Drainage Infrastructure Research Articles

The interface of disasters, sanitation, and poverty in Brazil: a sociological perspective

In Brazil, the high frequency and types of disasters are symptoms of misguided socioenvironmental public policies. While approximately 25% of municipalities decree emergency every year, over 75% of the occurrences are linked to sanitation issues. Such events range from the lack of urban drainage infrastructure to handle large volumes of rainwater to the insufficiency of backup water supply strategies during prolonged drought, both further impacting other precarious infrasystems such as solid waste management and sewage, with the most heavily and extensively affected group being the citizens facing poverty. Therefore, the issues of disaster, sanitation, and poverty are intertwined in Brazil. Using a network science approach, we investigate how the sociological debate is overcoming the fragmented approach about these subthemes and within the disciplinary fields in social sciences by analyzing the connections between the keywords of the open-access research articles from 2003 to 2022 from four databases. This mini review highlights the main contemporary axes between the themes, identifies the potential for tackling the gap at the interface, and clarifies the needs for future studies given the aims of the Sustainable Development Goals.

Impact assessment of groundwater-adapted drainage infrastructure in an agricultural lowland catchment in north-west Germany

Impact assessment of groundwater-adapted drainage infrastructure in an agricultural lowland catchment in north-west Germany

Performance evaluation of urban drainage systems: an analytic hierarchy process approach for the Jaracati basin in Brazil

The efficiency of drainage systems in urban centers and especially in their peripheral regions has deserved more and more special attention since their interrelationship with social and environmental aspects is associated with the performance of drainage infrastructures. Integrated urban water management is a major factor in the effectiveness of an urban drainage system. In large cities, negative effects caused by the disorderly urbanization process, especially those related to rainwater runoff, are increasingly present. An evaluation model of urban drainage systems was generated using System Fragility Indicators (IFS) and their ranking via Analytic Hierarchy Process (AHP), in the Jaracati River basin, Maranhão State, Brazil. Indicators were measured through the evaluation of the system and the experience of specialists in drainage systems. The results obtained allowed for the consolidation of a model to support planning and decision-making in the assessment processes of measures to mitigate socio-environmental impacts involved in the urban drainage of a watershed, with performance indicators capable of guaranteeing the support of a model being verified measurement of performance parameters of urban drainage systems.

Salt-affected soils in Tanzanian agricultural lands: Type of soils and extent of the problem

Salt-affected soils are a global challenge, affecting 1 billion ha of land, with 200 million ha found in Africa. The challenge brings adverse impacts on agricultural productivity, food security, environmental sustainability, and food security. In Tanzania, more than 2 million ha of land are salt-affected, of which 1.7 million ha are saline soil and 0.3 million ha are sodic soil. To cope with this threat, it is necessary to have a thorough understanding of its extent (coverage), existing types, and available management strategies. This review presents a comprehensive account of the challenges and opportunities of salt-affected soils in Tanzania and examines management options that have been observed to increase agricultural productivity in rice-growing areas. A systematic review of relevant articles published in databases was carried out using PRISMA guidelines and flowcharts. This review highlights the origin, extent, types, and various techniques for alleviating salt-affected soil problems. It also emphasize on the use of inorganic and organic amendments, salt-tolerant varieties, irrigation water quality, and drainage infrastructure. We revealed that farmers, use burned and unburned rice husks, sawdust, gypsum, and farm yard manure (FYM) as copping mechanisms. Furthermore, there have been continuing efforts to develop salt-tolerant rice varieties, coupled with maintenance of irrigation infrastructure and site-specific soil management options, as appropriate solutions to tackle salt issues. Given the light of existing data, the review recommends using RS and GIS for updating information on salt-affected soils, particularly in irrigated areas, as an essential component of sustainable management and preventing further loss of agricultural land.

