Spatial measurements of stream baseflow,a relevant method for aquifer characterization and permeability evaluation. Application to a hard‐rock aquifer,the Oman ophiolite

The structure, functioning and hydrodynamic properties of aquifers can be determined from an analysis of the spatial variability of baseflow in the streams with which they are associated. Such analyses are based on simple low‐cost measurements. Through interpreting the hydrological profiles (Q = f(A)) it is possible to locate the aquifer(s) linked to the stream network and to determine the type of interrelated flow, i.e. whether the stream drains or feeds the aquifer. Using an analytical solution developed for situations with a positive linear relationship, i.e. where the baseflow increases linearly with increasing catchment size, it is also possible to estimate the permeability of the aquifer(s) concerned at catchment scale. Applied to the hard‐rock aquifers of the Oman ophiolite, this method shows that the ‘gabbro’ aquifer is more permeable than the ‘peridotite’ aquifer. As a consequence the streams drain the peridotites and ‘leak’ into the gabbro. The hydrological profiles within the peridotite are linear and positive, and indicate homogeneity in the hydrodynamic properties of these formations at the kilometre scale. The permeability of the peridotite is estimated at 5 · 10^?7 to 5 · 10^?8 m/s. Copyright © 2004 John Wiley & Sons, Ltd.     

On salinity regimes and the vertical structure of residual flows in narrow tidal estuaries

An examination is made of the circulation in narrow estuaries subject to a predominant tidal forcing. Velocity structures are derived separately for residual flow components associated with (a) river flow, (b) wind stress, (c) a well-mixed longitudinal density gradient and (d) a fully stratified saline wedge. Dimensionless parameters are introduced to indicate the magnitude of each component and these parameters are evaluated for 9 major estuaries, thereby revealing their sensitivity to each component.For a channel of constant breadth and depth, formulae are deduced for the length of saline intrusion, L. Comparisons with observed data show that such formulae may be used with confidence to predict changes in L arising from variations in river flow, tidal range or channel depths.The level of stratification is shown to be related to a product of two parameters, one associated with velocity structure and a second involving the square of the ‘flow ratio’ $\text{u}\text{u}\text{?}$ (i.e. residual velocity/amplitude of the tidal velocity). This relationship provides a simple classification system for estuarine stratification which can be used to indicate the sensitivity of any particular estuary to changing conditions.     

海水声速剖面基函数的重构性能分析

海水声速剖面通常使用经验正交函数（Empirical Orthogonal Function,EOF）进行稀疏表示,然而基函数会受到数据完备性和数据测量时间的制约,其代表性误差会导致声速剖面重构精度受限。为了提高声速剖面的重构精度,本文利用模糊C均值聚类对BOA_Argo历史数据集进行聚类分析,探讨不同聚类空间的训练集数据对实测声速剖面重构精度的影响。研究表明,声速剖面具有明显的时空聚集特性,聚类后的历史声速剖面集生成的基函数和平均声速剖面具有最优的重构性能。本文研究结果有助于为历史声速剖面训练集的选取提供实际指导意义,进而提高声速剖面重构精度乃至反演精度。     

GPS反演上电离层剖面及实例

介绍了在利用GPS观测电离层TEC和反演上电离层剖面过程中，如何选择最适宜GPS星，如何计算卫星有关参数，如何计算卫星到测站间斜向TEC等问题，最后给出了一个剖面反演实例。     

汶川地震灾后农田和森林植被恢复遥感监测

2008年汶川8.0级特大地震对当地的生态系统造成了极大的破坏,为了评估5年来灾区农田和森林植被的恢复情况,利用逐年机载高分辨率遥感影像,结合星载遥感数据和地面调查数据,开展了灾区农林植被恢复状况监测。在农田恢复监测方面,结合2008年地震发生后以及2013年5月中旬的机载高分辨率遥感数据,采用目视解译的方式对汶川地震中受损农田的恢复状况进行监测与评估,同时利用GVG(GPS、Video和GIS)农情采样系统的作物种植成数调查结果,分析了灾后作物种植结构的变化。结果表明,灾区1592 ha受损农田,5年后仅有约17.5%得到了恢复和耕种使用。就耕地利用强度而言,重灾区耕地利用率较高,作物种植结构没有发生重大变化。在森林恢复状况监测方面,对典型区(岷江干旱河谷区和盆周山地区的3个重点区域)采用目视解译方式识别出森林变化,并结合大区域尺度规一化植被指数(NDVI)时间序列变化分析,对整个灾区的森林损毁和恢复情况做出评价。监测结果显示,汶川县、什邡市和绵竹市的森林植被恢复情况总体较好,但是一些坡度较大的损毁区、次生灾害频发区的森林尚未恢复,大区域尺度的统计结果显示,地震重灾区的46381 ha重度损毁森林植被和177025 ha中度损毁森林植被区域,完全恢复的区域占13.52%和25.84%,部分恢复的区域都占到50%。在自然恢复较为困难的区域,如汶川县中部和东北部、都江堰市北部、彭州市北部、什邡市北部、绵竹市北部、安县北部及北川县南部等,需要加强人工干预。遥感监测方法既适用于震后的农田和森林恢复状况动态监测,也适用于其他自然灾害发生时对灾区农田和森林植被破坏状况进行应急监测,具有实际应用价值和良好的发展前景。     

