Journal articles on the topic 'Watersheds Australia Mathematical models'
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1
Sathyamoor, Dinesh. "Extraction of Watersheds from Digital Elevation Models Using Mathematical Morphology." Journal of Applied Sciences 8, no. 6 (March 1, 2008): 956–65. http://dx.doi.org/10.3923/jas.2008.956.965.
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Copper, J. K., and A. B. Sproul. "Comparative study of mathematical models in estimating solar irradiance for Australia." Renewable Energy 43 (July 2012): 130–39. http://dx.doi.org/10.1016/j.renene.2011.11.050.
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Lee, Jacqueline. "Modeling the connections between internally and externally drained basins using GIS, Google Earth©, and remote sensing." Progress in Physical Geography: Earth and Environment 42, no. 3 (June 2018): 274–304. http://dx.doi.org/10.1177/0309133318776462.
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The development of internal drainage is intimately tied to the tectonic and climatic history of an area, but research into the exact causes and processes of internal drainage is constrained by the ability to accurately delineate both internally and externally draining watersheds. Until recently, existing global catalogs of internally drained regions were either hand-drawn or based upon digital elevation models whose resolution is much lower than those currently available. Here, the World Wildlife Fund’s HydroBASINS dataset is analyzed in a GIS program to identify points of former connectivity between endorheic and exorheic basins, to identify possible palaeolakes and palaeo-distributary channels, and to quantify on a global basis the extent of area lost to internal drainage for 101 large watersheds. The results have been made available in Google Earth© KMZ files, and a sample workflow is presented which uses the data to approximate the relative importance of tectonic vs climatic factors in initiating endorheism. As an example of how the dataset and workflow can be used, the drainage history is modeled for endorheic watersheds within two very different tectonic regimes, the Afar region of northeastern Africa and the Northern Territory of Australia. The methodology is readily adaptable to other endorheic basins and offers the ability to create drainage history models which can help in research areas such as climate change investigations and groundwater and economic mineral prospecting.
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Voronov, Yuri P. "DIGITAL TERRAIN MODELS IN SIBERIAN CITIES AND UTILITY NETWORKS DESIGN." Interexpo GEO-Siberia 3, no. 1 (May 21, 2021): 152–61. http://dx.doi.org/10.33764/2618-981x-2021-3-1-152-161.
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The article considers one of the important directions of innovative technologies in the urban economy, application of digital terrain models in the design, development and operation of utility networks. The author considers the five tasks of using the digital model sequentially: ) development of a digital terrain model, 2) allocation of watersheds and facies, 3) plotting contours (ridges) for all facies, 4) two-level modeling of surface runoff and storm sewer, 5) solving practical problems of determining silting zones and optimizing snow removal. The original principle proposed in the article is a multi-funnel model of surface runoff, in which each facies (local catchment) is replaced by an equivalent inclined funnel. This greatly simplifies the calculations, and also allows you to combine mathematical modeling with physical modeling.
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SHIQING, LIU, WANG JUNTAO, and DARIA LYUBINA. "REGIONAL FEATURES OF THE DEVELOPMENT OF ECONOMIC ZONES OF WATERSHEDS: COMPARISON OF INTERNATIONAL EXPERIENCE." Sociopolitical Sciences 11, no. 6 (December 6, 2021): 79–87. http://dx.doi.org/10.33693/2223-0092-2021-11-6-79-87.
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The article examines various forms of regional models of management of economic zones of catchment basins on the example of the experience of the United States of America, Great Britain, Canada and other countries. The purpose of the study is to analyze and compare models of economic management of watersheds, as well as to identify the features of development and models of basin management. Results. The search for effective mechanisms for watershed management was an incentive to create unified mechanisms for watershed management and predetermined the direction of reforms in this area. However, in regional international practice, there are disagreements about specific methods for implementing a unified management model. The USA offers the most centralized management model. The UK practices a market-based approach to solving this issue, and the experience of Australia is the least centralized management model, although it fully takes into account the interests of representatives of various classes and plays a positive role in public life.
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Santoro, Mariana Coelho, José Antonio Tosta dos Reis, and Antonio Sérgio Ferreira Mendonça. "Performance evaluation of optimization models in the determination of wastewater treatment efficiencies inside watersheds." RBRH 21, no. 4 (October 31, 2016): 694–706. http://dx.doi.org/10.1590/2318-0331.011616031.
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ABSTRACT Determination of sewage treatment plants pollutant removal efficiencies, considering the protection of water resources, is very difficult because it involves complex analysis that must take into account multiple discharges into watercourses presenting different self depuration capacities. The research aimed to evaluate different optimization models for determination of minimum sewage treatment efficiencies for plants located in a watershed. The analyzed optimization models involves minimization of the sum of treatment efficiencies and minimization of inequity between sewage treatment efforts. Water quality mathematical model and Genetic Algorithm were combined in a MatLab software computing environment. The Pardo river watershed is the study area. Pardo river is a tributary of the Itapemirim river, important watercourse located in the southern part of Espirito Santo State, in Brazil. The results indicate that the optimization models that incorporate measurement of equity as a problem restriction did not generate consistent answers, probably because of the wide range of sewage loads values considered in the Pardo river watershed. The models that incorporate equity measures in the objective function showed satisfactory performance and resulted in very close values for minimum sewage treatment efficiencies.
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Patel, Ajaykumar Bhagubhai, and Geeta S. Joshi. "Modeling of Rainfall-Runoff Correlations Using Artificial Neural Network-A Case Study of Dharoi Watershed of a Sabarmati River Basin, India." Civil Engineering Journal 3, no. 2 (February 28, 2017): 78–87. http://dx.doi.org/10.28991/cej-2017-00000074.
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The use of an Artificial Neural Network (ANN) is becoming common due to its ability to analyse complex nonlinear events. An ANN has a flexible, convenient and easy mathematical structure to identify the nonlinear relationships between input and output data sets. This capability could efficiently be employed for the different hydrological models such as rainfall-runoff models, which are inherently nonlinear in nature. Artificial Neural Networks (ANN) can be used in cases where the available data is limited. The present work involves the development of an ANN model using Feed-Forward Back Propagation algorithm for establishing monthly and annual rainfall runoff correlations. The hydrologic variables used were monthly and annual rainfall and runoff for monthly and annual time period of monsoon season. The ANN model developed in this study is applied to Dharoi reservoir watersheds of Sabarmati river basin of India. The hydrologic data were available for twenty-nine years at Dharoi station at Dharoi dam project. The model results yielding into the least error is recommended for simulating the rainfall-runoff characteristics of the watersheds. The obtained results can help the water resource managers to operate the reservoir properly in the case of extreme events such as flooding and drought.
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Ghanim, Abdulnoor A. J., Salmia Beddu, Teh Sabariah Binti Abd Manan, Saleh H. Al Yami, Muhammad Irfan, Salim Nasar Faraj Mursal, Nur Liyana Mohd Kamal, et al. "Prediction of Runoff in Watersheds Located within Data-Scarce Regions." Sustainability 14, no. 13 (June 30, 2022): 7986. http://dx.doi.org/10.3390/su14137986.
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The interest in the use of mathematical models for the simulation of hydrological processes has largely increased especially in the prediction of runoff. It is the subject of extreme research among engineers and hydrologists. This study attempts to develop a simple conceptual model that reflects the features of the arid environment where the availability of hydrological data is scarce. The model simulates an hourly streamflow hydrograph and the peak flow rate for any given storm. Hourly rainfall, potential evapotranspiration, and streamflow record are the significant input prerequisites for this model. The proposed model applied two (2) different hydrologic routing techniques: the time area curve method (wetted area of the catchment) and the Muskingum method (catchment main channel). The model was calibrated and analyzed based on the data collected from arid catchment in the center of Jordan. The model performance was evaluated via goodness of fit. The simulation of the proposed model fits both (a) observed and simulated streamflow and (b) observed and simulated peak flow rate. The model has the potential to be used for peak discharges’ prediction during a storm period. The modeling approach described in this study has to be tested in additional catchments with appropriate data length in order to attain reliable model parameters.
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Andrello, Avacir Casanova, Maria de Fátima Guimarães, Carlos Roberto Appoloni, and Virgílio Franco do Nascimento Filho. "Use of cesium-137 methodology in the evaluation of superficial erosive processes." Brazilian Archives of Biology and Technology 46, no. 3 (June 2003): 307–14. http://dx.doi.org/10.1590/s1516-89132003000300001.
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Superficial erosion is one of the main soil degradation agents and erosion rates estimations for different edaphicclimate conditions for the conventional models, as USLE and RUSLE, are expensive and time-consuming. The use of cesium-137 antrophogenic radionuclide is a new methodology that has been much studied and its application in the erosion soil evaluation has grown in countries as USA, UK, Australia and others. A brief narration of this methodology is being presented, as the development of the equations utilized for the erosion rates quantification through the cesium-137 measurements. Two watersheds studied in Brazil have shown that the cesium-137 methodology was practicable and coherent with the survey in field for applications in erosion studies.
