Characterizing rainfall–groundwater dynamics in a hard‐rock aquifer system using time series,geographic information system and geostatistical modelling          下载免费PDF全文

Deepesh Machiwal  Madan K. Jha 《水文研究》2014,28(5):2824-2843

The aim of this study was to investigate rainfall–groundwater dynamics over space and annual time scales in a hard‐rock aquifer system of India by employing time series, geographic information system and geostatistical modelling techniques. Trends in 43‐year (1965–2007) annual rainfall time series of ten rainfall stations and 16‐year (1991–2006) pre‐monsoon and post‐monsoon groundwater levels of 140 sites were identified by using Mann–Kendall, Spearman rank order correlation and Kendall rank correlation tests. Trends were quantified by Kendall slope method. Furthermore, the study involves novelty of examining homogeneity of pre‐monsoon and post‐monsoon groundwater levels, for the first time, by applying seven tests. Regression analysis between rainfall and post‐monsoon groundwater levels was performed. The pre‐monsoon and post‐monsoon groundwater levels for four periods – 1991–1994, 1995–1998, 1999–2002 and 2003–2006 – were subjected to geographic information system‐based geostatistical modelling. The rainfall showed considerable spatiotemporal variations, with a declining trend at the Mavli rainfall station (p‐value < 0.05). The Levene's tests revealed spatial homogeneity of rainfall at α = 0.05. Regression analyses indicated significant relationships (r² > 0.5) between groundwater level and rainfall for eight rainfall stations. Non‐homogeneity and declining trends in the groundwater level, attributed to anthropogenic and hydrologic factors, were found at 5–61 more sites in pre‐monsoon compared with post‐monsoon season. The groundwater declining rates in phyllite–schist, gneiss, schist and granite formations were found to be 0.18, 0.26, 0.21 and 0.14 m year^?1 and 0.13, 0.19, 0.16 and 0.02 m year^?1 during the pre‐monsoon and post‐monsoon seasons, respectively. The geostatistical analyses for four time periods revealed linkages between the rainfall and groundwater levels. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

施肥对新垦绿洲风沙土肥力及碳积累的影响     

苏永中  杨荣  刘婷娜 《中国沙漠》2019,39(3):1-6

利用2005年安排在临泽边缘绿洲沙地农田的长期施肥定位试验，研究不同用量有机肥、化肥、有机肥和化肥配施对绿洲沙地土壤肥力及有机碳积累的影响。试验包括高量有机肥单施（M3），氮磷化肥单施（NP3），低、中、高量氮磷钾化肥单施（NPK1，NPK2，NPK3），及低、中、高量氮磷钾化肥配施高、中、低量有机肥9个处理（NPK1M3，NPK2M2，NPK3M1），测定分析10年后不同施肥处理耕层（0~20 cm）土壤物理化学性状特征及有机碳动态。结果表明：施有机肥及有机无机配施处理较单施化肥处理容重下降0.13 g·cm^-3，田间持水量提高6.7%，单施有机肥、有机无机配施较单施化肥，土壤有机碳（SOC）和全氮含量分别提高64.8%、36.3%和64.9%、49.5%。高量施用氮磷化肥和氮磷钾化肥处理全磷含量最高，有机肥及有机无机配施较单施化肥有效氮含量显著增加，有机无机配施及高量施用磷肥土壤有效磷积累明显，高量施用有机肥能显著提升有效钾含量。连续施肥处理10年后，SOC含量提高了1.68~2.84倍，土壤全氮、全磷、碱解氮及有效磷均有一定程度的提高，但单施化肥及有机肥与氮磷化肥配施有效钾含量下降。SOC的积累速率单施化肥、有机无机配施，单施有机肥处理分别为0.27、0.59，0.87 g·kg^-1·a^-1。增施有机肥、适量减少化肥投入、氮磷钾化肥的平衡施用是绿洲沙地农田土壤肥力持续提升的施肥管理对策。  相似文献   

Genesis of S-type Granites in the Pengshan Sn-polymetallic Ore Field, Northern Jiangxi Province and its Implications     