Assessing Urban Flooding Extent of the Baunia Khal Watershed in Dhaka, Bangladesh

Due to the gradual encroachment of natural drainage channels (also known as khals) and the poor management of drainage infrastructures, any rainfall of higher intensity for a few hours causes urban flooding in Dhaka, Bangladesh, hindering the daily lives of city dwellers, especially in slum areas. The Intensity–Duration–Frequency (IDF) curves with return intervals of 2, 5, 10, 25, 50, and 100 years were estimated for a 3 h duration of rainfall using the Gumbel statistical method to assess urban flooding extent around the Baganbari slum within the Baunia Khal watershed. The spatial land use changes of the Baunia Khal were also delineated through the analysis of the areal changes of the khal from 2004 to 2020. The area of the khal was found to be 7.00 km2, 2.17 km2 and 0.41 km2 for the years 2004, 2010, and 2020, respectively. It appears that a gradual massive areal decrease of the khal (impervious land segment) was in progress during this period for high encroachments driven by various governmental agencies and other private entities’ urban developmental projects. The runoff coefficient was computed as 0.76 based on the existing land use pattern, slope, and soil type of the study area. The average runoff generated from the catchment was estimated using the rational method and was 103.41 m3/hr. The drainage length was calculated as 9.1 km using the Kirpich method, whereas the present drainage length was reported as only 6.95 km. The multiple rainfall intensities with return periods of 2, 5, 10, 25, 50, and 100 years were also applied to replicate a heightened extent of urban flooding in the Baunia Khal watershed. The study suggests that the depth, length and width of the Baunia Khal need to increase to hold the generated runoff to manage urban flooding around the Baunia Khal watershed.

Urban Drainage: The Challenges and Failure Assessment Using AHP, Addis Ababa, Ethiopia

Urban drainage infrastructures are facing critical challenges due to a lack of integrated asset management, periodic maintenance, improper design, and construction methodologies. The objective of this study is to understand the urban drainage challenges and assess the failure causes and their impacts to recommend possible mitigation measures. Drainage failure causes and impacts are analyzed using the analytical hierarchy process (AHP) qualitative multicriteria decision model after conducting technical group discussions, interviews, and technical field surveys. The assessment was performed by taking representative samples from both cross- and longitudinal drainage infrastructures. The AHP analysis results showed that approximately 35.5% and 28.6% of failure causes are debris and various solid wastes for cross- and longitudinal drainage structures with correlation coefficients of 0.93 and 0.95, respectively. The result showed that design and construction defects are the second major failure causes. The research results showed that urbanization has a direct relationship with major drainage failure causes, resulting from man-made debris and solid waste clogging. On the other hand, drainage failure caused by siltation, drifts, and vegetation is higher in newly developing semi-urban and agricultural areas. The number of barrels in cross-drainage structures also contribute significantly to cross-drainage failure by creating a flow barrier due to the intermediate columns. The drainage failure impact assessment result showed that both cross- and longitudinal drainage failures primarily impact road pavement following transport disruption and traffic accidents, accounting for 38.5%, 18%, and 16%, respectively. Our research recommended that the mitigation measures for drainage failure are proper asset management and maintenance, appropriate construction supervision, and awareness creation, with weights of 36.3%, 15.5%, and 15.3%, respectively. As a drainage problem mitigation measure, the longitudinal drainage analysis results showed that the provision of a combination of cross-fall slopes, gutter slopes, and local depressions at the inlets can contribute to an increase in the trapping efficiency of the drainage system by 50%, which can reduce surface flooding substantially.

Flood vulnerability and Risk assessment using the Integration of Analytical Hierarchy Process (AHP), GIS, and Remote Sensing: A Case Study of southern Oromia Region.

