Constructed Floating treatment wetlands: can they improve water quality in a northern USA climate?

Constructed floating treatment wetlands (FTWs) are a best management practice (BMP) applied in aquatic environments to improve water quality by mitigating nutrient pollution. We evaluated the efficacy of FTWs in Minnesota, USA as a tool for the removal of excess nutrients in surface water to enhance water quality. We began with a 2015 outdoor mesocosm study to quantify the removal efficiency of total phosphorus (TP), ortho-phosphate-P (PO4-P), nitrate-N, and ammonia-N. The FTWs were each planted with wetland plants Juncus effusus, Eleocharis acicularis, and Glyceria canadensis. A paired controlled TP budget was prepared to identify mesocosm sources and sinks. Mesocosm FTWs showed higher PO4-P reduction efficiencies than the control mesocosms. Mesocosms with FTWs had significantly lower pH and dissolved oxygen (DO) concentrations. Water quality measurements were made along with qualitative observations, such as durability, at two different field scales where FTWs were installed in a pond and lake in 2016. Field deployed FTWs showed measurable changes in several water quality parameters over the study period. Statistically significant reductions were observed in PO4-P, DO, and pH for the pond site but not at the lake site. Though positive results were observed, factors other than FTWs may better explain the field deployed FTW results. Overall, the high FTW spatial coverage (15%) in the mesocosms showed clear PO4-P removal, whereas low FTW spatial coverage (<1%) of the field scale surface water was likely the most limiting factor to achieving optimal water quality at the study sites and rather than individual FTW performance.

Power relations: a catalyst in the building of flood disaster resilience capacities in the orashi region of rivers state

Climate change-related disasters have in recent years become a global phenomenon with catastrophic consequences. Africa has had most of the consequences of climate change related disasters, resulting in monumental urban and rural flooding, widespread casualties, displacements, loss of property and sources of livelihood. Given the long-term implications of climate change, it is critically important to understand how vulnerable communities respond to the menace occasioned by flooding. The impact of the flooding is felt more in low-lying communities situated along the coastal fringes leaving inherently vulnerable communities to the vagaries of flooding. However, despite of their vulnerability to flooding disasters, some people displayed resilience capacities more than others because of their apparent access to resources and power within and outside their localities. The study investigated the issue, through the application of the qualitative approach that drew the Bourdieusian theory of practice, deploying the analytical concepts of fields, habitus and species of capital to gather useful information from relevant focus groups to understand how various forms of power was employed to capture resources that enhanced resilience capacities in the seasonal flood prone Orashi region of Rivers State of Nigeria. Following the outcome of the analysis of the information gathered from the focus group and a review of relevant literature, it was revealed that most of the vulnerable population displayed some ingrained disposition and the deployment of indigenous knowledge and social capital for adaptation to survive flood disasters. It is therefore concluded that dynamics of power is a key factor in the resilience capacities of the population of the study.

Evaluation and space representation of the maximum surface runoff in watersheds

In Cuba, regardless of the advances made in hydrological and hydraulic investigations related to floods, there are limitations with the detailed knowledge of the true maximum surface runoff or maximum flow that characterizes these phenomena in the season of intense rains, for which it is necessary to carry out complex hydrological study that, with the help of professional software and statistical techniques, help to determine and model spatially with certain reliability, the maximum water surface drained in watersheds. The general objective was pursued: To determine and represent spatially with the use of Geographic Information Systems (GIS) and hydrological methods, the runoff or maximum flow produced by the intense rains in a watershed, selecting to exemplify the watershed from the Magdalena River to the south east of the Santiago de Cuba municipality. As a result was obtained in the first instance, that it is feasible to apply this procedure to know in a preliminary way what maximum flow is available at any point of a main river or tributary. This approximation constitutes a significant advance for subsequent work in other watersheds of Cuba or internationally.

Seasonal analysis on land surface temperature (LST) and normalized difference vegetation index (NDVI) variations in the Iguatu semi-arid hinterland, ceará

The following paper analyzes the seasonal behavior of surface temperature and vegetation conditions from Landsat 8 satellite images in Iguatu, located in South-central Ceará, Brazil. The guiding method was the Urban Climate System (UCS) along with works with specific literature. Concerning the LSTs during the wet season, the urban area recorded 30.8°C, whereas the countryside verified milder thermal conditions than in downtown, especially in the southwestern region (19.2°C to 23.1°C). The NDVI values in April (wet season) for the urban area and part of the suburbs showed (0.00) because of civil constructions and little vegetation present in the area, except for the surroundings of the Bastiana and Cocobó lagoons – ranging between (0.59 and 0.79), which represents a green area. In August (dry season), there was an expressive spatial distribution of surface temperature around 32 °C. The NDVI was (-0.01) in the densely occupied area and (0.67) in the urban lagoons during the same period. The land use and its plant cover reflect significantly in the distribution and intensity of surface temperatures, as verified in the research.

