西藏地质灾害易发性及对水能开发适宜度影响     

张玺国  周雄冬  徐梦珍  梁馨月 《地理学报》2022,77(7):1603-1614

西藏自治区是中国水能资源的战略储备库与未来重点开发区域,然而该区域地质灾害频发,给水能开发带来极大挑战,亟需系统研究。本文综合考虑西藏地区地质地貌、水文气象和植被覆盖等致灾因子,基于最大熵（MaxEnt）模型分析泥石流、崩塌、滑坡等典型地质灾害的易发性,结合水能资源分布禀赋,实现西藏地区水能开发适宜度评价。结果表明,雅鲁藏布江大拐弯羌纳—帮辛段水能开发适宜度最高,可优先开发;雅鲁藏布江上游夏如—拉孜段、怒江中游马利—林卡段、中林卡—察瓦龙段、支流伟曲河田妥—碧土段、澜沧江中游察雅—措瓦段、如美—盐井段、金沙江上段木协—戈波段、喜马拉雅山脉朋曲河流域为高水能开发高风险地区,需谨慎开发;雅鲁藏布江中游仁布—曲水段、易贡藏布忠玉—易贡段、察隅河下察隅以南段、朗钦藏布下游段为中水能开发低风险区,可根据需求局部开发或暂缓开发;其余区域水能开发适宜度较低,不建议开发。本文针对西藏地区提出一种快速有效的水能开发适宜度评价体系,可为该区域水能开发规划提供科学依据。  相似文献   

DLM-FvCB模型光合能力关键参数季节性参数化方案及模拟效果评估     

林晓凤  陈报章 《地理科学》2022,42(7):1260-1271

选取包含9种植被功能型的15个通量塔观测数据（60站点年）,采用控制变量法,分别在月尺度和年尺度上对25℃时最大羧化速率（V_cmax25）进行优化,并利用未参与参数反演的站点年数据集定量评估这2种参数化方案的模拟效果。研究发现：① 在参数的季节变异方面：9种植被功能型的V_cmax25均呈现明显的季节性波动。V_cmax25的波动幅度为：冬季>秋季>春季>夏季,不同植被类型季节变化幅度相差不大,而寒带植被V_cmax25季节变化幅度接近温带植被的2倍;② 对生态系统初级生产力（GPP）估算的影响方面：V_cmax25季节性参数化方案显著提高了GPP的模拟能力和模拟精度,其中森林和灌木冬季提升最显著（R²提高了35.7%,RMSE降低了23.24%）,春秋季次之,夏季最小。然而,对于C₃草地,DLM无论采取V_cmax25季节性参数化方案还是年尺度参数化方案,均为系统低估GPP。  相似文献   

关于城市暴雨强度公式推求的研究          下载免费PDF全文

许拯民  荆燕燕 《水文》2014,34(3):53-56

城市暴雨强度公式的准确性直接影响着城市排水管网的规划设计,老一代的暴雨强度公式已经不能正确反映当地的降雨规律,亟需重新修订。本文以郑州市降雨资料为例,采用年最大值法选样和年多个样法选样对公式进行推求,通过对比分析发现年最大值法操作简单,误差更小,该方法有利于新一轮暴雨强度公式修编的普及。  相似文献   

莫拉克台风暴雨移置香港地区的PMP分析研究   总被引：1，自引：0，他引：1       下载免费PDF全文

张叶晖  陈宏  兰平 《水文》2014,34(5):25-30

基于台湾66个站点年最大日雨量历史资料、台湾中央气象局2009年8月8~10日莫拉克台风暴雨期间251个台湾雨量站逐时降雨资料和香港地区65个雨量站的历史逐时降雨资料,以及与香港相邻的3个广东省雨量站(西沥站、横岗站和深圳站)资料,利用分时段地形增强因子法(SDOIF),将莫拉克台风暴雨最大24h实测暴雨中的辐合雨分量分割,并将其辐合雨成分移置到香港地区,与香港地区24h平均地形增强因子相结合,估算出香港地区的可能最大降水。结果显示,莫拉克最大24h降雨量中地形的增强幅度约为45%;得出香港地区最大24h平均可能最大降水分布图,其最大中心值1230.2mm(未考虑水汽放大),与香港地区历史暴雨中心一致,均发生在大帽山附近。  相似文献   

夹? 22 mm钢筋体复合锚杆原位锚固特性分析     

张景科  谌文武  李最雄  郭志谦  王楠 《岩土力学》2014,35(11):3139-3147

加钢筋体复合锚杆在土遗址载体锚固得到了较为成功的应用,但研究该类型锚杆机制刚刚起步。选择交河故城开展了夹? 22 mm钢筋复合体锚杆现场锚固测试,包括锚固性能测试和锚杆各界面层应变监测。锚固性能试验表明,3 m长复合锚杆极限锚固力可达190 kN,而且杆体表现出较强塑性变形。锚杆各界面层应变监测结果表明,钢筋-复合材料界面层轴向应变远大于其他界面层,锚固失效在该层;由于杆体的非均直性,楠竹-复合材料界面表现出轴向应变的非规律性,局部出现受压状态;楠竹-浆体界面剪应变与荷载变化一致,在较高荷载下出现剪应变向锚固末端的传递特征;鉴于杆体的多圈层构造,受力过程中出现明显的横向传递和剪胀特征。其研究成果可为复合锚杆的优化与工艺完善奠定基础。  相似文献   