Many people have died, and economies have been devastated by flooding, which is one of the world's most prevalent and catastrophic natural catastrophes. As a result of human activity on the land, the flooding patterns have changed. Imperfect drainage infrastructures, as well as various activities such as deforestation, are exacerbating the flood. In Ethiopia, southern Oromia is one of the regions affected by flooding, with the West Guji and Guji zones being the most frequently flooded places. People are exploiting natural vegetation for various purposes as a result of rapid population growth, resulting in deforestation and susceptibility to natural disasters such as floods. As a result, identifying flood-prone locations in great detail is essential for effective issue solving. Thus, this research was conducted to construct flood sensitive and flood risk mapping in southern Oromia utilizing the Remote Sensing, AHP (analytical hierarchy Process), and GIS. Eight flood-causing factors, such as drainage density, rainfall, elevation, slope, TWI, soil type, distance from the river, were developed in the GIS environment, and ERDAS Imagine software was employed to make land coverage and land usage data. The weighted overlay MCE approach was then used to construct a flood-sensitive map based on the AHP pairwise comparison of eigenvector value. To determine flood risk, population density, a vulnerable flood map, and land usage/land coverage layer were overlaid, having equal weightage. The flooding vulnerability outcome in the southern Oromia indicates that 0.3% (20.53km2), 31.4% (24986.4km2), 62 % (49310.6km2), 6.39% (5081.98km2), and 0.19% (148.866) is, very high, high, moderate, low, and very low flooding vulnerable region correspondingly. From the flood risk map, it was estimated that 2% (1587.3km2), 19.3% (15384.4km2), 75.5% (60071.7km2), and 3.15% (2505.3km2) of the area were endangered to very high, high, moderate, and low, flood risk levels correspondingly. As a result, the study will assist the relevant authorities in formulating development policies based on the existing flood danger and risk in the area.

Supporting Sustainable Communities in Slum Settlement Areas by Optimizing Geospatial Technology and Land Management Approaches in Kertapati District, Palembang

Slum areas have always been a concern in development planning. In fact, this has become one of the goals of the 2030 Sustainable Development Goals (SDGs), especially Sustainable Cities and Communities. According to the United Nations Development Program (UNDP), in the coming decades, 828 million people are estimated to live in urban slums and this number will continue to increase. While in Indonesia, there are slum areas covering an area of 86,548 hectares, 28% of which are located on the island of Sumatra. Palembang, one of the big cities in Sumatra, also faces the problem of slum settlements in its urban area, which is 3,607 hectares. This study aims to determine the level of slums in the residential area in Kertapati District which is included in the slum area in Palembang City and furthermore, recommends the concept of land management as a solution to these problems. The variables used in this study consisted of the physical variables of settlements, basic infrastructure and land ownership. Data on building density, building layout and building construction are used to describe the physical variables of settlements. While the basic infrastructure variables are explained by data on clean water infrastructure, solid waste infrastructure, drainage infrastructure, residential road infrastructure and sanitation infrastructure. For the variable of land ownership, data on status and land ownership are used. The data was obtained through Sentinel 2A satellite imagery in 2022 and from conducting field surveys and in-depth interviews with several local residents. Furthermore, the data was analyzed using a map overlay-based scoring of each variable using a Geographic Information Systems. The results of this study obtained a map of each variable level of settlement slums and a map of the slum level of settlements in Kertapati District with the level of settlement slums divided into light slum classes in 2 villages with a percentage of 11.51%, medium slum class in 1 village with a percentage of 35.96% and heavy slum class in 3 villages covering 52.53% of the total area of Kertapati District. This shows that the settlements in Kertapati District are dominated by heavy class slums, so this study recommends the concept of Land Consolidation land management with the Land Readjustment approach as an alternative to handling slum areas in Kertapati District, Palembang City.

Study on Planning and Design of Blue-Green-Gray Transformation of Lakeside Cities to Deal with the Complex Urban Waterlogging Caused by Extreme Rainstorm

Some lakeside cities may suffer from urban waterlogging owing to the backwater effect caused by the rise of lake water levels under a extreme rainfall scenario in the basin, but it is not suitable for large-scale gray drainage infrastructure upgrading in high-density lakeside urban built-up areas. This study, as per this, constructs the blue-green-gray infrastructure reconstruction planning and design mode to alleviate the waterlogging in the extreme rainstorm scenario of the lakeside city. Extending the Shiwuli River Basin in Hefei City, Anhui Province, China as an example, this study uses SWMM software to simulate the waterlogging situation in the study area under an extreme rainstorm under the urban planning scenario. According to the waterlogging situation, different hydrological scenarios (scenarios where the pipe network can and cannot discharge normally) are used to plan and design the blue-green-gray infrastructure reconstruction of the study area with both constructed land and non-constructed land. The research results show that just the planning and design of blue and green space can effectively reduce the degree of urban waterlogging, and with the cooperation of artificial pre-drainage, its own hydrological characteristics and geographical conditions can be used to prevent urban waterlogging caused by the backwater effects of a lake. In this study, the blue-green-gray transformation planning and design model of lakeside cities can deal with the complex urban waterlogging caused by extreme rainstorms, and the model could be extended to other cities along rivers or lakes with similar conditions.