全站仪断面测量方法

从野外断面测量的角度出发,主要讨论全站仪在断面测量中的野外观测方法、数据处理思路以及相应的软件研制.     

Single epoch GPS deformation signals extraction and gross error detection technique based on wavelet transform

IntroductionGPS technique is widely used for deformationmonitoring thanks for the high precision. Usual-ly , there are three working modes associatedwith GPS deformation observation: periodicalGPS deformation monitoring net , GPS monito-ring array and rea…     

Exploring the spatial and temporal dynamics of land use in Xizhuang watershed of Yunnan, southwest China

Over the last two decades, China has introduced a series of agricultural and forestland use reforms, aiming to feed the largest population in the world and maintain ecological services locally and nationally. This paper studies the impacts of local government-driven reforestation on land use and land cover change, as well as its further impacts on livelihoods of upland farmers in Xizhuang watershed. An analysis of aerial photographs and ASTER satellite imagery from 1987 to 2002, respectively, showed that the forest has significantly increased at the expense of decreasing farmland. However, the monoculture reforestation of pine has caused both biophysical and socio-economic consequences. This case study also shows forestry decentralization in China remains incomplete. Land use and land cover change is also a political economic issue. Some of the reforms designed to protect forest resources have had a negative impact on rural livelihoods.     

矿岩界线的自动推连

着重讨论了如何利用人工智能技术进行矿岩界线的自动推断和连接，包括对所研制的基于知识的矿岩界线自动推连系统（ＡＩＳＭＢ）的措述，关于数据与知识的表示和组织、推理过程、策略以及系统实现等内容。     

藏南卡鲁雄峰枪勇冰川新冰期冰川发育探讨

山地冰川对气候变化响应敏感,全新世以来,冰川呈加速退缩趋势。冰川地貌是冰川变化最直接的证据。枪勇冰川发源于卡鲁雄峰,位于喜马拉雅山中段北坡雨影区,雅鲁藏布江以南,冰川末端在海拔5000 m附近,冰川面积约为6.63 km2。枪勇沟从外至内共保存有4期冰碛垄,其中以"大枪勇错"外侧的新冰期冰碛垄最为高大,终碛垄高约30 m,且形态清晰。文章基于野外观察及谷歌影像（Google Earth）上冰碛垄的分布范围,恢复并计算了新冰期时枪勇冰川面积约为10.0 km2,较现代冰川扩张了1.5倍。采用VOLTA模型计算了现代冰川的体积为0.21±0.04 km3,平均厚度约为31.7 m。基于纵剖线模型模拟了新冰期冰川表面高程,新冰期冰川平均厚度约为58.5 m,冰川体积约0.59±0.12 km3,是现代冰川体积的2.8倍,体积减小较面积退缩更为剧烈。利用积累区面积比率法（Accumulation Area Ratio Method,简称AAR）,采用AAR值为0.7±0.05,基于现代冰川表面高程和模拟的新冰期冰川表面高程,计算现代冰川和新冰期冰川的物质平衡线高度（Equilibrium Line Altitude,简称ELA）分别为5780±70 m和5660±100 m,新冰期时平衡线高度降低了约120 m。而不利用模型恢复新冰期表面高程时,平衡线降低值为240 m,可能高估约120 m。新冰期时,枪勇冰川扩张受区域降温控制,冰川前进可能是对4.2 ka冷事件的响应。冰碛垄形成时代和大枪勇错孢粉数据表明,冰川可能在2.5 ka左右已经退缩,2.2 ka时退缩加剧。