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Lee, S. H., S. Vigneswaran, and K. Bajracharya. "Phosphorus transport in saturated slag columns: experiments and mathematical models." Water Science and Technology 34, no. 1-2 (July 1, 1996): 153–60. http://dx.doi.org/10.2166/wst.1996.0367.
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Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.
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Silva, A. T., M. M. Portela, and M. Naghettini. "Nonstationarities in the occurrence rates of flood events in Portuguese watersheds." Hydrology and Earth System Sciences Discussions 8, no. 5 (September 23, 2011): 8609–38. http://dx.doi.org/10.5194/hessd-8-8609-2011.
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Abstract. An exploratory analysis on the variability of flood occurrence rates in Portuguese watersheds is made, to ascertain if that variability is concurrent with the principle of stationarity. A peaks-over-threshold (POT) sampling technique is applied to 10 long series of mean daily streamflows and to 4 long series of daily rainfall in order to sample the times of occurrence (POT time data) of the peak values of those series. The kernel occurrence rate estimator, coupled with a bootstrap approach, was applied to the POT time data to obtain the time dependent estimated occurrence rate curves, ˆλ(t), of floods and extreme rainfall events. The results of the analysis show that the occurrence of those events constitutes an inhomogeneous Poisson process, hence the occurrence rates are nonstationary. An attempt was made to assess whether the North Atlantic Oscillation (NAO) casted any influence on the occurrence rate of floods in the study area. Although further research is warranted, it was found that years with a less-than-average occurrence of floods tend to occur when the winter NAO is in the positive phase, and years with a higher occurrence of floods (more than twice the average) tend to occur when the winter NAO is in the negative phase. The authors conclude that the mathematical formulation of the flood frequency models relying on stationarity commonly employed in Portugal, should be revised in order to account for nonstationarities in the occurrence rates of such events.
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Straškraba, Milan. "Ecotechnological methods for managing non-point source pollution in watersheds, lakes and reservoirs." Water Science and Technology 33, no. 4-5 (February 1, 1996): 73–80. http://dx.doi.org/10.2166/wst.1996.0490.
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Ecotechnological methods are considered those using technological means for environmental management in a way to minimize the harm to the global environment. Three reasons to use ecotechnological methods are given: they are cheap, minimize the use of raw materials and protect the global environment. In the article the most cost-efficient and environmentally friendly ecotechnologies for non-point source pollution management are given. These are divided into two categories: those done in the watershed and those used within the lake or reservoir. In the first category wetland use, restoration and construction is shown to efficiently reduce different kinds of pollution. The construction of small pre-impoundments is effective for trapping phosphorus as the main cause of eutrophication. In the category of in-lake approaches several are mentioned: biomanipulation or food web manipulation leading to decreased eutrophication, many approaches of mixing and aeration based on recent limnological knowledge, selective withdrawal as a manipulation of outflow and drinking water intake depths in reservoirs, the diversion of polluted inflow waters and sucking of hypolimnion waters. The limitations of the methods are given. Mathematical models helpful in optimizing the use of the corresponding methods are shown.
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Uchiyama, Tadayasu, Bruce P. Finney, and Milo D. Adkison. "Effects of marine-derived nutrients on population dynamics of sockeye salmon (Oncorhynchus nerka)." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 8 (August 2008): 1635–48. http://dx.doi.org/10.1139/f08-085.
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The effects of marine-derived nutrients (MDN) on the productivity of sockeye salmon ( Oncorhynchus nerka ) stocks in Alaska, USA, were examined through nitrogen stable isotope analysis of smolts and mathematical models of the sockeye stock–recruit relationship. Smolt δ15N was used to infer the degree to which smolts depend on MDN for their growth. We found that characteristics of sockeye nursery lakes and watersheds significantly affected the availability of MDN to juvenile sockeye. The magnitude of escapement and water residence time were the most important factors affecting the MDN availability to juvenile salmon. Analysis of stock–recruit models indicated that regional environmental fluctuations had a large effect on stock productivities. However, stock–recruitment data showed little evidence that increasing MDN input to nursery lakes increased stock productivities. Stock–recruitment data may be poorly suited to detection of the influence of MDN because of the multitude of factors that influence juvenile survival in the first several years of their life.
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Sun, Qiaohong, Chiyuan Miao, Amir AghaKouchak, Iman Mallakpour, Duoying Ji, and Qingyun Duan. "Possible Increased Frequency of ENSO-Related Dry and Wet Conditions over Some Major Watersheds in a Warming Climate." Bulletin of the American Meteorological Society 101, no. 4 (April 1, 2020): E409—E426. http://dx.doi.org/10.1175/bams-d-18-0258.1.
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Abstract Predicting the changes in teleconnection patterns and related hydroclimate extremes can provide vital information necessary to adapt to the effects of the El Niño–Southern Oscillation (ENSO). This study uses the outputs of global climate models to assess the changes in ENSO-related dry/wet patterns and the frequency of severe dry/wet events. The results show anomalous precipitation responding asymmetrically to La Niña and El Niño, indicating the teleconnections may not simply be strengthened. A “dry to drier, wet to wetter” annual anomalous precipitation pattern was projected during La Niña phases in some regions, with drier conditions over southern North America, southern South America, and southern central Asia, and wetter conditions in Southeast Asia and Australia. These results are robust, with agreement from the 26 models and from a subset of 8 models selected for their good performance in capturing observed patterns. However, we did not observe a similar strengthening of anomalous precipitation during future El Niño phases, for which the uncertainties in the projected influences are large. Under the RCP4.5 emissions scenario, 45 river basins under El Niño conditions and 39 river basins under La Niña conditions were predicted to experience an increase in the frequency of severe dry events; similarly, 59 river basins under El Niño conditions and 61 river basins under La Niña conditions were predicted to have an increase in the frequency of severe wet events, suggesting a likely increase in the risk of floods. Our results highlight the implications of changes in ENSO patterns for natural hazards, disaster management, and engineering infrastructure.
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Silva, A. T., M. M. Portela, and M. Naghettini. "Nonstationarities in the occurrence rates of flood events in Portuguese watersheds." Hydrology and Earth System Sciences 16, no. 1 (January 25, 2012): 241–54. http://dx.doi.org/10.5194/hess-16-241-2012.
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Abstract. An exploratory analysis on the variability of flood occurrence rates in 10 Portuguese watersheds is made, to ascertain if that variability is concurrent with the principle of stationarity. A peaks-over-threshold (POT) sampling technique is applied to 10 long series of mean daily streamflows and to 4 long series of daily rainfall in order to sample the times of occurrence (POT time data) of the peak values of those series. The kernel occurrence rate estimator, coupled with a bootstrap approach, was applied to the POT time data to obtain the time dependent estimated occurrence rate curves, λˆ(t), of floods and extreme rainfall events. The results of the analysis show that the occurrence of those events constitutes an inhomogeneous Poisson process, hence the occurrence rates are nonstationary. An attempt was made to assess whether the North Atlantic Oscillation (NAO) casted any influence on the occurrence rate of floods in the study area. Although further research is warranted, it was found that years with a less-than-average occurrence of floods tend to occur when the winter NAO is in the positive phase, and years with a higher occurrence of floods (more than twice the average) tend to occur when the winter NAO is in the negative phase. Although the number of analyzed watersheds and their uneven spatial distribution hinders the generalization of the findings to the country scale, the authors conclude that the mathematical formulation of the flood frequency models relying on stationarity commonly employed in Portugal should be revised in order to account for possible nonstationarities in the occurrence rates of such events.
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Razali, K., J. Amin, GJ Dore, MG Law, and HCV Projections Working Group. "Modelling and calibration of the hepatitis C epidemic in Australia." Statistical Methods in Medical Research 18, no. 3 (November 26, 2008): 253–70. http://dx.doi.org/10.1177/0962280208094689.
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Hepatitis C virus (HCV) infection in Australia is predominantly transmitted through injecting drug use. A reduction in the heroin supply in Australia in late 2000 and early 2001 may have impacted the number of injecting drug users (IDUs) and the number of new hepatitis C infections. This paper updates estimates of HCV incidence between 1960 and 2005 and models long-term sequelae from infection. Outcomes among those with HCV were also recently assessed in a linkage study assessing cancer and causes of death following HCV diagnosis in New South Wales. Linkage study outcomes have been used here to calibrate modelled outcomes. Mathematical models were used to estimate HCV incidence among IDUs, migrants to Australia from high HCV-prevalence countries, and other HCV exposure groups. Recent trends in numbers of IDUs were based on indicators of injecting drug use. A natural history of HCV model was applied to estimate the prevalence of HCV in the population. Model predicted endpoints that were calibrated against the NSW linkage data over the period 1995—2002 were: (i) incident hepatocellular carcinoma (HCC); (ii) opioid overdose deaths; (iii) liver-related deaths; and (iv) all-cause mortality. Modelled estimates and the linkage data show reasonably good calibration for HCC cases and all-cause mortality. The estimated HCC incidence was increased from 70 cases in 1995 to 100 cases in 2002. All-cause mortality estimated at 1000 in 1995 increased to 1600 in 2002. Comparison of annual opioid deaths shows some agreement. However, the models underestimate the rate of increase observed between 1995 and 1999 and do not entirely capture the rapid decrease in overdose deaths from 2000 onwards. The linkage data showed a peak of overdose deaths at 430 in 1999 compared to 320 estimated by the models. Comparison of observed liver deaths with the modelled numbers showed poor agreement. A good agreement would require an increase in liver deaths from the assumed 2 to 5% per annum following cirrhosis in the models. Mathematical models suggest that HCV incidence decreased from a peak of 14,000 infections in 1999 to 9700 infections in 2005, largely attributable to a reduction in injecting drug use. The poor agreement between projected and linked liver deaths could reflect differing coding of causes of deaths, underestimates of the numbers of people with cirrhosis following HCV, or underestimates of rates of liver death following cirrhosis. The reasonably good agreement between most of the modelled estimates with observed linkage data provides some support for the assumptions used in the models.
