WATER QUALITY MODEL CALIBRATION: A COMPARISON OF INPUT AND OUTPUT ERROR CRITERIA1

ABSTRACT: A common framework for the analysis of water resources systems is the input-parameter-output representation. The system, described by its parameters, is driven by inputs and responds with outputs. To calibrate (estimate the parameters) models of these systems requires data on both inputs and outputs, both of which are subject to random errors. When one is uncertain as to whether the predominant source of error is associated with inputs or outputs, uncertainty also exists as to the correct specification of a calibration criterion. This paper develops and analyzes two alternative least squares criteria for calibrating a numerical water quality model. The first criterion assumes that errors are associated with inputs while the second assumes output errors. Statistical properties of the resulting estimators are examined under conditions of pure input or output error and mixed error conditions from a theoretical perspective and then using simulated results from a series of Monte Carlo experiments.     

测定地表水中悬浮物的空白校正

进行了测定地表水中悬浮物空白校正与不作空白校正的对比试验 ,得出不作空白校正存在较大误差 ,认为测定地表水中悬浮物时应作空白校正。同时用测定海水中悬浮物的方法作测定地表水中悬浮物的试验 ,试验效果较好 ,符合测定要求。建议可用测定海水中悬浮物的方法来测定地表水中悬浮物     

HYDROLOGIC CALIBRATION OF THE SWAT MODEL IN A WATERSHED CONTAINING FRAGIPAN SOILS1

ABSTRACT: The Soil and Water Assessment Tool (SWAT) model, designed for use on rural ungaged basins and incorporating a GRASS GIS interface, was used to model the hydrologic response of the Ariel Creek watershed of northeastern Pennsylvania. Model evaluation of daily flow prior to calibration revealed a deviation of runoff volumes (D_v) of 68.3 percent and a Nash-Sutcliffe coefficient of-0.03. Model performance was affected by unusually large observed snowmelt events and the inability of the model to accurately simulate baseflow, which was influenced by the presence of fragipans. Seventy-five percent of the soils in the watershed contain fragipans. Model calibration yielded a D_v of 39.9 percent and a Nash-Sutcliffe coefficient of 0.04, when compared on a daily basis. Monthly comparisons yielded a Nash-Sutcliffe coefficient of 0.14. Snowmelt events in the springs of 1993 and 1994, which were unusually severe, were not adequately simulated. Neglecting these severe events, which produced the largest and third largest measured flows for the period of record, a D_v of 4.1 percent and Nash-Sutcliffe coefficient of 0.20 were calculated on a daily comparison, while on a monthly basis the Nash-Sutciffe coefficient was 0.55. These results suggest that the SWAT model is better suited to longer period simulations of hydrologic yields. Baseflow volumes were accurately simulated after calibration (D_v= -0.2 percent). Refinements made to the algorithms controlling subsurface hydrology and snowmelt, to better represent the presence of fragipans and snowmelt events, would likely improve model performance.     

1020型总有机碳水质分析仪校准方法

总有机碳水质分析仪需定期进行检定,制定合理可行的校准方法,并根据标准方法对仪器进行检定,校准结果为重复性1.69%,零点漂移0.045%,直线性1.98%,相关系数0.9984,绝缘阻抗＞20MΩ,满足校准方法技术要求,根据检定结果,该仪器出具数据准确可靠.     

分布式水文模型的参数率定及敏感性分析探讨

参数率定与敏感性分析是分布式水文模型应用和发展中的难点问题,论文对当前典型的、应用比较成功的全局最优化参数率定和敏感性分析方法进行归纳和分析,包括:遗传算法(Genetic Algorithm)、SCE-UA算法(Shuffled Complex Evolution)、贝叶斯方法(Bayesian Method)、RSA方法(Regionalized Sensitivity Analysis)、GLUE方法(Generalized Likelihood Uncertainty Estimation)等等。并对计算机自动优化方法和人工参数调试方法的利弊进行讨论,展望了分布式水文模型的参数率定与敏感性分析的发展方向。     

烟气中SO2采样测量技术的应用与改进

简要总结了目前常用的烟气SO2测试方法及使用过程中常见问题，并提出了相应的解决措施。目前被普遍使用的便携式烟气分析仪存在由于烟气中水蒸汽结露和采样系统抽力不够而严重影响测量结果的问题，针对这2个问题，设计采用一种辅助采样装置，并对测量结果进行分析。     

二氧化氮标准物质校准氮氧化物分析仪的差异性

采用一氧化氮、二氧化氮标准物质对化学发光法的氮氧化物分析仪进行校准,并分析校准系统中零气源、连接管路、动态气体校准仪和标准物质对二氧化氮校准的影响,发现一氧化氮标准物质中的二氧化氮杂质会影响氮氧化物的校准结果,得出氮氧化物分析仪校准需要进行二氧化氮补偿的结论;同时,通过比较国产二氧化氮和进口二氧化氮标准物质产生的校准结果,得出进口二氧化氮标准物质较国产二氧化氮标准物质的稀释结果具有更好的稳定性和一致性。     

A PRELIMINARY QUANTIFICATION OF THE IMPACTS OF ASPEN TO CONIFER SUCCESSION ON WATER YIELD - I. HEAT PULSE METHODOLOGY FOR MODEL CALIBRATION1

ABSTRACT: Twenty-six aspen (Populus tremuloides Michx.), 20 subalpine fir (Abies lasiocarps (Hook.) Nutt.), and 20 Engelmann spruce (Pices engelmanil (Parry) Engelm.) of various sizes were cut under water and suspended in permanent reserviors at a northern Utah site. The reservoirs were asealed so that all water loss was due to consumption by the trees. Sap velocities, as computed from heat pulse velocities, were related to conducting areas of the tree trunks. Computed transpiration volumes were then correlated with actual water losses from the reservoirs. Coefficients of determination (R²) of 0.87, 0.86, and 0.82 were obtained for the fir, aspen, and sprucs, respectively. Reservoir water loss for each species for each season was then used to adjust a plant activity index for computing transpiration within ASPCON, a model describing the hydrology of aspen to conifer succession. The plant activity index reflects the variation in the capability of a plant community to transpire water over the year. Assumptions and limitations of the heat pulse velocity technique are also outlined.     

EFFICIENTLY REDUCING NONPOINT PHOSPHORUS LOADS TO LAKES AND RESERVOIRS1

ABSTRACT: Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania.     

基于Matlab软件自动化求取参数的HEC-RAS模型构建

水质模型是水环境模拟的重要工具,近年来越来越多的应用于水环境预测与管理中,但平原河网水质模拟一直是个难点.本研究采用HEC-RAS模型开展湖州市长兴城区平原河网水动力和水质模拟.模型的水质模块率定采用Matlab软件自动化求取参数,代替常规试错法求参率定,减少了人工干预,提高了模型率定效率.HEC-RAS模型在平原河网地区水动力模拟结果较好,水质模拟结果基本符合要求,证明了HEC-RAS模型在平原河网应用的可行性,但模型的精度通常受水系概化、水文状况、污染源信息等因素影响,对于信息比较充分的短时段水质模拟其精度相对较好.