From an open-access to a state-controlled resource: the case of groundwater in the Kathmandu Valley,Nepal

Groundwater is no longer an open-access resource in Kathmandu. Perceptions of groundwater are changing from an “infinite” to a “finite” resource and the role of the government from supply developer to caretaker of the resource. In this context, this paper aims to unfold how perceptions of groundwater in Kathmandu Valley, Nepal, are changing from an open-access resource to an overexploited, depleted, degraded, vulnerable and state-controlled resource. In the process, it produces an aggregated picture of resource availability, development dynamics, impacts and responses in the area; suggests some “soft-path” approaches for groundwater management; and discusses implications of the experience for other areas.     

Drought Subsidence Prediction Model for the Western San Joaquin Valley,California

Abstract

Land subsidence due to groundwater extraction in the western San Joaquin Valley has been studied and monitoredfor almost six decades. Although its subsidence rates diminished after 1970, the problem is still of great concern during droughtperiods. Knowing how big the social impact and cost of subsidence were in the past decades, the paper proposes an innovative approach to predicting its further occurrence. Extrapolation is based on analysis of historical groundwater subsidence relationship, drought pattern, and acceptance of new explanatory mechanisms for clay inelastic compaction. Average predicted magnitudes of subsidence in the western San Joaquin Valleyfor the next five decades are in the range 4 m to 8 m.     

基于BP神经网络模型的水库塌岸预测研究

考虑水库塌岸预测的非线性,构建基于BP神经网络模型的水库塌岸非线性预测模型,以漳河流域内岳城水库为研究对象,结合野外实地勘察数据,对岳城水库塌岸进行预测。研究结果表明:所建水库塌岸非线性预测模型预测结果与实际情况较为吻合,预测的左右岸水库塌岸和实地调查塌岸相对误差分别为1.92%和2.15%,岳城水库左右岸塌岸宽度预测平均值分别为31.8m和36.9m;水库下游预测塌岸速度小于1m/a,中上游塌岸速度大于1m/a,下游库岸态势较为稳定,中上游塌岸趋势将加剧。研究成果对于水库塌岸非线性预测及岳城水库塌岸防治和岸坡加固设计提供参考价值。     

高磨蚀性硬岩地段敞开式TBM掘进参数优化和适应性研究

通过论述敞开式TBM的施工特点,结合敞开式TBM在引汉济渭工程秦岭隧洞高磨蚀性硬岩地段施工的具体情况,详细陈述敞开式TBM在隧洞掘进过程中遇到的典型问题及现场采取的施工措施,对TBM在高磨蚀性硬岩地段掘进中掘进速度的影响因素和敞开式TBM适应能力进行分析。结果表明,在高磨蚀性硬岩地段,TBM掘进参数拟定宜采用高转速、低贯入度、高推力、低扭矩的"两高两低"模式。研究成果为引汉济渭工程秦岭隧洞TBM施工段岭南工程后续掘进施工提供了掘进施工依据,且对实现TBM快速掘进提出了具体建议。     

引汉济渭工程黄三隧洞地下水渗流同位素综合示踪探测分析研究

引汉济渭工程黄三段深埋长输水隧洞岩性复杂多变,水文地质条件极其复杂。为深入分析黄三段水文地质条件,采用地下水同位素综合示踪探测手段,对黄三隧洞沿线钻孔、大坪隧道、良心河、沙坪河等区域进行现场测试及取样室内分析。通过对温度、电导、水化学及环境同位素、地下水流速等方面的综合分析,结合水文地质测绘、试验等基础性工作,对地下水补给、径流、排泄条件,水力联系及连通性等方面进行了评价。研究结果表明:黄三隧洞南部和中部存在富水带,地下水主要受大气降水补给;围岩可划分为中等富水区、弱富水区、贫水区,分别占隧洞全长的7.9%、15.4%、76.7%;实际揭露涌水量与原设计预测情况一致,验证了同位素综合示踪探测方法的有效性。研究成果对同类工程具有一定的工程实际应用参考价值。     

