Population-level variation in plant secondary chemistry,and the population biology of herbivores

Summary Modern population ecology is becoming increasingly spatially-explicit. For insect hervibores, spatial variation in plant quality is a critical component of distribution and abundance. We argue that populationlevel measurements of phytochemical variation among individual plants has not kept pace with recent developments in population ecology. With examples from our own work, we demonstrate the importance of spatial variation in plant chemistry for insect herbivores, and suggest that phytochemistry should play a central role in the development of any spatially-based ecological theory.     

DEVELOPING AND IMPLEMENTING DECISION SUPPORT SYSTEMS: A CRITIQUE AND A CHALLENGE1

ABSTRACT: Computer-based models together with their interactive interfaces are typically called decision support systems. DSSs are interactive computer-based information providers. The common objective of all DSSs, regardless of the frameworks, methodologies, or techniques used, is to provide timely information that supports human decision makers - at whatever level of decision making. The informational needs of the decision making process are the key considerations that motivate the development of DSSs. The growth of DSS development and use has been substantial. In spite of this impressive growth, computer-aided decision support systems can still be improved and made more useful to those they are intended to support. Researchers and practitioners, and indeed the computer industry, continue to identify ways of doing this. This paper reviews some of these needs and opportunities by focusing on the process of successful DDS development and implementation. The paper outlines an approach and some guidelines for developing DSSs. The approach emphasizes and requires considerable interaction between the DSS developers (analysts) and the DSS users (decision makers). This interaction and feedback is required throughout the entire DSS building, testing and evaluation (debugging), and implementation processes. The paper concludes by identifying some research needs and opportunities affecting DSS development and effective use.     

火灾定量预测方法研究

应用预测学原理，对火灾定量预测方法进行了探讨，建立了一套适应不同火灾历史统计特点的平滑预测模型：滑动平均预测模型和指数平滑预测模型；考虑火灾事故的季节性变化，建立了季节性平滑预测模型。应用二重指数平滑预测模型和季节性平滑预测模型，对荆州地区１９９３￣１９９４年的火灾统计资料进行分析和预测，结果表明该地区今后的火灾发生呈上升趋势，提请有关部门注意防火安全。     

Shopping studies for regional planning

This paper is based on a shopping study carried out by the Department of Geography, University of Utrecht, during 1983. It is concerned with retail planning research for larger regions and starts with a state of the art review of retail planning research in the Netherlands. The aim, in developing a new research strategy, was to reduce time and costs through using computer facilit es for both data handling and data collection. There is discussion of methodology and some outcomes to demonstrate the possibilities of the strategy.     

LOADING FUNCTIONS FOR PREDICTING NUTRIENT LOSSES FROM COMPLEX WATERSHEDS1

ABSTRACT: A loading function methodology is presented for predicting runoff, sediment, and nutrient losses from complex watersheds. Separate models are defined for cropland, forest, urban and barnyard sources, and procedures for estimating baseflow nutrients are provided. The loading functions are designed for use as a preliminary screening tool to isolate the major contributors in a watershed. Input data sources are readily available and the functions do not require costly calibrations. Data requirements include watershed land use and soil information, daily precipitation and temperature records and rainfall erosivities. Comparison of predicted and measured water, sediment, and nutrient runoff fluxes for the West Branch Deleware River in New York, indicated that runoff was underpredicted by about 14 percent while dissolved nutrients were within 30 percent of observed values. Sediment and solid-phase nutrients were overpredicted by about 50 percent. An annual nutrient budget for the West Branch Delaware River showed that cornland was the major source of sediment, solid phase nutrients, and total phosphorus. Waste water treatment plants and ground water discharge contributed the most dissolved phosphorus and dissolved nitrogen, respectively.     

POLLUTANT RUNOFF MODELS: SELECTION AND USE IN DECISION MAKING1

Models for pollutant runoff can be useful in water quality management planning if appropriately structured for the problem at hand. Accordingly, a “top-down” approach is proposed for the examination of extant pollutant runoff models. The approach consists of the identification of objectives and attributes that reflect the needs of planners and decision makers when these models are used for water quality management planning. Ideally, the attributes should concern the effect of model information on improved decision making and the cost of model application. Practical difficulties with the first attribute necessitates substitution of surrogate attributes reflecting model appropriateness, resolution, and uncertainty. Common pollutant runoff models, in particular export coefficients and hydrology-driven simulation models, are found to have serious weaknesses on some of the attribute scales. The “top-down” approach leads to a set of desirable pollutant runoff model attributes; alternate modeling techniques are thus examined in order to identify promising future directions for model development. The focus of this examination is phosphorus, due to its importance in the eutrophication of surface waters. Models for both sediment-attached and dissolved phosphorus are considered. Among the conclusions is the belief that the partial contributing area concept can yield an effective yet simple simulation despite the variable and complex nature of runoff.     

UTILIZATION OF MODELS IN WATER RESOURCES1

ABSTRACT: A 1984 survey of water resources personnel was conducted to determine the current and future uses of mathematical models in planning, design and operations of water resources systems. Eighty-six percent of those responding indicated they have used mathematical models in the last year. Lack of appropriate data, inadequate time and funding to do the modeling and lack of models that represent the “real world” situation were the most frequently mentioned constraints to model use. Microcomputers were seen as having a positive influence on mathematical model use in water resources.     

INTERVENTION ANALYSIS OF WATER USE RESTRICTIONS,AUSTIN, TEXAS1

ABSTRACT: Mandatory water conservation in the form of restrictions on outdoor watering, car washing, and recreation was implemented in the City of Austin, Texas, during the summers of 1984 and 1985. Three different stages of restrictions were implemented limiting the number of watering hours per day, as well as a restriction that allowed lawn watering once every five days according to the last digit of the street address, Intervention analysis using a transfer function-noise model of daily water use is applied to assess the impact of the restrictions. Compared to a peak water use rate of about 170 MGD, it is shown that mandatory restrictions in 1984 reduced water use by an average of 13.5 MGD, while similar restrictions during the summer of 1985 reduced usage by an average of 5.5 MGD. Lawn watering restrictions on a five-day cycle produced a corresponding five-day cycle in water use of more than 10 MGD in amplitude in 1985. An alternative lawn watering scheme that eliminates this cycle is prescribed.     

APPLICATIONS OF A GIS FOR MODELING THE SENSITIVITY OF WATER RESOURCES TO ALTERATIONS IN CLIMATE IN THE GUNNISON RIVER BASIN,COLORADO1

ABSTRACT: The Gunnison River drains a mountainous basin in western Colorado, and is a large contributor of water to the Colorado River. As part of a study to assess water resource sensitivity to alterations in climate in the Gunnison River basin, climatic and hydrologic processes are being modeled. A geographic information system (GIS) is being used in this study as a link between data and modelers - serving as a common data base for project personnel with differing specialties, providing a means to investigate the effects of scale on model results, and providing a framework for the transfer of parameter values among models. Specific applications presented include: (1) developing elevation grids for a precipitation model from digital elevation model (DEM) point-elevation values, and visualizing the effects of grid resolution on model results; (2) using a GIS to facilitate the definition and parameterization of a distributed-parameters, watershed model in multiple basins; and (3) nesting atmospheric and hydrologic models to produce possible scenarios of climate change.