Small river basin and estuarine sediment fluxes: The magnitude necessary for coastal dispersion and siltation effects on a coral reef     

《国际泥沙研究》2019,34(6):591-599

Increasing continental suspended sediment influx to coral reefs is an example of land-sea coupling that requires the identification of sources, magnitude of transport, and controlling processes. In Brazil, a small coastal basin (Macaé River) was identified as a source of suspended sediment to a coral reef on the coast of Cape Armação dos Búzios. Biannual suspended sediment loads were measured at the basin as were fluxes within the estuary and towards the coast during eight tidal cycles. Particle load and yield from this basin were typical of small coastal basins, showing high to moderate slopes and transitional land management. However, the magnitude of the river loads was lower than the sediment transport within the estuary, indicating that the estuary amplifies river fluxes and sustains the transference of suspended sediment alongshore to the coral reef. Nonetheless, the estuary displays both suspended particle retention and export capacity and, therefore, fluxes to the coast and the coral reef occur as episodic events.  相似文献   

新疆艾比湖流域枯、丰水期三维荧光光谱特性及其与水质的关系     

王迪  张飞  张兆永  张海威  朱世丹  张贤龙 《湖泊科学》2020,32(2):483-495

以艾比湖流域主要入湖河流为研究对象，在5月（丰水期）和8月（枯水期）分别沿博尔塔拉河（博河）和精河进行采样，采用平行因子模型（PARAFAC）和三维荧光区域积分法对水体三维荧光特性进行研究并对其与水质的关系在枯、丰水期下的变化进行探讨.结果表明①河流DOM在枯水期与丰水期都含有C1（240、425 nm） UVC类腐殖质，C2（225、290 nm）紫外区内络氨酸类有机物，C3（230/280、330 nm）蛋白类有机物，C4（265、260 nm）腐殖质类共4种组分.通过对水体三维荧光进行区域积分可以看出DOM荧光成分的占比在不同时期的变化.博河在枯水期时EEM光谱中的区域Ⅲ富里酸含量低于丰水期，枯水期时区域Ⅱ芳香类蛋白质、区域Ⅳ可溶性微生物代谢物以及区域Ⅴ类腐殖质酸高于丰水期；对于精河来说，区域Ⅱ芳香类蛋白质和区域Ⅳ可溶性微生物代谢物在枯水期的含量高于丰水期，区域Ⅲ富里酸和区域Ⅴ类腐殖质酸的含量枯水期低于丰水期，这表明水体腐质化程度较高.②本研究选取了一些常规的荧光指数来描述枯、丰水期水体的荧光指数特性.经研究发现，精河的荧光指数、自生源指数和腐殖化指数在不同时期的变化幅度较小，而博河的变化幅度较大.③将荧光指数与水质参数进行相关性分析并建模，结果表明枯水期自生源指数（BIX）与化学需氧量呈显著正相关，相关系数R=0.688；丰水期时BIX与铵态氮浓度呈显著负相关，相关系数R=-0.493.通过对比分析艾比湖主要入湖河流的三维荧光光谱特性与水质在枯、丰水期时的关系进一步表明水体中DOM的特性以及在枯、丰水期下的差异，为艾比湖流域的治理改善提供一定的理论支持和参考依据.  相似文献   

Organic carbon concentrations and transport in small mountain rivers,Panama     

《Applied Geochemistry》2015

Tropical small mountainous rivers (SMRs) are increasingly recognized for their role in the global export of dissolved organic carbon (DOC) to the oceans. Here we utilize the Isthmus of Panama as an ideal place to provide first-order estimates of DOC yields across a wide assemblage of bedrock lithologies and land cover practices. Samples for dissolved organic carbon (DOC) analysis were collected across Panama along an E–W transect from the central Panama area to the Costa Rican border for 24 mainstem rivers, 3 large tributary rivers, and one headwater stream. Sampling occurred during both the wet and the dry seasons. DOC concentrations during the wet season are higher than during the dry season in all but three of the rivers. Concentrations vary greatly from river to river and from season to season, with values as low as 0.64 mg l⁻¹ to greater than >25 mg l⁻¹ with the highest concentrations observed for the rivers draining Tertiary marine sedimentary rocks in the Burica and Azuero peninsulas. DOC yields from Panamanian rivers (2.29–7.97 tons/km²/y) are similar to or slightly lower than those determined for other tropical SMR systems. Areas underlain by Tertiary aged sediments exhibited significantly higher mean DOC yields compared to their igneous counterparts, despite maintaining substantially lower aboveground carbon densities, suggesting the important influence of lithology. Finally, regression analyses between DOC yields and select watershed parameters revealed a negative and statistically significant relationship with maximum and mean gradient suggesting lower soil retention times may be linked to lower DOC yields.  相似文献   