YIN Qingqing  XIANG Xinkui  YU Zhendong  YANG Xiufeng  WANG Tianchen  ZHONG Bo  TAN Rong  LIAO Jianhai  ZHU Yuansong 《《地质学报》英文版》2020,94(6):1860-1873

The Pengshan Sn-polymetallic ore field is located in the southeastern part of the Yangtze block, spanning the southeast edge of the MLYDZ and the northern edge of the mid-segment of the Jiangnan Uplift, and on one side of the MLYDZ. The studies of LA–ICP–MS zircon U–Pb chronology and petrogeochemistry for Early Cretaceous acid granites from the Pengshan ore field were carried out in this paper. We report zircon U–Pb geochronology and whole-rock geochemistry for acid granites in the Pengshan ore field. The zircon U–Pb ages of the muscovite-granite, biotite adamellite and granite-porphyry are 127.6 ± 1.7 Ma, 126.9 ± 1.6 Ma and 126.6 ± 2.0 Ma, respectively. The granites in Pengshan are characterized by a high silicon content and are rich in alkali. They belong to high-potassium, calc-alkaline, peraluminous granite. The rocks have a relatively high Rb/Ba ratio, and the data points for muscovite-granite and biotite adamellite all fall within the clay-rich sources region, near the pelite-derived end-member, showing that the Pengshan muscovite-granite and biotite adamellite mainly originated from the partial melting of metapelites with high maturity. The transformation of the compressional and extensional tectonics in this region approximately 128 Ma obviously lags behind that in the mid-segment of the Jiangnan Uplift (135 Ma), but occurred earlier than the MLYDZ (126 Ma). The Pengshan ore field extends from the mid-segment of the Jiangnan Uplift to the MLYDZ. Although the tectonic stress field is constrained by the combination of the two secondary tectonic units, the time of tectonic system transformation is closer to the MLYDZ because the spatial orientation of the area is enclosed in the MLYDZ. Relevant geophysical and drilling data confirm the rationality of Pengshan–Ao’xia as a multi-center vertical zoning ore field, and show the scientificity of the prospecting idea of abutting joint between the north-west of Pengshan area and the south-east of Ao’xia area.  相似文献   

Numerical artifacts associated with Rayleigh and modal damping models of inelastic structures with massless coordinates     

J. Enrique Luco  Armando Lanzi 《地震工程与结构动力学》2019,48(13):1491-1507

The paper presents a detailed reexamination of the effects of three damping models on the inelastic seismic response of structures with massless degrees of freedom. The models considered correspond to (a) Rayleigh damping based on current properties (tangent stiffness), (b) Rayleigh damping based on initial properties, and (c) modal damping. The results suggest that some nonzero damping forces/moments at massless DOFs obtained in multistory frames for the case of Rayleigh damping with tangent stiffness may be numerical artifacts rather than a deficiency of the damping model. The results also indicate that significant artificial numerical oscillations in the velocities of the secondary components of MDOF structures are introduced when modal damping or mass-proportional damping is used.  相似文献   

基于水资源约束的中国城镇化SD模型与模拟   总被引：1，自引：0，他引：1  

曹祺文  鲍超  顾朝林  管卫华 《地理研究》2019,38(1):167-180

中国城镇化正处于快速发展阶段,尽管经济和社会发展主控要素还在发挥重要作用,但水资源在生产、生活和生态方面发挥主控作用的局面愈益明显。在中国城镇化系统动力学（system dynamics,SD）模型基础上,从水资源供给、需求和水环境等层面将水资源作为主控要素嵌入原有模型中,拓展出基于水资源约束的中国城镇化SD模型,并对水资源利用进行了多情景模拟。结果表明：① 系统存流量和灵敏度检验证明模型模拟效果良好,具有可操作性。② 部门用水效率一定时,产业发展对水资源供需平衡的影响比人口增长更为明显。③ 在实行节水农业、节水工业、高生活需水、高生态环境需水和高再生水利用的综合协调方案中,2050年中国城镇化的发展约共需6789.70亿 m³水资源,基本实现水资源供需平衡。  相似文献   

Quantifying flow resistance in mountain streams using computational fluid dynamics modeling over structure-from-motion photogrammetry-derived microtopography     

Yunxiang Chen  Roman A. DiBiase  Nicholas McCarroll  Xiaofeng Liu 《地球表面变化过程与地形》2019,44(10):1973-1987

