A Comparative Study of Mathematical Models for Migration of Pesticides in Surface and Subsurface Waters

Proceedings of the 1991 Georgia Water Resources Conference, March 19-20, 1991, Athens, Georgia.Development, validation, and application of mathematical models for evaluating fate and transport of pesticide in the environment have received considerable attention during recent years. Mathematical modeling provides a conceptually valid and meaningful approach to integrate environmental properties and chemical processes affecting ecological and/or human health. Additionally, modeling results can be used by Federal and State Regulatory Agencies to support registration decisions or generally planning decision-making efforts. A part of this comprehensive management-oriented modeling process is the simulation of transport and transformation of pesticides in agricultural watersheds. A number of models have been developed during the last decade and are used widely as predictive tools for assessing the impact of pesticides on surface and groundwater quality. Usually these models are used as screening tools to evaluate a new pesticide or an existing one used in a specific agricultural area which may pose an environmental problem. The models are also useful as management tools for assessing the effects of agricultural management practices on non-point source pollution control. In this study, comparisons between two well known pesticide loading models are performed. Model predictions are compared for a number of parameters, including surface runoff, soil erosion, and mass transport of two herbicides in surface runoff and in the soil profile. Given the ability of both models for potential use for environmental risk assessment problems, historical data were used in order to estimate frequency distributions of the pesticide mass reaching the edge of the field and leaching from the crop root zone.Sponsored by U.S. Geological Survey, Georgia Department of Natural Resources, the University of Georgia, Georgia State University, and Georgia Institute of Technology.This book was published by the Institute of Natural Resources, The University of Georgia, Athens, Georgia 30602 with partial funding provided by the U.S. Department of the Interior, Geological Survey, through the Georgia Water Research Institute as authorized by the Water Resources Research Act of 1984 (P.L. 98242). The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia or the U.S. Geological Survey or the conference sponsors

Development and application of artificial neural network models to estimate values of a complex human thermal comfort index associated with urban heat and cool island patterns using air temperature data from a standard meteorological station

© 2018, ISB. The present study deals with the development and application of artificial neural network models (ANNs) to estimate the values of a complex human thermal comfort-discomfort index associated with urban heat and cool island conditions inside various urban clusters using as only inputs air temperature data from a standard meteorological station. The index used in the study is the Physiologically Equivalent Temperature (PET) index which requires as inputs, among others, air temperature, relative humidity, wind speed, and radiation (short- and long-wave components). For the estimation of PET hourly values, ANN models were developed, appropriately trained, and tested. Model results are compared to values calculated by the PET index based on field monitoring data for various urban clusters (street, square, park, courtyard, and gallery) in the city of Athens (Greece) during an extreme hot weather summer period. For the evaluation of the predictive ability of the developed ANN models, several statistical evaluation indices were applied: the mean bias error, the root mean square error, the index of agreement, the coefficient of determination, the true predictive rate, the false alarm rate, and the Success Index. According to the results, it seems that ANNs present a remarkable ability to estimate hourly PET values within various urban clusters using only hourly values of air temperature. This is very important in cases where the human thermal comfort-discomfort conditions have to be analyzed and the only available parameter is air temperature

Data on verbal expressions for thermal sensation and comfort in the Greek language

This article presents data collected during a web-based survey on expressions used to describe thermal sensation and comfort in the Greek language. The survey used a structured questionnaire and delivered through Google Forms. The survey was promoted through social networks and conducted in spring 2019. The data presented herein comprise of the participants’ responses to the questionnaire. A total of 359 questionnaires were completed. The participants were Greek speakers, older than 12, with at least a basic knowledge of the English language. The participants were asked to: (a) select the most appropriate translation, from English to Greek, of the nine-point ISO 10551 scale of perceptual judgment on personal thermal state, (b) formulate five, seven and nine-point thermal sensation scales, (c) report the category of the thermal sensation scale that signifies thermal comfort and (d) to assess the relative distances between the thermal sensation categories of the five, seven and nine-point thermal sensation scales. For the translation of the ISO 10551, the respondents were allowed to choose from a list of 30 Greek wordings. The data have been analysed in the research article entitled “Native influences on the construction of thermal sensation scales” [1]

An Assessment To Evaluate Potential Passive Cooling Patterns For Climate Change Adaptation In A Residential Neighbourhood Of A Mediterranean Coastal City (Athens, Greece)