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Raeisi, Narges, Shahram Moradi, and Miklas Scholz. "Surface Water Resources Assessment and Planning with the QUAL2KW Model: A Case Study of the Maroon and Jarahi Basin (Iran)." Water 14, no. 5 (February 23, 2022): 705. http://dx.doi.org/10.3390/w14050705.
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Mathematical models are useful for predicting the reactions of watercourses such as rivers due to the entry of contaminants. Some of these models are able to simulate the effects of present and future loadings as well as aid managers and officials in making decisions even if the data are sparse. In other words, river water quality preservation requires more investment in wastewater treatment and/or the installation of collection and control systems; it may also limit activity expansion in the river basin. The conservation of watersheds such as the Maroon and Jarahi basin, which provide water for drinking and for industrial and agricultural use, is socio-economically vital. Therefore, the first stage of managing the conservation of water resources is understanding their qualitative changes. For this purpose, the QUAL2KW mathematical model was utilized to simulate the river water quality in this example region. According to the reported values of water quality parameters and pollutants at monitoring stations, it was established that the river is at a critical condition in terms of biochemical oxygen demand (BOD) pollution due to the discharge of urban and industrial wastewater, as well as high electrical conductivity (EC) due to the drainage of agricultural lands. Based on the statistics calculated during the validation step, the authors concluded that the QUAL2KW water quality model is reliable in the simulation of qualitative parameters and the pollution data of the study area; namely the Maroon and Jarahi river basin located in the south-west of Iran. This will help stakeholders to better manage watersheds with sparse data. This region has been suffering from climate change which has led to droughts and the construction of several dams to retain water. For the second and third stations, the NASH (named after the mathematician John Forbes Nash) values were 0.96 and 0.92, respectively, indicating a relatively high model accuracy. The evaluation using the root mean square errors (RMSE) and NASH showed that the quality of water at the second station was better than the other two stations based on the coefficient of determination R2. Since there were three drains at station number 3, the wastewater entering the Maroon River had a higher level of contamination.
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Batista, Lucas dos Santos, Raimundo Rodrigues Gomes Filho, Clayton Moura de Carvalho, Alceu Pedrotti, Igor Leonardo Nascimento Santos, Gregorio Guirado Faccioli, Sara Julliane Ribeiro Assunção, and Douglas Romeu da Costa. "Water infiltration rate in the soil under different uses and covers in the Poxim River basin, Sergipe, Brazil." International Journal for Innovation Education and Research 8, no. 11 (November 1, 2020): 321–39. http://dx.doi.org/10.31686/ijier.vol8.iss11.2756.
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Watersheds are units of planning and environmental management having a great importance in the management of water resources and their use. To this end, knowledge about the soil's physical and water attributes is of paramount importance in the context of water dynamics in aquifer recharge areas. Water infiltration rate into the soil is considered an important variable in the hydrological cycle, as the increase in this process can lead to a reduction in erosion and consequently greater groundwater recharge. Thus, the present work aimed to evaluate the soil water infiltration rate in the phytophysiognomy of the Poxim River basin in the State of Sergipe, in the agriculture, eucalyptus and forest areas, and to observe the effect of the infiltration water rate in areas of no-till, minimum and conventional cultivation. The soil water infiltration rate was obtained through the use of double cylinder infiltrometer and estimated through the mathematical models of Kostiakov, Kostiakov-Lewis, Horton and Philip. When making comparisons between the models for estimating of soil water infiltration rates, the Horton model showed a better fit compared to the other models used, and the type of soil cover that obtained the highest infiltration rate was the forest. No-till areas provided higher water infiltration rates in the soil, contributing to greater groundwater recharge.
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Zhang, Song, Ling Kang, Liwei Zhou, and Xiaoming Guo. "A new modified nonlinear Muskingum model and its parameter estimation using the adaptive genetic algorithm." Hydrology Research 48, no. 1 (January 30, 2016): 17–27. http://dx.doi.org/10.2166/nh.2016.185.
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First, a novel nonlinear Muskingum flood routing model with a variable exponent parameter and simultaneously considering the lateral flow along the river reach (named VEP-NLMM-L) was developed in this research. Then, an improved real-coded adaptive genetic algorithm (RAGA) with elite strategy was applied for precise parameter estimation of the proposed model. The problem was formulated as a mathematical optimization procedure to minimize the sum of the squared deviations (SSQ) between the observed and the estimated outflows. Finally, the VEP-NLMM-L was validated on three watersheds with different characteristics (Case 1 to 3). Comparisons of the optimal results for the three case studies by traditional Muskingum models and the VEP-NLMM-L show that the modified Muskingum model can produce the most accurate fit to outflow data. Application results in Case 3 also indicate that the VEP-NLMM-L may be suitable for solving river flood routing problems in both model calibration and prediction stages.
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Yong, Bin, Li-Liang Ren, Yang Hong, Jonathan J. Gourley, Xi Chen, You-Jing Zhang, Xiao-Li Yang, Zeng-Xin Zhang, and Wei-Guang Wang. "A novel multiple flow direction algorithm for computing the topographic wetness index." Hydrology Research 43, no. 1-2 (February 1, 2012): 135–45. http://dx.doi.org/10.2166/nh.2011.115.
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The topographic wetness index (TWI), frequently used in approximately characterizing the spatial distribution of soil moisture and surface saturation within a watershed, has been widely applied in topography-related geographical processes and hydrological models. However, it is still questionable whether the current algorithms of TWI can adequately model the spatial distribution of topographic characteristics. Based upon the widely-used multiple flow direction approach (MFD), a novel MFD algorithm (NMFD) is proposed for improving the TWI derivation using a Digital Elevation Model (DEM) in this study. Compared with MFD, NMFD improves the mathematical equations of the contributing area and more precisely calculates the effective contour length. Additionally, a varying exponent strategy is adopted to dynamically determine the downslope flow-partition exponent. Finally, a flow-direction tracking method is employed to address grid cells in flat terrain. The NMFD algorithm is first applied to a catchment located upstream of the Hanjiang River in China to demonstrate its accuracy and improvements. Then NMFD is quantitatively evaluated by using four types of artificial mathematical surfaces. The results indicate that the error generated by NMFD is generally lower than that computed by MFD, and NMFD is able to more accurately represent the hydrological similarity of watersheds.
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LAKSMI, PUTU IKA OKTIYARI, KOMANG DHARMAWAN, and LUH PUTU IDA HARINI. "PERAMALAN KUNJUNGAN WISATAWAN MENGGUNAKAN MODEL ARMAX DENGAN NILAI KURS DAN EKSPOR-IMPOR SEBAGAI FAKTOR EKSOGEN." E-Jurnal Matematika 3, no. 4 (November 28, 2014): 138. http://dx.doi.org/10.24843/mtk.2014.v03.i04.p076.
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Forecasting is science to estimate occurrence of the future. This matter can be conducted by entangling intake of past data and place to the next period with a mathematical form. This research aims to estimate the number of foreign tourists visiting Bali models using autoregressive moving average exogenous (ARMAX). The data used in this study is the number of tourists in Australia and the number of tourists in the RRC as a variable Y, and foreign currency exchange rate AUD, Chinese Yuan, and Export Import as the X factor from the period July 2009 to July 2014. In the analysis can be obtained in the best ARMAX models of the number of tourists in Australia is ARMAX(1,2,2) and the best model of the number of tourists in the RRC does not exist because the data for the ARMAX model parameters tourists no significant RRC.
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Lau, Henry. "Monitoring Quality of Components by Fuzzy Control Principle." International Journal of Reliability, Quality and Safety Engineering 05, no. 02 (June 1998): 133–45. http://dx.doi.org/10.1142/s0218539398000145.
