共查询到19条相似文献，搜索用时 232 毫秒
1.
基于1990—2018年于桥水库流域入库河流与水库的逐月总氮(TN)和总磷(TP)监测数据,整理并分析了1990-2002、2003—2014和2015—2018年3个时段TN、TP浓度和氮磷比(TN/TP)的时空变化特征,探究流域内点面源污染削减、调水、氮磷滞留等对营养盐浓度变化的影响。结果表明,1990—2018年于桥水库TN浓度年均值在1.14～3.74 mg/L之间,水库TP浓度年均值在0.025～0.131 mg/L之间,多年TN/TP平均值为45,远高于淡水磷限氮磷比,是磷限水库。于桥水库流域5个测点中,沙河TN浓度最高,黎河TP浓度最高,入库TN、TP浓度大于库区,水库TP滞留率略大于TN。水库TN、TP浓度在2000s中后期下降,之后出现反弹。原因是2003年水源保护工程实施后,入库营养物浓度降低;2014年底南水北调中线一期工程通水后,于桥水库的引滦水量减少,TN的稀释效应弱化,上游来水TP浓度上升与水库内夏秋两季浮游植物的增殖,导致第三时段水库内TP浓度上升。基于月尺度水质分析,夏季水库TN浓度最低,TP浓度达到峰值,主成分分析表明,历年6—10月的水库Chl.a浓... 相似文献
2.
在巢湖市烔炀镇西宋村农田示范基地中建立生态拦截沟来处理农业生产排放的农业面源污水,就生态拦截沟中浮游植物丰度、生物量和群落结构进行了研究.实验历时6个月,研究中共检测到浮游植物9门48属75种.研究发现尽管农田生态拦截沟中的水生植被能有效削减水体中的氮、磷营养盐,但对浮游植物群落结构产生的影响不大.生态拦截沟中主要藻类为绿藻、蓝藻和硅藻,且出水口蓝藻所占比例较进水口有显著上升.生态拦截前后浮游植物优势种类的变化不大,主要为蓝藻门的铜绿微囊藻(Microcystis aeruginosa)、绿藻门的微球衣藻(Chlamydomonas microsphaera)和硅藻门的孟氏小环藻(Cyclotell meneghiniana)等.藻类生物多样性研究表明生态拦截沟中的水体主要为清洁或寡污型水体,仅在夏季的7月份出现了轻微的水体污染.典型对应分析发现,TN/TP对浮游植物种类分布的解释度最高.同时,发现水体总磷的对数、总溶解磷的对数与藻类的生物量呈正比,而TN/TP与藻类的生物量呈反比.研究表明农田生态拦截沟尽管具有削减农业氮、磷营养盐面源污染的作用,但不能有效地降低水体中蓝藻的生物量.农业面源污水中的藻类营养盐限制主要为磷限制,削减农田径流中的磷含量是控制巢湖流域水体富营养化和遏制蓝藻水华的关键环节. 相似文献
3.
红壤农田小流域径流组分对氮素流失动态的影响 总被引：1，自引：0，他引：1
《中国科学:地球科学》2019,(12)
明确关键带中农田流域水文过程对氮负荷的影响,对于理解关键带中的物质迁移过程,尤其是农业面源污染中氮素的迁移转化具有重要意义.文章以红壤关键带丘陵区孙家农田小流域为对象,在2017年3月至2018年2月水文年对流域降水、土壤水、地下水及径流进行了较为系统的水量和水质监测,借助端元混合模型,探究了径流组分动态对氮素流失的影响.结果表明,流域不同水体之间氮素浓度差异显著.土壤水和地下水的氮素浓度最高,约为降水和灌溉水的3～5倍,流域径流氮素浓度的2倍.红壤农田流域氮素负荷较高.孙家小流域全氮(TN)年净流失量占总氮肥投入的15%.雨季是氮流失的高风险期,仅降水量最为丰沛的6月氮素流失就占到全年总流失量的1/3以上.地下径流是农田小流域氮素流失的重要途径,其径流量占到流域径流量的25%左右.径流组分的改变是径流氮素浓度变化的重要因素,且径流组分可以用来预测水田与旱地生态系统交错存在的小流域的氮素负荷,其预测结果与实测结果的线性决定系数达到0.9左右(p0.001).本研究的结果对于提高红壤农田小流域的水肥管理水平和加深对红壤关键带水氮耦合关系均具有重要指导价值. 相似文献
4.