The decision-making process towards implementing energy efficiency in a university-built park in southern Brazil

Sustainability has been increasingly incorporated as an essential life perspective into educational institutions as well as local communities. Universities play an important role into the society by debating theoretical contributions and implementing concrete actions. The present research was developed to evaluate a university’s energy efficiency by using the Polytechnic University of Catalonia, Spain as a reference for University of Passo Fundo, Brazil. The reference values and index ratings obtained for energy performance, in the Universities’ building stock, were evaluated based on positive and negative features. The study identifies and assesses the evolution of incident factors towards energy consumption and its impacts on the hidropower generation, the main energy resource in Brazilian. Hence, the university can promote a reflection about its practices to develop feasible tools that contribute to sustainable measures. As a result, guidelines and strategies were proposed, not only on targeted evaluated buildings but also on the entire building stock. The research indicates the importance to follow well-defined guidelines in the decision-making process by institutions of higher education, in order to consider integrated sustainable practices. The methodology and findings contribute to improve and promote Education for Sustainability, which should encourage other similar universities to put sustainable projects into practice and encourage the whole society to face the inevitable change of paradigms for achieving the Sustainable Development Goals (SDGs).

Investigating effects of deficit irrigation levels and fertilizer rates on water use efficiency and productivity based on field observations and modeling approaches

Investigating the effects of optimized fertilizer and irrigation levels on water use efficiency and productivity of wheat crop at small farms is of great importance for precise and sustainable agriculture in Pakistan's irrigated areas. However, traditional farmer practices for wheat production are inefficient and unsustainable. This study aimed to investigate the effects of deficit irrigation and nitrophos fertilizer levels on bread wheat grain yield, yield parameters, nutrient use and water use efficiencies in bed planting wheat compared to traditional farmers' practices in the flat sowing method. The two-year field experiment followed a randomized complete block design of three replications, taking three irrigation treatments according to the requirement of crop estimated by CROPWAT model (100% of ETC), deficit irrigation (80% of ETC), and deficit irrigation 60% of ETC and three nitrophos fertilizer treatments (farmer practice 120 kg N ha-1, optimized 96 kg N ha-1, and 84 kg N ha-1) at different growth stages. Crop ETC was calculated using the FAO CROPWAT 8.0 model from the last ten years (2003-2013) average climate data of the experimental station. The traditional farmer practice treatment was included as a control treatment with a flat sowing method compared with other sown-by-bed planter treatments. All treatments were provided with an equivalent amount of fertilizer at the basal dose. Before the first and second irrigation, top-dressing fertilizer was used in traditional farmers' treatment at the third leaf and tillering stages. It was applied in optimized treatments before the first, second, and third irrigation at the third leaf, tillering and shooting stages, respectively, under the bed planting method. The deficit level of irrigation (80% of ETc) and optimized fertilizer (96 kg N ha-1) showed the optimum grain yield, nutrient use, and water use efficiencies, with 20% reduced irrigation water and fertilizer levels than traditional farming practice. The results suggest that bread wheat should be irrigated with 80% of ETC and applied 96 kg N ha-1 nitrophos fertilizer at the third leaf, tillering, and shooting stages to achieve higher grain yield and water and nutrient use efficiencies under bed planting.

Spatial modelling of urban heat islands and its planning implications in Obio/Akpor local government area

Urban Heat Island (UHI) has become a global recurring phenomenon in most urban centres. Obio/Akpor Local Government Area has had a fair share of this phenomenon owing to its thriving trend in both planned and unplanned urbanisations. The study looks at the impact of UHI in selected communities in Obio/Akpor Local Government in five epochs of 2000, 2005, 2010, 2015 and 2020. Parts of the objectives include identifying the UHI in these communities in the Local Government Area, modelling of UHI in selected communities in Obio/Akpor Local Government Area and determining the trend in UHI using Epoch data of Urban Surface Temperature from LANDSAT thermal imageries Figure 1. The study adopted Thermal Infrared Remote (TIR) Sensing and Geospatial Information System (GIS) Techniques using LANDSAT TM, LANDSAT ETM and LANDSAT OLI sensors to acquire Urban Surface temperature data emitted by objects in the study area and store the information as a digital number (DN) thermal band (B6, B61 and B10) as well as secondary data acquired from the Nigerian Meteorological Agency (NIMET). Urban Surface Temperature was obtained through the following processes: Acquisition of Urban Surface Temperature value of the study area in form of DN, the conversion of DN to Spectral radiance using the Spectral radiance equation. The data were processed, analysed, and modelled using ESRI’s ArcGIS 10.1. The results revealed that in 2000, the Average Urban Temperature of the study area was 23.480°C, the value increase to 27.647°C in 2005 with a difference of 4.167°C. The temperature of 2005 increased to 31.598°C in 2010 with a difference in temperature of 3.951°C. Accordingly, the temperature of 2010 increased to 33.054°C in 2015 with a temperature difference of 1.456°C and temperature of 2015 increased to 33.070°C with a difference of 0.016°C. The analysis shows an increasing trend of 40% in the Urban Surface Temperature in the study area in the various years under investigation. The study recommends that development should be extended to other Local Government Areas in the state to reduce rural-urban migration to Obio/Akpor Local Government. Tree planting should be encouraged as a way of mitigating the effect of air pollution, heatwaves and harmful gases emitted into the environment by combust engines and gas flaring, the use of combustion engines be replaced by electric cars to reduce the level of carbon dioxide (CO2) emitted ti environment. Policymakers to restrict unplanned urban growth and to increase tree planting in the built-up areas.