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A fuzzy expert system uses fuzzy logic control,1 which is based on a "superset" of Boolean logic that has been extended to handle the concept of "partial truth." It replaces mathematical models with models that are built from a number of rules with fuzzy variables such as output temperature, and fuzzy terms such as extremely hot, fairly cold. A fuzzy expert system has been implemented in a plastic moulding shop in Australia for monitoring dimensional quality of output products. Because these plastic parts are used as assembly components for production of gear boxes, their dimensional accuracy is of utmost importance. This paper presents the implementation of this monitoring system adopting a graphical and non-mathematical approach, and examines the application of fuzzy control systems in quality control. Practical examples with descriptions of how the fuzzy rules are shown and the operations of the fuzzy inference engine are covered.
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Law, Helen. "Why do adolescent boys dominate advanced mathematics subjects in the final year of secondary school in Australia?" Australian Journal of Education 62, no. 2 (July 23, 2018): 169–91. http://dx.doi.org/10.1177/0004944118776458.
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In Australia, many students, especially girls, choose not to study advanced mathematics in Year 12 even though their schools offer relevant subjects. Previous studies have rarely examined, using nationally representative samples of Australian students, the extent to which teenage educational experiences and occupational expectations influence gender differences in later pursuits of advanced mathematics subjects. To fill this gap, I use multilevel logistic regression models to analyse the data from the 2003 cohort of the Longitudinal Survey of Australian Youth. My results show that students’ mathematics achievement, occupational expectations and self-assessed mathematical competence are crucial in explaining why boys are considerably more likely than girls to enrol in advanced mathematics subjects. The gender gap would decrease greatly if girls were as likely as boys to perform well in mathematics, to aspire to mathematically intensive careers and to have more confidence in their mathematical abilities when they were 15 years old.
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Benke, Kurt K., and Nathan J. Robinson. "Quantification of Uncertainty in Mathematical Models: The Statistical Relationship between Field and Laboratory pH Measurements." Applied and Environmental Soil Science 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/5857139.
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The measurement of soil pH using a field portable test kit represents a fast and inexpensive method to assess pH. Field based pH methods have been used extensively for agricultural advisory services and soil survey and now for citizen soil science projects. In the absence of laboratory measurements, there is a practical need to model the laboratory pH as a function of the field pH to increase the density of data for soil research studies and Digital Soil Mapping. The accuracy and uncertainty in pH field measurements were investigated for soil samples from regional Victoria in Australia using both linear and sigmoidal models. For samples in water and CaCl2 at 1 : 5 dilutions, sigmoidal models provided improved accuracy over the full range of field pH values in comparison to linear models (i.e., pH < 5 or pH > 9). The uncertainty in the field results was quantified by the 95% confidence interval (CI) and 95% prediction interval (PI) for the models, with 95% CI < 0.25 pH units and 95% PI = ±1.3 pH units, respectively. It was found that the Pearson criterion for robust regression analysis can be considered as an alternative to the orthodox least-squares modelling approach because it is more effective in addressing outliers in legacy data.
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Cubillo, Francisco. "Management of a Complex Water Supply Network for the Stabilization of Aquatic Habitat." Water Science and Technology 24, no. 6 (September 1, 1991): 117–24. http://dx.doi.org/10.2166/wst.1991.0147.
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The detailed study of the needs and feasibility of the maintenance of the flow regimes established in the river reaches located downstream from dams is an issue which is appearing more and more often as part of the basic considerations for hydraulic and environmental planning as well as for the exploitation of hydraulic resources. The management of a complex system of reservoirs, rivers and waste treatment plants, such as in the case of the Canal de Isabel II of Madrid, regards the needs and feasibility factors as parts of the overall hydraulic planning program of its watersheds. The complexity of Madrid's hydraulic system and the influence that erroneous conclusions could exert upon determining the discharge regimes has prompted the Canal de Isabel II to adopt more technical aids than commonly used for these types of studies. It was necessary to integrate a wide range of mathematical models for water quality, resource management and instream flow, so that ultimately, each alternative could be contrasted with its corresponding economic and social costs.
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Robson, Edward, and Vinayak V. Dixit. "Constructing a Database for Computable General Equilibrium Modeling of Sydney, Australia, Transport Network." Transportation Research Record: Journal of the Transportation Research Board 2606, no. 1 (January 2017): 54–62. http://dx.doi.org/10.3141/2606-07.
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In the search for benefits to justify transport projects, economic appraisals have increasingly incorporated the valuation of impacts to the wider economy. Computable general equilibrium (CGE) models provide a framework to estimate these impacts by simulating the interactions of urban economies and transport networks. In CGE models, households and firms are represented by microeconomic behavioral functions, and markets adjust according to prices. As markets both inside and outside the transport network are taken into account, a wide variety of measures that can assist in economic appraisals can be extracted. However, urban CGE models are computationally burdensome and require detailed, spatially disaggregate data. This paper discusses the methodology used to develop a database, including an input–output table, for the calibration of an urban CGE model for Sydney, Australia. Official and publicly available data sources were manipulated by using a number of mathematical and statistical techniques to compile a table for 249 regions and 20 sectors across Sydney. Issues, such as determining the appropriate level of aggregation, generating incomplete data, and managing conflicting data, that other input–output table developers may encounter when constructing multiregional tables were addressed in the study. The table entries themselves were mapped and explored, as they provide a useful study of the spatial economy of Sydney. Future work will focus on streamlining the construction of input–output tables and incorporating new data sources.
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Robin, Libby. "Uncertain Seasons in the El Niño Continent: Local and Global Views." Australia, no. 28/3 (January 15, 2019): 7–19. http://dx.doi.org/10.7311/0860-5734.28.3.02.
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As global climate change shifts seasonal patterns, local and uncertain seasons of Australia have global relevance. Australia’s literature tracks extreme local weather events, exploring ‘slow catastrophes’ and ‘endurance.’ Humanists can change public policy in times when stress is a state of life, by reflecting on the psyches of individuals, rather than the patterns of the state. ‘Probable’ futures, generated by mathematical models that predict nature and economics, have little to say about living with extreme weather. Hope is not easily modelled. The frameworks that enable hopeful futures are qualitatively different. They can explore the unimaginable by offering an ‘interior apprehension.’
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Her, Younggu, and Chounghyun Seong. "Responses of hydrological model equifinality, uncertainty, and performance to multi-objective parameter calibration." Journal of Hydroinformatics 20, no. 4 (March 20, 2018): 864–85. http://dx.doi.org/10.2166/hydro.2018.108.
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Abstract Multi-objective calibration can help identify parameter sets that represent a hydrological system and enable further constraining of the parameter space. Multi-objective calibration is expected to be more frequently utilized, along with the advances in optimization algorithms and computing resources. However, the impact of the number of objective functions on modeling outputs is still unclear, and the adequate number of objective functions remains an open question. We investigated the responses of model performance, equifinality, and uncertainty to the number of objective functions incorporated in a hierarchical and sequential manner in parameter calibration. The Hydrological Simulation Program – FORTRAN (HSPF) models that were prepared for bacteria total maximum daily load (TMDL) development served as a mathematical representation to simulate the hydrological processes of three watersheds located in Virginia, and the Expert System for Calibration of HSPF (HSPEXP) statistics were employed as objective functions in parameter calibration experiments. Results showed that the amount of equifinality and output uncertainty overall decreased while the model performance was maintained as the number of objective functions increased sequentially. However, there was no further significant improvement in the equifinality and uncertainty when including more than four objective functions. This study demonstrated that the introduction of an adequate number of objective functions could improve the quality of calibration without requiring additional observations.
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Rahimi, Iman, Amir H. Gandomi, Panagiotis G. Asteris, and Fang Chen. "Analysis and Prediction of COVID-19 Using SIR, SEIQR, and Machine Learning Models: Australia, Italy, and UK Cases." Information 12, no. 3 (March 3, 2021): 109. http://dx.doi.org/10.3390/info12030109.
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The novel coronavirus disease, also known as COVID-19, is a disease outbreak that was first identified in Wuhan, a Central Chinese city. In this report, a short analysis focusing on Australia, Italy, and UK is conducted. The analysis includes confirmed and recovered cases and deaths, the growth rate in Australia compared with that in Italy and UK, and the trend of the disease in different Australian regions. Mathematical approaches based on susceptible, infected, and recovered (SIR) cases and susceptible, exposed, infected, quarantined, and recovered (SEIQR) cases models are proposed to predict epidemiology in the above-mentioned countries. Since the performance of the classic forms of SIR and SEIQR depends on parameter settings, some optimization algorithms, namely Broyden–Fletcher–Goldfarb–Shanno (BFGS), conjugate gradients (CG), limited memory bound constrained BFGS (L-BFGS-B), and Nelder–Mead, are proposed to optimize the parameters and the predictive capabilities of the SIR and SEIQR models. The results of the optimized SIR and SEIQR models were compared with those of two well-known machine learning algorithms, i.e., the Prophet algorithm and logistic function. The results demonstrate the different behaviors of these algorithms in different countries as well as the better performance of the improved SIR and SEIQR models. Moreover, the Prophet algorithm was found to provide better prediction performance than the logistic function, as well as better prediction performance for Italy and UK cases than for Australian cases. Therefore, it seems that the Prophet algorithm is suitable for data with an increasing trend in the context of a pandemic. Optimization of SIR and SEIQR model parameters yielded a significant improvement in the prediction accuracy of the models. Despite the availability of several algorithms for trend predictions in this pandemic, there is no single algorithm that would be optimal for all cases.
