农业非点源模型--AGNPS概述

非点源污染在国内外已越来越受到关注，其中农业非点源又占相当大的份额。由于非点源污染产生机制的特殊性。导致实地调查和试验研究不易实行。故而数学模型方法在这一领域尤其能够体现出它的优点，对它的研究也受到了学术界越来越多的重视。目前，国外已开发出了大量的非点源数学模型，而其中A3NPS模型是应用较为广泛者之一，并已在我国得到了应用。基于此，文中介绍了AGNPS模型的基本结构，主要包括水文、侵蚀和化学污染物的迁移三部分。自从该模型被建立以来，国外已对它进行了大量的研究，本文从研究最多的几个方面进行了讨论，即计算网格的优化、模型输入输出与GIS的结合以及模型的风险性等，以期为在我国的具体应用提供一定的参考。     

Validation of an agricultural non-point source （AGNPS） pollution model for a catchment in the Jiulong River watershed, China

This study tested and evaluated the agricultural non-point source(AGNPS)model for the Wuchuan catchment, a typical agricultural area in the Jiulong River watershed, Fujian Province. China. The AGNPS model was calibrated and validated for the study area with observed data onten storms. Thedata on eight stormsin 2002 were used for calibration while data on two stormswere used for validation of the model. Considering the lack of water quality data over a long-term series, a novel method, comparing an internal nested catchment with its surrounding catchment, was used to supplement the less long-term series data. Dual calibration and validation of the AGNPS model was obtained by this comparison. The results indicate that the correlation coefficients were 0. 99 and 0. 98 for runoff, 0. 94 and 0. 95 forthe peak runoff rate of the large catchment and the small catchment, respectively, and 0. 76 forthe sediment of the small catchment only. Each pair of correlation coefficients is homogeneous for the same event for the two catchments. With the exception of the sediment yield and particulate phosphorus, the peak nmofr rate and other nutrients were well predicted. Sensitivity analysis showed that the Soil Conservation Service curve number and rainfall quantity were the most sensitive parameters, which resulted in high output variations. Erosivitv and other parameters had little influence on the hydrological and quality outputs.     

Time Series Analysis of Nebraska Daily Rainfall Data to Simulate Atrazine Runoff1

Abstract: Measured atrazine concentrations in Nebraska surface water have been shown to exceed water‐quality standards, posing risks to humans and to the ecosystem. To assess this risk, atrazine runoff was simulated at the field‐scale in Nebraska based on the pesticide component of the AGNPS model. This project’s objective was to determine the frequency that the atrazine concentration at the field outlet exceeded three different atrazine water‐quality criteria. The simulation was conducted for different farm management practices, soil moisture conditions, and five Nebraska topographic regions. If the criteria were exceeded, a risk to the drinking water consumer or freshwater aquatic life was hypothesized to exist. Three pesticide fate and transport processes were simulated with the model. Degradation was simulated using first‐order kinetics. Adsorption/desorption was modeled assuming a linear soil‐water partitioning coefficient. Advection (runoff) was based primarily on the USDA‐NRCS curve number method. Daily rainfall from the National Weather Service was used to compute the soil moisture conditions for the 1985‐2000 growing seasons. After each runoff event, the pesticide runoff concentration was compared with each of the three atrazine water‐quality criteria. The results show that environmental receptors (i.e., freshwater aquatic species) are exposed to unacceptable atrazine runoff concentrations in 20‐50% of the runoff events.     

我国农业非点源污染研究进展分析

非点源污染具有分散性、隐蔽性、随机性、滞后性和形成机理复杂等特征,目前以模型方法为主要研究手段。介绍了比较著名的流域尺度的非点源污染模型AGNPS模型、SWAT模型和输出系数模型。指出我国的农业非点源污染研究开始于20世纪80年代初,目前以引进国外模型进行验证、应用为主。从研究区域上看,目前国内的非点源污染研究多集中在南方地区。     

WATERSHED AND LAKE WATER QUALITY ASSESSMENT: AN INTEGRATED MODELING APPROACH1

Watershed planning groups and action agencies seek to understand how lake water quality responds to changes in watershed management. This study developed and demonstrated the applicability of an integrated modeling approach for providing this information. An integrated model linking watershed conditions to water-quality of the receiving lake incorporated the following components: (1) an event-based AGNPS model to estimate watershed pollutant losses; (2) annualization of AGNPS results to produce annual lake pollutant loadings; (3) a base flow separation package, SAM, to estimate base flow; (4) estimates of nutrients in base flow and point sources; and (5) linkage of watershed loadings directly to EUTROMOD lake water quality algorithms. Results are presented for Melvern Lake, a 28-km² multipurpose reservoir with a 900-km² agricultural watershed in east central Kansas. Reasonable estimates of current lake quality were attained using an average phosphorus availability factor of 31 percent to calibrate model results to measured in-lake phosphorus. Comparison of a range of possible scenarios, including all cropland changed to no-till (best case) and all CRP and good-condition grasslands changed to cropland (worst case), indicated only a (4 percent change for in-lake phosphorus and a (2 percent change for chlorophyll a. These results indicated that this watershed is not sensitive to projected changes in land use and management.     