如何精细量化降雨径流污染负荷是流域尺度实现面源精准治污全过程控制的重要前提.本研究以水污染较为严重的望虞河西岸综合示范区为例,通过开展不同土地利用类型的降雨观测实验,修正SCS-CN模型中的初损率,并基于土地利用类型遥感解译和降雨径流污染物浓度测定,精细刻画降雨径流中总磷(TP)、总氮(TN)、氨氮(NH3-N)、化学需氧量(COD) 4类主要污染物的时空分布格局.结果表明:研究区绿地和农田、硬质地表的降雨初损率分别为0.3和0.9;径流深、污染负荷与降雨深之间存在显著的正相关性.随着降雨量逐年递减,研究区降雨径流中TP、TN、NH3-N、COD四类污染物的负荷量分别从2017年的190、1359、445和16041 t减少至2019年的118、949、314和11250 t;单位面积TN和COD负荷最高的用地类型是农村住宅用地,草地的四种污染物单位面积负荷均最低,林地次之.相关研究结果为望虞河流域水污染控制提供了基础数据,也为定量测算平原河网区面源污染负荷提供了方法参考. 相似文献
5.
引水等综合整治后杭州西湖氮、磷营养盐时空变化(1985-2013年) 总被引：2，自引：0，他引：2
经引水等综合整治后,西湖外湖、西里湖总磷(TP)浓度累计下降58%和78%,总氮(TN)浓度累计下降16.7%和7.7%,透明度提高100%~200%,富营养状态得到极大缓解.比较1986年治理前,西湖各湖区因来水、引水和排水格局差异较大,TP浓度的年内变化特点及驱动因素也存在较大差异:杨公堤以西的上游湖区因优质水源补充TP浓度总体较低,同时受流域降雨径流面源输入影响,呈现时段性升高;杨公堤和苏堤之间的中游湖区优质水源补充量最大,湖区水体更新最快,TP浓度最低且变化相对最为稳定;苏堤以东的外湖区水体更新相对最慢,在夏、秋高温季节因底泥污染释放,TP浓度出现峰值.因外来引水量大且未经脱氮处理,西湖各湖区TN年内变化基本与钱塘江取水口TN浓度变化一致,同时因流域降雨径流面源输入而出现时段性波动.基于TP质量平衡模型分析,各湖区水质空间差异主要受水体年交换次数影响,其次受单位水体的年污染负荷影响. 相似文献
6.
太湖地区西苕溪流域营养盐污染负荷结构分析 总被引：6，自引：0，他引：6
污染负荷研究是实施污染物总量控制、保护水质的基础,由于非点源污染一直是水环境研究的一个难题,致使河流污染负荷估算缺乏合理的估算方法.本项研究针对太湖的富营养化问题,选取太湖上游西苕溪流域,采用GIS的流域分析方法,选取单一土地利用类型的小流域,分析流域土地类型与径流量及流域出口浓度的统计关系,获取不同土地利用类型营养盐污染的产出率,合理估算了西苕溪流域的非点源营养盐污染负荷,并根据西苕溪流域社会经济统计数据及已有的污染产出率研究成果,估算了西苕溪的点源营养盐污染负荷,在此基础上估算了西苕溪流域的营养盐污染总负荷量,分析了不同污染源在总负荷量的比例.最后通过比较估算的总负荷量与实测负荷量,计算了西苕溪流域河网体系对营养盐的降解能力.研究得出, 林地产出径流浓度总氮0.715mg/L、总磷0.039mg/L,耕地产出径流浓度总氮为2.092mg/L, 总磷0.166mg/L,西苕溪流域总氮负荷量为3143.43t/a,非点源污染负荷量为1589.52t/a;总磷负荷量为226.32t/a,非点源为108.36t/a,西苕溪流域河网体系对总氮、总磷的年降解率分别为 35.39%、21.48%. 相似文献
7.
