Euler deconvolution in a radial coordinate system

This paper introduces the conversion of Euler's equation from a Cartesian coordinate system to a radial coordinate system, and then demonstrates that for sources of the type 1/r^N (where r is the distance to the source, and N is the structural index) it can be solved at each point in space without the need for inversion, for a known structural index. It is shown that although the distance to the source that is obtained from Euler's equation depends on the structural index used, the direction to the source does not. For some models, such as the gravity and magnetic response of a contact, calculation of the analytic signal amplitude of the data is necessary prior to the application of the method. Effective noise attenuation strategies, such as the use of moving windows of data points, are also discussed. The method is applied to gravity and magnetic data from South Africa, and yields plausible results.     

调制模式、调制比预报方法应用朔望潮的理论依据

朔望潮触发和调制地震的发生已是一个基本事实,朔望潮即是半月潮幅度最大时段再迭加半日潮和全日潮。由于朔望潮量值大,所以它作用到震源系统上影响震源过程的７种效应也大,因而朔望潮与地震的相关性较好。由此作者认为用朔望潮比单纯用半日潮来判断震源过程的不稳定性更好,它可以回避震源地方的很多复杂问题而不影响预报地震的效能。     

利用遥感技术进行干旱半干旱区找水的方法和实践

随着遥感技术和地面物探技术的发展和深入应用,产生了一种现代的综合勘探方法。本文介绍了在内蒙古锡林浩特市胜利煤田露天矿区供水水文地质普查中运用综合水文地质勘察方法的情况、遥感方案的选择、技术思路,以及利用遥感方法进行区域水文地质调绘所取得的成果,对遥感水文地质的发展提出了作者的看法。     

全(半)自动地形因子智能提取方法研究与设计实现

结合工作流思想,采用XML建模语言实现支撑全(半)自动地形因子智能提取模型的设计与过程描述。结合地形因子提取算子体系与模型,建立全(半)自动地形因子智能提取系统,并以地面起伏度提取为实验样例,通过流程组合、因子模型建立、参数配置、程序驱动执行等环节实现地形因子流程化、全(半)自动智能提取。系统解耦流程、算法以及专业软件对传统地形因子提取模式的捆绑,通过订制提取模型,灵活提取专题地形因子,提取效率、精度与扩展性较为理想。     

Analysis for temperature and pressure fields in process of hydrate dissociation by depressurization

An improved axisymmetric mathematic modeling is proposed for the process of hydrate dissociation by depressurization around vertical well. To reckon in the effect of latent heat of gas hydrate at the decomposition front, the energy balance equation is employed. The semi‐analytic solutions for temperature and pressure fields are obtained by using Boltzmann‐transformation. The location of decomposition front is determined by solving initial value problem for system of ordinary differential equations. The distributions of pressure and temperature along horizontal radiate in the reservoir are calculated. The numeric results indicate that the moving speed of decomposition front is sensitively dependent on the well pressure and the sediment permeability. Copyright © 2010 John Wiley & Sons, Ltd.     

Semi‐automated GIS techniques for detecting floodplain earthworks

Levees, channels and water storages built on the world's floodplain wetlands control flows for irrigation, flood mitigation and erosion management. Assessing their distribution and hydrological impacts through time and across broad extents is limited by significant costs and technical challenges. We tested the effectiveness of three new semi‐automated geographic information systems and traditional visual interpretation techniques for detecting earthworks. We used commercially or freely available two‐dimensional and three‐dimensional spatial imagery within 19 quadrats in an agricultural floodplain of the Murray–Darling Basin, southeastern Australia. Semi‐automated digital elevation model (DEM) analysis performed best for spatial accuracy (78% of earthworks correctly predicted within 25 m), overall classification accuracy (97.7%) and kappa (0.64), compared with traditional visual interpretation techniques using Landsat TM (52%, 96.3%, 0.39), SPOT (53%, 95.8%, 0.27) and aerial photography (72%, 97.2%, 0.31). DEM analysis also outperformed semi‐automated image segmentation (16%, 93%, 0.29) and integrated analysis (75%, 96.0%, 0.43) that used spectral information. Semi‐automated techniques were slow (DEM analysis: 27 418 s/km²; integrated analysis: 27 737 s/km²; and image segmentation: 1439 s/km²) compared with visual interpretation (Landsat TM: 109 s/km²; SPOT: 166 s/km²; and aerial photography: 276 s/km²); however, processing speed of semi‐automated techniques can be further increased without compromising accuracy. Semi‐automated techniques also offered operational autonomy following model calibration. High quality, cost‐effective earthwork mapping techniques, particularly the semi‐automated techniques in this study, are critical for understanding and managing ecosystem health, flood risk and water security in developed floodplains worldwide and should be implemented by governing institutions. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of the introduction of rice on evapotranspiration in seasonal wetlands

