Combining CFD and GIS software capabilities to enhance rapid fine-scale urban micro- and bioclimatic modelling

<p>Cities around the world are under constant change. Population growth is leading to an increasing demand for residential, commercial and traffic areas and thus leading to progressive surface sealing and urban densification. Adding on the existing and growing challenging situation, the Earth’s climate is undergoing dramatical changes. Globally affecting cities by altering local temperature patterns, enhancing the occurrence of dry periods and increasing the frequency of Excessive Heat Events (EHE) as well as tropical nights per year, urban planning is becoming increasingly demanding. These consequences put cities (citizens and infrastructure) at risk, amplifying urban heat and the Urban Heat Island (UHI) effect. To ensure anticipatory and holistic planning approaches to counteract the consequences of climate change, specific tools must be developed enabling consideration of different aspects and boundary conditions as well as analysis of crucial processes and complex relationships within the urban environments. Therefore, we introduce a simple and fast spatial GIS-based modelling approach to carry out fine-scale simulations for land surface temperature (LST), mean radiant temperature (MRT) and Universal Thermal Climate Index (UTCI) in a 2D urban environment. This modelling approach combines a fine-scale surface classification, comprised of eight different surface classes, thermal characteristics (global radiation, direct radiation and diffuse radiation), surface characteristics (Emissivity and Bowen-Ratio values) and meteorological input data. Based on this combined dataset and well-established physical relations in the model set-up, the model uses an adapted approach to first evaluate LST, followed by the MRT and finally the UTCI. A DEM (Digital Elevation Model), a CIR-Image (Coloured Infrared Image) and a vector layer depicting building geometry are required as model input datasets. The accuracy of the input datasets determines the accuracy of the output datasets including the three main indicators. To improve this modelling approach and to consider the effects of climate change, we combine this spatial GIS-approach with the capabilities of computational fluid dynamics (CFD). We use CFD software to simulate wind velocities as well as air temperatures based on certain input parameters. Simulation time strongly depends on the complexity of the urban form within the area of interest. Therefore, a specific urban area was selected and the building structure, as well as the tree structure, was approximated by a self-designed 3D model. An additional input data set containing LST is provided by the modelling approach described above. Temperature data of the building envelope was conducted using a thermal infrared camera, with on-site measurements in the study area carried out during the summer of 2020. Among other settings, an initial wind speed and air temperature define the boundary conditions. Transferring calculated wind speed and air temperature datasets for different heights across the study area using CFD into the GIS based approach, leads to improved spatial LST, MRT and UTCI calculations and results and thus enhanced urban micro- and bioclimatic modelling.</p>

Use of meteorological data in biosecurity

Pests, pathogens and diseases cause some of the most widespread and damaging impacts worldwide — threatening lives and leading to severe disruption to economic, environmental and social systems. The overarching goal of biosecurity is to protect the health and security of plants and animals (including humans) and the wider environment from these threats. As nearly all living organisms and biological systems are sensitive to weather and climate, meteorological, ‘met’, data are used extensively in biosecurity. Typical applications include, (i) bioclimatic modelling to understand and predict organism distributions and responses, (ii) risk assessment to estimate the probability of events and horizon scan for future potential risks, and (iii) early warning systems to support outbreak management. Given the vast array of available met data types and sources, selecting which data is most effective for each of these applications can be challenging. Here we provide an overview of the different types of met data available and highlight their use in a wide range of biosecurity studies and applications. We argue that there are many synergies between meteorology and biosecurity, and these provide opportunities for more widespread integration and collaboration across the disciplines. To help communicate typical uses of meteorological data in biosecurity to a wide audience we have designed the ‘Meteorology for biosecurity’ infographic.

Asphodelus fistulous L., a newly discovered plant invader in South Africa: Assessing the risk of invasion and potential for eradication

Background: Naturalised populations of Asphodelus fistulosus (onion weed) were recorded in South Africa for the first time during the early 1990s. Initial records lodged in 2012 indicated the presence of two populations. Five additional populations were found between 2012 and 2016, as a result of surveys and the distribution of awareness materials. All populations in South Africa occurred along roadsides, but in other parts of the world the species has demonstrated the ability to spread into adjacent native vegetation and crop fields.Objectives: The aim of this study was to assess the risk of invasion and potential for eradication.Method: A risk assessment tool was used to establish invasion risk. Of the seven known populations, five test populations were selected to gather data on the feasibility for eradication. Randomised fixed plots were used to monitor the response of A. fistulosus populations to mechanical and chemical plant control methods and to track spread over time. The germinability of seeds was also tested.Results: The Standard Australian Risk Assessment method for invasive alien plants gave a relatively high score for the threat posed by this species. In this assessment, a threshold score is used to indicate sufficient invasive risk to fail a species as part of a preborder risk assessment. Invasiveness elsewhere (Australia and USA) contributed to the relatively high score. The bioclimatic modelling map highlighted the south-western region of South Africa as most suitable climatically for A. fistulosus. Both mechanical and chemical control methods were shown to be effective in killing live plants. Results, based on plant removal and monitoring, over a four-year research period suggest that suppression of reproduction is possible, partly as a result of high detectability and ease of control.Conclusion: It is recommended that A. fistulosus be listed as a National Environmental Management: Biodiversity Act 10 of 2004 1a invasive species (eradication target) under national legislation, thus requiring compulsory management. We estimate that extirpation of all known populations of A. fistulosusmay be possible with continual effort at an annual investment of approximately ZAR 50 000 per year. Further surveillance for undiscovered populations and monitoring of known populations must be conducted to produce a definitive comment about the feasibility of countrywide eradication.

Long-Term Bioclimatic Modelling the Distribution of the Fire-Bellied Toad, Bombina Bombina (Anura, Bombinatoridae), Under the Influence of Global Climate Change

The article describes the potential distribution area of B. bombina and fi gure out the signifi cant climatic factors of the species at a home range scale. Th is species is listed on Appendix II of the Bern Convention and on Annexes II and IV of the EU Natural Habitats Directive. It is protected by national legislation in many countries, occurs in many protected areas, and is listed in many national and sub-national Red Data books and lists. We collected the occurrence records and a set of climatic variables including 19 factors from 10’ resolution historical (summarizing annual trends, seasonality and extreme conditions during 1961-1990) and projected data (2050) available at the CliMond database. As a result, under climate predictions for 2050 there may be a substantial north and north-west shift of optimal habitat. Under such a scenario B. bombina populations may suff er mostly in the east and south of Ukraine. Under the modelled scenario the species representation in protected areas throughout the home range should be considered, but especially in Ukraine.