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White, DH, and PJ Bowman. "Economics of feeding energy-based supplements to grazing ewes before mating in order to increase the reproduction rate of a wool-producing flock." Australian Journal of Experimental Agriculture 27, no. 1 (1987): 11. http://dx.doi.org/10.1071/ea9870011.
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The financial wisdom of feeding energy-based supplements to ewes before mating to increase fecundity was evaluated using mathematical models of sheep production systems. It was concluded that, for a wool-producing enterprise in southern Australia, feeding supplements to ewes pre-mating is likely to be highly unprofitable. This is partly because relatively few ewes would have extra ova and also because multiple embryos and lambs have a lower probability of survival than single embryos and lambs. Further more, the extra lambs reared would be associated with an increase in grazing pressure which would necessitate a reduction in either stocking rate or in ewe liveweight at mating and thus fecundity in the subsequent season.
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REGAN, D. G., J. G. WOOD, C. BENEVENT, H. ALI, L. WATCHIRS SMITH, P. W. ROBERTSON, M. J. FERSON, C. K. FAIRLEY, B. DONOVAN, and M. G. LAW. "Estimating the critical immunity threshold for preventing hepatitis A outbreaks in men who have sex with men." Epidemiology and Infection 144, no. 7 (November 13, 2015): 1528–37. http://dx.doi.org/10.1017/s0950268815002605.
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SUMMARYSeveral outbreaks of hepatitis A in men who have sex with men (MSM) were reported in the 1980s and 1990s in Australia and other countries. An effective hepatitis A virus (HAV) vaccine has been available in Australia since 1994 and is recommended for high-risk groups including MSM. No outbreaks of hepatitis A in Australian MSM have been reported since 1996. In this study, we aimed to estimate HAV transmissibility in MSM populations in order to inform targets for vaccine coverage in such populations. We used mathematical models of HAV transmission in a MSM population to estimate the basic reproduction number (R0) and the probability of an HAV epidemic occurring as a function of the immune proportion. We estimated a plausible range forR0of 1·71–3·67 for HAV in MSM and that sustained epidemics cannot occur once the proportion immune to HAV is greater than ~70%. To our knowledge this is the first estimate ofR0and the critical population immunity threshold for HAV transmission in MSM. As HAV is no longer endemic in Australia or in most other developed countries, vaccination is the only means of maintaining population immunity >70%. Our findings provide impetus to promote HAV vaccination in high-risk groups such as MSM.
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THOMAS, EMMA G., HANNAH E. BARRINGTON, KAMALINI M. LOKUGE, and GEOFFRY N. MERCER. "MODELLING THE SPREAD OF TUBERCULOSIS, INCLUDING DRUG RESISTANCE AND HIV: A CASE STUDY IN PAPUA NEW GUINEA’S WESTERN PROVINCE." ANZIAM Journal 52, no. 1 (July 2010): 26–45. http://dx.doi.org/10.1017/s1446181111000587.
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AbstractHigh tuberculosis (TB) prevalence in Papua New Guinea (PNG) is a serious public health concern. The epidemic in this region is exacerbated by the presence of drug-resistant TB strains as well as HIV infection. This presents a public health threat not only locally but also to Australia due to the high potential for cross-border transmission between PNG’s Western Province and the Australian Torres Strait Islands. We present two mathematical models of TB in the Western Province: a simple model of the underlying TB dynamics, and a detailed model which accounts for the additional effects of HIV and drug resistance. The detailed model is used to make quantitative predictions about the impact of expanding the TB case detection rate under the Directly Observed Treatment, Short-course treatment regimen. This paper provides a framework for future investigation into the economic costs and public health benefits of potential TB interventions in this region, with the eventual aim of providing recommendations to guide policy makers in both PNG and Australia.
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Ellahi, Rahmat. "Special Issue on Symmetry and Fluid Mechanics." Symmetry 12, no. 2 (February 13, 2020): 281. http://dx.doi.org/10.3390/sym12020281.
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This Special Issue invited researchers to contribute their original research work and review articles on “Symmetry and Fluid Mechanics” that either advances the state-of-the-art mathematical methods through theoretical or experimental studies or extends the bounds of existing methodologies with new contributions related to the symmetry, asymmetry, and lie symmetries of differential equations proposed as mathematical models in fluid mechanics, thereby addressing current challenges. In response to the call for papers, a total of 42 papers were submitted for possible publication. After comprehensive peer review, only 25 papers qualified for acceptance for final publication. The rest of the papers could not be accommodated. The submissions may have been technically correct but were not considered appropriate for the scope of this Special Issue. The authors are from geographically distributed countries such as the USA, Australia, China, Saudi Arabia, Iran, Pakistan, Malaysia, Abu Dhabi, UAE, South Africa, and Vietnam. This reflects the great impact of the proposed topic and the effective organization of the guest editorial team of this Special Issue.
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NDII, MEKSIANIS Z., ROSLYN I. HICKSON, and GEOFFRY N. MERCER. "MODELLING THE INTRODUCTION OF WOLBACHIA INTO AEDES AEGYPTI MOSQUITOES TO REDUCE DENGUE TRANSMISSION." ANZIAM Journal 53, no. 3 (January 2012): 213–27. http://dx.doi.org/10.1017/s1446181112000132.
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AbstractInfecting Aedes aegypti mosquitoes with the bacteria Wolbachia has been proposed as an innovative new strategy to reduce the transmission of dengue fever. Field trials are currently being undertaken in Queensland, Australia. However, few mathematical models have been developed to consider the persistence of Wolbachia-infected mosquitoes in the wild. This paper develops a mathematical model to determine the persistence of Wolbachia-infected mosquitoes by considering the competition between Wolbachia-infected and non-Wolbachia mosquitoes. The model has four steady states that are biologically feasible: all mosquitoes dying out, only non-Wolbachia mosquitoes surviving, and two steady states where non-Wolbachia and Wolbachia-infected mosquitoes coexist. The stability of the steady states is determined with respect to the key parameters in the mosquito life cycle. A global sensitivity analysis of the model is also conducted. The results show that the persistence of Wolbachia-infected mosquitoes is dominated by the reproductive rate, death rate, maturation rate and maternal transmission. For the parameter values where Wolbachia persists, it dominates the population, and hence the introduction of Wolbachia has great potential to reduce dengue transmission.
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Om, Dorji, Chompunooch Thamanukornsri, kado, and Montip Tiensuwan. "Application of Box-Jenkins Models to the Tourist Inflow in Bhutan." Journal of Mathematical Sciences & Computational Mathematics 3, no. 1 (October 4, 2021): 13–25. http://dx.doi.org/10.15864/jmscm.3102.
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Bhutan has now increasingly become a popular destination for many international tourists. Tourism in Bhutan is considered as one of the largest foreign earning industries. The number of tourist inflow in the country is increasing year by year. Forecasting is very necessary for administration and tourist agent for creating awareness and planning for the future development. It can also predict the future trends as accurately as possible and helps in staying one step ahead of the competition. This study aims to apply mathematical model for forecasting monthly tourist inflow from Malaysia, Singapore, China, USA, England, France, Germany, Thailand, Australia and Japan to Bhutan. The Box-Jenkins model is used to identify the parameters of Autoregressive integrated moving average (ARIMA) model of monthly tourist visited data of above mentioned countries in the period 2011-2015 obtained from Tourism Council of Bhutan. An Akaike's Information Criterion, Schwartz's Bayesian Criterion and estimate variance of white noise are used throughout to test for the identification of best fit model. Further, the periodogram analysis was used to confirm the seasonal period of the model. The results showed ARIMA model for Thai, Chinese, Malaysian and Japanese, while seasonal ARIMA for American, Australian, British, French, Singaporean and German. Further, seasonal ARIMA model was obtained as the best fit model for the overall data. These models are illustrated and could possibly forecast the monthly tourist inflow of one year ahead with acceptable accuracy.
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Klein, R. "An unified approach to meteorological modelling based on multiple-scales asymptotics." Advances in Geosciences 15 (March 18, 2008): 23–33. http://dx.doi.org/10.5194/adgeo-15-23-2008.
