Projections of the impacts of climate change on the water deficit and on the precipitation erosive indexes in Mantaro River Basin,Peru     

Sly C. Wongchuig  Carlos R. Mello  Sin C. Chou 《山地科学学报》2018,15(2):264-279

Projections of climate change are essential to guide sustainable development plans in the tropical Andean countries such as Peru. This study assessed the projections of precipitation and potential evaporation, rain erosive potential, and precipitation concentration in the Mantaro River Basin, in the Peruvian Andes, which is important for agriculture and energy production in Peru. We assumed the Intergovernmental Panel on Climate Change (IPCC) A1B greenhouse gas emission scenario and simulated the global climate change by the HadCM3 global climate model. Due to the steepness of the mountain slopes and the narrowness of the river valley, this study uses the downscaling of the global model simulations by the regional Eta model down to 20-km resolution. The downscaling projections show decrease in the monthly precipitation with respect to the baseline period, especially during the rainy season, between February and April, until the end of the 21st century. Meanwhile, a progressive increase in the monthly evaporation from the baseline period is projected. The Modified Fournier Index (MFI) shows a statistically significant downward trend in the Mantaro River Basin, which suggests a possible reduction in the rain erosive potential. The Precipitation Concentration Index (PCI) shows a statistically significant increasing trend, which indicates increasingly more irregular temporal distribution of precipitation towards the end of the century. The results of this study allow us to conclude that there should be a gradual increase in water deficit and precipitation concentration. Both changes can be negative for agriculture, power generation, and water supply in the Mantaro River Basin in Peru.  相似文献   

Variability in Particle Mixing Rates in Sediments with Polymetallic Nodules in the Equatorial Eastern Pacific as Determined from Measurements of Excess <Superscript>210</Superscript>Pb     

Kiseong Hyeong  Inah Seo  Hyun-Bok Lee  Chan Min Yoo  Sang-Bum Chi  In Kwon Um 《Ocean Science Journal》2018,53(2):355-368

Radionuclide activities of ²¹⁰Pb and ²²⁶Ra were measured to determine bioturbation coefficients (D_b) in seven sediment cores from the Korean licensed block for polymetallic nodules in the Clarion–Clipperton Fracture Zone. Variability in D_b is considered in the context of the sedimentological, geochemical, and geotechnical properties of the sediments. D_b values in the studied cores were estimated using a steady-state diffusion model and varied over a wide range from 1.1 to 293 cm²/yr with corresponding mixing depths (L) of 26 to 144 cm. When excepting for spurious results obtained from cores where diffusive mixing does not apply, D_b values range from 1.1 to 9.0 cm²/yr with corresponding mixing depths (L) of 26 to 63 cm. Such wide variability in D_b and L values is exceptional in sites with water depths of ～5000 m and is attributed in this study to an uneven distribution of sediment layers with different shear strengths and total organic carbon (TOC) contents, caused by erosion events. The studied cores can be grouped into two categories based on lithologic associations: layers with high maximum shear strength (MSS) and low TOC content, showing a narrow range of D_b values (1.1–9.0 cm²/yr); and layers with low MSS and high TOC content, yielding much higher D_b values of over 30 cm²/yr. The distribution of different lithologies, and the resultant spatial variability in MSS and labile organic matter content, controls the presence and maximum burrowing depth of infauna by affecting their mobility and the availability of food. This study provides a unique case showing that shear strength, which relates to the degree of sediment consolidation, might be an important factor in controlling rates of bioturbation and sediment mixing depths.  相似文献   

Quantitative estimation of submarine groundwater discharge using airborne thermal infrared data acquired at two different tidal heights     

Ki‐mook Kang  Duk‐jin Kim  Yunjee Kim  Eunhee Lee  Bong‐Gwan Kim  Seung Hee Kim  Kyoochul Ha  Dong‐Chan Koh  Yang‐Ki Cho  Guebuem Kim 《水文研究》2019,33(7):1089-1100