Bathymetric components towards ensuring navigable channel along a section of lower river Niger, lokoja, kogi state, Nigeria

Navigation in Lower River Niger is seasonal because of insufficient water depth during the dry season. This is a limitation to economic benefits derivable compared to when the river is navigable throughout the year. Government and stakeholders alike have exerted efforts in the past years to create an unimpeded navigable channel without much success. The need to ensure all-year-round navigation in the Lower River Niger for industrial and commercial purposes necessitated this research work. The main thrust of this work is to determine bathymetric components parameters of the river necessary for the design of an appropriate river training structure to divert river flow from the secondary channel to the main channel. The specific objective hereto is to assess the extent and geometry of the river banks, the configuration of the river bed, the river flow velocity and discharge. The approach deployed in this work is the classical method of acoustic principle premised on Remote Sensing techniques. The shape of the river was obtained through waypoint survey using Garmin eTrex 10 handheld GPS, while the riverbed configuration was determined through bathymetric survey using Odom Echotrack MK III single beam Echo Sounder and the flow velocity data was acquired using Valeport 106 Current Meter. Data processing and analysis were achieved using Garmin Basecamp 4.7.3, Wintopo V7.03, Valeport Datalog X2 and Surfer 13 software. The length of the study area measured along the main channel was obtained as 5.94km while that of secondary channel gave 4.30km. Area occupied by the main channel was found to be 2,636,331.3m2 and 1,759,045.4m2 for the secondary channel. Average depth on the main channel was 0.21m while on the secondary channel was -0.89m, depth figures referred to Lokoja local datum. The average flow velocity was obtained to be 0.449m/s and the cross-sectional area of the river as 1568.75m2, which gave a value of 704.2m3/s for the river discharge. The research produced the digital terrain model (DTM) and bathymetric charts of the study area. The parameters obtained in this study is a useful tool in defining an appropriate embankment dam suitable to divert the flow from the secondary channel to the main channel to enhance depth towards all-season navigation in Lower River Niger.

Characterization of an area susceptible to floods and inundations in a medium size city in Southern Brazil

The change in precipitation patterns that has occurred over the past decades establishes the discussion about the risks arising from rainfall in urban areas. These risks include floods, inundations and overflow, which are influenced by different conditions. The purpose of this work is to characterize a risk area, susceptible to inundations and floods, in the city of Passo Fundo, in the south of Brazil. In order to propose solutions aimed at mitigating risks for the area, a GIS (Geographic Information System) characterization was applied to prepare thematic maps to identify conditions of infrastructure networks, as well as other constraints of the built environment. The analysis showed that the area, predominantly residential, is currently susceptible to environmental risks, given the proximity to streams, the topography with slopes and impermeable surfaces, despite the existence of rain network infrastructure. Furthermore, the mitigation strategies were proposed, based on the concept of green infrastructure such as the implementation of draining surfaces, rain gardens and a linear park. The data collected in this study will provide subsidies to elaborate the risk maps of the area, deepening the analysis in future studies, assisting the decision making of the public power to prevent and mitigate risks such as floods, according to the identified vulnerability, as well as contribute to Goal 11 - Sustainable cities and communities on the United Nations Agenda 2030.

Events linked to Geosmin and 2-methylisoborneol (2-MIB) in a Water Supply in the State of Rio de Janeiro, Brazil: a case study

Tastes and odors in tap water are problems faced by water companies worldwide, with consumers complaints mainly during summer, when cyanobacterial blooms occur and produce compounds such as geosmin and 2-methylisoborneol (2-MIB). We analyzed the data on taste and odor intensity and total concentration of geosmin and 2-MIB compounds in drinking water and raw water collected by the sanitation company supplying of the metropolitan region of Rio de Janeiro (Brazil) during the 2020 and 2021 water crises. Statistical and metagenomic analyses of the raw water samples of the year 2020, were performed. Organoleptic data allowed to signal the presence of these taste and odor (T&O) compounds in the drinking water, and the mean values of taste intensity were above the maximum allowed value of the Brazilian legislation, on average 37.5 times in 2020 and 5 times in 2021, indicating that the measures did not eliminate the problem. There was a linear correlation of 0.97 between the standard organoleptic taste and the total concentration of T&O in 2020. Metagenomic data, from raw water in the year 2020, for the mtf, mic and glys genes indicated 2-MIB as responsible for T&O. Modifications in the surveillance system of catchment and drinking water quality need to be adopted to circumvent the problems of cyanobacterial blooms in the Guandu basin, as conditions favorable to blooms will occur as long as the sanitation problems in this watershed are not solved.