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Each year millions of larval and 0+ juvenile fishes are recruited into estuarine fish populations around the world. For several decades the roles of littoral aquatic and emergent macrophyte habitats as nursery areas for many of these species have been studied and debated at length. This review attempts to collate the published literature and provide a synopsis of the varying, and sometimes conflicting, views on this topic. A large number of studies have shown that a range of species and an abundance of juvenile fishes are associated with littoral macrophytes in estuaries, some of which are found almost exclusively within particular plant habitats. Other studies have shown the movement of certain juvenile fishes from one type of littoral plant habitat to another as they grow and develop new feeding strategies and dietary requirements. Overall, it would appear that seagrass beds and mangrove forests are particularly favoured by fishes as nursery areas in both estuaries and the nearshore marine environment, and that the loss of these habitats leads to a decline in juvenile fish diversity and abundance. Salt marshes and reed beds generally have a lower diversity of fishes than seagrass and mangrove habitats, possibly due to the more temperate location of salt marshes and the dense structure of some reed beds. Stable isotope studies in particular are providing increasing evidence that carbon assimilated by juvenile fishes in mangrove, marsh and reed habitats is not primarily derived from these macrophytes but comprises a mixture of these sources and a diverse range of macro- and microalgae, particularly epiphytic, epipsammic, epipelic and epilithic diatoms and algae found in these areas. The closest trophic link between the macrophyte food chain and associated fishes occurs in seagrass habitats where a significant portion of the overall macrophyte leaf biomass often consists of epiphytic algae and diatoms. Structurally, mangrove forests, salt marshes and reed beds provide more substantial and complex habitats for juvenile fish refuge, but some of these habitats are constrained with regard to nursery provision by being fully exposed at low tide. Under such circumstances the small fish are sometimes forced into creeks and channels where larger piscivorous fishes are often present. Overall, in terms of a broad ranking of the four habitats as potential fish nursery areas, seagrass meadows are ranked first, followed by mangrove forests, salt marshes and then reed beds. This ranking does not imply that the lower ranked habitats are unimportant, since these plants perform a myriad of ecosystem services that are not related to the provision of fish nursery areas, e.g. bank stabilization. It is also emphasized that the protection of specific plant species should not be encouraged because it is important to have an ecosystem approach to conservation so that the diversity of habitats and their connectivity for fishes is maintained.

The Silurian-age rise of land plants is hypothesized to have caused a global revolution in the mechanics of rivers. In the absence of vegetation-controlled bank stabilization effects, pre-Silurian rivers are thought to be characterized by shallow, multithreaded flows, and steep river gradients. This hypothesis, however, is at odds with the pancontinental scale of early Neoproterozoic river systems that would have necessitated extraordinarily high mountains if such river gradients were commonplace at continental scale, which is inconsistent with constraints on lithospheric thickness. To reconcile these observations, we generated estimates of paleogradients and morphologies of pre-Silurian rivers using a well-developed quantitative framework based on the formation of river bars and dunes. We combined data from previous work with original field measurements of the scale, texture, and structure of fluvial deposits in Proterozoic-age Torridonian Group, Scotland—a type-example of pancontinental, prevegetation fluvial systems. Results showed that these rivers were low sloping (gradients 10−5 to 10−4), relatively deep (4 to 15 m), and had morphology similar to modern, lowland rivers. Our results provide mechanistic evidence for the abundance of low gradient, single-threaded rivers in the Proterozoic eon, at a time well before the evolution and radiation of land plants—despite the absence of muddy and vegetated floodplains. Single-threaded rivers with stable floodplains appear to have been a persistent feature of our planet despite singular changes in its terrestrial biota.

River systems are increasingly under stress and pressure from agriculture and urbanization in riparian zones, resulting in frequent engineering interventions such as bank stabilization or flood protection. This study provides guidelines for a more sustainable approach to river management based on hydrogeomorphology concepts applied to three contrasted rivers in Quebec (Canada). Mobility and flooding spaces are determined for the three rivers, and three levels of “freedom space” are subsequently defined based on the combination of the two spaces. The first level of freedom space includes very frequently flooded and highly mobile zones over the next 50 years, as well as riparian wetlands. It provides the minimum space for both fluvial and ecological functionality of the river system. On average for the three studied sites, this minimum space was approximately 1.7 times the channel width, but this minimum space corresponds to a highly variable width which must be determined from a thorough hydrogeomorphic assessment and cannot be predicted using a representative average. The second level includes space for floods of larger magnitude and provides for meanders to migrate freely over a longer time period. The last level of freedom space represents exceptional flood zones. We propose the freedom space concept to be implemented in current river management legislation because it promotes a sustainable way to manage river systems, and it increases their resilience to climate and land use changes in comparison with traditional river management approaches which are based on frequent and spatially restricted interventions.

Riparian zones act as ecological engineers through stream bank stabilization, pollutant buffering, energy provision to food webs, and groundwater recharge. In the ongoing situation of declining river water quality and global environmental changes, an integrated strategy involving aspects of riparian zone monitoring and management is essential for policy-making and socio-economic services. To address this, a review of papers and policies from 1980 to 2023 is conducted to identify existing technologies and their gaps. 298 articles were reviewed to understand riparian habitats and their ecological function. Analysis shows that field-based monitoring approaches have considerable limitations, including increased labor costs, and methodologies that result in ineffective riparian zone management. These issues can be overcome using geospatial technologies due to their high-quality and long-term inventories and ease of map updates. Unmanned aerial vehicles are widely used for low-cost monitoring in recent times. The result shows that there is no policy framework specifically addressing riparian zone management across the South Asian region which is home to the world’s largest population. Riparian buffer width requires attention across all stakeholders which are missing in the South Asian region and a few other countries across the globe. The authors suggest the use of buffer width consisting of Vetiver grasses of at least 5 m used in conjunction with woody vegetation of a 25-m filter strip. Strategies from the USA and Australia can also show the path towards the riparian zone sustainability.

