常州市数字化测绘工程及GIS建库概述

数字化地形图和地籍图是城市规划、建设和管理及国土资源管理的重要基础资料．也是开展数字城市和信息化建设的最基础平台。通过对系统总体结构的设计和应用成果介绍，分析了目前基础地理数据生产、管理和应用的现状，介绍了基于GIS的常州市数字化地形图、地籍图测绘工程总体目标及基础地理信息系统总体设计．并概述了整个数字化测绘工程的实施过程和特点。     

地质微生物地球化学作用的意义与展望

概要论述了地质微生物学、地下水微生态学、微生物地球化学作用的基本概念、研究内容、研究现状、科学意义、关键问题、发展前景和在地下水环境保护中的作用。该研究领域不仅拓宽了整个地质科学的研究范畴,而且推动了地质科学的发展,具有一定的创新性。     

“雪龙号”2003北极航次气相多环芳烃纬度分布观测

2003年“雪龙号”北极科学考察期间,对沿途海洋大气进行采样,分析其中气相多环芳烃的空间分布。结果显示,气相中主要是2-4环的多环芳烃,其中菲为主要的化合物,平均占到总多环芳烃的55.1%。在整个航程的广泛区域尺度内,气相总多环芳烃浓度在1043.9-92993.1pg/m3。空间分布上,远东亚的海面>北太平洋海面>北极圈以内海面;总多环芳烃的浓度随纬度升高呈现显著降低的趋势。通过Clausius-Clapeyron方程对浓度和温度相互关系的分析表明,温度是控制气相多环芳烃长距离传输的主要因素。     

Piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events on the Loess Plateau,China

Establishing a universal watershed‐scale erosion and sediment yield prediction model represents a frontier field in erosion and soil/water conservation. The research presented here was conducted on the Chabagou watershed, which is located in the first sub‐region of the hill‐gully area of the Loess Plateau, China. A back‐propagation artificial neural model for watershed‐scale erosion and sediment yield was established, with the accuracy of the model, then compared with that of multiple linear regression. The sensitivity degree of various factors to erosion and sediment yield was quantitatively analysed using the default factor test. On the basis of the sensitive factors and the fractal information dimension, the piecewise prediction model for erosion and sediment yield of individual rainfall events was established and further verified. The results revealed the back‐propagation artificial neural network model to perform better than the multiple linear regression model in terms of predicting the erosion modulus, with the former able to effectively characterize dynamic changes in sediment yield under comprehensive factor conditions. The sensitivity of runoff erosion power and runoff depth to the erosion and sediment yield associated with individual rainfall events was found to be related to the complexity of surface topography. The characteristics of such a hydrological response are thus closely related to topography. When the fractal information dimension is greater than the topographic threshold, the accuracy of prediction using runoff erosion power is higher than that of using runoff depth. In contrast, when the fractal information dimension is smaller than the topographic threshold, the accuracy of prediction using runoff depth is higher than that of using runoff erosion power. The developed piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events, which introduces runoff erosion power and runoff depth using the fractal information dimension as a boundary, can be considered feasible and reliable and has a high prediction accuracy. Copyright © 2013 John Wiley & Sons, Ltd.     

Size and spatial distribution of loess slides on the Chinese Loess Plateau

ABSTRACT

The size and spatial distribution of loess slides are important for estimating the yield of eroded materials and determining the landslide risk. While previous studies have investigated landslide size distributions, the spatial distribution pattern of landslides at different spatial scales is poorly understood. The results indicate that the loess slide distribution exhibits a power-law scaling across a range of the size distribution. The mean landslide size and size distribution in the different geomorphic types are different. The double Pareto and inverse gamma functions can coincide well with the empirical probability distribution of the loess slide areas and can quantitatively reveal the rollover location, maximum probability, and scaling exponents. The frequency of loess slides increases with mean monthly precipitation. Moreover, point distance analysis showed that > 80% of landslides are located < 3 km from other loess slides. We found that the loess slides at the two study sites (Zhidan and Luochuan County) in northern Shaanxi Province, China show a significant clustered distribution. Furthermore, analysis results of the correlated fractal dimension show that the landslides exhibit a dispersed distribution at smaller spatial scales and a clustered distribution at larger spatial scales.     