流域尺度面源污染的监测是系统认识农业面源污染的发生、迁移及转化过程, 并对其进行有效控制的重要基础. 当前, 田块尺度的面源污染监测方法比较成熟, 而流域尺度的监测, 尤其是监测断面的布设及采样频率设置等方面的研究较少. 本文详细梳理了小流域采样断面布设、采样频率优化和河流断面通量估算3方面的主要进展. 1)从小流域样点布设来看, 包括常规监测采样设计、针对性监测采样设计和融合前两种类型的监测采样设计3种类型, 点位布设方法上有遗传算法、模糊逻辑法、熵值法和模型法等, 样品采集方式包括随机采样、复合采样、综合采样以及连续采样4种类型, 其中复合采样应用广泛;2)从采样频率来看, 1~2周一次的采样频率即可精准获取污染负荷通量, 若需要进一步提高精度, 可在水文/水质变异大的时期提高监测频率及在特殊断面加密布点;3)在通量估算上, 当前主要的计算方法有平均法、插值法和回归/曲线法3类方法, 其中流量加权的浓度估计法、插值算法和LOADEST法是简便且精确的方法, 方法的选择上也可根据不同时期流域污染源特征进一步优化. 相似文献
8.
滇池流域水污染特征(1988-2014年)及防治对策 总被引：6，自引：5，他引：1
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. 相似文献
9.
为探明稻虾轮作模式面源污染排放特征并合理评价该模式的环境可持续性，通过对江汉平原稻虾轮作模式小龙虾养殖排放尾水中总氮(TN)、总磷(TP)、COD和氨氮(NH3-N)浓度进行监测，对稻虾轮作模式稻田养殖小龙虾的排污系数进行了估算，并采用等标污染负荷法进行了主要污染物解析。运用能值分析方法对稻虾轮作模式进行了包含面源污染的能值评估，对比单季稻模式，对其可持续发展能力进行了定量评价。结果表明：江汉平原稻虾轮作模式小龙虾养殖排放尾水中TN、TP、COD和NH3-N的浓度范围分别为0.53～5.36、0.12～0.70、6.60～78.39和0.34～1.75 mg/L,TN、TP和COD平均排放浓度高于《地表水环境质量标准》(GB 3838-2002)Ⅲ类水质标准。等标污染负荷法分析结果表明TN的等标负荷比最高，是稻虾轮作模式面源污染控制的关键污染物。稻虾轮作模式小龙虾养殖排放尾水中TN、TP、COD和NH3-N的排污系数分别为2.994、0.458、35.132和1.405 kg/t，表明稻虾轮作模式面源污染排放系数较低，对... 相似文献
10.
洱海流域低污染水类型、污染负荷及分布 总被引：7，自引：0，他引：7
为科学、合理地评估湖泊流域低污染水的类型及其污染负荷,以洱海流域为例,系统研究低污染水的概念及类型,确定了低污染水调查方法,并分析了洱海流域低污染水的来源、类型、产生量、污染物量和分布特征.结果表明,洱海流域低污染水主要包括污水处理厂处理尾水、城镇地表径流、农田排水(含村落地表径流)3种主要类型,产生量为20069×104m3/a.由低污染水带来的总氮(TN)负荷为1393 t/a,总磷(TP)负荷为77 t/a.从空间分布上看,洱海流域西部和北部片区低污染水TN、TP负荷比例最大,分别达到88%和87%,因此应主要针对西部和北部片区特点制定洱海流域低污染水控制措施. 相似文献
11.