This study investigates the potential for passive cooling patterns inside the urban fabric in the Mediterranean climate city of Athens (Greece), especially with regard to quantify air temperature reduction and thermal comfort amelioration at the neighbourhood scale. Using both field measurements and an urban microclimate simulation model, we assessed cooling and warming patterns in various sites of an Athens residential neighbourhood. Results show that, under Mediterranean climate conditions, urban design elements such as wooded courtyards and appropriately oriented urban design elements such as galleries have a considerable cooling effect and can be used as cool places inside the neighbourhood for occupants\u27 comfort amelioration and also as passive cooling tools for buildings to reduce summer energy consumption. They may then function as passive design strategies to adapt the urban site form to different climate change scenarios

An assessment to evaluate potential passive cooling patterns for climate change adaptation in a residential neighbourhood of a Mediterranean coastal city (Athens, Greece)

© 2018 Inderscience Enterprises Ltd. This study investigates the potential for passive cooling patterns inside the urban fabric in the Mediterranean climate city of Athens (Greece), especially with regard to quantify air temperature reduction and thermal comfort amelioration at the neighbourhood scale. Using both field measurements and an urban microclimate simulation model, we assessed cooling and warming patterns in various sites of an Athens residential neighbourhood. Results show that, under Mediterranean climate conditions, urban design elements such as wooded courtyards and appropriately oriented urban design elements such as galleries have a considerable cooling effect and can be used as cool places inside the neighbourhood for occupants\u27 comfort amelioration and also as passive cooling tools for buildings to reduce summer energy consumption. They may then function as passive design strategies to adapt the urban site form to different climate change scenarios

Lake Water Level Management as a Tool for the Control of the Littoral Zone: An Optimization Approach

Proceedings of the 1991 Georgia Water Resources Conference, March 19-20, 1991, Athens, Georgia.The reduction of the littoral zone is used as a lake restoration technique that results in nutrient control and water quality improvement (Yount and Crossman, 1970; Burton et al, 1979;). In contrast, in other cases the littoral zone operates as a protective and pollutant filtering zone and its maintenance is desired (Toth, 1972; Water Resources Management Program Workshop, 1986); in some cases also its protection as a freshwater wetland is desired. A number of studies and observations indicate that, in both cases, the fluctuations of the lake water level can be used as a management tool for controlling the littoral zone's existence and extent. ( Jorgensen, 1983; Clausen and Johnson, 1990). The reduction or protection of the littoral zone requires totally different lake water level management during the year. The water balance of the lake and a number of constraints reflecting the specific characteristics of the system, the several water uses and the requirements for the protection or reduction of the littoral zone pose an optimal control problem. Based on the above concepts, an optimization approach has been developed for management of the water levels in lakes and reservoirs where the littoral zone plays an important role. Inputs to the model consist of hydrological data for the watershed and the lake or the reservoir and data on water demand. The model can also be linked with an appropriate watershed model for direct input of hydrologic data. The objective function and the constraints formulations are based on the management purposes and on historical data concerning the status of the vegetation zone versus different water elevations. Model outputs are the amount of the water that must be released and the monthly averaged lake elevations during the year. The optimization model uses a dynamic programming algorithm. Detailed descriptions of the approach, sensitivity and testing of the algorithm for hypothetical cases are given in (Tsiros, 1987). The theoretical background of the approach is based on the results of a comprehensive field monitoring program presented and discussed extensively in (J0rgensen, 1983). This paper describes the model's formulation, its major assumptions, and its application in a real case problem where impacts to the littoral zone have occurred because of a water development project. The applicability of the approach to regional reservoir planning and management, the limitations and further extensions of the approach are also discussed in the context of applying the proposed approach for management guidelines and recommendations concerning lake management with regard to lakeside vegetation zone control.Sponsored by U.S. Geological Survey, Georgia Department of Natural Resources, the University of Georgia, Georgia State University, and Georgia Institute of Technology.This book was published by the Institute of Natural Resources, The University of Georgia, Athens, Georgia 30602 with partial funding provided by the U.S. Department of the Interior, Geological Survey, through the Georgia Water Research Institute as authorized by the Water Resources Research Act of 1984 (P.L. 98242). The views and statements advanced in this publication are solely those of the authors and do not represent official views or policies of The University of Georgia or the U.S. Geological Survey or the conference sponsors

Air quality and meteorological patterns of an early spring heatwave event in an industrialized area of Attica, Greece