Drivers and coping mechanisms for floods: experiences of residents in urban Kumasi, Ghana

Over the last few years, the occurrence and severity of climate change-induced floods in urban Kumasi, Ghana, have increased considerably, leading to devastating effects on both lives and properties. Yet, policy developments have often ignored the perspectives of residents who have experienced these floods. This study used a mixed-method approach including household surveys with 150 households and 5 key informant interviews to determine the drivers and coping mechanisms for floods in three selected communities in urban Kumasi, Ghana. Rainfall data (2001–2021) were analyzed using the Mann–Kendall trend test. A binary logistic regression was used to determine the enablers and barriers to coping mechanisms for floods. Results showed that the study respondents perceived changes in rainfall and floods through increasing amounts of rainfall, increasing duration of the rainy season, and increased incidences of floods. The perceptions of the respondents regarding rainfall changes were consistent with the analyzed rainfall data (2001–2021) which showed an increasing annual rainfall. A multiplicity of causes including poor design of drains, choked drains, and inadequate drainage infrastructure were reported by the study respondents. Destruction of properties, decreased economic productivity and soil erosion were reported as the major effects of floods. The respondents implemented various coping mechanisms including temporary migration and relying on family and friends to manage the adverse effects of floods. Findings indicated that access to climate information, access to household communication gadgets, age of respondents, and period of staying in the community significantly affected the coping mechanisms employed by the respondents (p < 0.05). Barriers impeding the implementation of these coping mechanisms reported by the study respondents included financial constraints, inadequate support from government and non-governmental institutions, and a lack of understanding of early warning systems. Accessibility to timely climate information should be prioritized to help people improve their information-sharing and decision-making processes in managing floods in urban Kumasi.

Assessment of Microbial Contamination in the Infulene River Basin, Mozambique

Water microbial contamination is one of the major threats to human health. The study focus is on Infulene River Basin, a urban catchment with mainly informal settlements, with limited water supply and sanitation. In the catchment there are two wastewater treatment plants, one hospital and beer factory located on the banks of the main stream; water from this stream is used for urban agriculture and domestic uses by some dwellers. These factors present a significant health risk from water-borne diseases. At the moment there is limited knowledge about the level of microbial contamination of the different sources of water at the disposal of the communities. Thus, a preliminary study on fecal microbial contamination was conducted targeting the Infulene River and the drainage system from the nearby Maputo city draining into the system, with additional investigation on the drinking water provided by the city water supply company. The quantification of Total Coliforms (TC) and Escherichia coli (EC) was conducted at several sampling locations. Results were compared with official drinking water standards. Eighty two percent (82%) and 61% of Infulene river water and drainage water samples were positive for TC (105 to 109 NPN/100 mL) and EC (105 to 107 NPN/100 mL), respectively. For drinking water samples, 63% and 23% were positive for TC (up to 6000 NPN/100 mL) and EC (up to 1000 NPN/100 mL), respectively. Higher microbial contamination was found in neighborhoods with the poorest sanitation and shallow groundwater, i.e., Chamanculo, Xipamanine, Mafalala, Aeroporto and Maxaquene, a situation that was more expressive during the rainy season. Overall, the study confirmed the high vulnerability to microbial contamination of all sources investigated due to poor sanitation and lack of drainage infrastructure. The risks to human health might be even higher considering that contaminated water is used for gardening of vegetable watering and domestic use.