An analytical study on three‐dimensional versus two‐dimensional water table‐induced flow patterns in a Tóthian basin

Although it has been increasingly acknowledged that groundwater flow pattern is complicated in the three‐dimensional (3‐D) domain, two‐dimensional (2‐D) water table‐induced flow models are still widely used to delineate basin‐scale groundwater circulation. However, the validity of 2‐D cross‐sectional flow field induced by water table has been seldom examined. Here, we derive the analytical solution of 3‐D water table‐induced hydraulic head in a Tóthian basin and then examine the validity of 2‐D cross‐sectional models by comparing the flow fields of selected cross sections calculated by the 2‐D cross‐sectional model with those by the 3‐D model, which represents the “true” cases. For cross sections in the recharge or discharge area of the 3‐D basin, even if head difference is not significant, the 2‐D cross‐sectional models result in flow patterns absolutely different from the true ones. For the cross section following the principal direction of groundwater flow, although 2‐D cross‐sectional models would overestimate the penetrating depth of local flow systems and underestimate the recharge/discharge flux, the flow pattern from the cross‐sectional model is similar to the true one and could be close enough to the true one by adjusting the decay exponent and anisotropy ratio of permeability. Consequently, to determine whether a 2‐D cross‐sectional model is applicable, a comparison of hydraulic head difference between 2‐D and 3‐D solutions is not enough. Instead, the similarity of flow pattern should be considered to determine whether a cross‐sectional model is applicable. This study improves understanding of groundwater flow induced by more natural water table undulations in the 3‐D domain and the limitations of 2‐D models accounting for cross‐sectional water table undulation only.     

Influence of heterogeneity on unsaturated hydraulic properties: (1) local heterogeneity and scale effect

Spatial heterogeneity is ubiquitous in nature, which may significantly affect the soil hydraulic property curves. The models of a closed‐form functional relationship of soil hydraulic property curves (e.g. VG model or exponential model) are valid at point or local scale based on a point‐scale hydrological process, but how do scale effects of heterogeneity have an influence on the parameters of these models when the models are used in a larger scale process? This paper uses a two‐dimensional variably saturated flow and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil flume under a constant head boundary condition. By changing different numerical simulation block sizes, a quantitative evaluation of parameter variations in the VG model, resulting from the scale effects, is presented. Results show that the parameters of soil hydraulic properties are independent of scale in homogeneous media. Parameters of α and n in homogeneous media, which are estimated by using the unsaturated hydraulic conductivity curve (UHC) or the soil water retention curve (WRC), are identical. Variations of local heterogeneities strongly affect the soil hydraulic properties, and the scale affects the results of the parameter estimations when numerical experiments are conducted. Furthermore, the discrepancy of each curve becomes considerable when moisture content becomes closer to a dry situation. Parameters estimated by UHC are totally different from the ones estimated by WRC. Copyright © 2012 John Wiley & Sons, Ltd.     

基于外弹道计算的人影高炮作业安全评估方法

随着经济的高速发展,各个高炮作业点所在地的周边环境已经发生了很大变化,为了进一步提高人工影响天气作业的安全性,针对高炮作业特点提出了一套安全论证方法。推导了弹道计算的方法,在此基础上结合安全射界法和地理信息系统对作业安全性进行了更精确的评估,并给出实例说明。提出用危险系数的方法进行安全性评估,给出了具体的危险系数定义方法,通过评估系统的一次实际作业评估证明了危险系数进行安全性评估的可行性。以该方法进行安全性评估可有效保障人影作业的安全性,为人影作业提供重要的参考。     

塔里木盆地库车坳陷中生界构造古地理分析

运用区域地面地质、地震、钻测井等资料的综合分析,对库车坳陷中生界的盆地结构、构造样式、中生界各层序原始地层厚度和沉积相分布、古隆起形态、区域构造演化等方面进行研究,重建了库车坳陷中生代盆地构造古地理,并对盆地原型成因进行分析。库车坳陷残留中生界总体上为北厚南薄、北剥南超的地质结构,北部强烈角度不整合在南天山海西期褶皱带,南部微角度不整合面在寒武-奥陶系之上,南部边缘沿着温宿-西秋-牙哈古隆起有基底断裂活动。北部单斜带为冲积扇和辫状河三角洲,克拉苏构造带为深湖,南部沿着古隆起带为缓坡三角洲、浅湖。库车坳陷中生代原型盆地位于南天山海西期造山带和塔里木克拉通边缘过渡带之上,地壳均衡可能是盆地沉降的主要动力。南缘古隆起带在南天山洋扩张期为塔里木克拉通台地与被动大陆边缘的台地边缘,南天山洋闭合期为前陆隆起带,发育基底断裂和断块差异活动,在中生代有继承性活动,晚新生代新天山挤压隆升使古隆起带发生挤压变形,成为新天山逆冲变形造山楔的前锋。