ON THE MISMATCH BETWEEN DATA AND MODELS OF HYDROLOGIC AND WATER RESOURCE SYSTEMS1

ABSTRACT: Many difficulties exist in the matching of models with data. This paper identifies elements of this problem and discusses considerations involved in model evaluation. The well known multivariate linear regression model is used to illustrate the distinctions between accuracy and precision and between estimation and prediction (because the model is commonly misused.) No amount of additional data will improve the accuracy of a poor model. A high R², while indicative of a good matching between the observed data and model estimates, is a poor criterion for judging adequacy of the model to make good predictions of future events. Model evaluation also includes the problem of introducing secondary data and proxy variables into a model. Secondary data frequently enter, for example, the mass, energy and water budget equations because of difficulties in measuring the primary variables. Proxy variables arise because of a desire to collapse a vector of incomparable values, say, of water quality into a single number. Review of the above issues indicates that model evaluation is a multi-criterion problem, often imbedded in a larger framework where models are intended to meet multiple objectives. The mismatch of models and data has increasing legal and social consequences.     

新形势下的教师工资激励机制探讨

教育在社会发展中起能动作用,教师的工资结构应符合社会主义市场经济规律和教师工作特点,实行按劳分配原则,除标准工资外,还要建立等级津贴和特殊工资,从而保证教育人才的稳定和提高,提高教育的国际竞争力。     

城市旅游市场分类研究及其意义--以汕头市为例

运用旅游市场分类法，通过对旅游流、旅游市场细分和旅游者行为等方面分析，以及对汕头市旅游市场的实证研究，作者初步认证了旅游市场分类法的科学性和有效性。区分城市旅游者与景点旅游者两类市场，对比这两类市场旅游者的空间结构、出游目的结构、时间分配结构的差异，对分析汕头旅游发展的主导旅游吸引、旅游需求趋势和需求预测以及确定区域旅游发展的动力模型、旅游发展动力机制，制定产品战略和市场战略具有重要的意义。     

南京市旅游农业市场开发研究

立足于南京市旅游农业市场开发的现状和存在的问题，从客源地结构、农业旅游者决策行为、旅游方式、出游时间、旅游者对南京旅游农业资源评价等五个方面分析了当前南京市旅游农业客源市场状况。提出了相应的市场开发策略。     

电子商务与旅游市场运行机制研究

基于互联网的旅游电子商务的发展，变革着旅游交易的方式，创造了新的虚拟市场空间，使旅游市场的效率得到提高、旅游供需匹配功能得到强化，同时也加剧了旅游市场的内部竞争。旅游电子商务市场的虚拟化发展也为旅游市场管理提出了新课题，需要研究开发一系列新的技术手段和市场规范制度来保证旅游市场健康、良性发展。文章从电子商务与旅游市场运行的机制方面进行了一定的研究与探讨，力求说明以旅游电子商务来改造传统旅游市场的运作方式，提升旅游市场运行效率所具有的重要意义及可操作性。     

MODELING ACTUAL EVAPOTRANSPIRATION FROM FORESTED WATERSHEDS ACROSS THE SOUTHEASTERN UNITED STATES1

ABSTRACT: About 50 to 80 percent of precipitation in the southeastern United States returns to the atmosphere by evapotranspiration. As evapotranspiration is a major component in the forest water balances, accurately quantifying it is critical to predicting the effects of forest management and global change on water, sediment, and nutrient yield from forested watersheds. However, direct measurement of forest evapotranspiration on a large basin or a regional scale is not possible. The objectives of this study were to develop an empirical model to estimate long‐term annual actual evapotranspiration (ART) for forested watersheds and to quantify spatial AET patterns across the southeast. A geographic information system (GIS) database including land cover, daily streamflow, and climate was developed using long term experimental and monitoring data from 39 forested watersheds across the region. Using the stepwise selection method implemented in a statistical modeling package, a long term annual AET model was constructed. The final multivariate linear model includes four independent variables—annual precipitation, watershed latitude, watershed elevation, and percentage of forest coverage. The model has an adjusted R² of 0.794 and is sufficient to predict long term annual ART for forested watersheds across the southeastern United States. The model developed by this study may be used to examine the spatial variability of water availability, estimate annual water loss from mesoscale watersheds, and project potential water yield change due to forest cover change.     

区域经济开发中的生态建设——以天山北坡经济带昌吉州为例

昌吉州区域经济开发在新疆地方经济发展中占有重要地位，在发展区域经济时也对生态环境造成了影响或污染，加强生态建设,做好区域环境保护的规划十分必要。昌吉州在石油勘探开发、土地资源开发中重视生态建设，在保护耕地、保护森林、野生动、植物方面制定出台了一系列措施，行至有效，取得了一定的实效。     

浅析市场经济体制下高等学校教职工的激励因素

如何调动广大教师的积极性,已成为非常重要的课题。本文通过对教师激励因素的探讨,阐明在市场经济体制下,高等学校如何调动教师工作的积极性、主动性和创造性,更好地完成教育、教学任务。     

HYDRAULIC GEOMETRY RELATIONSHIPS FOR URBAN STREAMS THROUGHOUT THE PIEDMONT OF NORTH CAROLINA1

ABSTRACT: Hydraulic geometry relationships, or regional curves, relate bankfull stream channel dimensions to watershed drainage area. Hydraulic geometry relationships for streams throughout North Carolina vary with hydrology, soils, and extent of development within a watershed. An urban curve that is the focus of this study shows the bankfull features of streams in urban and suburban watersheds throughout the North Carolina Piedmont. Seventeen streams were surveyed in watersheds that had greater than 10 percent impervious cover. The watersheds had been developed long enough for the streams to redevelop bankfull features, and they had no major impoundments. The drainage areas for the streams ranged from 0.4 to 110.3 square kilometers. Cross‐sectional and longitudinal surveys were conducted to determine the channel dimension, pattern, and profile of each stream and power functions were fitted to the data. Comparisons were made with regional curves developed previously for the rural Piedmont, and enlargement ratios were produced. These enlargement ratios indicated a substantial increase in the hydraulic geometry for the urban streams in comparison to the rural streams. A comparison of flood frequency indicates a slight decrease in the bankfull discharge return interval for the gaged urban streams as compared to the gaged rural streams. The study data were collected by North Carolina State University (NCSU), the University of North Carolina at Charlotte (UNC), and Charlotte Storm Water Services. Urban regional curves are useful tools for applying natural channel design in developed watersheds. They do not, however, replace the need for field calibration and verification of bankfull stream channel dimensions.     

在城市水体恢复与水环境建设中应运用市场机制

文章论述了要吸引众多的企业参与城市水体恢复与水环境建设，必须为企业营造一定的利润空间，并通过着力形成环保项目的造血机制和建立长效管理模式来完成。