基于修正SWAT模型的岩溶地区非点源污染模拟初探——以横港河流域为例 总被引：3，自引：0，他引：3
岩溶流域含水系统的主要特征之一是连通地表的落水洞等垂直管道将近水平的地下暗河联系起来，降水及其形成的地表径流可以通过这些管道迅速地灌入地下河系，从而改变了水及其所携带的非点源污染物质在垂直与水平方向的传输速度与数量，使岩溶流域内地表-地下之间的物质交换与传输过程变得比较复杂；应用广泛的SWAT模型在模拟岩溶地区的水文、水质时会存在一些不足与局限.为此，本文针对岩溶水系统特征，引入落水洞、伏流、暗河的水文过程以及主要营养盐的输移过程，修正SWAT模型原有的水文循环过程及相关算法，改变其只适用于松散均匀介质流域非点源污染模拟的单一特征，并研究建立适合于岩溶流域的非点源污染模型和相应的模拟方法.选取横港河流域岩溶地区作为非点源污染的对象，应用修正后的模型通过控制性的模拟方法和敏感性性分析，定量评估落水洞、伏流、暗河等岩溶特征对氮、磷等主要非点源污染物质输移的影响及其带来的时空效应，并进一步探讨落水洞、伏流、暗河等对地表-地下水文与营养盐的交互作用及转换机理.结果表明，岩溶特征对流域的氮、磷负荷有增加作用，其中总磷的增加明显大于总氮的增加，总磷和总氮的增量分别为0.86%和2.12%；植被岩溶指数的增加会导致流域可溶性磷、有机磷的产出量增加，有机氮、地表产流中硝酸氮和沉积磷的产出量则居其次，落水洞改变了降雨的产流方式，增加了落水洞所在流域的有机磷和有机氮的产出，其增量变化在0~0.7和0~0.3 kg/hm2之间. 相似文献
12.
《水文科学杂志》2013,58(3)
Abstract Abstract Current research suggests that strategies to control sediment and phosphorus loss from non-point sources should focus on different runoff components and their spatial and temporal variations within the river basin. This is a prerequisite for determining effective management measures for reducing diffuse source pollution. Therefore, non-point source models, especially in humid climatic regions, should consider variable hydrologically active source areas. These models should be able to consider runoff generation by saturated overland flow, as well as Hortonian overland flow. A combination of the hydrological model WaSiM-ETH and the erosion and P-transport model AGNPS was chosen for this study. The models were run in the WaSiM runoff generation mode (Green & Ampt/TOPMODEL or Richards equation approach) and the SCS curve number mode to assess the effect of these different runoff calculation procedures on the dissolved phosphorus yield. A small and a medium-sized river basin, of the area of 1.44 and 128.9 km2, respectively, in central Germany were selected for the investigation. The results show that the WaSiM–AGNPS coupling produces more accurate results than the SCS curve number method. For the spatial distribution, the more physically-based model approach computed a much more realistic distribution of water and phosphorus yield-producing areas. 相似文献
13.
