Experimental research on the effect of slope morphology on bank collapse in mountain reservoir

Farmers along the Amazon River each year face multiple natural hazards that threaten crop production and limit the potential for agricultural development of the expansive floodplain and active channel. In this paper we report the findings of a study of natural hazard-related risk associated with rice production on silt bars in the active channel of the Amazon River near Iquitos, Peru. Data were gathered in four rice producing communities in 2014 using household surveys (n = 83 households), focus group discussions, surveying of land elevations along the Amazon River, and interpretation of remote sensing imagery. The probability, extent, and severity of rice crop shortfalls were estimated for recent production years and the economic losses to farming households were also assessed. Our findings point to a very high risk of crop shortfalls due to natural hazards, suggesting that a good year brings rice farmers bounty and a bad year, near penury. River stage reversals (repiquetes) and edaphic conditions were found to be more problematic than the often cited hazard of high and/or early floods. Also surprisingly, farmers’ perceptions of hazards and risk diverged markedly from actual shortfalls experienced during the production years studied. Our results provide the first quantitative estimates of risk due to the multiple natural hazards along the Amazon River and point to the need to assist lowland farmers with risk mitigation so as to unlock the considerable potential of Amazon floodlands for agricultural production.     

石笋记录的西南地区MIS4阶段夏季风的演化

基于重庆市丰都县羊子洞石笋Y-02的12个²³⁰Th年龄和503个氧同位素数据重建了中国西南地区60~73ka B.P.时段夏季风的演化历史。Y-02的δ¹⁸O记录显示中国季风区D/O18、D/O19a和D/O19共3个千年尺度夏季风增强事件与格陵兰间冰阶（GIS）18~19相对应。此外,Y-02记录显示：紧接着D/O18事件以后,夏季风强度突然减弱,而此时北半球高纬度地区正经历着明显的降温过程。Y-02记录捕捉到的这次东亚夏季风突然且短暂的一次减弱过程,可能是H6事件或者是H6事件季风最弱的时段。Y-02的δ¹⁸O记录显示,D/O18事件是一次较强烈的千年尺度季风增强事件,持续时间近千年,而D/O19事件在持续时间和强度上不如D/O18事件,这不同于格陵兰冰芯记录。中国季风区气候变化与格陵兰地区存在着如此紧密的联系进一步支持：东亚夏季风演化受到北半球高纬度地区气候变化的影响,但是对具体的气候事件响应可能存在不同的模式。

     

地图手工数字化对点误差的统计分布

定义了对点误差,导出了统计分布密度和分布函数,给出了矩母函数、特征函数和数字特征,以及对点误差及其投影分量和标准化分布。     

Single Nucleotide Polymorphism of FSHβ Gene Associated with Reproductive Traits in Japanese Flounder (Paralichthys olivaceus)

Follicle stimulating hormone β (FSHβ) of Japanese flounder (Paralichthys olivaceus) plays a key role in the regulation of gonadal development.This study aimed to investigate molecular genetic characteristics of the FSHβ gene and elucidate the effects of single nucleotide polymorphisms (SNPs) of FSHβ on reproductive traits in Japanese flounder.We used polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and sequencing of the FSHβ gene in 60 individuals.We identified only an SNP (T/C) in the coding region of exon3 of FSHβ.The SNP (T/C) did not lead to amino acid changes at the position 340 bp of FSHβ gene.Statistical analysis showed that the SNP was significantly associated with testosterone (T) level and gonadosomatic index (GSI) (P0.05).Individuals with genotype TC of the SNP had significantly higher serum T levels and GSI (P0.05) than that of genotype CC.Therefore, FSHβ gene could be a useful molecular marker in selection for prominent reproductive trait in Japanese Flounder.     

白龙江流域上游径流年内分配变化规律分析

在气候变化与人类活动双重影响下,河川径流的年内分配特征随着发生变化。本文根据白龙江上游4个站点的实测月径流量资料,分析了年内分配不均匀性,集中程度与变化幅度等指标。结果表明:在1965~1969年、1971~1984年和2002~2006年,径流年内分配不均匀性较强;白龙江上游集中度较小,集中度随时间的增加均呈现降低趋势。流域自上游向下游,在不同年代集中期均表现为逐渐缩短的变化趋势。Cm、Cm-max和ΔR随时间增加而减小,Cm-min随时间增加而增大。总体上看,随着时间的推移,白龙江上游径流年内分配不均匀性越来越低,逐渐由不均匀向相对均匀转变。     