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Abstract. In 2003, the author suggested a mathematical framework for the derivation of reduced meteorological models at a Mathematics conference (5th ICIAM, Sydney, Australia), (Klein, 2004). The framework consists of (i) non-dimensionalization of the 3-D compressible flow equations on the rotating sphere, (ii) identification of universal non-dimensional parameters, (iii) distinguished limits between these and additional problem-specific parameters, and (iv) multiple scales expansions in the remaining small parameter ε. This parameter may be interpreted as the cubic root of the centripetal acceleration due to the Earth's rotation divided by the acceleration of gravity, see also Keller (1951), Eq. (10). For the mojority of reduced models of theoretical meteorology that we have come across, the approach allowed us to generate systematic derivations starting directly from the 3-D compressible flow equations on the rotating sphere. The framework's potential fully shows in multiscale interaction studies such as Klein (2006), in which we incorporated bulk microphysics closures for moist processes and derived scale interaction models for deep convection. Currently, we study the structure, evolution, and motion of Hurricane strength H1/H2 vortices (Mikusky, 2007), large-scale stratocumulus cloud decks, and planetary-synoptic scale interaction models which should be relevant for Earth System Models of Intermediate Complexity (EMICs). Here we summarize the general framework and use the example of quasi-geostrophic theory to demonstrate its application.
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Kvartenko, Oleksandr, and Igor Prysiazhniuk. "Modeling the process of biological deferrization of underground waters in contact loading of bioreactor." Problems of Water supply, Sewerage and Hydraulic, no. 41 (December 9, 2022): 19–30. http://dx.doi.org/10.32347/2524-0021.2022.41.19-30.
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The conducted analysis of modern biotechnologies in the field of groundwater treatment showed that one of the development trends is the direction of biological iron removal, which has not only a long history and fundamentality of research into the physiology, ultrastructure and life mechanisms of ferrobacteria, but also a wide implementation of the method at water treatment plants in Europе, Australia, Canada, USA, Japan. The introduction of modern technological equipment at such stations calls for the need to forecast their work using methods of mathematical modeling of processes with their subsequent computer implementation. The work provides a brief analysis of existing mathematical models, most of which are based on the kinetics of enzymatic reactions and are presented as modifications of the Michaelis-Menten and Monod equations.
Despite the large number of studies on this topic, until now there is no comprehensive model that would take into account all the processes that take place in the contact loading of bioreactors, in contrast to the physicochemical mechanisms in the filtering process, for which modern multicomponent mathematical models have been developed.
The aim of the work is to development of a mathematical model of the kinetics of the process of biological iron removal groundwater in bioreactors and verification of its computer implementation with the data of experimental studies. The mathematical model is represented by the Cauchy problem for a nonlinear system of differential equations in partial derivatives of the first order. The system of the Cauchy problem consists of five equations with five unknown functions, which describe the distribution the concentration of ferrum cations, bacteria and the matrix structures in two phases (movable and immobilized) both in space and time The inverse influence of the characteristics of the process, in particular, the concentration of matrix structures in the inter-pore space, as well as characteristics of the medium with the help of coefficients of mass exchange and porosity, were taken into account. The model makes it possible to predict changes in cleaning efficiency depending on the duration of the filter cycle, filtration speed, Fe2+ concentration, the content of iron bacteria and their matrix structures in the interpore space, and to determine the optimal time of operation of the bioreactor between washings
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Zhang, N., D. K. Liu, J. M. Jeyakumaran, and L. Villanueva. "Modelling of dynamic characteristics of an automatic transmission during shift changes." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 216, no. 4 (June 1, 2002): 331–41. http://dx.doi.org/10.1177/095965180221600403.
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This paper describes modelling of the transient dynamics of an automatic transmission during gear changes. A brief introduction to the automatic transmission system and the dynamic characteristics of the transmission components during the gear changes are presented. Then, detailed mathematical models of a four-speed automatic transmission manufactured by BTR Automotive, Australia, are developed. A mode description method is used to describe the transient shifting process and a modular structure of the transmission system, which consists of a torque converter module, geartrain module, hydraulic system module and modules of clutches and bands, is presented. As an application, the developed simulation system is applied to investigate the transient performance of the automatic transmission during the 1–2 shift process. The output torque profiles predicted by the model simulation correlate very well with the experimental data measured from vehicle tests.
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Al Hinai, Adnan, Reza Rezaee, Ali Saeedi, and Roland Lenormand. "Permeability prediction from mercury injection capillary pressure: an example from the Perth Basin, Western Australia." APPEA Journal 53, no. 1 (2013): 31. http://dx.doi.org/10.1071/aj12003.
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For shale gas reservoirs, permeability is one of the most important and difficult parameters to determine. Typical shale matrix permeabilities are in the range of 10 microdarcy–100 nanodarcy, and are heavily dependent on the presence of natural fractures for gas transmissibility. Permeability is a parameter used to measure the ability of a rock to convey fluid. It is directly related to porosity and depends on the pore geometry features, such as tortuosity, pore shape and pore connectivity. Consequently, rocks with similar porosity can exhibit different permeability. Generally, permeability is measured in laboratories using core plugs. In some cases, however, it is difficult to obtain suitable core plugs. In these instances, other approaches can be used to predict permeability, which are chiefly based on mathematical and theoretical models. The approach followed in this peer-reviewed paper is to correlate permeability with capillary pressure data from mercury injection measurements. The theoretical and empirical equations, introduced in the literature for various conventional and unconventional reservoir rocks, have been used to predict permeability. Estimated gas shale permeabilities are then compared with results from transient and steady state methods on small pieces of rocks embedded in a resin disk. The study also attempts to establish a suitable equation that is applicable to gas shale formations and to investigating the relationship between permeability and porosity.
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Ellis, Kathryn K., Timothy Callahan, Dianne I. Greenfield, Denise Sanger, Joshua Robinson, and Martin Jones. "Measuring and Modeling Flow Rates in Tidal Creeks: A Case Study from the Central Coast of South Carolina." Journal of South Carolina Water Resources, no. 4 (June 1, 2017): 21–39. http://dx.doi.org/10.34068/jscwr.04.03.
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The purpose of this study was to collect site- and condition-specific hydrology data to better understand the water flow dynamics of tidal creeks and terrestrial runoff from surrounding watersheds. In this paper, we developed mathematical models of tidal creek flow (discharge) in relation to time during a tidal cycle and also estimated terrestrial runoff volume from design storms to compare to tidal creek volumes. Currently, limited data are available about how discharge in tidal creeks behaves as a function of stage or the time of tide (i.e., rising or falling tide) for estuaries in the southeastern United States, so this information fills an existing knowledge gap. Ultimately, findings from this study will be used to inform managers about numeric nutrient criteria (nitrogen-N and phosphorus-P) when it is combined with biological response (e.g., phytoplankton assemblages) data from a concurrent study. We studied four tidal creek sites, two in the Ashepoo-Combahee-Edisto (ACE) Basin and two in the Charleston Harbor system. We used ArcGIS to delineate two different watersheds for each study site, to classify the surrounding land cover using the NOAA Coastal Change Analysis Program (C-CAP) data, and to analyze the soils using the NRCS Soil Survey Geographic database (SSURGO). The size of the U.S. Geological Survey’s Elevation Derivatives for National Application (EDNA) watersheds varied from 778 to 2,582 ha; smaller geographic watersheds were delineated for all sites (except Wimbee) for stormwater modeling purposes. The two sites in Charleston Harbor were within the first-order Horlbeck Creek and the second-order Bulls Creek areas. The ACE Basin sites were within the third-order Big Bay Creek and the fourth-order Wimbee Creek areas. We measured the stage and discharge in each creek with an acoustic Doppler current profiler (ADCP) unit for multiple tide conditions over a 2-year period (2015–2016) with the goal of encompassing as large of a range of tide stage and discharge data measurements as possible. The Stormwater Runoff Modeling System (SWARM) was also used to estimate the potential water entering the creeks from the land surface; this volume was very small relative to the tide water volume except for the more-developed Bulls Creek watershed. The results show that the peak discharge occurred on the ebb tide and that the duration of the flood tide spanned a longer period of time; both of these observations are consistent with traits associated with an ebb-dominated tidal creek system. The tidal inflow and outflow (flood and ebb tides, respectively) showed an asymmetrical pattern with respect to stage and discharge; peak discharge during the flood (rising) tide occurred at a higher stage than for the peak discharge during the ebb (falling) tide. This is not an unexpected result, as the water on an ebb tide is moving down gradient funneled through the creek channel toward the coast. Furthermore, water moving with the rising flood tide must overcome frictional losses due to the marsh bank and vegetation; i.e., the peak discharge can only happen when the water has risen above these impediments. We infer from the flow dynamics data that faster water velocities during ebb tide imply that more erosive energy could transport a larger mass of suspended solids and associated nutrients (e.g., orthophosphate) from the estuary to the coastal ocean. However, the discharge and runoff modeling indicate that land-based flux was important in the developed Bulls Creek watershed, but not at the larger and less-developed Big Bay Creek watershed. At Big Bay Creek, the relatively large tidal discharge volume compared to the smaller potential runoff generated within the watershed indicates that the creek could potentially dilute terrestrial runoff contaminants. Smaller, more-urbanized tidal wetland systems may not benefit from such dilution effects and thus are vulnerable to increased runoff from adjacent developed landscapes.