半干旱地区洪水模拟效果差异性分析及影响因子响应评估          下载免费PDF全文

刘玉环  李致家  刘志雨  罗赟  霍文博 《湖泊科学》2022,34(2):652-663

中国北方半干旱地区的降水与下垫面条件具有明显的时空异质性,如何完整准确地描述该类区域的水文过程是当代水文学研究的难点之一.选择半干旱地区水文实验区域——绥德流域和曹坪流域,通过构建不同时空规律的降水场,并结合3种不同产流机制的水文模型,进行大型数值模拟实验,去探究时间、空间、产流机制等因素对半干旱地区洪水模拟的影响,为该类地区水文模型的研制工作提供借鉴.结果 表明:1)半干旱地区中小流域的产流对降雨强度较为敏感,因此降水输入的时间步长对洪水模拟效果的影响程度较大;相比之下,流域雨量站数量的增减,仅体现在降雨分布场的暴雨中心缺失以及面平均降雨量的微小差别,对洪水模拟效果的影响程度较小.2)水文模型能否准确描述主导水文过程是半干旱地区洪水模拟效果优良的关键,流域的尺度效应及其下垫面条件的空间异质性是半干旱地区不同水文模型研制和调整应当优先考虑的问题,无论时间步长、雨量站数量怎么组合,产流结构适宜的模型其模拟效果总是趋于较好的结果.  相似文献   

黑河流域生态—水文过程综合遥感观测联合试验总体设计   总被引：17，自引：4，他引：13  

李新  刘绍民  马明国  肖青  柳钦火  晋锐  车涛  王维真  祁元  李弘毅  朱高峰  郭建文  冉有华  闻建光  王树果 《地球科学进展》2012,27(5):481-498

介绍了"黑河流域生态—水文过程综合遥感观测联合试验"的背景、科学目标、试验组成和试验方案。试验的总体目标是显著提升对流域生态和水文过程的观测能力,建立国际领先的流域观测系统,提高遥感在流域生态—水文集成研究和水资源管理中的应用能力。由基础试验、专题试验、应用试验、产品与方法研究和信息系统组成。其中,①基础试验:搭载微波辐射计、成像光谱仪、热像仪、激光雷达等航空遥感设备,开展一系列关键生态和水文参量的观测;发展遥感正向模型及反演和估算方法。形成覆盖全流域的水文气象综合观测网,为流域生态—水文模型研究提供更有代表性的模型参数、驱动数据及更高精度的验证数据。构建无线传感器网络,度量生态水文模型所需的若干关键的驱动、参数和模型状态的空间异质性。开展航空遥感定标和地基遥感试验。依托传感器网络,并辅之以地面同步和加密观测,开展遥感产品真实性检验。②专题试验:开展"非均匀下垫面多尺度地表蒸散发观测试验",采用密集的涡动相关仪、大孔径闪烁仪与自动气象站的观测矩阵,为揭示地表蒸散发的空间异质性,实现非均匀下垫面地表蒸散发的尺度扩展,发展和验证蒸散发模型提供基础数据。③应用试验:在流域上、中、下游分别开展针对积雪和冻土水文、灌溉水平衡和作物生长、生态耗水的综合观测试验,将观测数据和遥感产品用于上游分布式水文模型、中游地表水—地下水—农作物生长耦合模型、下游生态耗水模型,通过实证研究提升遥感在流域生态—水文集成研究和水资源管理中的应用能力。加强试验将在2012年5月起按中游、上游、下游的顺序展开,全流域持续观测期为2013—2015年。在各类试验的支持下,开展全流域生态—水文关键参量遥感产品生产,发展尺度转换方法,建立多源遥感数据同化系统。  相似文献   

Case history of the disastrous debris flows of Tianmo Watershed in Bomi County,Tibet, China: Some mitigation suggestions   总被引：3，自引：1，他引：2  

Yong-gang Ge  Peng Cui  Feng-huan Su  Jian-qiang Zhang  Xing-zhang Chen 《山地科学学报》2014,11(5):1253-1265

Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Watershed on Sept. 4, 2007, July 25, 2010 and Sept. 4, 2010, blocked Parlung Zangbo River and produced dammed lakes, whose outburst flow made 50 m high terrace collapse at the opposite bank due to intense scouring on the foot of the terrace. As a result, the traffic was interrupted for 16 days in 2010 because that 900 m highway base was destructed and 430 m ruined. These debris flows were initiated by the glacial melting which was induced by continuous higher temperature and the following intensive rainfall, and expanded by moraines along channels and then blocked Parlung Zangbo. At the outlet of watershed,the density, velocity and peak discharge of debris flow was 2.06 t/m3, 12.7 m/s and 3334 m3/s, respectively. When the discharge at the outlet and the deposition volume into river exceeds 2125 m3/s and 126×103 m3, respectively, debris flow will completely blocked Parlung Zangbo. Moreover,if the shear stress of river flow on the foot of terrace and the inclination angel of terrace overruns 0. 377 N/m2 and 26°, respectively, the unconsolidated terrace will be eroded by outburst flow and collapse. It was strongly recommended for mitigation that identify and evade disastrous debris flows, reduce the junction angel of channels between river and watershed, build protecting wall for highway base and keep appropriate distance between highway and the edge of unconsolidated terrace.  相似文献   

