Assessing the influence of climate change and inter-basin water diversion on Haihe River basin,eastern China: a coupled model approach

The modeling of changes in surface water and groundwater in the areas of inter-basin water diversion projects is quite difficult because surface water and groundwater models are run separately most of the time and the lack of sufficient data limits the application of complex surface-water/groundwater coupling models based on physical laws, especially for developing countries. In this study, a distributed surface-water and groundwater coupling model, named the distributed time variant gain model–groundwater model (DTVGM-GWM), was used to assess the influence of climate change and inter-basin water diversion on a watershed hydrological cycle. The DTVGM-GWM model can reflect the interaction processes of surface water and groundwater at basin scale. The model was applied to the Haihe River Basin (HRB) in eastern China. The possible influences of climate change and the South-to-North Water Diversion Project (SNWDP) on surface water and groundwater in the HRB were analyzed under various scenarios. The results showed that the newly constructed model DTVGM-GWM can reasonably simulate the surface and river runoff, and describe the spatiotemporal distribution characteristics of groundwater level, groundwater storage and phreatic recharge. The prediction results under different scenarios showed a decline in annual groundwater exploitation and also runoff in the HRB, while an increase of groundwater storage and groundwater level after the SNWDP’s operation. Additionally, as the project also addresses future scenarios, a slight increase is predicted in the actual evapotranspiration, soil water content and phreatic recharge. This study provides valuable insights for developing sustainable groundwater management options for the HRB.     

Two‐dimensional dictionary learning for suppressing random seismic noise

Dictionary learning is a successful method for random seismic noise attenuation that has been proven by some scholars. Dictionary learning–based techniques aim to learn a set of common bases called dictionaries from given noised seismic data. Then, the denoising process will be performed by assuming a sparse representation on each small local patch of the seismic data over the learned dictionary. The local patches that are extracted from the seismic section are essentially two‐dimensional matrices. However, for the sake of simplicity, almost all of the existing dictionary learning methods just convert each two‐dimensional patch into a one‐dimensional vector. In doing this, the geometric structure information of the raw data will be revealed, leading to low capability in the reconstruction of seismic structures, such as faults and dip events. In this paper, we propose a two‐dimensional dictionary learning method for the seismic denoising problem. Unlike other dictionary learning–based methods, the proposed method represents the two‐dimensional patches directly to avoid the conversion process, and thus reserves the important structure information for a better reconstruction. Our method first learns a two‐dimensional dictionary from the noisy seismic patches. Then, we use the two‐dimensional dictionary to sparsely represent all of the noisy two‐dimensional patches to obtain clean patches. Finally, the clean patches are patched back to generate a denoised seismic section. The proposed method is compared with the other three denoising methods, including FX‐decon, curvelet and one‐dimensional learning method. The results demonstrate that our method has better denoising performance in terms of signal‐to‐noise ratio, fault and amplitude preservation.     

Geochronology and geochemistry of the Early Cretaceous Jigongshan and Qijianfeng batholiths in the Tongbai orogen, central China: implications for lower crustal delamination

The Jigongshan and Qijianfeng batholiths in the Tongbai orogen consist mainly of porphyritic hornblende-biotite monzogranite, biotite monzogranite, and biotite syenogranite, which are variably intruded by lamprophyre, diorite, and syenogranite dykes. Mafic microgranular enclaves commonly occur in the hornblende-biotite monzogranite, whereas surmicaceous enclaves are found in the biotite monzogranite. Both batholiths have zircon U–Pb ages ranging from ca. 139 to 120 Ma, indicating their emplacement in the Early Cretaceous. The hornblende-biotite monzogranite has an adakitic affinity marked by relatively high Sr/Y and (La/Yb) _N ratios, lack of Eu anomalies, low MgO and Ni contents, and Na₂O > K₂O. Its chemical compositions, combined with enriched Sr–Nd isotopic signatures, suggest formation by dehydration melting of mafic rocks in a thickened lower crust. This thickened crust resulted from the Permo-Triassic subduction-collision between the North China and South China blocks and persisted until the Early Cretaceous. The biotite monzogranite and biotite syenogranite have low Al₂O₃, CaO, and Sr contents, low Rb/Sr, FeOt/MgO, and (Na₂O + K₂O)/CaO ratios, and flat HREE patterns with moderate to weak Eu anomalies. They were produced by partial melting of crustal materials under relatively low pressure. Partial melting at different crustal levels could have significantly contributed to mechanical weakening of the crust. The diorite and lamprophyre dykes show linear trends between SiO₂ and major or trace elements on Harker diagrams, with two lamprophyre samples containing normative nepheline and olivine. These rocks have high La/Yb and Dy/Yb ratios, both displaying co-variation with contents of Yb. They were originated from relatively deep lithospheric mantle followed by fractionation of olivine + clinopyroxene + apatite + Fe–Ti oxides. Extensive partial melting in the lithospheric mantle indicates relatively high temperatures at this level. We suggest that the presence of adakitic magmas, thickened but weakened crust and high temperatures in the lithosphere mantle point to lower crustal delamination in the Early Cretaceous in the Tongbai orogen.     

