Rain runoff exceeding river channel capacities has been increasing in Japan. Although excess runoff events are still local and not very frequent, this trend is thought to be growing due to global climate change, and the government is discussing the need for flexible disaster mitigation measures by allowing river overflow to enter floodplains. However, the framework for formulating facility design based on this policy has not yet been established. Nevertheless, civil engineers of the early modern age developed flood control systems to avoid catastrophic flooding in important areas by inducing deliberate and safe river overflows without knowledge of modern hydraulics. This paper discusses the flood control strategy common in early modern times using numerical case studies with a shallow water model on three typical types of flood control systems. The results suggest that civil engineers at that time understood the natural flow tendency during flooding based on floodplain topography measurements together with flood trace inspections, allowing them to deal with excess runoff.

Incineration is any procedure, technique or method that transforms waste to flue gases and by-products by means of oxidation. Although the recommended way of treating healthcare risk waste is through incineration, the utilization of incinerators is still disputable. The fundamental problem for incinerators in the Republic of South Africa started with the new amended Section 21 of the National Environmental Management Act: Air Quality Act known as NEMA: AQA 39 of 2004 that requires stack emissions to be reduced by almost 50%. Since the promulgation of the standard, incineration facilities have not been complying with the emissions standard. This study was conducted to investigate the optimum hydrated lime [Ca(OH)₂] dosage required to reduce acid gas emissions to the required level. The dosage rate was then raised and kept between 2.5 and 3.5 kg/h. This technology was able to achieve a high removal efficiency of 97% for HCl, 86% for HF, 83% for NO, 87% for SO₂ and 74% for NO₂. The optimum emissions removal temperature for HCl was between 1190°C and 1200°C, 1020°C for SO₂ and NO₂, and between 1120°C and 1200°C for NO₂. The optimum Ca(OH)₂ dosage for maximum NO removal was 3.1 kg/h, HF was 2.9 kg/h, SO₂ was 2.8 kg/h, NOx was 2.8 kg/h and HCl was 3.2 kg/h.

The concentration of pharmaceutical compounds and nutrients present in perennial streams, springs and a lake on the island of O‘ahu, Hawai‘i were measured under drought conditions between 2020 and 2022. The combined island-wide daily release of wastewater to the environment on O‘ahu from the continued use of legacy On-Site Sewage Disposal Systems (OSDS) and from exfiltration from the 3,400-kilometer network of underground sewer lines has been estimated to be about 80 million liter per day (mld), or around 3.9% of the total island-wide groundwater flux to the ocean. The 36 streams and 11 springs sampled were located down-gradient of areas with varying densities of OSDS and sewage lines while the lake sampled (Lake Wilson) receives direct input from the wastewater treatment plant that serves Central O‘ahu. Average pharmaceutical and nutrient levels in streams and springs sampled in areas with high densities of OSDS and sewer lines were slightly higher, but not statistically different than concentration levels measured in streams and springs in areas with low densities of OSDS and low sewer line densities. The average sulfamethoxazole and carbamazepine levels measured in Lake Wilson, the only water body on O‘ahu where treated wastewater is discharged into fresh water, are three to four times higher than average levels measured in the island’s streams and springs. The presence of elevated concentrations of nitrate and silica in some streams and springs on O‘ahu predominately reflects the impact of the historical use of up-gradient lands for sugarcane cultivation rather than wastewater input. The trace levels of pharmaceuticals detected in O‘ahu streams and springs under baseflow conditions suggest that the actual combined input of wastewater to the environment from legacy OSDS and exfiltration from sewer lines is less than 20% the wastewater flux previously estimated.

Systems Thinking and adequate modelling skills related to System Dynamics (SD) are essential for sustainable functioning of human society. The process of learning these skills can be considerably facilitated through hands-on experience with modern interactive tools in a play-like activity. Here we present a concise hands-on course on SD Modelling and Systems Thinking, give a brief description of its teaching materials (available online for free download), and discuss its potential developments, overall relevance and further implications. The course contains a session on ‘Systems Thinking’, and two hands-on sessions aiming to provide basic and more advanced modelling skills. Central to the latter are the examples of structural modifications for the Ebbsfleet Garden City water management model. The model represents complex processes associated with a multitude of interconnected social, technical and environmental issues. This publication provides both an important update of this model incorporating a dimensional analysis and the hands-on teaching support designed to aid knowledge transfer. It is envisaged that, with modifications, this freely downloadable course could be of use for modules related to a wide range of fundamental and applied disciplines, including e.g., Ecology, Geography, Engineering, Social and Environmental Sciences. It is expected that University students and other users will not only benefit from enhancing their understanding of the complexity of the specific problems considered by the examples used, but will also gain valuable basic system modelling skills through ‘learning by doing’. The teaching materials presented here may be particularly useful for environmental projects involving participatory approaches.

Air quality monitoring is fundamental to mitigating the impacts of air pollution on human health and the environment. This ensures that air quality management is effective and that the potential negative effects on the environment and human health associated with poor air quality are understood and mitigated. Despite this, Africa continues to struggle with a lack of sufficient air pollution exposure data that can influence the understanding of air pollution status. The purpose of this research is to look at the progress made by African countries in developing monitoring techniques for pollutants such as particulate matter and nitrogen oxides in urban settings. The study conducted meta-analyses of studies that looked at technological advancements in monitoring PM and NO_x exposure levels on the African continent. Every country in the African continent that has monitored both PM and NO_x ambient pollutants was included in the review. Furthermore, in an attempt to include the most recent studies that monitored PM and NO_x only ambient air quality studies published between 2010 to 2022 were eligible for inclusion in the current study. From eligible studies, authors, publication year, exposure characterization method, study setting, pollutants and technique used were extracted. Microsoft Excel 2019 was used for data analysis. To this end, the data was presented using graphs and numerical techniques. The results of this study show that 67% of African countries use fixed monitoring systems, which has a serious limitation. Whilst, on the other hand only 10% of the countries, geographically located within North Africa (Tunisia, and Algeria), and Southern Africa (South Africa) regions used the mixed monitoring techniques, such as active sampling and remote sensing. In conclusion, most African regions rarely conduct air quality exposure assessments that incorporate air quality modelling techniques.

Avoidance of impacts on areas of environmental significance is a desired outcome of environmental planning. This paper describes the process of constraint mapping that was used in the route selection for the Moomba to Stony Point hydrocarbon liquids pipeline in South Australia. The Flinders Ranges were on the direct line between Moomba and Stony Point so alternative alignments to the west and east of the ranges were considered as well as alternative crossings of the ranges for eastern alignments. Constraint mapping provided an effective tool for comparing the alignment alternatives and for identifying areas requiring more detailed impact evaluation. The aftermath of route selection was based on a major review of environmental impacts undertaken 25 years after construction and annual reporting of environmental incidents. Analysis of the aftermath confirms many of the considerations used in constraint mapping. It indicated that revegetation over the buried pipeline had occurred and that erosion at creek crossings was the major operational issue. The access road has more permanent impacts than the pipeline right-of-way while maintenance activities involving excavation and hydrocarbon release required effective management. With pipeline alignment selection through constraint mapping avoiding sensitive areas and effective management of operation and maintenance activities, the pipeline has been classified as ‘low impact’ by the regulator.