Submarine groundwater discharge (SGD) plays an important role in coastal biogeochemical processes and hydrological cycles, particularly off volcanic islands in oligotrophic oceans. However, the spatial and temporal variations of SGD are still poorly understood owing to difficulty in taking rapid SGD measurements over a large scale. In this study, we used four airborne thermal infrared surveys (twice each during high and low tides) to quantify the spatiotemporal variations of SGD over the entire coast of Jeju Island, Korea. On the basis of an analytical model, we found a linear positive correlation between the thermal anomaly and squares of the groundwater discharge velocity and a negative exponential correlation between the anomaly and water depth (including tide height and bathymetry). We then derived a new equation for quantitatively estimating the SGD flow rates from thermal anomalies acquired at two different tide heights. The proposed method was validated with the measured SGD flow rates using a current meter at Gongcheonpo Beach. We believe that the method can be effectively applied for rapid estimation of SGD over coastal areas, where fresh groundwater discharge is significant, using airborne thermal infrared surveys.  相似文献   

Simulation of drilling‐induced compaction bands using discrete element method     

H. Rahmati  A. Nouri  D. Chan  H. Vaziri 《国际地质力学数值与分析法杂志》2014,38(1):37-50

Rock failure is observed around boreholes often with certain types of failure zones, which are called breakouts. Laboratory‐scale drilling tests in some high‐porosity quartz‐rich sandstone have shown breakouts in the form of narrow localized compacted zones in the minimum horizontal stress direction. They are called fracture‐like breakouts. Such compaction bands may affect hydrocarbon extraction by forming barriers that inhibit fluid flow and may also be a source of sand production. This paper presents the results of numerical simulations of borehole breakouts using 3D discrete element method to investigate the mechanism of the fracture‐like breakouts and to identify the role of far‐field stresses on the breakout dimensions. The numerical tool was first verified against analytical solutions. It was then utilized to investigate the failure mechanism and breakout geometry for drilled cubic rock samples of Castlegate sandstone subjected to different pre‐existing far‐field stresses. Results show that failure occurs in the zones of the highest concentration of tangential stress around the borehole. It is concluded that fracture‐like breakout develops as a result of a nondilatant failure mechanism consisting of localized grain debonding and repacking and grain crushing that lead to the formation of a compaction band in the minimum horizontal stress direction. In addition, it is found that the length of fracture‐like breakouts depends on both the mean stress and stress anisotropy. However, the width of the breakout is not significantly changed by the far‐field stresses. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

柴达木盆地那棱格勒河及其尾闾盐湖锂成矿物源：来自水化学和锶、硫同位素证据   总被引：2，自引：0，他引：2  

李庆宽  王建萍  吴蝉  樊启顺  秦占杰  陈亮  魏海成  都永生  袁秦  李建森  山发寿 《地质学报》2021,95(7):2169-2182

柴达木盆地那棱格勒河尾闾盐湖（一里坪干盐滩、东台吉乃尔盐湖、西台吉乃尔盐湖和察尔汗盐湖别勒滩区段）赋存了我国目前最大的卤水锂矿床。那棱格勒河及其尾闾盐湖锂的物源仍存在一定争议,主要有围岩风化、古湖残留、含盐系地层淋滤、油田水、深部水等,目前缺乏有力的地球化学证据。本文系统采集了那棱格勒河流域及其尾闾盐湖不同水体样品16件,分析了其主、微量元素含量及锶、硫同位素组成。结合前人的研究成果,对区域水体中锂的来源进行了探讨,得出结论如下：那棱格勒河水锂含量（0. 45~0. 79 mg/L）比楚拉克阿拉干河支流（0. 00~0. 05 mg/L）高出一个数量级,其高锂含量主要受洪水河支流的补给;洪水河高锂含量与其上游热泉水的补给有关,该热泉水锂、锶含量高、 87 Sr/ 86 Sr比值偏高, δ 34 S值偏低,与青藏高原典型热泉水地球化学特征（锂含量0. 4~34. 8 mg/L,锶含量0. 07~4. 24 mg/L, 87 Sr/ 86 Sr比值0. 71224~0. 71259, δ 34 S值- 10. 6‰~7. 6‰）较一致。那棱格勒河水（0. 71170）和尾闾盐湖卤水（0. 71143~0. 71156）相似的 87 Sr/ 86 Sr比值,以及研究区河、湖水硫同位素组成符合主要蒸发浓缩过程 δ 34 S值逐渐下降的变化趋势,均证明研究区尾闾盐湖卤水锂资源主要受那棱格勒河的补给;而古湖残留水、盆地西部含盐系地层淋滤水或油田水具有明显不同的水化学特征和锶、硫同位素组成,这些水体对研究区尾闾盐湖锂补给的贡献较小,可忽略不计。  相似文献   