Estimation of average long-term soil salinity of arable land Golodnaya Steppe in Kazakhstan

In the Syr-Darya River basin on the border between Kazakhstan and Uzbekistan there is an irrigation massif “Golodnaya Steppe”. In its Kazakh part, the agricultural procedure of winter washing of fields is practiced for cleaning from secondary salinization. It is carried out in January-February by flooding saline fields. At the same time, water mirrors are formed on the arable land, which can be recorded using satellite data. In this study, based on satellite information from Landsat 8,9 and Sentinel 1,2 for the period January-February 2016-2022, masks of water mirrors were created, located on irrigated arable land in winter. These masks diagnose seasonal farmers’ activity on cleaning arable land from secondary salinization. Analysis of the field washing frequency in the period 2016-2022 allowed to estimate the average long-term salinity of irrigated arable land in the analyzed region. The data obtained are of interest for the zoning of the territory of the irrigation massif “Golodnaya Steppe” in Kazakhstan according to the level of secondary salinization, which is important for optimizing the work to improve the irrigation and drainage infrastructure.

The Elephant and the Goddess: How Water Systems Models Could Help Preserve Civil Life

In this paper, the elephant in the room is the issue of projected longer-term population growths and declines in a finite world, while the Greek goddess Panacea is the opportunity to non-disruptively attain populations that live sustainably and solve some of the world’s most pressing problems. Particularly addressed in this paper is the potential of water systems models and modeling to facilitate a transition to planning for long-term sustainable lives of sustained quality. Anent “longer term”, for simplicity we consider both a typical period of family memory, for instance from 1880 to 2100, or 220 years, about seven or eight generations, as well as the anthropocene millenia. After setting down background definitions and introducing the underlying issues, we review key population and well-being trends, attitudes, and impacts, citing acknowledged experts. How, where, and when population and economic decline will occur is not covered; the paper rather suggests implications for water resources engineering and for water management modeling, even if the transition will be patchy in space and time. Confronting imminent degrowth, significant revisions of current water modeling practice are suggested: planned, phased, orderly removal of projected and existing urban development and drainage infrastructure and, for instance and where applicable, systematic restoration of keystone ecology and natural hydrology. Whether the imminent degrowth era will persist is uncertain, evidently. Also alluded to is degrowth’s countervailing assurance of improved well-being, providing more time for individuals to further their personal interests. The original PowerPoint presentation is at Robillynians.org and also at the CHI website (James 2023). Questions raised and the answers given at the presentation are included in the appendix to this paper.

NPA Cells in the Marine Environment

Novel Polymeric Alloy (NPA) cells are a cellular confinement system with the engineering properties required by international standards for long-term confinement in demanding infrastructure projects. Three-dimensional NPA cells are used as a cover protection system against channel, stream and shoreline erosion caused by flowing water and tractive forces. NPA cells enhance the performance of conventional erosion control materials and dissipate energy from flood, current and wave action for hydraulic and marine structures and are a best available technique for canals, channels, drainage, shorelines, riverbanks, sea-walls, dams and port infrastructure. Soft or hard armor is used to optimize the erosion protection for natural or man-made channels, hydraulic structures and barriers. The surface treatment is dependent upon the geometry, hydraulic, site and environmental conditions along the water course, as well as optimization and cost-efficiencies. For example, sand infill is used for beachfront erosion control, vegetation for riverbank protection, gravel in sites subject to moderate flow velocities and concrete hard-armor in high velocity channels and walls subject to wave action. Reinforcement of load support structures in port applications can use sand, granular or recycled materials. Whereas the suitability of a cellular confinement system is directly dependent on the key attributes of the cell as well as its geometry, cells made of Novel Polymeric Alloy (NPA) have measurable higher tensile strength, resistance to deformation and environmental durability to hydraulic forces and thermal cycling over the project lifespan than conventional HDPE-based soft-cells. This includes high resistance to photochemical degradation – leaching of additives, oxidation and UV light – to preserve confinement for the lifespan of the project. Concrete solutions in non-erodible canals and walls are particularly advantageous with NPA cells. While the cellular mattress eliminates form work for fast construction, NPA cells add high tensile strength to the concrete. The creates a strong yet flexible mattress, which absorbs hydraulic forces and ground movement and resists cracking of the concrete for improved surface durability. Additionally, the high reinforcement factor of the NPA system also enables a reduction in concrete thickness to improve cost-effectiveness and sustainability. These properties also make NPA cells suitable to load support pavements used in marine ports, wharfs, terminals and container yards situated on soft, compressible and saturated soils, using sand for structural infill with no loss in structural stability.