Flow resistance in mountain streams is important for assessing flooding hazard and quantifying sediment transport and bedrock incision in upland landscapes. In such settings, flow resistance is sensitive to grain-scale roughness, which has traditionally been characterized by particle size distributions derived from laborious point counts of streambed sediment. Developing a general framework for rapid quantification of resistance in mountain streams is still a challenge. Here we present a semi-automated workflow that combines millimeter- to centimeter-scale structure-from-motion (SfM) photogrammetry surveys of bed topography and computational fluid dynamics (CFD) simulations to better evaluate surface roughness and rapidly quantify flow resistance in mountain streams. The workflow was applied to three field sites of gravel, cobble, and boulder-bedded channels with a wide range of grain size, sorting, and shape. Large-eddy simulations with body-fitted meshes generated from SfM photogrammetry-derived surfaces were performed to quantify flow resistance. The analysis of bed microtopography using a second-order structure function identified three scaling regimes that corresponded to important roughness length scales and surface complexity contributing to flow resistance. The standard deviation σ_z of detrended streambed elevation normalized by water depth, as a proxy for the vertical roughness length scale, emerges as the primary control on flow resistance and is furthermore tied to the characteristic length scale of rough surface-generated vortices. Horizontal length scales and surface complexity are secondary controls on flow resistance. A new resistance predictor linking water depth and vertical roughness scale, i.e.  H/σ_z, is proposed based on the comparison between σ_z and the characteristic length scale of vortex shedding. In addition, representing streambeds using digital elevation models (DEM) is appropriate for well-sorted streambeds, but not for poorly sorted ones under shallow and medium flow depth conditions due to the missing local overhanging features captured by fully 3D meshes which modulate local pressure gradient and thus bulk flow separation and pressure distribution. An appraisal of the mesh resolution effect on flow resistance shows that the SfM photogrammetry data resolution and the optimal CFD mesh size should be about 1/7 to 1/14 of the standard deviation of bed elevation. © 2019 John Wiley & Sons, Ltd.  相似文献   

Ecosystem engineering by hummock-building earthworms in seasonal wetlands of eastern South Africa: Insights into the mechanics of biomorphodynamic feedbacks in wetland ecosystems     

Michael C. Grenfell  Rolf Aalto  Suzanne E. Grenfell  William N. Ellery 《地球表面变化过程与地形》2019,44(1):354-366

This paper resolves the origin of clay hummock micro-topography in seasonal wetlands of the Drakensberg Foothills, providing a review and appraisal of previously-suggested mechanisms of hummock formation in the context of new field and laboratory data. Field surveys revealed neo-formation of clay hummocks in a river channel that had been abandoned in c.1984. Fresh earthworm castings were located atop hummocks protruding from inundated abandoned channel margins. Earthworm castings, and sediment cores taken in hummocks and adjacent hollows, were analysed for soil-adsorbed carbon and nitrogen using an HCN analyser, and for ²¹⁰Pb activity using alpha-geochronology. ²¹⁰Pb activity profiles suggest relative enrichment of the isotope in hummocks, and relative depletion in adjacent hollows. Earthworm castings are characterised by very high ²¹⁰Pb activity, as well as high C and N contents. Hummocks have significantly higher C and N contents than adjacent hollows. Results suggest that it is the foraging activity of earthworms in litter-rich seasonal wetland hollows, and repeated excretion of castings atop adjacent hummocks, that is responsible for the elemental enrichment observed. The paper presents a conceptual model of hummock formation in wetlands through interactions between hydrogeomorphology and earthworm activity, and illustrates a mechanism of biogeomorphic inheritance through which ordered patterns of preferential flow can emerge in ecosystems. Further implications of hummock formation and nodal accumulation of nutrients are considered in relation to wetland resilience and regulatory ecosystem service provision.© 2018 John Wiley & Sons, Ltd.  相似文献   

