Paired catchment experiments is the method that estimates the change of runoff due to forest change by comparisons between runoff data from two or more adjacent catchments and evaluations the change of their relative relations between two periods when forest changes in catchments. The increase in volume of maximum daily runoff due to forest degradation was estimated in three treatment catchments in Japan using paired catchment experiments. In one catchment, slope failure occurred and 20% of the catchment area became bare, after which maximum daily runoff increased by approximately 1.1-fold. In the two other catchments, slope failure did not occur, while maximum daily runoff increased by only 6–8 mm day−1. This increase was irrespective of the rainfall volume. slope failure and the transition to bare land were identified as causes of the degradation of the flood mitigation function. The causes of slope failure were identified as inadequate forest management, such as clear-cutting in areas with high slope failure risk, simultaneous clear-cutting throughout a catchment, and delayed replanting after clear-cutting. Therefore, forest management strategies for the flood mitigation function of forests could include the avoidance of logging in locations with a high risk of slope failure, limits concerning the amount of logging, and prompt replanting after logging.

Environmental problems have been increasing at a disproportionate rate, contributing to global warming, one of humanity’s greatest challenges. As stated in the latest report of the Intergovernmental Panel on Climate Change ‘climate change is widespread, rapid and intensifying’ and there is certainty that this is a result of human activity. In this context, environmental social responsibility is fundamental to prevent, mitigate or repair the environmental damage generated by productive activity. This obliges us to take concrete actions and thus move from a linear economy approach to a circular economy approach that allows for sustainable development, where waste and pollution are eliminated from the design stage and materials are used for as long as possible. Chile must implement actions that allow it to meet the commitments obtained in its Nationally Determined Contribution of 2020, and move towards sustainable development. The Chilean case is interesting to study because it is a highly exposed and fragile country in the face of climate change. The purpose of this publication is to highlight the current problem of climate change and the threat it poses to our planet, to understand that the circular economy approach as a business model allows for a long-term solution to this problem, to understand the consequences of climate change in Chile and to know the current situation in terms of strategic planning at the country level in relation to the circular economy.

Rajang River Basin (RRB) comprise about 40% of the Sarawak State area in Malaysia. Any extreme storm event in the Upper RRB may cause a flood, affecting the downstream communities and infra- structures of the Rajang River. There are two large dams in a cascade scheme at upper RRB, Murum Dam and Bakun Dam. With the concern of changing climate impact, the future peak precipitation and peak river discharge are analysed in this study to assess the potential flood impact along the Rajang River. This study focused on developing flood modelling for downstream of Bakun Dam down to Be- laga Town. The peak rainfall analysis was carried out to generate peak discharge for the return period of 1 in 50 and 1 in 100 years of historical and projected future storm events. The corresponding flood- plains map pre- and post-Bakun Dam operations were generated using GeoHECRAS software. The study results show that the projected peak rainfall and peak discharge under future changing climate are increased between 6–27% and 7–30%, respectively, and this warrants attention from the relevant authorities and parties to access the flood risk downstream Bakun Dam continuously. The generated maps of pre- and post-Bakun Dam operation show that Bakun Dam can mitigate the flood from impacting the downstream structures and communities. The outcome from this study can be useful information to educate the local people and public about the benefit of having a Dam, not only for the source of power generation but also for flood mitigation.

Constructed wetlands (CW) can be considered an efficient municipal wastewater treatment technology, suitable to be used on a local level in both rural and urban environments. This technology is popular and normally used in Europe having the attributes of a success story – cheap in investment and simple in operation. Nevertheless, the transfer of this technology to developing countries is a challenge of some kind, the main reason being a different technological and cultural context there. The paper discusses the implementation process of CWs in the Kathmandu Valley, Nepal, the East. The concept of diffusion of innovation is used as the guideline, namely two of its perspectives – motivation of end-users to implement the technology, and the way the information about the technology is spread. Empirical data were obtained by use of semi-standardized interviews with the three types of stakeholders involved, the end-users themselves, local authorities, and pertinent NGOs. On this basis, three main reasons (moti- vations) to implement CWs for municipal sewage water treatment were found, which can appear in a combination – environmental-religious, pragmatical and prestigious. In parallel, three communication channels were identified which can be metaphorically named professional enlightenment, peer influence (or exempla trahunt) and direct external aid.