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环境因子及生态补水对乌梁素海“黄苔”年际暴发面积的影响(1986—2021年)

“黄苔”是丝状绿藻大量增殖并漂浮聚集在水面的一种藻类水华,是乌梁素海面临的重大水环境问题之一。本研究基于文献数据整合和Landsat TM/OLI系列卫星影像反演,追溯了乌梁素海近35年(1986—2021年)的水质变化和“黄苔”暴发历程,通过相关性分析和多元线性回归等方法,分析了乌梁素海“黄苔”暴发的年际影响因子。乌梁素海水体化学需氧量、总氮(TN)、总磷(TP)浓度在年尺度上呈下降趋势,但仍处于富营养状态(TLI(∑)>50)。相关性分析结果表明,乌梁素海“黄苔”暴发面积与TP、TN、氨氮、气温呈显著正相关,与出水量、风速、沉水植被面积、入水量呈显著负相关;多元线性回归结果表明,沉水植被面积和出水量是影响乌梁素海“黄苔”暴发面积的主要因子。生态补水工程的实施增加了乌梁素海出入水量,降低了水体TP、TN浓度,也造成沉水植被退化,使“黄苔”暴发的扩张趋势得以遏制。然而,乌梁素海现有营养条件、基质条件仍适宜附着藻生长和“黄苔”暴发。在全球气候变化背景下,气温升高和风力减弱可能会加剧这一现象。建议采取多种措施以防控乌梁素海“黄苔”暴发,如生态补水、外源营养盐管控、沉水植被调控、引水活...     

藏南拉康温泉地质特征及雄曲河谷两岸地热分布不均成因分析

西藏山南地区洛扎县雄曲河拉康段在600 m距离内出露温泉4处,仅1处位于河谷右岸;平硐勘查显示两岸岩性、产状、构造一致,地热异常却仅在左岸平硐内部显著,右岸平硐地热异常不明显.本次研究以此异常为出发点,通过片麻状花岗岩不同切面导热实验、片麻状花岗岩与板岩相同切面导热实验,温泉水δ2H,δ18O同位素测试分析等方法,探究...     

http://www.sciencedirect.com/science/article/pii/S1674987111000752

A series of environmentalegeological problems have been caused by over-exploitation of deep groundwater (i.e., confined aquifer water) in the North China Plain. In order to better understand the status of deep groundwater over-exploitation and the resultant environmentalegeological problems on a regional scale, the over-exploitation of groundwater has been assessed by way of the groundwater exploitation potential coefficient (i.e., the ratio of exploitable amount of deep groundwater to current exploitation), cumulative land subsidence, and long-term average lowering rate of the groundwater table. There is a good correlation among the results calculated by the different methods. On a regional scale, deep groundwater has been over-exploited and there is no further exploitation potential under the current conditions. The groundwater exploitation degree index takes the exploitation in 2003 as the reference for the calculations, so the results mainly reflect the degree of current groundwater exploitation. The results of over-exploitation of deep groundwater obtained by land subsidence data and long-term average rate of depression of the water table mainly reflect environmentalegeological problems caused by exploitation of deep groundwater.     

A comparative study of numerical approaches to risk assessment of contaminant transport

In risk analysis, a complete characterization of the concentration distribution is necessary to determine the probability of exceeding a threshold value. The most popular method for predicting concentration distribution is Monte Carlo simulation, which samples the cumulative distribution function with a large number of repeated operations. In this paper, we first review three most commonly used Monte Carlo (MC) techniques: the standard Monte Carlo, Latin Hypercube sampling, and Quasi Monte Carlo. The performance of these three MC approaches is investigated. We then apply stochastic collocation method (SCM) to risk assessment. Unlike the MC simulations, the SCM does not require a large number of simulations of flow and solute equations. In particular, the sparse grid collocation method and probabilistic collocation method are employed to represent the concentration in terms of polynomials and unknown coefficients. The sparse grid collocation method takes advantage of Lagrange interpolation polynomials while the probabilistic collocation method relies on polynomials chaos expansions. In both methods, the stochastic equations are reduced to a system of decoupled equations, which can be solved with existing solvers and whose results are used to obtain the expansion coefficients. Then the cumulative distribution function is obtained by sampling the approximate polynomials. Our synthetic examples show that among the MC methods, the Quasi Monte Carlo gives the smallest variance for the predicted threshold probability due to its superior convergence property and that the stochastic collocation method is an accurate and efficient alternative to MC simulations.