Modelling the impacts of subsurface drainage on surface runoff and sediment yield in the Le Sueur Watershed,Minnesota, USA     

F. K. Maalim 《水文科学杂志》2013,58(3):570-586

Abstract

Tile drainage influences infiltration and surface runoff and is thus an important factor in the erosion process. Tile drainage reduces surface runoff, but questions abound on its influence on sediment transport through its dense network and into the stream network. The impact of subsurface tiling on upland erosion rates in the Le Sueur River watershed, USA, was assessed using the Water Erosion Prediction Project (WEPP) model. Six different scenarios of tile drainage with varying drainage coefficient and management type (no till and autumn mulch-till) were evaluated. The mean annual surface runoff depth, soil loss rate and sediment delivery ratio (SDR) for croplands, based on a 30-year simulation for the watershed with untiled autumn mulch-till (Scenario 1), were estimated to be 83.5 mm, 0.27 kg/m² and 86.7%, respectively; on no-till management systems (Scenario 4), the respective results were 72.3 mm, 0.06 kg/m² and 88.2%. Tile drains reduced surface runoff, soil loss and SDR estimates for Scenario 1 by, on average, 14.5, 8.1 and 7.9%, respectively; and for Scenario 4 by an estimated 31.5, 22.1 and 20.2%, respectively. The impact of tile drains on surface runoff, soil loss and SDR was greater under the no-till management system than under the autumn mulch-till management system. Comparison of WEPP outputs with those of the Soil Water Assessment Tool (SWAT) showed differences between the two methods.

Editor Z.W. Kundzewicz

Citation Maalim, F.K. and Melesse. A.M., 2013. Modelling impacts of subsurface drainage on surface runoff and sediment yield in the Le Sueur Watershed in Minnesota, USA. Hydrological Sciences Journal, 58 (3), 570–586.  相似文献   

Analysis of flood propagation changes in the Kienstock—Bratislava reach of the Danube River/Analyse des changements de propagation des crues dans le tronçon Kienstock—Bratislava du Fleuve Danube     

《水文科学杂志》2013,58(4)

Abstract

In the first part of this study, a flood wave transformation analysis for the largest historical floods in the Danube River reach Kienstock–Bratislava was carried out. For the simulation of the historical (1899 and 1954) flood propagation, the nonlinear river model NLN-Danube (calibrated on the recent river reach conditions) was used. It was shown that the simulated peak discharges were not changed significantly when compared to their historical counterparts. However, the simulated hydrographs exhibit a significant acceleration of the flood wave movement at discharges of between 5000 and 9000 m³ s^-1. In the second part, the travel time-water level relationships between Kienstock and Bratislava were analysed on a dataset of the flood peak water levels for the period 1991–2002. An empirical regression routing scheme for the Danube short-term water level forecast at Bratislava station was derived. This is based on the measured water level at Kienstock gauging station.  相似文献   

GEOCHEMICAL CHARACTERISTICS OF PHOSPHORUS NEAR THE HUANGHE RIVER ESTUARY   总被引：5，自引：0，他引：5  

李悦  余季金 《中国海洋湖沼学报》1999,17(4):359-365

INTRODUCTIONPhosphorus (P)isanimportantlimitingelementinglobaloceanicproductivity (Holland ,1 978) ,soknowledgeofPisakeytobetterunderstandingofthecyclingofcarbon ,nitrogen,sulfur,andothernu trientelements.Inasimplemassbalancemodel,thelevelofdissolvedPintheoceanisafunctionoftherateofinputviarivers,andtherateofoutputviadepositioninsediments.Inthepresentstudy,thefocusisontheriverinePinputbytheHuangheRiver (YellowRiver)totheBohaiSea,andespeciallyontheamountofPsolubilizedfromsolidphasesupo…  相似文献   

近42年雅鲁藏布江中游四季气温变化特征分析   总被引：2，自引：0，他引：2  

周顺武  张勇 《成都信息工程学院学报》2000,15(4):307-311

利用 1957～ 1998年雅鲁藏布江中游拉萨、日喀则、泽当、江孜 4个站各月平均气温资料 ,通过线性趋势估计和多项式函数拟合分析了该流域春、夏、秋、冬 4季气温长期趋势变化和周期变化 ,并利用滑动T检验等方法讨论了气温突变的问题。结果表明 :在过去 4 2年里 ,雅鲁藏布江中游地区各季气温均有明显的上升趋势 ,其中冬春季增温显著 ,80年代初沿江四季气温除秋季外都出现了明显的增温突变  相似文献   

