The Urban River Syndrome: Achieving Sustainability Against a Backdrop of Accelerating Change

Human activities have been affecting rivers and other natural systems for millennia. Anthropogenic changes to rivers over the last few centuries led to the accelerating state of decline of coastal and estuarine regions globally. Urban rivers are parts of larger catchment ecosystems, which in turn form parts of wider nested, interconnected systems. Accurate modelling of urban rivers may not be possible because of the complex multisystem interactions operating concurrently and over different spatial and temporal scales. This paper overviews urban river syndrome, the accelerating deterioration of urban river ecology, and outlines growing conservation challenges of river restoration projects. This paper also reviews the river Thames, which is a typical urban river that suffers from growing anthropogenic effects and thus represents all urban rivers of similar type. A particular emphasis is made on ecosystem adaptation, widespread extinctions and the proliferation of non-native species in the urban Thames. This research emphasizes the need for a holistic systems approach to urban river restoration.

Assessment of Water Quality of a Transboundary River at Brahmanbaria

This investigation was undertaken to evaluate some physico-chemical parameter of water of the trans-boundary Haora River in Brahmanbaria during October 2018 to September 2019 from three different sites. The study revealed that air temperature at three different sites ranged 13 – 38 °C while the water temperature was 11 – 32 °C. Transparency of water varied from 18 – 55 cm Secchi depth and became more turbid during monsoon. The average values of pH and dissolved oxygen (DO) both in sites and seasons were within the standard limits for aquatic organisms. Total dissolved solids (TDS) were found between 77 and 352 mg/L and varied greatly in seasons. Electric conductivity (EC) was ranged 135 to 650 μS/cm. On the other hand, maximum and minimum hardness of water were recorded as 322 mg/L and 118 mg/L respectively and become lowest in monsoon. The rainy season bear high torrential water which brought huge amount of different types of garbage through the water flow from the Indian part. Most of the garbage are of floating and submerged type as plastic containers, bottles, polybags, cans, etc along with natural debris. During the study period highest (172 kg) and lowest (113 kg) plastic garbage were collected in May and July respectively. This foreign garbage may impair the normal healthiness of the river ecology. Bangladesh J. Zool. 49(1): 137-146, 2021

The Thames: Arresting Ecosystem Decline and Building Back Better

The Thames is an iconic river of cultural and historical importance. A cyclical process of deterioration during the last two centuries, followed by technology-driven restorations, including two major sanitation projects with a third currently underway, has produced detrimental effects on the Thames ecosystem. This paper overviews the river ecology, pollution and other anthropogenic pressures, which lead to biodiversity loss and the proliferation of non-native, pollution-tolerant species. This article further reviews past and current management, sampling and assessments trends and provides an objective overview of remediation, restoration and monitoring needs, practices and research gaps. Here, we argue that restoration work, if maladapted, can be ineffective in improving resilience or have unexpected side effects that make matters worse rather than better. We explain the need for a broader view of river restoration and management including consideration of species transplants in achieving overall sustainability against a backdrop of accelerating change in the Anthropocene.

In-stream turbines for sustainable hydropower development in the Amazon river basin

<p>Given the ongoing and planned hydropower development projects in the Amazon River basin, appalling losses in biodiversity, river ecology and river connectivity are inevitable. These hydropower projects are proposed to be built in exceptionally endemic sites, setting records in environmental losses by impeding fish movement, altering flood pulse, causing large-scale deforestation, and increasing greenhouse gas emissions. With the burgeoning energy demand combined with the aforementioned negative impacts of conventional hydropower technology, there is an imminent need to re-think the design of hydropower to avoid the potentially catastrophic consequences of large dams. It is certain that the Amazon will undergo some major hydrological changes in the near future because of the compounded effects of climate change and proposed dams, if built with the conventional hydropower technology. In this study, we present a transformative hydropower outlook that integrates low-head hydropower technology (e.g., in-stream turbines) and multiple environmental aspects, such as river ecology and protected areas. We employ a high resolution (~2km) continental scale hydrological model called LEAF-Hydro-Flood (LHF) to assess the in-stream hydropower potential in the Amazon River basin. We particularly focus on quantifying the potential and feasibility of employing instream turbines in the Amazon instead of building large dams. We show that a significant portion of the total energy planned to be generated from conventional hydropower in the Brazilian Amazon could be harnessed using in-stream turbines that utilize kinetic energy of water without requiring storage. Further, we also find that implementing in-stream turbines as an alternative to large storage-based dams could prove economically feasible, since most of the environmental and social costs associated with dams are eliminated. Our results open multiple pathways to achieve sustainable hydropower development in the Amazon to meet the ever-increasing energy demands while minimizing hydrological, social, and ecological impacts. It also provides important insight for sustainable hydropower development in other global regions. The results presented are based on a manuscript under revision for Nature Sustainability.</p>

Does river restoration result in improved environmental heterogeneity?

Rivers can shape diverse landscapes, determine the spatial connectivity of river and terrestrial life, and provide a variety of resources and services. Rivers are often over-bound due to the need for flood control and irrigation. Rivers affected by human disturbance often require restoration to improve the ecosystem services they provide. Environmental heterogeneity is generally considered to be the non-uniform variation of environmental elements in space and/or time. The relationship between variability in physical characteristics of restored rivers and biological communities in the river environment is a highly complex feedback, and studying and summarising changes in environmental heterogeneity following river restoration can help refine methodologies for monitoring river restoration outcomes. This study highlights the variability in river geomorphology and river ecology, and demonstrates the feasibility and necessity of incorporating environmental heterogeneity indicators into river restoration outcome evaluation systems at three levels: hydrological, geomorphological and ecological.