Heatwaves-excessively hot ambient conditions that are considered a serious threat to human health-are often associated with poor air quality. The aim of this study was to examine the impact of an early heatwave episode in an industrialized plain in the eastern Mediterranean region (Thriasio, Greece) on human thermal discomfort and urban air quality. The heatwave occurred in mid (15-20) May 2020, shortly after some of the restrictions that were improsed to halt the spread of coronavirus disease 2019 (COVID-19) in Greece were lifted (on 4 May). The discomfort index (DI) and the daily air quality index (DAQI) were calculated on an hourly basis throughout spring 2020 (March, April, May) using data from two stations that measure meteorological parameters and air pollutant concentrations in the Thriasio Plain. The analysis showed that the air temperature increased during 7-17 May to levels that were more than 10 degrees C above the monthly average value (25.8 degrees C). The maximum measured air temperature was 38 degrees C (on 17 May). The results showed a high level of thermal discomfort. The DI exceeded the threshold of 24 degrees C for several hours during 13-20 May. Increased air pollution levels were also identified. The average DAQI was estimated as 0.83 +/- 0.1 and 1.14 +/- 0.2 at two monitoring stations in the region of interest during the heatwave. Particulate matter (diameter < 10 mu m) appeared to contribute significantly to the poor air quality. Significant correlations between the air temperature, DI, and AQSI were also identified

A note on some uncertainties associated with Thornthwaite's aridity index introduced by using different potential evapotranspiration methods

Potential evapotranspiration (PET) is a key parameter for climate classification and aridity assessment. The widely used UNEP (1992) classification system is based on the estimation of the aridity index AI, which requires annual average values of precipitation P and PET. For the calculation of PET the Thornthwaite's (1948) formula is, in principle, suggested. Recent studies use more advanced and accurate methods for PET estimation but apply to AI the same thresholds proposed by UNEP for aridity classification. This work deals with the uncertainties introduced by the use of different PET methods in the estimation of the aridity index AI. Specifically, the Hargreaves-Samani (HS) method and four of its modifications, three modifications of Thornthwaite's formula and the equation of Hamon, are evaluated against the widely used Thornthwaite's original method, by assessing their impact on the AI. Climatic data as monthly average values of at least 30 years of measurements from 122 stations in the Greek peninsula are used. Results show that AI is highly affected by the PET method adopted, resulting thus to changes in climatic classification of a region. Further, results imply the need for an adjustment of the threshold values that determine aridity classes according to the method each time adopted. Therefore, new threshold values for the aridity classes are developed and presented in this work. The proposed threshold values cover a range of sites that belong to semi-arid SA, sub-humid SH and humid H aridity classes of the Greek peninsula

Atmospheric Factors Affecting Global Solar and Photosynthetically Active Radiation Relationship in a Mediterranean Forest Site

Light availability and its composition in components affecting plant growth as photosynthetically active radiation (PAR), are of critical importance in agricultural and environmental research. In this work, radiation data for the period 2009–2014 in a forest site in Greece were analyzed to identify the effect of meteorological variables on the formation of the photosynthetically active to global solar radiation ratio. The temporal changes of the ratio are also discussed. Results showed that the ratio values are higher in summer (0.462) and lower in autumn (0.432), resulting in an annual average of 0.446. In addition, for the investigated site, which was characterized by relatively high water content in the atmosphere, the atmospheric water content and clearness were found to be the most influential factors in the composition of the global solar radiation in the wavelengths of PAR. On the contrary, temperature and related meteorological attributes (including relative humidity, vapor pressure deficit and saturation vapor pressure) were found to have minor effect

Ground temperature estimations using simplified analytical and semi-empirical approaches

In this work, subsurface ground temperature profiles are estimated by exploiting two different approaches. In the first one, an analytical model is examined which, considering a quasi steady state system, implements the superposition of annual and daily sinusoidal fluctuations. In the second one, semi-empirical models are developed based on the general formula of the preceding, by replacing the steady state soil temperature with easily obtained daily average temperatures. Various subsets of soil temperature were used for model development, in order to explore the possibility of minimizing data requirements. Comparison of observational data with model results reveals that the observational patterns of hourly soil temperature are fairly well approximated by both by the analytical and the semi-empirical models. All models seem to capture the main characteristics of the annual course of soil temperature, with the results obtained from the semi-empirical models fluctuating in a much more realistic way than those of the analytical model. It is concluded that the proposed models may serve as useful tools for estimating and predicting soil temperatures to be used as practical reference in various environmental and energy applications