The connectivity and upscaling of overland runoff and sediment transport are important issues in hillslope hydrology to identify water flux and sediment transport within landscape. These processes are highly variable in time and space with regard to their interactions with vegetation and soil surface conditions. The generation of overland runoff and its spatial connectivity were examined along a slope to determine the variations in the transport mechanism of runoff and soil particles by rain splash and overland runoff. Field experiments were conducted by erosion plots on a steep hillslope at lengths of 5, 10, and 15 m. The overland runoff connectivity and flow transport distance decreased with the slope length, while spatial variability of infiltration increased significantly with the slope length. Observation of subsurface flow revealed that surface soil and litter layer could have important role in water transport. However, the surface soil water content and water flux transport along the slope was highly variable for different storm events; the variability was related to the complexity of the system, mainly by way of the initial wetness conditions and infiltration characteristics. Only net rain‐splashed soil was measurable, but examination of the water flux, overland runoff and sediment transport connectivity, characteristics of sheetwash, and the variability in spatial infiltration indicated an increase in the contribution of the rain splash transport mechanism along the slope. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
Water is a major limiting factor in arid and semi‐arid agriculture. In the Sahelian zone of Africa, it is not always the limited amount of annual rainfall that constrains crop production, but rather the proportion of rainfall that enters the root zone and becomes plant‐available soil moisture. Maximizing the rain‐use efficiency and therefore limiting overland flow is an important issue for farmers. The objectives of this research were to model the processes of infiltration, runoff and subsequent erosion in a Sahelian environment and to study the spatial distribution of overland flow and soil erosion. The wide variety of existing water erosion models are not developed for the Sahel and so do not include the unique Sahelian processes. The topography of the Sahelian agricultural lands in northern Burkina Faso is such that field slopes are generally low (0–5°) and overland flow mostly occurs in the form of sheet flow, which may transport large amounts of fine, nutrient‐rich particles despite its low sediment transport capacity. Furthermore, pool formation in a field limits overland flow and causes resettlement of sediment resulting in the development of a surface crust. The EUROSEM model was rewritten in the dynamic modelling code of PCRaster and extended to account for the pool formation and crust development. The modelling results were calibrated with field data from the 2001 rainy season in the Katacheri catchment in northern Burkina Faso. It is concluded that the modified version of EUROSEM for the Sahel is a fully dynamic erosion model, able to simulate infiltration, runoff routing, pool formation, sediment transport, and erosion and deposition by inter‐rill processes over the land surface in individual storms at the scale of both runoff plots and fields. A good agreement is obtained between simulated and measured amounts of runoff and sediment discharge. Incorporating crust development during the event may enhance model performance, since the process has a large influence on infiltration capacity and sediment detachment in the Sahel. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
15.
Two‐dimensional continuous simulation of spatiotemporally varied hydrological processes using the time‐area method 
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下载免费PDF全文 Distributed, continuous hydrologic models promote better understanding of hydrology and enable integrated hydrologic analyses by providing a more detailed picture of water transport processes across the varying landscape. However, such models are not widely used in routine modelling practices, due in part to the extensive data input requirements, computational demands, and complexity of routing algorithms. We developed a two‐dimensional continuous hydrologic model, HYSTAR, using a time‐area method within a grid‐based spatial data model with the goal of providing an alternative way to simulate spatiotemporally varied watershed‐scale hydrologic processes. The model calculates the direct runoff hydrograph by coupling a time‐area routing scheme with a dynamic rainfall excess sub‐model implemented here using a modified curve number method with an hourly time step, explicitly considering downstream ‘reinfiltration’ of routed surface runoff. Soil moisture content is determined at each time interval based on a water balance equation, and overland and channel runoff is routed on time‐area maps, representing spatial variation in hydraulic characteristics for each time interval in a storm event. Simulating runoff hydrographs does not depend on unit hydrograph theory or on solution of the Saint Venant equation, yet retains the simplicity of a unit hydrograph approach and the capability of explicitly simulating two‐dimensional flow routing. The model provided acceptable performance in predicting daily and monthly runoff for a 6‐year period for a watershed in Virginia (USA) using readily available geographic information about the watershed landscape. Spatial and temporal variability in simulated effective runoff depth and time area maps dynamically show the areas of the watershed contributing to the direct runoff hydrograph at the outlet over time, consistent with the variable source area overland flow generation mechanism. The model offers a way to simulate watershed processes and runoff hydrographs using the time‐area method, providing a simple, efficient, and sound framework that explicitly represents mechanisms of spatially and temporally varied hydrologic processes. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
For efficient and targeted management, this study demonstrates a recently developed non-point source (NPS) pollution model for a year-long estimation in the Pingqiao River Basin (22.3 km2) in China. This simple but physically reasonable model estimates NPS export in terms of land use by reflecting spatial hydrological features and source runoff measurements under different land-use types. The NPS export was separately analysed by a distributed hydrological model, a spatial hydrograph-separation technique, and an empirical water quality sub-model. Simulation results suggest that 57 890 kg of total nitrogen (TN) and 1148 kg of total phosphorus (TP) were delivered. The results, validated with observed stream concentrations, show relative errors of 23.3% for TN and 47.4% for TP. Countermeasures for urban areas (5.3% of total area) were prioritized because of the high contribution rate to TN (14.1%) and TP (26.2%) which is caused by the high degree of runoff (8.5%) and pollution source. 相似文献
17.
