标记分水岭算法及区域合并的遥感图像分割   总被引：4，自引：0，他引：4  

陈波  张友静  陈亮 《国土资源遥感》2007,18(2):35-38

传统的分水岭算法通常对梯度图像进行无标记分割，其结果是容易造成过度分割。本文采用了一种基于标记的分水岭算法，首先,利用Sobel边缘算子对原遥感图像进行梯度重建，获得梯度幅值图像，同时计算待分割区域的周长、面积和形态因子，并对其进行标记； 然后,利用距离函数图标定种子法和等值线跟踪法获得初始分割图像； 最后，利用改进的区域合并方法获得最终的分割结果。实验结果表明了该方法的有效性。  相似文献   

INTEGRATION OF THE MODELS OF ANNAGNPS AND REMM TO ASSESS RIPARIAN BUFFER SYSTEM FOR SEDIMENT REDUCTION     

Yongping YUAN Ronald BINGNER Randall WILLIAMS Richard LOWRANCE David BOSCH Joe SHERIDAN 《国际泥沙研究》2007,22(1):60-69

The United States Department of Agriculture (USDA) Annualized Agricultural Non-Point Source Pollution model (AnnAGNPS) is used to help evaluate a watershed response to agricultural management practices to control water quality. However, AnnAGNPS version 3.5 does not contain features to estimate the effect of a riparian buffer (RB) system on water quality. The Riparian Ecosystem Management Model (REMM) is used to simulate the impact of riparian buffer systems on water quality. However, frequently the lack of measured upland loadings that are required by REMM simulation limits the application of REMM. To address this data gap, a study was conducted to integrate AnnAGNPS with REMM for RB system simulation. AnnAGNPS was used to simulate water and sediment loadings from an upland field into a three-zone RB system at the Gibbs Farm located in the Georgia coastal plain. These AnnAGNPS outputs were used as the inputs to REMM. REMM was used to simulate water and sediment movement along the riparian buffers. The AnnAGNPS simulated amount of annual runoff at the edge of the field was close to observed amounts (Nash-Sutcliffe efficiency of 0.92). It is believed that a substantial portion of sand was removed from the runoff one meter into the grass buffer where the samplers were located; therefore, sand was excluded from the AnnAGNPS simulation for comparison with observed sediment. Excluding sand, the AnnAGNPS predicted amount of annual sediment matches the observed amount fairly well (Nash-Sutcliffe efficiency of 0.46). In addition, based on evaluating the percent reduction of sediment at each zonal interface, the AnnAGNPS/REMM model well simulated the function of the RB system to reduce sediment.  相似文献   

近47a来青海湖流域气候变化分析   总被引：1，自引：1，他引：1  

许何也李小雁  孙永亮 《干旱气象》2007,25(2):50-54

选取青海湖流域内及临近7个气象站点,对各站1959～2005年的降水和气温数据采用泰森多边形法进行了计算,并运用Mann-Kendall方法对其变化趋势进行了分析,同时对流域近47 a的气候变化与青海湖水位变化做了相关分析。结果表明:①青海湖流域近47 a来降水存在明显的阶段性变化,20世纪60年代、80年代、90年代降水都呈上升的趋势,70年代为下降趋势;同时年、夏季降水有增加的趋势。②同时期气温存在显著的上升趋势,尤其是冬季增温显著,年变化倾向率达到0.53℃/10 a,1987～2000年与1961～1986年相比,平均气温增加了0.79℃,显著高于全国水平。③青海湖流域近47 a来春、夏、秋、冬陆面蒸发变化倾向率均为正值,夏季陆面蒸发增加趋势显著,年变化倾向率为4.17 mm/10 a。④流域降水量对湖水位的年变化、布哈河径流、沙柳河径流有着显著的影响;在9 a尺度上讲,未来5 a流域秋季降水处于上升阶段,湖水下降会有所减缓或者回升。  相似文献   

流域地形自动分割研究   总被引：26，自引：0，他引：26  

闾国年  钱亚东  陈钟明 《遥感学报》1998,2(4):298-304

本文提供了基于栅格数字高程模型（ＤＥＭ）提取流域空间结构,进行流域自动分割的技术方法。该方法包括地貌形态结构定义、流域结构定义和算法设计３个部分。基于本文设计的算法,可以从ＤＥＭ提取完整的汇流网络和分水线网络,两者组成的多边形集把流域分割成具有拓扑结构的多个子汇流区,这个子汇流区集作为存贮流域信息的基本地貌单元,是流域信息进入地学数据库的框架,也是进行空间分布式机理──过程流域分析模型的基础。并以山西离石黄土丘陵沟壑区的王家沟流域为试验区,获得了较为满意的结果。  相似文献   

淮河流域地下水资源调查评价与利用研究   总被引：1，自引：0，他引：1  

赵晖  刘淼  李瑞 《地下水》2010,32(3):44-47

在查明淮河流域地下水各含水岩组的水文地质特征、水资源总量、开采现状及存在的环境地质问题的基础上,对该区域地下水资源开发利用潜力进行了详细的评价,并提出了相应的治理措施及促进地下水资源可持续利用的对策,为该区未来更长时期水资源的合理配置和以水资源的可持续利用支撑经济社会的可持续发展提供科学依据。  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   

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   

Recent Publications     

《The Journal of geography》2012,111(1):33-44

Abstract

A call for combining the strengths of geographic education with environmental education to produce an ‘education for sustainability’ addresses local problems for sustainable development. A place-based approach encourages civic responsibility among students. Using service-learning to extend education beyond the classroom in this case study connected students with local clients in a watershed-based initiative. Theoretical underpinnings of service-learning for geographic education are discussed, and the case study is viewed from instructor, student, and client perspectives to identify successful outcomes and provide suggestions for those who might adopt service-learning for the first time.  相似文献   

近半个世纪来气候变暖背景下黄河流域潜在蒸散量的变化(英文)     

马雪宁  张明军  李亚举  王圣杰  马潜  刘文莉 《地理学报(英文版)》2012,22(6):977-988

According to the meteorological observation data of 72 stations from 1960 to 2010 in the Huanghe (Yellow) River Watershed, China, the long-term variations of potential evapotranspiration, calculated in the modified Penman-Monteith model of Food and Agriculture Organization of the United Nations, were presented, as well as the meteorological causes for the decrease of potential evapotranspiration were discussed. Since 1960, temperature has risen significantly and potential evapotranspiration a decreasing trend, which indicated the existence of "Evaporation paradox" in the Huanghe River Watershed. This phenomenon was not consistent spatially or temporally with the increase of temperature, potential evapotranspiration decreased in spring, summer and winter, mainly over most parts of Shanxi and Henan, and some parts of Gansu, Ningxia, Inner Mongolia, and Shaanxi. During the recent half century, the trends of temperature and potential evapotranspiration were negatively correlated at most of the stations, while precipitation and potential evapotranspiration exhibited a contrary trend. Calculated in multiple regressions, the contribution to potential evapotranspiration change of related meteorological factors was discussed, including mean pressure, maximum and minimum temperature, sunshine hours, relative humidity and average wind speed. The decrease of wind speed in the Huanghe River Watershed may be the dominating factor causing potential evapotranspiration decreasing.  相似文献