生产性服务业视角下城市网络的演化模式与机制研究——以长江三角洲为例   总被引：1，自引：3，他引：1  

王聪  曹有挥 《地理科学》2019,39(2):285-293

从行业属性、企业内部因素和城市所处的环境3个层面的耦合关系视角,对生产性服务业视角下城市网络的形成演化模式和演化机制进行了理论探索。在基于地理空间的行政等级体系基础上,考虑到生产性服务业发展对于城市网络的综合影响,归纳了由初始集聚阶段-非均衡扩散阶段-等级网络形成阶段-网络成熟阶段的生产性服务业视角下城市网络的一般演化模式。实证研究表明,长三角城市网络正处于非均衡扩散向等级网络阶段演化的过渡时期,表现出网络的层级特征愈发明显、水平联系不断增强、联系方向更加多样化、服务功能联系差距缩小等特征。联系便捷程度、创新要素支撑、制造业发展基础,以及城市能级推动等要素对于长三角城市网络的影响较大。  相似文献   

黄河口裸置管线对海床土影响范围研究   总被引：1，自引：0，他引：1  

杨秀娟  贾永刚  远航  张建  张衍涛  冯春健 《海洋地质与第四纪地质》2008,28(6)

裸置管线在波浪和潮流等作用下，对海床土强度和整体固结水平产生一定的影响，而产生影响的范围还是一个悬而未决的问题。2005年8月和2006年9月，分别对黄河口地区106钻井平台附近的一条裸置管线以及该地区海床土强度进行了现场微贯测量，结果发现，在该地区水动力作用下，水平方向，管线使得其两侧2m以内海床土强度降低，均匀性变差，尤其是降低了0～40cm深度海床土的强度，并使得其非均匀化程度加剧，使海床土出现成层现象。该研究成果为波浪-管线-土相互作用研究提供了典型实例，并对工程实践提供了借鉴。  相似文献   

Numerical study on salinity stratification in the Pamlico River Estuary     

Hongzhou Xu  Jing Lin  Dongxiao Wang 《Estuarine, Coastal and Shelf Science》2008

The variations of current circulation, salt intrusion, and vertical stratification under different river flow and wind conditions in the Pamlico River Estuary (PRE) were investigated in this paper using a three-dimensional numerical model. The model was calibrated and verified against water level variation, temperature, and salinity variations during 2003 and 2001, respectively. Eight sensitivity tests were conducted with different river flow and wind conditions specified in the model. Model results show that salinity intruded further upstream under scenarios with low flow, downriver local wind, and remote-wind-caused water level set-up conditions. In contrast, the responses of salinity stratification to different environmental forcing functions were different in different portions of the estuary. Salinity stratification was enhanced under high flow condition at the lower part of the estuary, under upriver wind near the river mouth, under downriver wind at the upstream to middle portion of the estuary, and under remote-wind-caused water level set-up condition at the majority of the estuary except near the river mouth. Model results also show that across-channel wind tended to reduce salt intrusion and salinity stratification in the PRE through increased vertical mixing.  相似文献   