The objective of this work is to evaluate the amount of CH₄, CO₂ and SO₂ that is currently emitted by the Hulene dump into the atmosphere. The work consisted in measuring these three gases using an S360 multigasometer that simultaneously measures eight gases. Measurements were made in April, May, June, July, August and September, which are considered the dry season in Maputo city. Measurements were made at 18 points of gas release pipes installed by the Municipality of Maputo. Point P10, presents the highest value of 2.56 and 2.59 (% vol of CH₄), respectively in the months of April and May. Point P14 had the highest value of 2.95 (% vol of CH₄) in April and 2.28 (% vol of CH₄) in May. Point P15 presented values of 2.78 and 2.72 (% vol of CH₄), respectively in the months of August and September.

Points P10, P14 and P15 showed higher values of CH4 in April, May, August and September. Points P9 to P13 showed marked variations of CO₂ in the months of July, August and September. Point P10 presented the highest value of 2.56 and 2.59 (ppm of CO₂), respectively in the months of April and May. Point P14 showed the highest value of 2.95 (ppm CO₂) in April and 2.28 (ppm CO₂) in May. Point P15 presented the highest value of 5,000 ppm of CO₂ in August and September. In April, points P1 to P6 showed values above 100 ppm of SO₂ and dropped drastically from point P7 to 3 ppm of SO₂. In April, P6 reached 137 ppm of SO₂. In August and September, the values gradually increased, reaching 178 ppm of SO₂ at point P18.

Climate change has led to triple digit temperatures globally, notably along the western coast of the United states. These changes have produced intense weather-related events such as fires and landslides. Green roofs are one strategy to mitigate these high temperatures. For this report, several studies were compiled, using data found from physical green roof models as well as on-site data from the Javits Center Green Roof. At the Javits Green Roof, an infrared camera was used to collect thermal images at various parts of the roof, to determine its effectiveness for thermal buffering. Off site, a rain simulator was used on model green roof and a control roof, to determine change in retention and peak runoff rate. The green roof was able to retain 2%–22% of rainfall and reduce peak runoff by 19%–28%. From the graph comparing roof temperatures, there were higher temperatures on the black top roof in comparison to the green roof, and the slopes of the lines indicated the mitigating effect of the green roof on heat waves. These models were also analysed with an infrared camera, which showed that green roofs can be, as much as 25°f cooler than their standard roof counterparts, providing valuable evidence for the usefulness of green roofs to combat heat waves. Runoff quality was experimentally measured using a green roof model, where nitrogen concentration is measured before and after to determine change in runoff quality. This concept is based on studies which claim that the addition of wood mulch to soil can reduce nitrogen content. This experiment revealed a 23% reduction in runoff nitrates for the wood-mulch treated soil, in comparison to a 6.5% reduction for the control roof. Furthermore, a mathematical model was used to determine the ceiling temperature of the Javits Center within 3%.

Satellite remote sensing techniques have been proved to be capable of quantifying chlorophyll-a (Chl-a) levels by estimating algal concentrations in water bodies. Harmful algal blooms (HABs) pose a signifcant threat to many water bodies in South africa. This study aimed at using a remote sensing solution to estimate chlorophyll concentrations in water bodies of vhembe district municipality using Landsat 8 OLI. This study seeks to provide quantitative water quality information for the vhembe region’s water bodies from a time series of satellite remotely sensed data and in-situ laboratory data. The 30 meters spatial resolution multispectral Landsat 8 OLI for 2016, 2017 and 2018 were used to derive Chl-a esti- mate at three water bodies, namely, nandoni, albasini and vondo reserviors. The Chl-a concentrations obtained from Landsat 8 (OLI) satellite were compared with the laboratory analysis using the Kappa coeffcient statistical analysis. This study show that landsat derived chl-a estimates have a high positive correlation of 80–90% accurate with feld measurements. In all the reservoirs, it was detected that there is low content of HABs and thus the water bodies are in good condition since the chl-a concentrations were very low. In conclusion, it can be stated that Landsat 8 OLI sensor can be used to map and monitor inland water bodies dominated by algal blooms to a certain extent.