The effect of sanitation risk on toddler stunting incident with geographically weighted regression approach in Malang Regency, Indonesia

Stunting is a fundamental problem in Indonesia's human development. The risk factors for stunting are very complex, including inadequate environmental sanitation. This study aims to analyze and map the influence of spatially correlated sanitation risk on the incidence of stunting toddlers in Malang Regency, Indonesia. Data collection was carried out by interviewing respondents using questionnaires, counting stunting toddlers, and observing environmental sanitation objects. Determination of respondents was done purposively with the following stages. First, at the village level, 75 sites were selected based on the following criteria: population density; poverty level; the presence of streams, drainage or irrigation canals; and flood vulnerability. Furthermore, in each village, 40 respondents were selected based on the following criteria: women aged between 18 to 65 years, came from poor families and had a child (or children). When the number of respondents who were willing to participate is less than 40 people in each village, they were replaced by other respondents based on recommendations from village officials. A total of 3000 respondents have participated in this study. The selected respondents include wives, dependent married women or widows. The spatial analysis approach was carried out using the Geographically Weighted Regression (GWR) method. Based on the results of the analysis of the spatial effect of the GWR model, the Sanitation Risk Factors that significantly affected the incidence of stunting in Malang Regency were; Environmental Drainage (greywater), Solid Waste, and Domestic Wastewater (black water). Clean and Healthy Lifestyles and Water Sources have less effect on sanitation risk. This study recommends government and public interventions to improve environmental sanitation including integrated waste management, improvement of drainage infrastructure, construction of standardized toilets, and carrying out health promotion efforts with education to increase public awareness.

Soil and Irrigation Water Salinity, and Its Consequences for Agriculture in Ethiopia: A Systematic Review

The salt problem in Ethiopia has been further exacerbated by a number of factors, including poor water quality, ineffective on-farm water management techniques, and a lack of appropriate and technically sound drainage infrastructure at irrigation sites. Despite its importance, no systematic review or documentation of the extent and consequences of the problem has been made so far. This scientific review primarily focuses on original studies published in the country, notably in arid and semi-arid regions where salinity issues have a significant influence. The data indicated that soil and irrigation water salinity have a substantial link with crops and agricultural communities in Ethiopia. Salinity has a significant impact on soil and water fertility, resulting in poorer agricultural production, food insecurity, and poverty. Salinity has a significant impact on crops in the country, from the germination stages to the harvesting stages during the growing season. If the current state of soil and water management continues, the severity of both soil and irrigation water salinity will reach an irreversible level that significantly impedes the country’s agricultural production capacity. As a result, cultured irrigation water treatment, crop selection based on salinity and sodicity levels, irrigation water quality, leaching, and fertilizer use in combination with organic manures are scientifically proven actions to address the salinity problem. Furthermore, to adequately reclaim and manage salinity in Ethiopia’s dryland saline zone, multi-stakeholder participation is required.

The Main Challenges for Improving Urban Drainage Systems from the Perspective of Brazilian Professionals

Urban drainage systems play an important role in the complex ecosystem of cities and are often subject to challenges that hinder their functioning. Although identifying these challenges is essential for developing policies and actions to improve drainage systems, there is a lack of studies addressing these challenges. This work has two objectives to contribute to filling this gap: (1) to research the main challenges that make it difficult to improve urban drainage systems; and (2) to prioritize them. We conducted extensive and detailed bibliographic research in which 15 challenges were identified, and a survey with 30 Brazilian professionals with experience in the concerned field. The results showed that 15 challenges identified in the literature were considered important by the survey respondents. It also showed that the most important challenges concern the inadequate functioning of drainage infrastructure, dynamics of city expansion, system maintenance, vulnerability of urban areas, public policies, and investments.