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APARECIDO, CAMILA FERNANDES FERREIRA, Luiz Sergio Vanzela, Gisele Herbst Vazquez, and Ronaldo Cintra Lima. "MANEJO DE BACIAS HIDROGRÁFICAS E SUA INFLUÊNCIA SOBRE OS RECURSOS HÍDRICOS." IRRIGA 21, no. 2 (June 18, 2018): 239. http://dx.doi.org/10.15809/irriga.2016v21n2p239-256.
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MANEJO DE BACIAS HIDROGRÁFICAS E SUA INFLUÊNCIASOBRE OS RECURSOS HÍDRICOS CAMILA FERNANDES FERREIRA APARECIDO1; LUIZ SERGIO VANZELA2; GISELE HERBST VAZQUEZ3 E RONALDO CINTRA LIMA4 1Mestranda em Ciências Ambientais, UNICASTELO, Campus de Fernandópolis - SP, CEP 15600-000. camilaff_gyn@hotmail.com2Prof. Titular do Departamento de Agricultura, Campus de Fernandópolis - SP, CEP 15600-000. lsvanzela@yahoo.com.br3Prof. Titular do Departamento de Agricultura, Campus de Fernandópolis - SP, CEP 15600-000. gisele-agro@uol.com.br4Prof. Professor Assistente Doutor da Coordenadoria de Curso de Engenharia Agronômica, FCAT-UNESP, CEP 17900-000. Dracena – SP. rclima@dracena.unesp.br 1 RESUMO Os estudos sobre o uso e ocupação do solo explorado pelos mais diversos seguimentos da sociedade, sejam eles, urbanos, rurais e industriais, associados às características das bacias hidrográficas são de extrema importância para o gerenciamento e a sustentabilidade dos recursos hídricos. Assim, este trabalho objetivou avaliar a influência de diferentes manejos de uso e ocupação do solo associados a declividade e ao escoamento superficial, sobre os recursos hídricos de bacias hidrográficas localizadas no Triângulo Mineiro - MG. O trabalho foi desenvolvido por meio do monitoramento das vazões e sedimentos em 4 bacias, no período de setembro de 2013 a outubro de 2014, além da determinação dos usos e ocupações do solo, declividade e dos escoamentos superficiais no período. Os modelos matemáticos obtidos demonstraram que a proporção entre os diferentes usos e ocupações do solo interfere na produção específica e na concentração de sedimentos, bem como na vazão específica das bacias hidrográficas, enquanto a quantidade de escoamento superficial interfere na produção específica de sedimentos. O resultado das simulações do manejo do uso e ocupação das bacias hidrográficas demonstrou que a conservação de matas nativas, as técnicas conservacionistas de uso do solo e as técnicas de minimização do transporte difuso originado das áreas urbanas, são essenciais na manutenção da disponibilidade e qualidade de água. Palavras-chave: escoamento superficial, uso e ocupação, declividade. APARECIDO, C. F. F.; VANZELA, L. S.; VAZQUEZ, G. H.; LIMA, R. C.WATERSHED MANAGEMENT AND ITS INFLUENCE ON THE HYDRIC RESOURCES 2 ABSTRACT Studies on the use and occupation of soil explored by various segments of urban, rural and industrial societies, associated to the watershed characteristics are extremely important for water resources management and sustainability. Therefore, this work aimed to evaluate the influence of different managements of soil use and occupation associated to declivity and superficial flow water resources of watersheds located in Triângulo Mineiro – MG. The study was conducted by monitoring the flow and sediment in 4 basins from September 2013 to October 2014, besides the determination of soil use and occupation, declivity and superficial flow during this time. The obtained mathematical models showed that the ratio of the different soil uses and occupations interferes with the specific production and sediment concentration and the specific flow of watersheds as well, while the amount of superficial flow interferes with the specific sediment production. The simulations results of the management of watersheds’ use and occupation showed that the conservation of native forests, the conservationist techniques of soil use and the minimization techniques of diffuse transport from urban areas are essential for keeping water availability and quality. Keywords: runoff, land use, slope
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Lydeamore, M. J., P. T. Campbell, W. Cuningham, R. M. Andrews, T. Kearns, D. Clucas, R. Gundjirryirr Dhurrkay, et al. "Calculation of the age of the first infection for skin sores and scabies in five remote communities in northern Australia." Epidemiology and Infection 146, no. 9 (May 8, 2018): 1194–201. http://dx.doi.org/10.1017/s0950268818001061.
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AbstractPrevalence of skin sores and scabies in remote Australian Aboriginal communities remains unacceptably high, with Group AStreptococcus(GAS) the dominant pathogen. We aim to better understand the drivers of GAS transmission using mathematical models. To estimate the force of infection, we quantified the age of first skin sores and scabies infection by pooling historical data from three studies conducted across five remote Aboriginal communities for children born between 2001 and 2005. We estimated the age of the first infection using the Kaplan–Meier estimator; parametric exponential mixture model; and Cox proportional hazards. For skin sores, the mean age of the first infection was approximately 10 months and the median was 7 months, with some heterogeneity in median observed by the community. For scabies, the mean age of the first infection was approximately 9 months and the median was 8 months, with significant heterogeneity by the community and an enhanced risk for children born between October and December. The young age of the first infection with skin sores and scabies reflects the high disease burden in these communities.
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GLASS, K., and N. G. BECKER. "Evaluation of measures to reduce international spread of SARS." Epidemiology and Infection 134, no. 5 (February 14, 2006): 1092–101. http://dx.doi.org/10.1017/s0950268806005863.
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Mathematical models are used to quantify the effect of border control measures in reducing the international spread of SARS. Border screening is shown to play a relatively minor role in reducing disease spread. Assuming detection rates similar to those reported for arrival screening in Australia, screening can detect up to 10% (95% CI 3–23) of infected travellers, and reduce the probability of a large outbreak by up to 7% (95% CI 2–17). Rapid reductions in the time to diagnosis and effective facilities for the isolation of cases are essential to ensure that there will not be a large outbreak, and each week of delay in responding to imported infection approximately doubles the total number of cases. While the control response is being developed in a currently uninfected region, border screening can provide up to one week's additional time in which to improve methods for early isolation of cases.
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Lambert, M. F., J. P. Whiting, and A. V. Metcalfe. "A non-parametric hidden Markov model for climate state identification." Hydrology and Earth System Sciences 7, no. 5 (October 31, 2003): 652–67. http://dx.doi.org/10.5194/hess-7-652-2003.
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Abstract. Hidden Markov models (HMMs) can allow for the varying wet and dry cycles in the climate without the need to simulate supplementary climate variables. The fitting of a parametric HMM relies upon assumptions for the state conditional distributions. It is shown that inappropriate assumptions about state conditional distributions can lead to biased estimates of state transition probabilities. An alternative non-parametric model with a hidden state structure that overcomes this problem is described. It is shown that a two-state non-parametric model produces accurate estimates of both transition probabilities and the state conditional distributions. The non-parametric model can be used directly or as a technique for identifying appropriate state conditional distributions to apply when fitting a parametric HMM. The non-parametric model is fitted to data from ten rainfall stations and four streamflow gauging stations at varying distances inland from the Pacific coast of Australia. Evidence for hydrological persistence, though not mathematical persistence, was identified in both rainfall and streamflow records, with the latter showing hidden states with longer sojourn times. Persistence appears to increase with distance from the coast. Keywords: Hidden Markov models, non-parametric, two-state model, climate states, persistence, probability distributions
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Baird, Mark E., Karen A. Wild-Allen, John Parslow, Mathieu Mongin, Barbara Robson, Jennifer Skerratt, Farhan Rizwi, et al. "CSIRO Environmental Modelling Suite (EMS): scientific description of the optical and biogeochemical models (vB3p0)." Geoscientific Model Development 13, no. 9 (September 25, 2020): 4503–53. http://dx.doi.org/10.5194/gmd-13-4503-2020.
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Abstract. Since the mid-1990s, Australia's Commonwealth Science Industry and Research Organisation (CSIRO) has been developing a biogeochemical (BGC) model for coupling with a hydrodynamic and sediment model for application in estuaries, coastal waters and shelf seas. The suite of coupled models is referred to as the CSIRO Environmental Modelling Suite (EMS) and has been applied at tens of locations around the Australian continent. At a mature point in the BGC model's development, this paper presents a full mathematical description, as well as links to the freely available code and user guide. The mathematical description is structured into processes so that the details of new parameterisations can be easily identified, along with their derivation. In EMS, the underwater light field is simulated by a spectrally resolved optical model that calculates vertical light attenuation from the scattering and absorption of 20+ optically active constituents. The BGC model itself cycles carbon, nitrogen, phosphorous and oxygen through multiple phytoplankton, zooplankton, detritus and dissolved organic and inorganic forms in multiple water column and sediment layers. The water column is dynamically coupled to the sediment to resolve deposition, resuspension and benthic–pelagic biogeochemical fluxes. With a focus on shallow waters, the model also includes detailed representations of benthic plants such as seagrass, macroalgae and coral polyps. A second focus has been on, where possible, the use of geometric derivations of physical limits to constrain ecological rates. This geometric approach generally requires population-based rates to be derived from initially considering the size and shape of individuals. For example, zooplankton grazing considers encounter rates of one predator on a prey field based on summing relative motion of the predator with the prey individuals and the search area; chlorophyll synthesis includes a geometrically derived self-shading term; and the bottom coverage of benthic plants is calculated from their biomass using an exponential form derived from geometric arguments. This geometric approach has led to a more algebraically complicated set of equations when compared to empirical biogeochemical model formulations based on populations. But while being algebraically complicated, the model has fewer unconstrained parameters and is therefore simpler to move between applications than it would otherwise be. The version of EMS described here is implemented in the eReefs project that delivers a near-real-time coupled hydrodynamic, sediment and biogeochemical simulation of the Great Barrier Reef, northeast Australia, and its formulation provides an example of the application of geometric reasoning in the formulation of aquatic ecological processes.