Land use changes in wetland areas can alter evapotranspiration, a major component of the water balance, which eventually affects the water cycle and ecosystem. This study assessed the effect of introduced rice‐cropping on evapotranspiration in seasonal wetlands of northern Namibia. By using the Bowen ratio–energy balance method, measurements of evapotranspiration were performed over a period of 2.5 years at two wetland sites—a rice field (RF) and a natural vegetation field (NVF)—and at one upland field (UF) devoid of surface water. The mean evapotranspiration rates of RF (1.9 mm daytime^?1) and NVF (1.8 mm daytime^?1) were greater than that in UF (1.0 mm daytime^?1). RF and NVF showed a slight difference in seasonal variations in evapotranspiration rates. During the dry season, RF evapotranspiration was less than the NVF evapotranspiration. The net radiation in RF was less in this period because of the higher albedo of the non‐vegetated surface after rice harvesting. In the early growth period of rice during the wet season, evapotranspiration in RF was higher than that in NVF, which was attributed to a difference in the evaporation efficiency and the transfer coefficient for latent heat that were both affected by leaf area index (LAI). Evapotranspiration sharply negatively responded to an increase in LAI when surface water is present according to sensitivity analysis, probably because a higher LAI over a surface suppresses evaporation. The control of LAI is therefore a key for reducing evaporation and conserving water. Copyright © 2013 John Wiley & Sons, Ltd.     

Evaluation of irrigation water use efficiency using remote sensing in the middle reach of the Heihe river,in the semi‐arid Northwestern China

Irrigation of agricultural oases is the main water consumer in semi‐arid and arid regions of Northwestern China. The accurate estimation of evapotranspiration (ET) on the oases is extremely important for evaluating water use efficiency so as to reasonably allocate water resources, particularly in semi‐arid and arid areas. In this study, we integrated the soil moisture information into surface energy balance system (SEBS) for improving irrigated crop water consumption estimation. The new approach fed with the moderate resolution imaging spectro‐radiometer images mapped spatiotemporal ET on the oasis in the middle reach of the Heihe river. The daily ET outputs of the new approach were compared with those of the original SEBS using the eddy correlation observations, and the results demonstrate that the modified SEBS remedied the shortcoming of general overestimating ET without regard to soil water stress. Meanwhile, the crop planting structure and leaf area index spatiotemporal distribution in the studied region were derived from the high‐resolution Chinese satellite HJ‐1/CCD images for helping analyse the pattern of the monthly ET (ET_monthly). The results show that the spatiotemporal variation of ET_monthly is closely related to artificial irrigation and crop growth. Further evaluation of current irrigation water use efficiency was conducted on both irrigation district scale and the whole middle reach of the Heihe river. The results reveal that the average fraction of consumed water on irrigation district scale is 57% in 2012. The current irrigation water system is irrational because only 52% of the total irrigated amount was used to fulfil plant ET requirement and the rest of the irrigation water recharged into groundwater in the oasis in 2012. However, in view of the whole middle reach of the Heihe river, the irrigation water use efficiency could reach to 66% in 2012. But pumping groundwater for reused irrigation wastes mostly energy instead of water. An improved irrigation water allocation system according to actual ET requirement is needed to increase irrigation efficiency per cubic meter water resource in an effort to save both water and energy. Copyright © 2014 John Wiley & Sons, Ltd.     

Evaluation of the hydrology of the IBIS land surface model in a semi‐arid catchment

This paper evaluates the Integrated BIosphere Simulator (IBIS) land surface model using daily soil moisture data over a 3‐year period (2005–2007) at a semi‐arid site in southeastern Australia, the Stanley catchment, using the Monte Carlo generalized likelihood uncertainty estimation (GLUE) approach. The model was satisfactorily calibrated for both the surface 30 cm and full profile 90 cm. However, full‐profile calibration was not as good as that for the surface, which results from some deficiencies in the evapotranspiration component in IBIS. Relatively small differences in simulated soil moisture were associated with large discrepancies in the predictions of surface runoff, drainage and evapotranspiration. We conclude that while land surface schemes may be effective at simulating heat fluxes, they may be ineffective for prediction of hydrology unless the soil moisture is accurately estimated. Sensitivity analyses indicated that the soil moisture simulations were most sensitive to soil parameters, and the wilting point was the most identifiable parameter. Significant interactions existed between three soils parameters: porosity, saturated hydraulic conductivity and Campbell ‘b’ exponent, so they could not be identified independent of each other. There were no significant differences in parameter sensitivity and interaction for different hydroclimatic years. Even though the data record contained a very dry year and another year with a very large rainfall event, this indicated that the soil model could be calibrated without the data needing to explore the extreme range of dry and wet conditions. IBIS was much less sensitive to vegetation parameters. The leaf area index (LAI) could affect the mean of daily soil moisture time series when LAI < 1, while the variance of the soil moisture time series was sensitive to LAI > 1. IBIS was insensitive to the Jackson rooting parameter, suggesting that the effect of the rooting depth distribution on predictions of hydrology was insignificant. Copyright © 2014 John Wiley & Sons, Ltd.     

资源量分类中勘查工程间距的确定方法研究

国内外的地质勘查规范中,对矿产资源量的分类(地质可靠程度)均有标准的定义,但没有确定资源量分类工程间距的定量方法,导致矿产勘查工作经常出现质量隐患。本文用变异函数模型统计学方法探讨这一问题。变异函数的变程反映了空间上区域化变量之间相关性的大小,当矿体样品品位服从正态分布时,正态分布函数位置参数μ等于样品平均品位,形状参数σ等于样品品位标准差,样品品位的方差等于变异函数的基台值;在拐点之间即区间(μ-σ,μ+σ],样品分布概率为0.6826,变异函数变程的0.6826倍(0.6826a)可作为划分控制资源量的分类工程间距;影响资源量分类可靠程度的主要因素是建立的理论变异函数模型的稳健性。