珠江河口界面特征与河口管理理念     

易小兵  王世俊  李春初 《海洋学研究》2008,26(4):86-92

河口是河流系统与海洋系统之间的界面,它首先是河流与海洋之间的物质界面。河流水体与海洋水体间最大的物质差异是盐分,因此,采用盐度作为河口界面的界定标准,将河口界面界定为盐度为0.5~30的由冲淡水控制的河口中心区域。在此基础上应用界面理论,分析了河口的渗透性和防御性及其动力、沉积、生物与地貌响应。借鉴Gilbert三角洲的动力分类方法,将河口界面按动力结构分为径流优势型、潮汐优势型、波浪优势型及其过渡类型。每一种河口界面又可细分为动力、沉积、地貌及生态等次一级界面。在珠江三角洲地区,磨刀门、蕉门河口等径流优势型河口界面主要承担泄洪任务,而虎门、崖门等潮汐优势型河口界面在纳潮能力上更有优势,其间通过河道支汊相互沟通和联系,形成了珠江河口界面的多层次结构。河口界面动力的复杂性,构成了河口界面形态和功能的复杂性。这些功能包括开发利用功能、生态功能、防洪功能和社会服务功能。河口管理的最高目标是河口的永续健康、结构和功能彼此协调,保持河口界面结构和功能的完整性。河口界面的复杂性对河口管理提出了更高的要求,要注重河口管理内容的综合性、问题的复杂性和管理效应的长周期性。针对珠江河口生境退化、海岸侵蚀、污染严重、咸潮活动加剧和口门淤积造成排水不畅等诸多问题,以及河口无序开发利用、管理体制混乱、公众参与少的管理现状,结合珠江河口界面整体、动态、彼此联系的特点,提出珠江河口管理"科学、和谐、安全和预警"的管理理念,由行政管理转变为服务管理,切实做好珠江河口管理工作。  相似文献   

多重压力对重点生态功能区农户生计资产可得性的影响——以甘南黄河水源补给区为例     

高志玉  赵雪雁  兰海霞  石育中 《地理研究》2020,39(5):1152-1165

重点生态功能区主要承担着提供持续、稳定生态服务的功能,农户作为维护其主体功能的最基础单元和该区最主要的经济活动主体,面临着自然、社会、政策等多重压力,其交互作用不仅加剧了农户的生计脆弱性,更影响到该区主体功能的发挥,当前急需辨明多重压力对农户生计的影响,以便寻求有效的生计脆弱性减缓对策。本文以甘南黄河水源补给区为例,运用入户调查数据与有序Logistic回归模型等方法在识别农户遭受关键压力的基础上,进一步探讨生计压力的交互作用对生计资产可得性的影响。结果显示：① 甘南黄河水源补给区大多数农户遭受自然+经济型多重压力,其中,重点保护区、恢复治理区及经济示范区农户遭受的多重压力分别以自然+经济型、自然+经济型、经济+社会型为主。② 在多重压力的冲击下,重点保护区与恢复治理区农户除了社会资产可得性变化处于稳定状态,其余各类资产可得性变化几乎处于降低态势,而经济示范区农户的金融资产与社会资产的可得性变化处于稳定状态,其余各类资产可得性变化均处于降低态势。③ 婚嫁支出高与农牧产品价格下降、牲畜患病与人畜饮用水困难、子女学费支出高+婚嫁支出高+农牧产品价格下降+养老无保障、建房开支高与生态政策、子女就业困难与农业病虫害等压力的交互作用分别对自然资产、物质资产、金融资产、社会资产、人力资产等的可得性变化影响最强烈。  相似文献   

Capturing the essential spatial variability in distributed hydrological modelling: Infiltration parameters     

Nadim S. Farajalla  Baxter E. Vieux 《水文研究》1995,9(1):55-68

Selecting the correct resolution in distributed hydrological modelling at the watershed scale is essential in reducing scale-related errors. The work presented herein uses information content (entropy) to identify the resolution which captures the essential variability, at the watershed scale, of the infiltration parameters in the Green and Ampt infiltration equation. A soil map of the Little Washita watershed in south-west Oklahoma, USA was used to investigate the effects of grid cell resolution on the distributed modelling of infiltration. Soil-derived parameters and infiltration exhibit decreased entropy as resolutions become coarser. This is reflected in a decrease in the maximum entropy value for the reclassified/derived parameters vis a vis the original data. Moreover, the entropy curve, when plotted against resolution, shows two distinct segments: a constant section where no entropy was lost with decreasing resolution and another part which is characterized by a sharp decrease in entropy after a critical resolution of 1209 m is reached. This methodology offers a technique for assessing the largest cell size that captures the spatial variability of infiltration parameters for a particular basin. A geographical information system (GIS) based rainfall-runoff model is used to simulate storm hydrographs using infiltration parameter maps at different resolutions as inputs. Model results up to the critical resolution are reproducible and errors are small. However, at resolutions beyond the critical resolution the results are erratic with large errors. A major finding of this study is that a large resolution (1209 m for this basin) yields reproducible model results. When modelling a river basin using a distributed model, the resolution (grid cell size) can drastically affect the model results and calibration. The error structure attributable to grid cell resolution using entropy as a spatial variability measure is shown.  相似文献