人工沟渠对流域水文格局的影响研究

人工沟渠是指以排水和灌溉为主要目的的人工挖掘的水道。目前,国内外对人工沟渠的研究主要集中在控制沟渠对农田或斜坡影响的水文过程上,而有关人工沟渠对流域水文格局影响的研究比较少,并且缺乏人工沟渠景观及其所携带污染物管理的研究。在流域的尺度上,从人工沟渠对流域径流、污染物传输和水文连通性的影响三方面,详细阐述了人工沟渠对流域水文格局的影响;并对目前人工沟渠对流域水文格局影响研究中存在的问题进行了讨论,同时指出了需要进一步开展的相关研究工作。     

典型岩溶农业区土地利用变化对土壤性质的影响——以云南小江流域为例

1 Introduction Because of modifying land-cover (Turner et al., 1991) and management measures of soil (Dalal, 1986), land use changes can cause significant modifications in soil properties (Islam, 2000; Mcalister, 1998; Braimoh, 2004; Lal, 1996; Shepherd, …     

南方红壤侵蚀区长汀县不同生态恢复年限下芒萁叶绿素含量的高光谱估算模型

芒萁是南方红壤侵蚀区生态恢复重要的地带性草本植物,对生态系统修复具有重要作用,监测其叶绿素含量能有效诊断生长健康状况。本文以福建省长汀县朱溪流域6个不同生态恢复年限下的芒萁叶片高光谱反射数据以及实测叶绿素含量为数据源,借助高光谱遥感技术分析不同恢复年限芒萁叶片原始光谱特征,筛选出光谱敏感波段并构建光谱指数,基于相关性分析,建立芒萁叶绿素单变量以及多元逐步回归模型,并确定最佳估算模型。结果表明：高光谱指数建立的单变量估算模型中,改进红边归一化植被指数（mNDVI₇₀₅）、叶面叶绿素指数（LCI）、红边指数（Vog）、比值光谱指数（RVI_603/407）、NDVI[603,407]高光谱指数建立的二次模型精度高,建模决定系数R²均超过了0.8,其中以高光谱指数为自变量建立的多元回归模型拟合R²值（0.886）最高。综合建模精度和模型验证精度,LCI指数构建的单变量模型以及基于高光谱指数的多元回归模型是估算芒萁叶片叶绿素含量最佳模型。本研究建立的叶绿素高光谱估算模型对快速、无损地监测水保植物芒萁生长具有重要意义。     

流域系统综合模拟与情景分析——自然地理综合研究的新范式?

在全球环境变化和经济快速发展的背景下,经济发展与资源环境保护之间的矛盾日益激化,为解决或减弱这一矛盾,管理者需要新的知识体系和科学的决策工具。自然地理综合研究以自然地理要素空间变化及交互过程为主要研究内容,肩负着提供管理者所需新知识体系和科学决策工具的责任。流域作为空间上相对封闭的自然地理单元,其相对独立性为管理者的决策提供了天然的空间单元。流域内各地理要素的空间分布及其过程的交互机理自然成为管理者解决日益激化的矛盾所需的新知识体系,而流域系统综合模拟恰恰为建立这样的知识体系提供了极为有效的研究方式;在管理者评价各种决策的成效时,必须知道各种决策所产生的经济和环境效益,基于流域系统综合模拟的情景分析为管理者提供了所需要的科学决策工具。因此,从解决经济发展与资源环境保护之间矛盾的角度出发,流域系统综合模拟与情景分析应该成为新时代背景下自然地理学综合研究的新范式。文章结合2个小流域情景分析的研究案例,探讨了以流域系统综合模拟与情景分析为核心的现代自然地理综合研究需要解决的科学挑战,即流域系统综合模拟的系统化、空间化、定量化、易用化和决策化。     

流域交通运输地理研究进展与展望

流域交通运输地理在区域交通运输地理的理论框架下,以流域或流域的部分区域为研究区开展交通运输组织及其发展规律研究。论文从交通网络、运输联系及区域效应3个方面梳理了流域交通运输地理的研究进展。 ① 交通网络相关研究围绕综合交通发展水平与格局、网络连接特征与可达性、港口体系的空间结构与供应链等展开,多式联运正成为流域交通运输地理研究的新热点;② 运输联系主要研究客货运输联系规律和交通流,流域物流地理的研究重点正从物流产业布局与企业选址向物流网络与空间组织、物流供应链转移;③ 区域效应偏重于经济增长效应,资源环境生态效应研究较为薄弱。基于流域交通运输地理研究的侧重点,结合当前研究进展与流域发展需求,流域交通运输地理学未来应重视流域港口体系与水运发展,关注综合交通网络构建与运输组织以及多式联运,探究不同层级流域交通运输间的关联性,同时应加强流域交通运输的资源环境与生态效应研究。     

Land use and landscape change driven by gully land consolidation project: A case study of a typical watershed in the Loess Plateau

Journal of Geographical Sciences - Exploring the impact of land consolidation on the changes of local land use and the landscape patterns is important for optimizing land consolidation models and...     