基于统计方法的干旱区地下水最大可开采量的确定     

穆振侠  李中邵  王培  姜卉芳 《地下水》2014,(5):6-9

为克服地下水可开采量确定过程中确定性模型的局限性、失真和参数确定困难等弊端,合理的确定地下水可开采量,基于研究区不同区域地下水水位与开采量监测资料,采用多元线性回归和非线性多元回归统计方法对不同情况下地下水最大开采量进行探讨。结果表明：1964—1990年期间百口泉水源地地下水开采量在持续增加,并以1976年前增加较明显,且地下水水位均表现为下降趋势;非线性多元回归分析法对降深与开采量拟合的结果和误差精度均优于多元线性回归分析法;基于拟合的非线性多元回归方程,可确定水源地正常运行条件下的开采量为1 391万m3、极限开采条件下的开采量1 856万m3、疏干开采条件下的开采量1 992万m3。  相似文献   

基坑开挖地表沉降模型适用性研究     

王强  ;陈春舒 《岩土工程技术》2014,(4):168-171

基坑开挖引起的地表沉降对周边建筑物的安全造成了一定的威胁,在已有大量实测数据分析的基础上,提出了一种新的数学函数模型,并结合模型函数性质提出了基于最大沉降量Smax和沉降范围r的沉降模型表达式,结合相关工程实例中的数据分析,证明该模型对基坑开挖引起的地表沉降规律有着较好的适用性,将该模型与其他类似的模型进行了对比.研究成果可为相关基坑工程开挖引起的地表沉降的预测和控制提供参考.  相似文献   

古潜山裂缝储层预测新方法   总被引：1，自引：1，他引：0  

谢风猛 《物探与化探》2010,34(2)

平南潜山油气藏属于"新生古储"型组合,主要为奥陶系、寒武系碳酸盐岩。裂缝是储层内油气的主要储集空间,寻找岩层内的裂缝是潜山油气藏勘探的关键。根据裂缝在几何属性上的表现,提出了用多种几何属性预测与描述储层中的裂缝体系,定量刻画裂缝的分布,取得了较好的效果,与实际钻井资料相吻合。  相似文献   

Relay ramps as pathways for turbidity currents: a study combining analogue sandbox experiments and numerical flow simulations     

WIEBKE ATHMER  REMCO M. GROENENBERG  STEFAN M. LUTHI  MARINUS E. DONSELAAR  DIMITRIOS SOKOUTIS  ERNST WILLINGSHOFER 《Sedimentology》2010,57(3):806-823

Unlike for subaerial settings, the impact of subaqueous relay ramps on sediment dispersal is still poorly understood. A combination of analogue laboratory experiments in a sandbox with numerical flow calculations is used to simulate relay ramp topographies on rifting continental margins and to analyse the resulting turbidity current pathways and their deposits. Various scenarios are investigated, including inflow perpendicular and oblique to the relay ramp axis as well as flow constrained by an incised channel on the ramp and by a landward‐directed tilt of the ramp. Without channelling, most sedimentation takes place on the basin floor because the bulk of the flow follows the steepest gradient down the fault and into the rift basin. With a channel along the relay ramp, significant flow occurs initially down the ramp axis, but channel spillover and basinward ramp tilting combine to redirect much of the sediment down the fault slope into the basin. When the relay ramp has a landward‐oriented tilt, most of the current flows down the ramp and deposits its sediment load there and at the foot of the ramp. However, also here a considerable amount of the flow is shed over the hanging wall fault and into the basin, forming a secondary depocentre, while ponding redistributes thin deposits over a wider area of the basin. The quantitative dependence of these results on the specific ramp geometries remains to be investigated further but may bear great importance for refined sedimentary models in subaqueous rifted settings as well as for hydrocarbon exploration therein.  相似文献   

Particle Dynamics and Trace Metal Reactivity in Estuarine Plumes     

A. Turner  G. E. Millward 《Estuarine, Coastal and Shelf Science》2000,50(6):761

Iron, Mn, Cu, Pb and Zn have been determined in suspended particulate matter (SPM) collected in the estuarine plume regions of the Humber (during winter, spring and summer) and Thames (winter only). Metal concentrations (w/w) were found to increase with SPM concentration and could be defined in terms of the mixing of an ambient, slow settling population, with variable proportions of a diluent population. The end-members of the particle mixing series are fine material derived from coastal erosion, which is modified seasonally by biological production, and contaminated estuarine material which is contained within the estuarine discharge or derived from local resuspension of reworked deposits by tidal currents and wave activity. Iron-normalized metal concentrations exhibited an inverse relationship with SPM concentration in the Humber region and regression analyses enabled seasonal changes in end-member compositions to be evaluated. Since the metal:Fe ratios of the ambient population did not accord with those of local cliff samples, additional sources of metal were proposed whose importance to particle composition increases with a reduction in SPM concentration. Qualitatively, the seasonal variation of end-member compositions was consistent with (i) the coupling between redox processes occurring in the bed sediment and adsorption of metals (Mn, Cu, Zn) released from the pore waters onto ambient and diluent suspended particles in the overlying water column, and (ii) adsorption of metal (Pb) by ambient suspended particles from an extraneous (atmospheric) source. In the Thames plume, an increase in Fe-normalized metal concentrations with increasing particle concentration resulted from the mixing of end-member particles and the effects of additional metal from an internal or extraneous source were less clear, possibly because of metal desorption from suspended particles traversing the salinity gradient in the outer estuary. The processes described in this study regulate the internal cycling of trace metals in estuarine plume regions and the export of metals to neighbouring shelf sea environments.  相似文献