A geospatial model for the optimization grazing management in semi-arid rangeland of Iran

Extensive livestock grazing even in unsuitable land has increasingly grown in most parts of semi-arid rangeland. Therefore, it is of paramount importance to identify suitable land for livestock grazing for optimum utilization while causing minimum impact to the environment. This paper adapted the schematic model based on the concepts presented by the Food and Agriculture Organization of suitability analysis for optimal grazing management in semi-arid rangeland in Iran. Factors affecting extensive grazing were determined and incorporated into the model. Semi-arid rangeland with variable such as climate and other agents were examined for common types of animal grazing and the advantages and limitations were elicited. Many ecosystem components affect land suitability for livestock grazing but due to time and funding restrictions, the most important and feasible elements were investigated. Within the model parameters, three submodels including water accessibility source, forage production, and erosion sensitivity were considered. Suitable areas at four levels of suitability were determined using geographic information systems. This suitability modeling approach was adopted due to its simplicity and the minimal time required for transforming and analyzing datasets. The most important reducing factors in model suitability were found to be: (a) land use and vegetation cover (in relation to soil erosion sensitivity), (b) the amount of the available forage in comparison with the total production, and (c) the existence of less palatability plants among the pasture plant species (forage production suitability). The results of the study would be beneficial to rangeland managers in devising measures more wisely to cope with the limitations and enhance the health and productivity of the rangelands.     

拉萨地块南木林盆地北缘中新世高锶低钇岩浆作用:锆石U-Pb年龄、Hf同位素和地球化学特征

拉萨地块南木林盆地北缘的林子宗群火山岩地层侵位有大量的花岗斑岩岩株和岩脉,空间分布上与南北向正断层的次级断裂相一致。本次研究对南木林盆地北缘的花岗斑岩进行了系统的元素地球化学,LA-MCICP-MS锆石U-Pb年代学和Lu-Hf同位素测试。数据结果表明:花岗斑岩具有高硅(68.31%~71.34%)、高钾(4.52%~4.96%)、高(La/Yb)N(21.59~36.81)、Sr/Y(Sr/Y=15.59~38.10)等特征,富集大离子亲石元素(LILE),亏损高场强元素(HFSE);花岗斑岩LA-MC-ICP-MS锆石U-Pb年龄为12.2±0.1Ma,ε_(Hf)(t)值为-0.6~+4.0。拉萨地块南木林盆地北缘花岗斑岩岩石学、地球化学特征显示其为新生下地壳部分熔融产物,且源区残留了石榴子石、金红石、角闪石,无斜长石残留,在岩浆上侵过程中,发生了碱性长石的分离结晶作用。花岗斑岩侵位于中新世,与区内南北向裂谷发育时代一致,成分上类似于拉萨地块南部同时期发育的高锶低钇斑岩、钾质岩,同为印度—欧亚大陆碰撞后东西向伸展背景产物。     

天然气运移的气体组分的地球化学示踪

本文通过我国不同含油气盆地典型地区岩石酸解气、罐顶气和天然气中化学组分分析,结合天然气的形成和盆地的地质演化,研究了天然气运移时组分的变化。结果表明,天然气通过地层孔隙系统运移时,组分会发生明显分馏,表现在甲烷相对重烃、异构丁烷相对正构丁烷的优先迁移。酸解气、罐顶气和成藏天然气中C₁/C₂+、iC₄/nC₄及总烃/非烃等比值,是天然气运移示踪的有效指标。     

掏土挤淤在某建筑物纠偏治理中的应用

通过对某倾斜建筑物的纠偏扶正处理,介绍了掏土挤淤纠偏法的作用机理、现场应用过程等,并从技术、经济等角度作了总结。     

船基系统海气通量测量方法研究

海气通量交换是海洋学和气象学许多领域共同研究的内容,是气候形成和变化的重要机制之一。文章通过比较测量海气通量的几种方法,提出了在船基仪器上使用直接协方差法测量海气通量的方法,并给出了船体运动造成测量结果误差的校正算法。     

Mechanical response of saturated and unsaturated gravels of different sizes in drained triaxial testing

Acta Geotechnica - During the construction of pavements, gravelly soil is used as the main material in the base and sub-base layers. Predicting the deformation behaviour of gravelly soil has been...     

Anisotropy parameter inversion in vertical axis of symmetry media using diffractions

Diffractions play a vital role in seismic processing as they can be utilized for high‐resolution imaging applications and analysis of subsurface medium properties like velocity. They are particularly valuable for anisotropic media as they inherently possess a wide range of dips necessary to resolve the angular dependence of velocity. However, until recently, the focus of diffraction imaging or inversion algorithms have been only on the isotropic approximation of the subsurface. Using diffracted waves, we develop a framework to invert for the effective η model. This effective model is obtained through scanning over possible effective η values and selecting the one that best fits the observed moveout curve for each diffractor location. The obtained effective η model is then converted to an interval η model using a Dix‐type inversion formula. The inversion methodology holds the potential to reconstruct the true η model with sufficiently high accuracy and resolution properties. However, it relies on an accurate estimation of diffractor locations, which in turn requires good knowledge of the background velocity model. We test the effectiveness and applicability of our method on the vertical transverse isotropic Marmousi model. The inversion results yield a reasonable match even for the complex Marmousi model.