个区域,其干旱等级序列和代表站资料反映出近55 a西北地区东部、河套及华北北部有变干的趋势,而新疆北部、东北北部、华北南部、江淮、江南地区降水量有增加的趋势。乌拉尔山—青藏高原脊、东亚大槽及西太平洋副高是影响北方冬麦区旱涝最主要的大气环流系统,其对分析、预测旱涝具有十分重要的指示意义。     

水分胁迫下马铃薯SnRK2基因的表达模式与生理响应

以 “大西洋”和“陇薯3号”两个品种盆栽苗为试验材料,研究了水分胁迫下马铃薯（Solanum tuberosum）StSnRK2基因家族的表达特征及其与植株生理指标变化的相关性。结果表明：在发生严重水分胁迫时,“陇薯3号”和“大西洋”的抗氧化酶活性、MDA含量、相对电导率和脯氨酸含量均较对照显著提高,但增长幅度在品种间存在差异;StSnRK2基因家族的8个成员的相对表达量在“大西洋”和“陇薯3号”之间也存在明显差异,StSnRK2.1、StSnRK2.2和StSnRK2.3在两个品种中均表现为水分胁迫后相对表达量显著高于对照的趋势;StSnRK2.7的相对表达量与对照无显著差异,而StSnRK2.4在“陇薯3号”的相对表达量是对照的9.5倍,是8个基因成员在受水分胁迫后相对表达量最高的一个基因;StSnRK2.1、StSnRK2.2、StSnRK2.3、StSnRK2.4和StSnRK2.6的相对表达量均与部分生理指标呈极显著正相关,StSnRK2.5和StSnRK2.8两个基因的相对表达量与部分生理指标呈极显著负相关,StSnRK2.7基因的相对表达量与生理指标无显著相关性。     

Projected changes in vertical temperature profiles for Australasia

The vertical temperature profile in the atmosphere reflects a balance between radiative and convective processes and interactions with the oceanic and land surfaces. Changes in vertical temperature profiles can affect atmospheric stability, which in turn can impact various aspects of weather systems. In this study, we analyzed recent-past trends of temperature over the Australian region using a homogenized monthly upper-air temperature dataset and four reanalysis datasets (NCEP, ERA-Interim, JRA-55 and MERRA). We also used outputs of 12 historical and future regional climate model (RCM) simulations from the NSW/ACT (New South Wales/Australian Capital Territory) Regional Climate Modelling (NARCliM) project and 6 RCM simulations from the CORDEX (Coordinated Regional Downscaling Experiment) Australasian project to investigate projected changes in vertical temperature profiles. The results show that the currently observed positive trend in the troposphere and negative trend in the lower stratosphere will continue in the future with significant warming over the whole troposphere and largest over the middle to upper troposphere. The increasing temperatures are found to be latitude-dependent with clear seasonal variations, and a strong diurnal variation for the near surface layers and upper levels in tropical regions. Changes in the diurnal variability indicate that near surface layers will be less stable in the afternoon leading to conditions favoring convective systems and more stable in the early morning which is favorable for temperature inversions. The largest differences of future changes in temperature between the simulations are associated with the driving GCMs, suggesting that large-scale circulation plays a dominant role in regional atmospheric temperature change.

     

降雨对Ku波段旋转扇形波束散射计影响

星载散射计测量的归一化后向散射截面是有关海面毛细重力波的大小和方向的函数:散射计的回波强度与海面毛细重力波的振幅成正比;风向对后向散射系数具有调制作用。因此,可以利用散射计的数据,根据地球物理模型反演出具有高精确度、无雨和中低风速条件下的海面风场矢量。然而高达10%的散射计测量数据会受到降雨影响(Nie,etal.,2008),尤其工作在Ku波段的散射计。降雨对海面散射幅度的影响主要包括:(1)降雨对雷达波的衰减和散射;(2)降雨改变海洋水面形态和海面粗糙度。     

基于方差-协方差分量估计的GM(1,1)模型及其应用

首先给出了基于灰色系统理论的GM(1,1)传统模型,指出该模型的实质是假设原始数列为独立、等精度观测数据,而事实上,独立且等精度观测对于实际测量难以从严格意义上实现。为此,从平差后得到的改正数入手,探讨基于方差-协方差分量估计的GM(1,1)模型,并将其应用于某变形监测预报,得到了较好的结果。