地质灾害威胁下的农村居民点用地适宜性评价——以彭州市银厂沟流域为例     

刘腾  任光明  王猛  余天彬 《中国地质调查》2020,7(2):95-100

目前针对受震灾威胁、地质灾害频发的山地环境下的农村居民点布局研究尚不多见。该文以彭州市龙门山镇银厂沟流域为例,首先在总结分析区内地质灾害发育特征的基础上,基于8项指标进行地质灾害危险性分区; 然后,将地质灾害危险性区划结果作为影响农村居民点用地适宜性评价的首要因素,再结合地形条件、社会经济和生态环境等方面,以地质灾害极高危险区、单体地质灾害危害范围、坡度≥25°和基本农田保护区为限制性条件,构建地质灾害威胁下的农村居民点用地适宜性评价指标体系; 最后,采用模糊综合评价法对彭州市银厂沟流域内居民点用地适宜性进行评价分级。研究结果表明: 高度适宜区占研究区总面积的4.2%,中度适宜区占11.4%,低度适宜区占10.5%,不适宜区占73.8%; 农村居民点用地“适宜”区域主要沿公路分布,并存在多个“块状”集中分布区,这些地区地形平坦,交通条件便利,可为新农村住宅位置的选择提供指导意见。  相似文献   

频率域海洋可控源电磁垂直各向异性三维反演   总被引：1，自引：0，他引：1       下载免费PDF全文

彭荣华  胡祥云  李建慧  刘亚军 《地球物理学报》2019,62(6):2165-2175

地层宏观电性各向异性会对可控源电磁响应产生重要影响.由于海底地层电性结构常表现为电导率各向异性，若仅对海洋可控源电磁（MCSEM）数据进行常规各向同性反演，有可能无法获得准确的反演解释结果，从而削弱MCSEM技术的可靠性.本文实现了电导率垂直各向异性（VTI）条件下频率域海洋可控源电磁数据三维反演算法.其中，三维正演采用基于二次场控制方程的交错网格有限体积法，并利用直接矩阵分解技术来求解离散所得的大型线性方程组，有利于快速计算多场源的响应.反演采用具有近似二次收敛性的高斯牛顿算法对目标函数进行最优化.最后，对具有VTI电性各向异性特征的盐丘构造模型的MCSEM合成数据分别进行了电导率各向同性和垂直各向异性三维反演，结果表明：各向同性三维反演算法无法对受VTI介质影响的MCSEM数据进行正确的反演解释，而垂直各向异性三维反演能够获得更为可靠的地下电阻率结构和异常体分布，展现出对海底电性各向异性结构更为优良的反演解释能力.  相似文献   

Modelling population retention in Australia’s Northern Territory – how do current forms of migration contribute to population turnover and retention?     

James Thurmer  D. Carson  A. Taylor 《The Australian geographer》2019,50(4):435-452

ABSTRACT

In the past, population growth in Australia's Northern Territory, as in other peripheral parts of high-income countries, has been driven by internal labour migration and migration from outside of Australia. These have been contributing to the high population turnover experienced in peripheral areas. Since 2010, the Northern Territory has experienced low (and even negative) population growth, and public policy is currently focused on migration as a lever to reverse this trend. However, the extent to which the characteristics of migrants influence the potential for longer-term population growth is poorly understood. This paper uses a new method to analyse the contributions of various types of migrants to both population turnover and retention. Two major sets of findings emerge: First, the significance of separating newer in-migrants from longer-term residents when analysing migration patterns; and secondly, the contribution of age, gender, Indigenous status, international origin, wages and industry of employment to the Northern Territory's population turnover. The research suggests that current forms of migration favour people who are likely to stay for only short periods, and have high wage demands. The main policy inference is that long-term population growth will likely not eventuate unless new forms of migration can be stimulated.  相似文献   

APPLYING 3D INVERSION OF SINGLE-PROFILE MAGNETOTELLURIC DATA TO IDENTIFY THE SHADE AND YUNONGXI FAULTS          下载免费PDF全文