Combining CLUE-S and SWAT models to forecast land use change and non-point source pollution impact at a watershed scale in Liaoning Province,China   总被引：2，自引：0，他引：2  

Miao Liu  Chunlin Li  Yuanman Hu  Fengyun Sun  Yanyan Xu  Tan Chen 《中国地理科学(英文版)》2014,24(5):540-550

Non-point source （NPS） pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent （CLUE-S） and Soil and Water Assessment Tool （SWAT） models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen （TN） and total phosphorus （TP） were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. How- ever, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effec- tively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.  相似文献   

黄河中游砒砂岩地区长川流域土地利用变化分析   总被引：2，自引：0，他引：2  

高清竹  江源 《地理科学进展》2004,23(4):52-62,i002

根据1976年的Landsat-MSS影像数据以及1987年和2000年的Landsat-TM影像数据,应用遥感和地理信息系统手段以及转移矩阵和景观空间格局指数分析方法,对地处黄河中游砒砂岩地区的内蒙古准格尔旗长川流域土地利用及其变化进行研究。结果表明：1)研究区内分布最多的土地利用类型是灌木林地、草地和难利用地,该三个土地利用类型的面积占研究区域总面积75％;2)从1976～2000年期间,虽然乔木和灌木林地的面积明显增加,但同时也存在林地和草地向难利用土地、沙地和农地的转变过程。与此同时水域亦明显减少;3)水土保持生物措施的实施、农田开垦和降雨量偏少可能是导致研究区土地利用变化的主要原因。  相似文献   

柴达木盆地盐湖锂矿床成矿过程及分布规律   总被引：2，自引：1，他引：1  

余俊清  洪荣昌  高春亮  成艾颖  张丽莎 《盐湖研究》2018,26(1):7-14

柴达木盆地盐湖蕴藏230×10~4t锂,集中分布在别勒滩、东西台等4个盐湖,占我国卤水锂资源总量~80%,战略资源地位不言而喻。近年来提锂技术及工程化研究倍受重视,而对盐湖锂矿成因和分布规律的了解凸显不足,锂矿资源流失严重与之不无关联。研究查明,昆仑山高温热泉群含锂泉水长期注入洪—那河,流入终端盐湖,蒸发富集成矿;锂的年输入通量748.8 t,结合区内盐湖锂矿总储量保守估算,成矿期始于14 ka BP之后;洪—那河早期主要流向别勒滩,在山前冲积扇向北推进、扇前河改道北流后,方才形成含锂河水当前分配格局。据此,破解了别勒滩锂矿在研究区储量最大的原由。还查明了锂矿床仅存在于别勒滩,而在达布逊等3个区段不能成矿的原因。阐明了锂的来源与新生代火山喷发岩、深部岩浆房、昆仑大断裂活动有关,以及含锂热水持续远程输送至盐湖成矿的地貌和水文气候动因。企业应当根据锂的分布规律和矿床特征,迅速转变钾肥生产模式。  相似文献   

Use a Spatial Analysis Model to Assess Habitat Quality in Lashihai Watershed     

LI Haiping  QI Yanan  QU Yunying 《资源与生态学报(英文版)》2018,9(6):622-631

Habitat quality assessments are of great significance for protecting biodiversity. This study analyzes the changing habitat quality of Lashihai watershed based on SPOT satellite images. We extracted the land use data for Lashihai watershed in Yunnan province for the years 2000 and 2015, and then used an InVEST model to evaluate habitat degradation, habitat quality and habitat scarcity in the study area from 2000 to 2015. Spatial statistical methods were used to determine changes to spatial dynamics. Results indicate that the number of areas with habitat degradation was generally small, and that both the number of areas with habitat degradation and the degree of degradation had fallen noticeably during the fifteen-year study period. In general, the quality of habitats was maintained or improved, while the quality of habitats decreased in only a few areas. The scarcity of habitats for cultivated land had increased, the tension between people and land use was relatively prominent. The reason habitat quality in Lashihai watershed has improved can be attributed to three factors: 1) The policy of returning farmland to forests since 2000 has been well implemented and has achieved remarkable results. Loss of forests from logging and deforestation has basically been eliminated, and great progress has been made restoring the ecological environment. 2) High background value of quality habitat suitability benefits from the research area’s high vegetation coverage. 3) The development of the local tourism economy has transformed the area’s ecological advantages into an economic bonus, greatly increasing the income level and living standards of residents. At the same time, the ecological resource bonus has increased the enthusiasm of residents for ecological protection and has helped to promote the protection of local eco-systems, both reducing ecological degradation and improving habitat quality. At the same time, increasing conflicts between land and people should be addressed. Support is needed to promote development of the ecological economy while continuously reducing ecological degradation and further increasing residents’ income. There must be less reliance on industry and less pressure on both land and people, all the while ensuring that the local economy and ecology can more forward together in a sustainable way.  相似文献