The existence of transversal homoclinic orbits in a planar circular restricted four-body problem

In this paper, we study the existence of transversal homoclinic orbits in a planar circular restricted four-body problem, based on the perturbation theory of integrable Hamiltonian systems. We start from a planar circular restricted four-body model and regard it as a perturbation of the two-body model. Then, in order to conveniently study unbounded orbits, we transform the infinite points to finite points by a non-canonical transformation, arriving at a non-Hamiltonian system with degenerate fixed points. According to the extended Melnikov method, we finally prove that there exist transversal homoclinic orbits in this four-body model.     

川东北下三叠统飞仙关组鲕粒白云岩孔喉的空间展布与刻画

孔喉特征是储集层研究的核心,厘清储集层孔喉在三维空间中的展布对油气勘探与开发意义重大。文中借助微纳米CT立体成像技术和数字岩心技术对川东北飞仙关组残余鲕粒白云岩的孔喉特征进行刻画与描述,建立了微纳米级的孔喉三维空间展布模型,并计算了孔喉半径、形状因子、空间连通性等表征参数。此外,结合扫描电镜、压汞曲线等传统方法,对所建立的模型进行了有益的探讨和补充。结果表明,川东北地区残余鲕粒白云岩孔隙类型主要有粒间孔、粒间溶孔（铸模孔）、晶间（溶）孔、晶间缝和微裂隙等。其中,晶间孔和微裂隙为连通的喉道,其最小值可达20～30 nm。样品重结晶强烈,受重结晶晶体的生长及后期压实等改造作用的影响,喉道堵塞,储集层渗透性差。     

Effects of forest gaps on some microclimate variables in Castanopsis kawakamii natural forest

The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features of air temperature (TA ), soil temperature (TS ), relative humidity (h) and soil water content (Ψ) were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that: (1) the variations of TA , h, and TS in four seasons were extremely significant. The variations of Ψ in four seasons were extremely significant except for those between spring and summer. (2) The diurnal variations of TA and T S were expressed with a single peak curve. The diurnal variations of h and Ψ presented a high-low-high trend. (3) The variations of TA , h, and TS were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were just contrary to medium gaps. The variations of Ψ were extremely significant for large, medium and small gaps except those between the medium and large gaps. (4) The TA , h, TS and Ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest.     

华北克拉通北缘赤峰地区显生宙麻粒岩的发现及其意义

华北克拉通构造体制从稳定向活动的转折是值得关注的问题。文中结合华北克拉通北缘赤峰和宁城晚古生代和早中生代两期麻粒岩捕虏体及其寄主闪长岩的研究,讨论其形成的不同构造背景,从而探讨体制转折的起始时期。赤峰柴胡栏子二叠纪镁铁质麻粒岩及其寄主闪长岩的锆石SHRIMP U-Pb年龄分别为（262.3±3.1） Ma和（256.6±6.5） Ma,宁城河南营子三叠纪镁铁质麻粒岩及其寄主闪长岩的锆石SHRIMP U-Pb年龄分别为（229.7±2.6） Ma和（221±3） Ma。在上述两个地区还发现晚古生代二叠纪的闪长岩脉等。通过对比研究认为：二叠纪岩浆活动具有大陆裂谷初始阶段的特点,高场强元素含量比较低;而三叠纪高场强元素的增高显示地幔部分熔融程度的提高。二叠纪岩浆活动与此时全球构造演化及邻兴蒙造山带出现的双峰式火山活动密切相关。而晚三叠世岩浆活动则与底侵背景下陆内伸展作用有关,是构造体制转折的标志。     