特大断面TBM组装洞室爆破施工技术研究

为确保TBM组装洞室施工安全,对已建成的陕西省引汉济渭工程秦岭隧洞TBM施工段岭南工程TBM组装洞室在施工过程中的爆破施工技术进行剖析、研究和优化。通过光面爆破,采用分层分步开挖的方式,在开挖前对爆破孔位的布置、装药参数以及爆破顺序等进行周密的设计,再根据围岩情况和实际爆破效果进行及时的优化,使最终的开挖断面满足设计及规范要求,保证施工安全和质量。结果表明:各断面平均每次爆破开挖进尺为2.73~4.10 m,无欠挖,爆出石渣块度为15~40 cm,适合装渣、运输要求;周边炮眼痕迹保存完整,残孔率为77%~82%,在开挖轮廓面呈均匀分布,爆破衔接台阶平均4~7 cm。需要根据岩层节理裂隙发育、岩性软硬情况修正眼距、用药量,尤其是在Ⅳ类围岩以上且节理裂隙较为发育的洞段,要做到每排炮调整。研究成果为类似特大断面的TBM组装洞室爆破开挖施工提供借鉴。     

磺厂沟流域煤系地层边坡崩塌成因机制及治理

山西煤炭资源丰富,普遍存在着不合理采煤现象,导致崩塌地质灾害频发。为了探讨崩塌灾害成因,以山西磺厂沟为例,在全面调查地质环境条件的基础上,分析了边坡的结构特征和变形破坏模式,认为边坡是在采煤和差异风化的影响下不断变形破坏的。运用有限元法分析了坡体内部应力应变特征,根据变形破坏机制提出了"清方+排水+浆砌块石+SNS防护系统"的治理方案。     

蒙特卡罗法在嫩江流域汛期降雨量预测中的应用

以蒙特卡罗理论为基础,采用P-Ⅲ型分布函数来概括流域汛期降雨量的概率特性,并以包含预测值样本系列的均值不超出历史均值范围为控制条件,经有限次试验确定预测值。结合嫩江流域尼尔基站控制断面以上1970年-2009年汛期(6月-9月)降雨资料,以1970年-2005年汛期降雨量为计算样本,预报2006年汛期降雨量,并以2006年实测降雨量进行检验,不断外推预测与检验,直至2010年。预测结果表明:当实际汛期降雨量属平水时,都会获得较高的预报精度,如2006年和2008年;在极枯情况,如2007年(降雨保证率为99.82%)的相对误差较大,为0.75;在较丰情况,如2009年(降雨保证率为19.63%)的相对误差也较大,为-0.20。所以,本方法适合平水年的预测,对于如何进行丰枯极值预报,最后从原理和方法上进行了探讨性思考。     

滇池流域湿地植物的引种繁育研究

随着“湿地”概念和“生态”理论在城市水体景观设计和建设中的引入,大量的湿地植物开始应用于城市园林水景中。对再力花(Thaliadealbata)等17种湿地植物在引入滇池流域栽植应用后的生态适应性及繁殖培育技术进行了试验研究,旨在为这些湿地植物品种在该地区以及气候环境相似的其他地区的进一步推广应用提供科学的依据和参考。     

A risk factor study of coccidioidomycosis by controlling differential misclassifications of exposure and susceptibility using a landscape ecology approach

State-reported coccidioidomycosis cases in Arizona have dramatically increased since 1997, raising concerns about a possible epidemic, its cause, and associated risk factors, including spatio-temporal differences in susceptibility and exposure. This stratified, two-stage, cross-sectional study evaluates inherent, socio-economic, and environmental risk factors of coccidioidomycosis from information collected during an address-based telephone survey of 5460 households containing 14,105 individuals in greater Tucson, Arizona. Three geomorphic and two demographic strata controlled for differences in group-level exposures and susceptibility, and assured recruitment of a minority population. Logistic regression of self-reported cases indicates that location of residence by geomorphic and demographic strata was a risk factor that confounded the associations of coccidioidomycosis with age, race-ethnicity, and educational attainment. The risk due to age is more evenly distributed across the population than bivariate results when individual- and group-level exposure and susceptibility factors are controlled. Similarly the association for being Hispanic decreased from strong bivariate 0.28 odds ratio to a weak multivariate 0.75. Location of residence confounded the risk due to race-ethnicity and was an effect modifier of risk due to age. Differential misclassification of exposure to Coccidioides spores and susceptibility to coccidioidomycosis was reduced through landscape stratification by demographics and geomorphic types. Landscape epidemiological studies of diseases with strong environmental and demographic determinants can reduce residual confounding and account for spatial and temporal differences between neighborhoods and at broader scales.