Soil moisture estimates over sporadically flooded farmlands: synergies and biases of remote sensing and in situ sources

ABSTRACT Soil moisture plays a key role in hydrological processes in ecosystems and regulates water and energy exchanges between the surface and the atmosphere. Global coverage of surface soil moisture (SSM) satellite estimates makes them a fundamental source of information, while the validation of these estimates is usually based on in situ measurements, ideally from networks that cover areas similar to the satellite data resolution. However, as we expose in this study, both SSM data sources face challenges over extremely flat regions with large SSM variability. A homogenous farming region in the subhumid Pampas of Argentina, characterized by a large interannual rainfall variability as well as a marked annual cycle of rainfall and cropping, was taken as a case study. The region is almost devoid of irrigation and drainage infrastructure, is subject to large episodic flood and waterlogging events and holds an in situ network belonging to the Argentinean National Commission for Space Activities. This in situ network was set to evaluate the soil moisture estimated by satellite missions, such as SMAP and SAOCOM. However, several of these sites have been placed close to homesteads in a more uniform perennial vegetation than the prevailing seasonal crop. In this work, we examine how this placement bias influences SSM dynamics and its interpretation. We find that in situ data fails to capture the large seasonal and daily SSM variability caused by the cropping dynamics as well as the situation of waterlogging. As for the satellite SSM estimates, provided by the SMOS and SMAP missions in this study, while they capture the impact of cropping on SSM, data gaps can hinder robust statistical analysis. During periods of waterlogging, SSM values can lie outside the dynamic range considered valid by satellite missions, and thus are usually removed by users, creating ‘blind spots’ for high soil water content stages in flood-prone lands. Our study underlines the importance of using multiple sources of information to interpret the hydrological status, including data from in situ measurements and remote sensing estimations of SSM as well as, when available, locally collected information such as reports from national, sub-national and private agro-industrial agencies.

Impacts of climate change on IDF curves for urban stormwater management systems design: the case of Dodola Town, Ethiopia.

Climate change impacts are one of the global challenges that change the intensity and frequency of rainfall. The Dodola town has previously experienced rainfall-induced flooding effects, and future floods may be more frequent and severe due to possible variations in rainfall intensity due to climate change. In this study, the rainfall intensity-duration-frequency (IDF) curves are updated for the design of urban stormwater drainage infrastructures under climate change to reduce flooding risks. To assess the variations in the rainfall intensity, the future IDF curves for the periods (2020-2100) and two GCMs (CanESM2 and HadGEM2-ES) were derived and compared to the current IDF curves. It was found that rainfall intensities for future climate conditions will differ from the current period for all durations and return periods. The comparison results show that the relative change between future rainfall intensities and historic rainfall ranges from 1.5 to 30.6%, 2.48 to 42.6%, and 3.7 to 23.24% for 2020-2040, 2041-2070, and 2071-2100, respectively. The IDF relationships revealed that as a result of climate change, urban flooding will increase in the future. This study will help to better understand the impacts of climate change on rainfall IDF relationships, as well as have implications for the design of current and future stormwater management systems in Dodola, Ethiopia.

Nitrogen loads in urban surface runoff from a major, cold-region North American city in 1991–2021

Long-term monitoring of pollutant loads in urban surface runoff is important but uncommon. In this study, we examined nitrogen loads in stormwater and snowmelt runoff from four urban catchments of a major, cold-region North American city over the past 31 years (1991–2021). Temporal variability of total organic nitrogen (TON), nitrate and nitrite nitrogen (NOx-N), total ammonia nitrogen (TAN), and total nitrogen (TN) were similar in the four catchments, which had an increasing trend from 1992 (TN: 1.3–3.4 kg/ha/year) to 2006–2011 (TN: 5.5–19.3 kg/ha/year) and a decreasing trend afterward. Trends and change points in the four urban catchments were influenced by storm/snowmelt events, land use, urban drainage infrastructure issues, and stormwater management facilities. The maximum monthly fluctuation occurred in March/April and July due to high variations of snowmelt and storm events. The ratios of monthly loads during the storm season (April to October) to the snow season (November to March) for TON, NOx-N, and TN were 1.31, 1.12, and 1.15, respectively; whereas it was 0.95 for TAN. TKN, TAN, and TN event mean concentrations (EMCs) in snowmelt were higher (18.0%, 94.0%, and 10.8%, respectively) than those in stormwater. However, the NOx-N EMC in snowmelt was lower (9.3%) than in stormwater.