Uncertainty of the Linear Trend in the Zonal SST Gradient Across the Equatorial Pacific Since 1881     

Chan Zhang  Youmin Tang  Jun Ying  Junde Li 《大气与海洋》2019,57(1):61-72

The change in the zonal sea surface temperature gradient (ZSSTG) across the equatorial Pacific plays an important role in the global climate system. However, there has not yet been a consensual conclusion about the changing ZSSTG at either a short-term (from 20 to 90 years) or a long-term time scale (longer than 90 years) in the literature. In this study, the uncertainty of the trend in ZSSTG for different sub-periods since 1881 was examined using four interpolated datasets and four un-interpolated datasets. It was found that the trend in ZSSTG on the short-term time scale could be significantly influenced by internal variability such as the El Niño–Southern Oscillation and the Pacific Decadal Oscillation. On the long-term time scale, the sign of the ZSSTG trend depends on the dataset used. In particular, it was not possible to draw a uniform conclusion about the secular trends in ZSSTG in recent history, given the high sensitivity of the ZSSTG trends to the period, dataset, and regions used to calculate the trends. Our results imply that it may not be possible to detect the response of ZSSTG to global warming until a longer data record becomes available in the future.  相似文献   

1961—2016年我国区域性暴雨过程的客观识别及其气候特征     

叶殿秀  王遵娅  高荣  王荣  肖潺 《气候变化研究进展》2019,15(6):575-583

利用全国2287个气象观测站1961—2016年逐日降水资料,基于对暴雨区进行连续追踪的思路,采用暴雨相邻站点数和暴雨区中心距离确定了中国区域性暴雨过程的客观识别方法;根据区域性暴雨过程的平均强度、持续时间和平均范围构建了区域性暴雨过程的综合强度评估模型。利用该客观方法对1961—2016年中国的区域性暴雨过程进行识别,并分析其气候和气候变化特征。结果显示：我国区域性暴雨过程年均38.5次;区域性暴雨过程一年各月均可出现,但主要出现在4—9月,其中7、8月发生最为频繁,6月区域性暴雨过程持续时间长、范围广、综合强度强,这与长江中下游地区梅雨现象有关。一年中,区域性暴雨过程首次出现日期平均为3月6日,末次出现日期平均为11月14日;1961—2016年,我国年区域性暴雨过程首次出现日期呈明显提前、末次日期呈显著推后、暴雨期呈显著延长的变化趋势;年发生总频次呈微弱增多,较强区域性暴雨过程次数呈明显增加趋势;区域性暴雨过程的覆盖范围和综合强度均呈显著增大趋势。南方型区域暴雨过程变化趋势与全国的基本一致;北方型首次日期呈提前、末次日期呈推后趋势,发生频次有微弱减少趋势,覆盖范围、持续时间、综合强度均无明显变化趋势。  相似文献   