JIANG Feng  CHEN Xiao-bin  DONG Ze-yi  CUI Teng-fa  LIU Zhong-yin  WANG Pei-jie 《地震地质》2019,41(6):1444-1463

Many synthetic model studies suggested that the best way to obtain good 3D interpretation results is to distribute the MT sites at a 2D grid array with regular site spacing over the target area. However, MT 3D inversion was very difficult about 10 years ago. A lot of MT data were collected along one profile and then interpreted with 2D inversion. How to apply the state-of-the-art 3D inversion technique to interpret the accumulated mass MT profiles data is an important topic. Some studies on 3D inversion of measured MT profile data suggested that 2D inversions usually had higher resolution for the subsurface than 3D inversions. Meanwhile, they often made their interpretation based on 2D inversion results, and 3D inversion results were only used to evaluate whether the overall resistivity structures were correct. Some researchers thought that 3D inversions could not resolute the local structure well, while 2D inversion results could agree with the surface geologic features much well and interpret the geologic structures easily. But in the present paper, we find that the result of 3D inversion is better than that of 2D inversion in identifying the location of the two local faults, the Shade Fault(SDF)and the Yunongxi Fault(YNXF), and the deep structures. In this paper, we first studied the electrical structure of SDF and YNXF based on a measured magnetotelluric(MT) profile data. Besides, from the point of identifying active faults, we compared the capacity of identifying deep existing faults between 2D inversion models and 3D models with different inversion parameters. The results show that both 2D and 3D inversion of the single-profile data could obtain reasonable and reliable electrical structures on a regional scale. Combining 2D and 3D models, and according to our present data, we find that both SDF and YNXF probably have cut completely the high resistivity layer in the upper crust and extended to the high conductivity layer in the middle crust. In terms of the deep geometry of the faults, at the profile's location, the SDF dips nearly vertically or dips southeast with high dip angle, and the YNXF dips southeast at depth. In addition, according to the results from our measured MT profile, we find that the 3D inversion of single-profile MT data has the capacity of identifying the location and deep geometry of local faults under present computing ability. Finally, this research suggests that appropriate cell size and reasonable smoothing parameters are important factors for the 3D inversion of single-profile MT data, more specifically, too coarse meshes or too large smoothing parameters on horizontal direction of 3D inversion may result in low resolution of 3D inversions that cannot identify the structure of faults. While, for vertical mesh size and data error thresholds, they have limited effect on identifying shallow tectonics as long as their changes are within a reasonable range. 3D inversion results also indicate that, to some extent, adding tippers to the 3D inversion of a MT profile can improve the model's constraint on the deep geometry of the outcropped faults.  相似文献   

Comparison of abstraction scenarios simulated by SWAT and SWAT-MODFLOW     

Eugenio Molina-Navarro  Ryan T. Bailey  Hans Estrup Andersen  Hans Thodsen  Anders Nielsen  Seonggyu Park 《水文科学杂志》2019,64(4):434-454

In hydrological modelling of catchments, wherein streams are groundwater-fed, an accurate representation of groundwater processes and their interaction with surface water is crucial. With this purpose, a coupled model was recently developed linking SWAT (Soil and Water Assessment Tool) with the fully-distributed groundwater model MODFLOW (Modular Groundwater Flow). In this study, SWAT and SWAT-MODFLOW were applied to a Danish groundwater-dominant catchment, simulating groundwater abstraction scenarios and assessing the benefits and drawbacks of SWAT-MODFLOW. Both models demonstrated good performance. However, SWAT-MODFLOW provided more realistic outputs when simulating abstraction: the decrease in streamflow was similar to the volume of water abstracted, while in SWAT the impact was negligible. SWAT also showed impacts on streamflow only when abstractions were taken from the shallow aquifer, not from the deep aquifer. Overall, SWAT-MODFLOW demonstrated wider possibilities for groundwater analysis, providing more insights than SWAT in supporting decision making in relation to environmental assessment.  相似文献   

A continuous modelling approach for design flood estimation on sub-daily time scale     