Unsupervised hydrologic classification of rivers: Watershed controls on natural and anthropogenic flow regimes,Alabama, USA

Watershed hydrology has often focused on modelling studies of individual watersheds, which consider each river system as unique. Classification is an alternative approach that instead focuses on the similarities among different watersheds. Although both supervised and unsupervised hydrologic classifications have been developed, few previous studies have used classification to assess the degree of anthropogenic modification of hydrologic regime. Here, we conducted an unsupervised hydrologic classification of 189 U.S. Geological Survey gages, including 41 minimally impacted gages from the Hydro‐Climatic Data Network (HCDN), in the five major interstate river basins in the U.S. state of Alabama. For the natural classification, the most significant predictor variables for cluster membership were related to compressive strength of bedrock, bedrock depth, hydraulic conductivity, elevation, temperature, and soil texture, and several land‐cover variables were also significant in the anthropogenic classification. We then developed two random‐forest models: one based on all 189 gages using both natural and anthropogenic variables from the Stream‐Catchment (StreamCat) dataset and one based on the 41 HCDN gages using natural StreamCat variables only. We used the random‐forest models to predict natural and anthropogenic normative hydrologic class for over 158,000 National Hydrography Dataset Plus catchments in the study area. Catchments that changed their class between the natural and anthropogenic classifications can be identified as those that have a large amount of anthropogenic influences on their hydrologic regime, including many catchments on the coast, in the north‐western Coastal Plain, in the Interior Low Plateaus, and in the Piedmont. Using unsupervised hydrologic classifications is a promising approach for uncovering the physical processes that affect hydrologic regime. There are also potential applications in river management, including predicting the hydrologic behaviour of ungaged watersheds, identifying relatively unimpaired rivers to serve as conservation and restoration targets, and regionalization of environmental instream flow standards and climate‐change impacts.     

滇池流域水污染特征(1988-2014年)及防治对策

为明确滇池流域水污染特征并提出有针对性的污染控制对策,对流域污染变化规律及其组成和空间分布特征进行分析.研究表明,近二三十年,滇池流域点源污染负荷的产生量和削减量显著增加,入湖量有所削减;城市面源入湖量随建成区面积的扩张而持续上升;农业面源入湖量在1990s出现峰值,随后下降.目前,滇池流域化学需氧量主要来源于城市面源;总氮主要来自污水处理厂尾水;总磷主要来自农业面源和未收集的点源;各控制单元入湖污染负荷已基本演变为以未收集的点源和城市面源为主.针对流域目前存在的问题,应继续坚持点源污染治理,高度重视城市面源污染治理,加强农业面源治理,进一步完善流域截污治污体系,为滇池水质改善创造条件.     

Wood export prediction at the watershed scale

Wood export from a watershed is a function of peak annual discharge, but one hydrologic relationship alone does not fully explain observed variability. Consideration of physical processes that influence the amount of wood available for transport is needed. However, wood recruitment, storage, mobilization, breakage, and transport rates and processes remain difficult to quantify. A theoretical wood transport equation focused on variations in discharge was the motivation for investigation into watershed‐specific wood export rates. Herein, multiplicative coefficients categorized by water year type are developed, paired with the equation, and validated to provide a new method for prediction of wood export at the watershed scale. The coefficients are defined as representing a broad suite of watershed processes that encompass spatio‐temporally variable scales. Two complementary datasets from the 1097 km² mountainous North Yuba River, California watershed were used. Wood surveys above New Bullards Bar Reservoir yielded a wood availability estimate of 250 000–300 000 m³ along the channel network. Annual wood export into the reservoir was field‐surveyed in 2010, 2012 and 2013, and estimated in seven years via remotely sensed images over the 30 year study period of water years 1985–2014. Empirical, watershed‐scale wood export rates ranged from 0.3–5.6%. Comparison of predicted quantities using the new DVWP (discharge variations modified by watershed processes) wood export equation to observed wood export quantities resulted in an aggregate error rate of ±10%. When individual wood export quantities were compared, predicted to observed varied by 0.5–3.0 times. Total wood export of 59 000–71 000 m³ was estimated over the 30 year period, yielding a rate of 1.8 to 2.2 m³/year/km². Wood export predictive capabilities at the watershed scale may help water resource and regulatory agencies plan for wood transfers to augment downstream ecosystems. Copyright © 2017 John Wiley & Sons, Ltd.     

Automated watershed subdivision for simulations using multi-objective optimization

A qualitative trial-and-error approach is commonly used to define watershed subdivisions through varying a single topographic threshold value. A methodology has been developed to quantitatively determine spatially variable threshold values using topography and a user-defined landscape reference layer. Optimization and topographic parameterization algorithms were integrated to create solutions that minimize the number of sub-watersheds and maximize the agreement between the discretized watershed and the reference layer. The system was evaluated using different reference datasets such as soil type, land management, and landscape form. Comparison of simulated results indicated that the scenario using land management as the reference layer yielded results closer to the scenario subdivided using a constant topographic threshold but with approximately 10 times more sub-catchments and therefore indicating customization of the watershed subdivision to the user-defined reference layer. The proposed optimization technology could be used in adequately applying watershed modeling technology in developing conservation practice implementation plans.