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McCallum, H. I., and G. R. Singleton. "Models to assess the potential of Capillaria hepatica to control population outbreaks of house mice." Parasitology 98, no. 3 (June 1989): 425–37. http://dx.doi.org/10.1017/s0031182000061515.
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SUMMARYPopulation outbreaks of house mice (Mus domesticus) occur periodically in the wheatlands of southeastern Australia. This paper uses mathematical models to assist in the evaluation of the potential of a nematode, Capillaria hepatica, as a biological control agent to reduce the severity of these ‘plagues’. C. hepatica is unique amongst helminths of mammals in that its eggs are released only upon the death of an infected host. The major goal of the modelling in this paper is to determine the impact of this feature on the population dynamics of the host-parasite interaction. Simple differential equation models are used to examine the general properties of the system and determine which population parameters are most crucial to the outcome of the interaction. These models are supplemented by age-structured models which investigate the initial behaviour of the system after introduction of the parasite. The necessity of host death for transmission is a strongly destabilizing factor, suggesting that C. hepatica cannot regulate most populations stably in the absence of strong resource limitation, although it has the potential to depress mouse populations below infection-free levels. Although C. hepatica influences mouse fecundity at lower burdens than it affects mortality, the age-structured models show that parasite-induced host death cannot be neglected. Because transmission requires host death, the parasite life-cycle operates on a time-scale similar to that of the hosts, and introduction of the parasite as early as possible in the development period of an outbreak will therefore be necessary to achieve substantial reductions in plague intensity.
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Vino, Thiripura, Gurmeet R. Singh, Belinda Davison, Patricia T. Campbell, Michael J. Lydeamore, Andrew Robinson, Jodie McVernon, Steven Y. C. Tong, and Nicholas Geard. "Indigenous Australian household structure: a simple data collection tool and implications for close contact transmission of communicable diseases." PeerJ 5 (October 26, 2017): e3958. http://dx.doi.org/10.7717/peerj.3958.
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Households are an important location for the transmission of communicable diseases. Social contact between household members is typically more frequent, of greater intensity, and is more likely to involve people of different age groups than contact occurring in the general community. Understanding household structure in different populations is therefore fundamental to explaining patterns of disease transmission in these populations. Indigenous populations in Australia tend to live in larger households than non-Indigenous populations, but limited data are available on the structure of these households, and how they differ between remote and urban communities. We have developed a novel approach to the collection of household structure data, suitable for use in a variety of contexts, which provides a detailed view of age, gender, and room occupancy patterns in remote and urban Australian Indigenous households. Here we report analysis of data collected using this tool, which quantifies the extent of crowding in Indigenous households, particularly in remote areas. We use these data to generate matrices of age-specific contact rates, as used by mathematical models of infectious disease transmission. To demonstrate the impact of household structure, we use a mathematical model to simulate an influenza-like illness in different populations. Our simulations suggest that outbreaks in remote populations are likely to spread more rapidly and to a greater extent than outbreaks in non-Indigenous populations.
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Parsons, Scott A., and Robert A. Congdon. "Plant litter decomposition and nutrient cycling in north Queensland tropical rain-forest communities of differing successional status." Journal of Tropical Ecology 24, no. 3 (May 2008): 317–27. http://dx.doi.org/10.1017/s0266467408004963.
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Abstract:Soil processes are essential in enabling forest regeneration in disturbed landscapes. Little is known about whether litterfall from dominating pioneer species in secondary rain forest is functionally equivalent to that of mixed rain-forest litter in terms of contribution to soil processes. This study used the litterbag technique to quantify the decomposition and nutrient dynamics of leaf litter characteristic of three wet tropical forest communities in the Paluma Range National Park, Queensland, Australia over 511 d. These were: undisturbed primary rain forest (mixed rain-forest species), selectively logged secondary rain forest (pioneer Alphitonia petriei) and tall open eucalypt forest (Eucalyptus grandis). Mass loss, total N, total P, K, Ca and Mg dynamics of the decaying leaves were determined, and different mathematical models were used to explain the mass loss data. Rainfall and temperature data were also collected from each site. The leaves of A. petriei and E. grandis both decomposed significantly slower in situ than the mixed rain-forest species (39%, 38% and 29% ash-free dry mass remaining respectively). Nitrogen and phosphorus were immobilized, with 182% N and 134% P remaining in E. grandis, 127% N and 132% P remaining in A. petriei and 168% N and 121% P remaining in the mixed rain-forest species. The initial lignin:P ratio and initial lignin:N ratio exerted significant controls on decomposition rates. The exceptionally slow decomposition of the pioneer species is likely to limit soil processes at disturbed tropical rain-forest sites in Australia.
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Hui, Ben B., David P. Wilson, James S. Ward, Rebecca J. Guy, John M. Kaldor, Matthew G. Law, Jane S. Hocking, and David G. Regan. "The potential impact of new generation molecular point-of-care tests on gonorrhoea and chlamydia in a setting of high endemic prevalence." Sexual Health 10, no. 4 (2013): 348. http://dx.doi.org/10.1071/sh13026.
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Background Despite the availability of testing and treatment, bacterial sexually transmissible infections (STIs) continue to occur at endemic levels in many remote Indigenous communities in Australia. New generation molecular point-of-care (POC) tests have high sensitivity, comparable with conventional diagnostic tests, and have the potential to increase the impact of STI screening. Methods: We developed mathematical models of gonorrhoea (Neisseria gonorrhoeae) and chlamydia (Chlamydia trachomatis) transmission in remote Indigenous communities in Australia to evaluate screening and treatment strategies that utilise POC tests. Results: The introduction of POC testing with 95% sensitivity could reduce the prevalence of gonorrhoea and chlamydia from 7.1% and 11.9% to 5.7% and 8.9%, respectively, under baseline screening coverage of 44% per year. If screening coverage is increased to 60% per year, prevalence is predicted to be reduced to 3.6% and 6.7%, respectively, under conventional testing, and further reduced to 1.8% and 3.1% with the introduction of POC testing. Increasing screening coverage to 80% per year will result in a reduction in the prevalence of gonorrhoea and chlamydia to 0.6% and 1.5%, respectively, and the virtual elimination of both STIs if POC testing is introduced. Conclusions: Modelling suggests that molecular POC tests of high sensitivity have great promise as a public health strategy for controlling chlamydia and gonorrhoea. However, evaluation of the cost-effectiveness of POC testing needs to be made before widespread implementation of this technology can be considered.
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Rathi, Vinay Kumar, Shobha Ram, Rohitashw Kumar, Avinash Agarwal, and R. K. Nema. "Hydrological classification and performance of Himalayan springs in climate change scenario – a case study." Water Supply 20, no. 2 (December 27, 2019): 594–608. http://dx.doi.org/10.2166/ws.2019.191.
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Abstract The present study was conducted to evaluate 33 springs' hydrology (discharge and yield estimation) of Chandrabhaga and Danda watersheds of Uttarakhand, India. The springs were classified using Meinzer method and evaluated the relative performance for rejuvenation strategy. It was found that most of springs fall in sixth and seventh class order with flow rate 6.5 to 65.5 and 0.8 to 6.5 m3·day−1, respectively. The relative performance of springs were analyzed based on four methods: (i) spring flow variability, (ii) normalized spring flow (short and long duration), (iii) rainfall spring flow lag and (iv) spring flow gradient. The relative results of springs were analyzed on a scale of 0–5. The Chandrabhaga springs 01, 03, 4B, 05, 06 and 13 were found to be relatively good on a scale value of 4 out of 5 as compared to springs 4A, 07, and 10A with a scale value of 1. For the Danda watershed, the relative performance of springs 4A and 28 found on scale value of 5 and springs 4B, 11 and 20 with a scale value of 4 are relatively good compared to springs 02, 06, 07, 15 and 17. The cumulative flow of spring showed a linear response with cumulative rainfall for the period of June to September (monsoon period). The spring-shed was delineated and evaluated for optimization for the maximum efficiency, spring flow, ratio of area and relief versus maximum spring flow yield. The results revealed that the quantification of water fluxes for water balances, storage of groundwater and development of mathematical models can be used for sustainable water resources development and to revive the mountain springs which helped the adverse impacts of climate change.