B. Winter  K. Schneeberger  N.V. Dung  M. Huttenlau  S. Achleitner  J. Stötter 《水文科学杂志》2019,64(5):539-554

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Parametric uncertainty assessment of hydrological models: coupling UNEEC-P and a fuzzy general regression neural network   总被引：1，自引：1，他引：0  

Arman Ahmadi  Dimitri P. Solomatine 《水文科学杂志》2019,64(9):1080-1094

Due to the complicated nature of environmental processes, consideration of uncertainty is an important part of environmental modelling. In this paper, a new variant of the machine learning-based method for residual estimation and parametric model uncertainty is presented. This method is based on the UNEEC-P (UNcertainty Estimation based on local Errors and Clustering – Parameter) method, but instead of multilayer perceptron uses a “fuzzified” version of the general regression neural network (GRNN). Two hydrological models are chosen and the proposed method is used to evaluate their parametric uncertainty. The approach can be classified as a hybrid uncertainty estimation method, and is compared to the group method of data handling (GMDH) and ordinary kriging with linear external drift (OKLED) methods. It is shown that, in terms of inherent complexity, measured by Akaike information criterion (AIC), the proposed fuzzy GRNN method has advantages over other techniques, while its accuracy is comparable. Statistical metrics on verification datasets demonstrate the capability and appropriate efficiency of the proposed method to estimate the uncertainty of environmental models.  相似文献   

Effect of rainfall uncertainty on the performance of physically based rainfall–runoff models     

Ignacio Fraga  Luis Cea  Jernimo Puertas 《水文研究》2019,33(1):160-173

This paper analyses the effect of rain data uncertainty on the performance of two hydrological models with different spatial structures: a semidistributed and a fully distributed model. The study is performed on a small catchment of 19.6 km² located in the north‐west of Spain, where the arrival of low pressure fronts from the Atlantic Ocean causes highly variable rainfall events. The rainfall fields in this catchment during a series of storm events are estimated using rainfall point measurements. The uncertainty of the estimated fields is quantified using a conditional simulation technique. Discharge and rain data, including the uncertainty of the estimated rainfall fields, are then used to calibrate and validate both hydrological models following the generalized likelihood uncertainty estimation (GLUE) methodology. In the storm events analysed, the two models show similar performance. In all cases, results show that the calibrated distribution of the input parameters narrows when the rain uncertainty is included in the analysis. Otherwise, when rain uncertainty is not considered, the calibration of the input parameters must account for all uncertainty in the rainfall–runoff transformation process. Also, in both models, the uncertainty of the predicted discharges increase in similar magnitude when the uncertainty of rainfall input increase.  相似文献   

Interannual variability in glacier contribution to runoff from a high‐elevation Andean catchment: understanding the role of debris cover in glacier hydrology     

Flavia Burger  Alvaro Ayala  David Farias  Thomas E. Shaw  Shelley MacDonell  Ben Brock  James McPhee  Francesca Pellicciotti 《水文研究》2019,33(2):214-229

We present a field‐data rich modelling analysis to reconstruct the climatic forcing, glacier response, and runoff generation from a high‐elevation catchment in central Chile over the period 2000–2015 to provide insights into the differing contributions of debris‐covered and debris‐free glaciers under current and future changing climatic conditions. Model simulations with the physically based glacio‐hydrological model TOPKAPI‐ETH reveal a period of neutral or slightly positive mass balance between 2000 and 2010, followed by a transition to increasingly large annual mass losses, associated with a recent mega drought. Mass losses commence earlier, and are more severe, for a heavily debris‐covered glacier, most likely due to its strong dependence on snow avalanche accumulation, which has declined in recent years. Catchment runoff shows a marked decreasing trend over the study period, but with high interannual variability directly linked to winter snow accumulation, and high contribution from ice melt in dry periods and drought conditions. The study demonstrates the importance of incorporating local‐scale processes such as snow avalanche accumulation and spatially variable debris thickness, in understanding the responses of different glacier types to climate change. We highlight the increased dependency of runoff from high Andean catchments on the diminishing resource of glacier ice during dry years.  相似文献   

Streamwater ages in nested,seasonally cold Canadian watersheds     

Samuel Bansah  Genevieve Ali 《水文研究》2019,33(4):495-511

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