气候变化对长江上游径流影响预估     

秦鹏程  刘敏  杜良敏  许红梅  刘绿柳  肖潺 《气候变化研究进展》2019,15(4):405-415

利用第五次国际耦合模式比较计划(CMIP5)中5个气候模式在3种典型浓度路径(RCPs)下的预估结果驱动SWAT水文模型,预估了21世纪气候变化对长江上游年径流量、季节分配以及极端径流的影响。结果表明：预估的长江上游平均气温呈显著上升趋势,21世纪末较当前(1986—2005年)升高1.5~5.5℃,降水总体呈增加趋势,在21世纪30年代后高于当前气候平均值,21世纪末相对于当前增加5%~15%。流域内气候变化存在明显空间差异,金沙江和岷沱江流域气温升高和降水增加幅度均大于流域平均值。预估的长江上游年径流量及各月平均径流均有增加趋势,在21世纪30年代后高于当前多年平均值,21世纪中期增加4%~8%,21世纪末增加10%~15%。预估的径流年内分布的均匀性有所增加,但年际变化明显增大,极端旱涝事件的频率和强度明显增加。预估的各子流域径流变化对气候变化的响应也存在差异,金沙江和岷沱江流域年径流量、年际变化和年内分布变化小,对气候变化的响应表现为低敏感;嘉陵江流域、乌江流域和长江上游干流径流增加幅度大,同时极端丰枯出现的频率和程度增加显著,是气候变化响应的敏感区域。  相似文献   

A brief introduction to BNU-HESM1.0 and its earth surface temperature simulations     

Shili Yang  Wenjie Dong  Jieming Chou  Jinming Feng  Xiaodong Yan  Zhigang Wei  Wenping Yuan  Yan Guo  Yanli Tang  Jiacong Hu 《大气科学进展》2015,32(12):1683-1688

Integrated assessment models and coupled earth system models both have their limitations in understanding the interactions between human activity and the physical earth system. In this paper,a new human–earth system model,BNUHESM1.0,constructed by combining the economic and climate damage components of the Dynamic Integrated Model of Climate Change and Economy to the BNU-ESM model,is introduced. The ability of BNU-HESM1.0 in simulating the global CO2 concentration and surface temperature is also evaluated. We find that,compared to observation,BNU-HESM1.0underestimates the global CO2 concentration and its rising trend during 1965–2005,due to the uncertainty in the economic components. However,the surface temperature simulated by BNU-HESM1.0 is much closer to observation,resulting from the overestimates of surface temperature by the original BNU-ESM model. The uncertainty of BNU-ESM falls within the range of present earth system uncertainty,so it is the economic and climate damage component of BNU-HESM1.0 that needs to be improved through further study. However,the main purpose of this paper is to introduce a new approach to investigate the complex relationship between human activity and the earth system. It is hoped that it will inspire further ideas that prove valuable in guiding human activities appropriate for a sustainable future climate.  相似文献   

U–Pb and Hf isotopic study of zircons from migmatised amphibolites in the Cathaysia Block: Implications for the early Paleozoic peak tectonothermal event in Southeastern China     

Long-Ming Li  Min Sun  Yuejun Wang  Guangfu Xing  Guochun Zhao  Shoufa Lin  Xiaoping Xia  Lungsang Chan  Feifei Zhang  Jean Wong 《Gondwana Research》2011,19(1):191-201

Amphibolites occur in a number of localities in the Cathaysia Block, some of them have been migmatised and their protoliths represent basaltic magmas erupted in various tectonic settings. Four migmatised amphibolites were collected from Jiangxi and Fujian Provinces. Cathodo-luminescence images of zircons extracted from the representative amphibolites show unzoned or sector-zoned structure. LA-ICP-MS analysis indicates that most zircons have high Th/U ratios and yield U–Pb zircon ages of 446 ± 5, 435 ± 2, 434 ± 4 and 423 ± 2 Ma, respectively. Lu–Hf isotopic analysis on these zircons gives Hf model ages ranging from 900 to 1200 Ma. Based on lithological observations and previously published geochronological data, we interpret that these U–Pb ages record an important tectonothermal event that led to the migmatization. This early Paleozoic (Caledonian) tectonothermal event in the Southeastern China has a great tectonic implication for the evolutionary history of the Cathaysia Block.  相似文献