Multifractal and long memory of humidity process in the Tarim River Basin

Based on the daily data of relative humidity from 23 meteorological stations in the Tarim River Basin of northwest China during the period from 1961 to 2010, this paper analyzed the multifractal and long memory property of humidity process. Main findings are as follows: (1) The processes present scaling and multifractal property. (2) The left-skewed multifractal spectrum f(α) indicates that the time series of relative humidity is predominated by small fluctuations. (3) There exists long memory with the δ ∈ (0, 0.5) in the processes, except for Kalpin and Aksu’s exhibiting non-stationary long memory with the parameter δ being 0.67 and 0.69 respectively. (4) We found that on the whole, the degree of multifractality exhibits a strengthening trend with the longitude and latitude increasing, but decreasing trend with elevation rising; For length of long memory, we investigated that on the whole, the δ values increased with the longitude and latitude increasing, which indicates that the bigger the longitude and latitude is, the longer the memory of humidity process is, but the higher the elevation is, the shorter the memory of humidity process is.     

2D地震数据规则化中随机稀疏采样方案

地震数据规则化是地震信号处理中一个重要步骤,近年来受到广泛关注的压缩感知技术已经被应用到地震数据规则化中。压缩感知技术突破了传统的Shannon-Nyqiust采样定理的限制,可以用采集的少量地震数据重构完整数据。基于压缩感知技术的地震数据规则化质量主要受三个因素影响,除了受地震信号在不同变换域的稀疏表达和11范数重构算法的影响外,极大地取决于地震道随机稀疏采样方式。尽管已有学者开展了2D地震数据离散均匀分布随机采样方式研究,但设计新的稀疏采样方案仍然很有必要。在本文中,我们提出满足Bernoulli分布规律的Bernoulli随机稀疏采样方式和它的抖动形式。对2D数值模拟数据进行四种随机稀疏采样方案和两种变换（Fourier变换和Curvelet变换）实验,对获取的不完整数据应用11范数谱投影梯度算法（SPGL1）进行重构。考虑到不同随机种子点产生不同约束矩阵R会有不同的规则化质量,对每种方案和每个稀疏采样因子进行10次规则化实验,并计算出相应信噪比（SNR）的平均值和标准偏差。实验结果表明,我们提出的新方案好于或等于已有的离散均匀分布采样方案。     

涪江上游泥石流灾损土地资源化利用模式

长江流域涪江上游以高山峡谷地貌为主,人地矛盾突出,水热条件较好的泥石流灾损土地是山区居民主要的生产生活场所,高效利用灾损土地是山区发展的重要途径。通过野外调查,初步查明目前涪江上游42处泥石流灾损土地利用类型主要为耕地、林地和建筑用地,分别占调查总数的41.5%、32.8%和12.1%。这42处泥石流灾损土地总面积为2.47 km²,可利用面积为2.12 km²(含已利用建筑用地等),占调查总面积的86%,潜在可利用面积较高。选取土壤肥力、水土保持特性及工程地质特性3个因子进行泥石流灾损土地资源化利用评价,得出涪江上游泥石流灾损土地资源化利用模式。评价结果表明,涪江上游泥石流灾损土地可利用潜力主要以中等和较低程度为主,占调查总数的88.09%,因此,涪江上游泥石流灾损土地资源具有较大的开发潜力。另外,本文以涪江上游黄家坝为例,得出4种灾损土地利用模式,即村落聚集优化区模式、现代农业耕作区模式、水土保持缓冲区模式及工民建设潜力区模式,并在此基础上提出相应的灾损土地利用建议,为山区土地资源化开发利用提供指导。