This study integrates a simple overland flow module (isochronous cells model) with the river module of MODFLOW such that temporal and spatial interactions between stream flow and groundwater can be simulated using net rainfall data of a watershed. The isochronous cells model is an efficient travel time runoff approach based on geographic information system (GIS) that considers both spatial and temporal variations of net rainfall through hill slope of the watershed. This overland module is easily coupled with MODFLOW river routing module. Specifically, the stream flow from the isochronous cells model is directly assigned to both sides of river cells of the MODFLOW model. Such an integration of MODFLOW and isochronous cells model is especially useful in watersheds where river flow data are limited. The feasibility of this integrated model was demonstrated using a case study in the middle and downstream regions of the Yitong River watershed, China. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
18.
The Annualized Agricultural Non‐point Source (AnnAGNPS) pollution model has been widely used to assess and predict runoff, soil erosion, sediment and nutrient loading with a geographic information system. This article presents a case study of the effect of land‐use changes on nonpoint source (NPS) pollution using the AnnAGNPS model in the Xizhi River watershed, eastern Pearl River Delta of Guangdong province, China. The land‐use changes in the Xizhi River watershed between 1998 and 2003 were examined using the multitemporal remote sensing data. The runoff, soil erosion, sediment transport and nutrient loading 1998 and 2003 were assessed using AnnAGNPS. The effects of land‐use changes on NPS were studied by comparing the simulation results of each year. Our results showed that (i) the NPS loadings increased when forest and grass land converted into paddy, orchard and farmland land, and population size and gross domestic product size as well as the usage amounts of fertilizer and pesticide in the entire watershed were firmly correlated with the NPS loadings; (ii) the land‐use change during fast urbanization in particular when other land types were converted into the development land and buildup land led to increasing of NPS pollution; and (iii) urban land expansion showed more important effects on total organic carbon (TOC) loading compared with nitrogen and phosphorus loadings. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
19.
Preliminary study on assessment of nutrient transport in the Taihu Basin based on SWAT modeling 总被引：4，自引：0，他引：4
With the Taihu Basin as a study area, using the spatially distributed and mechanism-based SWAT model, preliminary simulations of nutrient transport in the Taihu Basin during the period of 1995-2002 has been carried out. The topography, soil, meteorology and land use with industrial point pollution discharge, the loss of agricultural fertilizers, urban sewerage, and livestock drainages were all considered in the boundary conditions of the simulations. The model was calibrated and validated against water quality monitoring data from 2001 to 2002. The results show that the annual total productions of nitrogen (TN) and phosphorus (TP) into Lake Taihu are 40000t and 2000t respectively. Nutrient from the Huxi Region is a major resource for Lake Taihu. The non-point source (surface source) pollution is the main form of catchment sources of nutrients into Lake Taihu, occupied TN 53% and TP 56% respectively. TN and TP nutrients from industrial point pollution discharge are 30% and 16%, and sewerage in both forms of point source and non-point source are TN 31 % and TP 47%. Both the loss of agricultural fertilizers and livestock drainages from the catchment should be paid more attention as an important nutrient source. The results also show that SWAT is an effective model for the simulation of temporally and spatially nutrient changes and for the assessment of the trends in a catchment scale. 相似文献