伏牛山地区森林生态系统服务权衡/协同效应多尺度分析   总被引：3，自引：0，他引：3  

张静静  朱文博  朱连奇  李艳红 《地理学报》2020,75(5):975-988

森林生态系统服务权衡与协同研究已成为当前相关学科的研究热点和前沿,对服务权衡与协同关系的多尺度分析有助于更加有效地实施森林资源管理。综合森林类型图、NDVI、气象和土壤等多源数据,借助CASA模型、InVEST 3.2模型和ArcGIS 10.2软件,开展伏牛山地区森林生态系统服务评估,运用空间叠置方法从多个空间尺度（区域、南北坡、垂直带）探讨服务权衡与协同效应。结果表明：① 研究区森林生态系统平均蓄积量为49.26 m ³/hm ²,碳密度为156.94 t/hm ²,供水深度为494.46 mm,土壤保持量为955.4 t/hm ²,生境质量指数为0.79。② 区域尺度上,28.79%的森林服务之间存在高协同效应,10.15%的森林存在低协同效应,61.06%的森林存在强权衡和弱权衡效应。③ 南北坡尺度上,南坡服务之间的协同关系优于北坡。垂直带尺度上,南坡中山落叶阔叶林带（SIII）服务之间协同关系最好,北坡低山落叶阔叶林带（NI）协同关系最差。  相似文献   

黑龙江省兴凯湖自然保护区生态系统固碳服务功能评价     

肖红叶  戴慧敏  杨泽  刘国栋  高铁  杨佳佳  张一鹤 《地质与资源》2020,29(6):570-573

湿地是自然界中重要的“碳汇”，其碳储量变化对全球气候变化和温室效应有重要的影响.选择地理位置独特的黑龙江兴凯湖自然保护区作为研究区，根据保护区内不同土壤类型采集表层（0～20 cm）土壤样品，利用遥感解译的保护区土地利用图、土壤储碳量和植物固碳量计算公式，核算兴凯湖自然保护区生态系统固碳服务总量，同时借鉴瑞典碳税法和中国造林成本法，估算兴凯湖保护区固碳服务功能价值为4.9亿元.结果显示，兴凯湖自然保护区湿地固碳服务功能高于全国平均水平，且高于同纬度同属东北平原的莫莫格湿地，为保护区今后的保护管理策略提供了有效的参考依据.  相似文献   

Mercury cycling during acid rain recovery at the forested Lesní potok catchment,Czech Republic     

Tomáš Navrátil  James B. Shanley  Jan Rohovec  Irena Dobešová  Šárka Matoušková  Michal Roll  Tereza Nováková  Filip Oulehle 《水文研究》2021,35(6):e14255

From 2011 to 2019, mercury (Hg) stores and fluxes were studied in the small forested catchment Lesní potok (LES) in the central Czech Republic using the watershed mass balance approach together with internal measurements. Mean input fluxes of Hg via open bulk deposition, beech throughfall and spruce throughfall during the periodwere 2.9, 3.9 and 7.6 μg m⁻² year⁻¹, respectively. These values were considerably lower than corresponding deposition Hg fluxes reported in the early years of the 21st century from catchments in Germany. Current bulk precipitation inputs at unimpacted Czech mountainous sites were lower than those in Germany. The largest Hg inputs to the catchment were via litterfall, averaging 22.6 and 17.8 μg m⁻² year⁻¹ for beech and spruce stands. The average Hg input, based on the sum of mean litterfall and throughfall deposition, was 23.0 μg m⁻² year⁻¹, compared to the estimated Hg output in runoff of 0.5 μg m⁻² year⁻¹, which is low compared to other reported values. Thus, only ~2% of Hg input is exported in stream runoff. Stream water Hg was only weakly related to dissolved organic carbon (DOC) but both concentrations were positively correlated with water temperature. The estimated total soil Hg pool averaged 47.5 mg m⁻², only 4% of which was in the O-horizon. Thus Hg in the O-horizon pool represents 72 years of deposition at the current input flux and 3800 years of export at the current runoff flux. Age-dating by ¹⁴C suggested that organic soil contains Hg from recent deposition, while mineral soil at 40–80 cm depth contained 4400-year old carbon, suggesting the soil had accumulated atmospheric Hg inputs through millennia to reach the highest soil Hg pool of the soil profile. These findings suggest that industrial era intensification of the Hg cycle is superimposed on a slower-paced Hg cycle during most of the Holocene.  相似文献