Arcadis NV is a global design, engineering and management consulting company based in the Zuidas, Amsterdam, Netherlands. It currently operates in excess of 350 offices across forty countries. The company is a member of the Next 150 index. Arcadis was founded as the land reclamation specialist Nederlandsche Heidemaatschappij in 1888. Over the following decades, the firm became involved in various development projects, initially with a rural focus. During the second half of the 20th century, the company developed its international presence as well as its shift into urban development. As a consequence of a drastic restructuring in 1974 that divided the company, it became Heidemij. It pursued a European-orientated expansion programme immediately following the end of the Cold War. During 1993, the firm merged with the North American business Geraghty & Miller, resulting in its listing on the NASDAQ index. During 1997, the company adopted its current name, Arcadis; subsidiaries were similarly rebranded. Since 1990, the company has largely expanded itself via a series of acquisitions and mergers, which have allowed it to both expand its presence in existing markets as well as to enter new ones. It performs design and consultancy services on a wide variety of undertakings. Arcadis (either directly or via subsidiaries) has been involved in several high profile construction projects, including London City Airport and the A2 motorway.
Enhanced seismic hazard assessments are needed to improve codes of practice for use in earthquake-prone regions. In 2020, Nepal published an update to the 1994 building code, which incorporates learning from new research after the 7.8 Mw 2015 Gorkha earthquake and best practices from seismic codes at the international level. In this technical note, the seismic hazard of the latest version of the code is compared with recent probabilistic seismic hazard analysis studies developed for the region including some results from the Seismic Safety and Resilience of Schools (SAFER) project in Nepal. The comparison is contextualized within the overall framework of best performance requirements to effectively improve the building stock at the national level accounting for available resources.
Potable reuse is becoming increasingly common wherein reverse osmosis (RO) is often employed for desalination and removal of trace organic compounds including per- and polyfluoroalkyl substances (PFAS). While PFAS are well-removed by RO, to our knowledge, there are no published data documenting their accumulation in fouling layers on end-of-life membranes. This represents a critical knowledge gap that could (i) inform safe handling/ disposal of end-of-life elements, (ii) mechanistically understand PFAS removal and associated transient changes as fouling progresses, and (iii) model their transport across membranes. Herein, we report concentrations of PFAS comingled with surface foulants in lead and lag elements from all 3-stages of a full-scale potable reuse RO facility that were replaced after 4-years of operation. Long-chain perfluoroalkyl carboxylic acids (C >= 8) and perfluoroalkyl sulfonic acids (C >= 6), and perfluoroalkyl acids precursors accumulated along with bioorganic foulants. Contrapositively, only a negligible amount of PFAS were detected on the stage 3 lag element, which was dominated by inorganic fouling. Overall, prevalence of long-chain PFAS (perfluorooctanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid) and perfluoroalkyl carboxylic acid precursors were strongly correlated with selected characteristics of bioorganic foulants. This included volatile organic matter, proteins and polysaccharides content of extracellular polymeric substances, the humification index, and selected protein secondary structures. Results suggested the role of hydrophobic interactions on PFAS accumulation (with possible contributions from other mechanisms) and pointed to the need for additional measurements to develop a global picture of the extent, magnitude, and mechanisms of their accumulation on end-of-life membranes.
The aim of this study was to analyze historical land use and land cover (LULC) changes in the Upper Vistula Basin (Central Europe, Poland) during the period 1990–2018 and to develop a long-term projection of LULC changes until 2100 using the CA–Markov model. The analyses were based on the CORINE Land Cover database. The results showed that the dominant processes shaping the land-use structure were urbanization, agricultural land transformation, and forest succession, with the most dynamic changes occurring after 2000. Agricultural land represented the primary source of land-use transitions, mainly converting into built-up areas and forests. Model validation confirmed its high predictive performance (OA = 0.917, Kappa coefficient = 0.888, Macro F1 = 0.846, Weighted F1 = 0.917, Quantity Disagreement = 0.025, and Allocation Disagreement = 0.057), supporting its application for long-term LULC projections. The forecasts indicate that the area of built-up land will increase from 3307.4 km2 in 2025 to 3460.3 km2 by 2100, while the forest area will expand from 16,698.1 km2 to 17,366.6 km2. In contrast, mosaic agricultural areas are projected to decline markedly, from 4052.3 km2 to 3349.6 km2, representing the largest change among all analyzed land-use classes. Although the rate of change is expected to gradually decrease after 2025, the cumulative effects of long-term urbanization, forest succession, and the reduction of agricultural land will lead to substantial landscape transformation across the Upper Vistula Basin by the end of the twenty-first century. These projected changes reflect persistent socio-economic processes, including urban expansion, agricultural restructuring, and the abandonment of marginal farmland, as well as environmental processes promoting natural vegetation succession. The findings provide valuable information to support long-term spatial planning, environmental management, and the development of sustainable land-use policies under ongoing socio-economic and environmental change.
Bridges and viaducts are primary assets on transport infrastructure systems. The recent failures of the Francis Scott Key Bridge and the Polcevera Viaduct have highlighted the need to regularly reconsider the resilience of bridges. The disruption to railways and seaways below these bridges has highlighted the need to consider all uses of the bridge, not just those on the structure. This paper outlines a new method to estimate the resilience, using data on the use of the bridge based on the number of road lanes, rail lines, footways or navigable waterways on or under the bridge as the measure of performance or functionality. The data for ten bridge collapses, with use functionality data and dates from which the restoration times are derived, are used to determine resilience. The results of the study show a correlation of increased resilience index with increasing restoration time. There is less correlation of resilience with bridge size based on number of lanes or lines. The consideration of all uses of the bridge (both over and under) can affect the calculated resilience index.
Periodic impulsive interventions arise naturally in the management of biological populations, including chemotherapy, pesticide application, and infectious-disease treatment. We develop general conditions for permanence in n-species population models subject to periodic multiplicative pulse disturbances. Our main result provides a sufficient condition for permanence in terms of weighted long-term growth rates on a Morse decomposition of the extinction set, explicitly separating the contributions of continuous population dynamics from those of the periodic pulse. To establish this result, we transform the impulsive system into an associated autonomous continuous-time dynamical system and use this correspondence to extend classical permanence theory to periodically pulsed models. We further show that the same conditions imply robust permanence under sufficiently small perturbations to the continuous dynamics, pulse period, and pulse effects. We illustrate the framework with two Lotka-Volterra models motivated by biological control: competition between chemotherapy-sensitive and chemotherapy-resistant cancer cells, and integrated control of an agricultural pest using pesticides and parasitoids. These examples demonstrate how intervention frequency and intensity interact with underlying ecological interactions to determine whether populations coexist or are excluded. Our results provide a general framework for analyzing persistence in ecological systems subject to repeated discrete disturbances.