三峡库区兰陵溪小流域养分流失特征

三峡库区蓄水后,库区部分支流速度变缓,小流域面源污染已经成为库区面临的重要环境问题.本文以兰陵溪小流域的一个封闭式集水区为研究对象,监测集水区尺度典型降雨条件下氮磷流失的过程和负荷,比较不同养分流失途径,结果表明:①TN的浓度随着径流量的增加的逐渐降低,降雨停止后缓慢上升,而TP的浓度随着径流量的增加而迅速升高,降雨停止后则迅速下降;②TN的负荷流失过程和降雨量关系较为密切,TP的负荷流失受降雨强度影响较大,N素的流失以溶解态为主,而P素则以颗粒态为主;③地表径流是研究区P素和N素流失主要途径,同时壤中流对N素流失的影响也非常大;④N和P各形态的流失负荷与径流量均呈显著的线性关系;⑤集水区TP的年流失负荷为28.94 kg·(a·km2)-1,TN的年流失负荷为1 040.41 kg·(a·km2)-1。     

长江上游平原丘陵区农业非点源污染输出特征和驱动机制

农村非点源污染格局和机制研究对于区域生态环境治理意义重大.以长江上游平原丘陵区为研究区,借助多元数据,提出一种基于空间距离修正的污染物测算方法,利用克里金（Kriging）插值和逻辑回归（LR）方法研究农村非点源污染物的排放格局和影响机制.结果表明,2005～2015年间COD、 BOD₅、 NH⁺₄-N、 TN和TP排放总量分别增加15.46×10⁴、 25.66×10⁴、 3.49×10⁴、 1.26×10⁴和0.38×10⁴ t.成都平原、川中丘陵和川东平行岭谷耕作区是排放量高值区,而城镇城区和三峡库区腹地是低值区. COD、 BOD₅和NH⁺₄-N整体风险等级有所增加,TN整体排放风险等级有所增加,TP整体排放风险偏高且有继续恶化的趋势.综合风险等级呈“中部高,四周低”的空间格局,极高和次高风险等级呈镶嵌分布,成都平原和川东平行岭谷区为高风...     

INTEGRATION OF GEOGRAPHIC INFORMATION SYSTEMS AND A COMPUTER MODEL TO EVALUATE IMPACTS OF AGRICULTURAL RUNOFF ON WATER QUALITY1

ABSTRACT: This study integrates an Agricultural Non-Point Source Pollution Model (AGNPS), the Geographic Resource Analysis Support System (GRASS) (U.S. Army Corps of Engineers, 1987), and GRASS WATERWORKS (a hydrologic modeling tool box being developed at the Michigan State University Center for Remote Sensing) to evaluate the impact of agricultural runoff on water quality in the Cass River, a subwatershed of Saginaw Bay. AGNPS is used to estimate the amounts, origin, and distribution of sediment, nitrogen (N), and phosphorus (P) in the watershed. GRASS and GRASS WATERWORKS are used to generate parameters needed for AGNPS from digital maps, which include soil association, land use, watershed boundaries, water features, and digital elevation. Outputs of the model include spatially distributed estimates of volume and peak runoff, overland and channel erosion, sediment yields, and concentrations of nitrogen and phosphorus. Management scenarios are explored in the AGNPS model to minimize sedimentation and nutrient loading. Scenarios evaluated include variations in crop cover, tillage methods, and other agricultural management practices. In addition, areas vulnerable to erosion are identified for best management practices.     

农业非点源模型——AGNPS计算

由于非点源污染产生机制的特殊性，导致实地调查和试验研究不易实行。而数学模型方法在这一领域尤其能够体现出它的优点，其中AGNPS模型是应用较为广泛者之一。介绍了AGNPS模型的基本结构，主要包括水文、侵蚀和化学污染物的迁移3部分。     

AGNPS在我国东南亚热带地区的检验

利用地理信息系统（GIS），基于数字高程模型（DEM），提取AGNPS（A Agricultural Non-Point Source Model)模型所需的水文和地形参数，并通过实地调查及专题制图等手段获取AGNPS模型所需的土地利用、土壤质地及施肥水平等其它参数，最后利用监测降水，实测水文参数、营养盐及沉积物负荷等验证AGNPS模型在我国东南亚热带地区的应用。