Agricultural headwater streams are important pathways for diffuse sediment and nutrient losses, requiring mitigation strategies beyond in-field measures to intercept the transport of pollutants to downstream freshwater resources. As such, floodplains can be constructed along existing agricultural streams and ditches to improve fluvial stability and promote deposition of sediments and particulate phosphorus. In this study, we evaluated 10 remediated agricultural streams in Sweden for their capacity to reduce sediment and particulate phosphorus export and investigated the interplay between fluvial processes and phosphorus dynamics. Remediated streams with different floodplain designs (either on one side or both sides of the channel, with different width and elevation) were paired with upstream trapezoidal channels as controls. We used sedimentation plates to determine seasonal patterns in sediment deposition on channel beds and floodplains and monthly water quality monitoring. This was combined with continuous flow discharge measurements to examine suspended sediment and particulate phosphorus dynamics and reduction along reaches. Remediated streams with floodplains on both sides of the channel reduced particulate phosphorus concentrations and loads (−54 µg L−1, −0.21 kg ha−1 yr−1) along reaches, whereas increases occurred along streams with one-sided floodplains (27 µg L−1, 0.09 kg ha−1 yr−1) and control streams (46.6 µg L−1). Sediment deposition in remediated streams was five times higher on channel beds than on floodplains and there was no evident lateral distribution of sediments from channel to floodplains. There was no effect from sediment deposition on particulate phosphorus reduction, suggesting that bank stabilization was the key determinant for phosphorus mitigation in remediated streams, which can be realized with two-sided but not one-sided floodplains. Further, the overall narrow floodplain widths likely restricted reach-scale sediment deposition and its impact on P reductions. To fully understand remediated streams' potential for reductions in both nitrogen and different phosphorus species and to avoid pollution swapping effects, there is a need to further investigate how floodplain design can be optimized to achieve a holistic solution towards improved stream water quality.

To materialize the inherent opportunities of incoming sediment load, various interventions are being practiced for sediment management in rivers and delta systems. Broadly, the practiced methods can be divided into two categories: (i) management for accelerating siltation to enhance land reclamation and counterbalancing bank erosion (ii) management for de-siltation in the channels to maintain required navigational flow depth. The prerequisites for achieving the above targets at the same time are quite contradictory, as land reclamation requires more sediment, while maintaining navigational depth requires less sediment load. To address the aforementioned constraints, Bandal-like Structures (BLS), an indigenous nature-based solution, has proposed for redistributing the local flow-sediment regime to create a sediment deficit zone within the river side and a sediment surplus zone along the bankside, which can eventually be useful for the maintenance of navigational channels as well as bank stabilization. Based on research conducted over the last 20 years, this article discusses BLS's experiences in achieving both functions simultaneously. A well-documented case study of its application along a reach of the braided Jamuna River is one of many implemented BLS at various scales in the Ganges-Jamuna-Brahmaputra (GBM) system. Based on the performance of the implemented case study and existing indigenous knowledge, a hybrid approach integrating conventional and community sciences is proposed as a nature-based solution for sustainable sediment management in Bangladesh's river systems.

Soil erosion is expected to worsen in the future as a result of climate change, growing population demands, improper land use, and excessive exploitation of natural resources in India. Due to the growing population and changes in land use, it has become increasingly crucial to map and quantitatively assess soil for the purpose of sustainable agricultural usage and planning conservation efforts. The problem of soil erosion is mainly on steeper slopes with intense rainfall in parts of Western Ghats. The 20.17% of geographical area have been converted into wasteland due to soil erosion. The Revised Universal Soil Loss Equation (RUSLE) is a highly prevalent and effective technique utilized for estimating soil loss in order to facilitate the planning of erosion control measures. Despite the fact that RUSLE is accurately estimate sediment yields from gully erosion, it is an effective tool in estimating sheet and rill erosions losses from diverse land uses like agricultural to construction sites. The current study is mainly about combining the RUSLE model with GIS (Geographic Information System) to find out how much soil is being lost, particularly in Noyyal and Sanganur watersheds which is located in Coimbatore district of Tamil Nadu, India. This analysis is based on the soil order, with a significant proportion of alfisols and inceptisols being considered. The obtained outcome is contrasted with the established soil loss tolerance threshold, leading to the identification of the areas with the highest susceptibility to erosion. Within the narrower and more inclined section of the watershed, yearly soil loss scales from 0 to 5455 tonnes/ha/year, with an average annual loss of soil of 2.44 tonnes/ha. The severe soil erosion of 100 to 5455 tonnes/ha/year is found along the steep and greater slope length. The generated soil map was classified into six categories: very slight, slight, moderate, high, severe, and very severe. These classifications, respectively, occupied 6.23%, 14.88%, 10.56%, 15.70%, 7.73%, and 6.63% of the basin area. Based on the results of cross-validation, the estimated result of the present study was found to be very high compared to past studies conducted 0 to 368.12 tonnes/ha/year especially in very severe erosion zones. But very slight to severe erosion zones nearly matched with same level of soil loss. To protect the soil in the study area from erosion, more specific actions should be taken. These include micro-catchment, broad bed furrows, up-and-down farming, soil amendment with coconut coir pith composition, streambank stabilization with vegetation, and micro-water harvesting with abandoned well recharge. These actions should be carried out over time to make sure to work.

River ecosystems of regulated rivers are threatened by water extraction and flow regime alteration in the context of climate change and increasing human populations. Riparian plant root growth is important to sustain plant health and provide functions including bank stabilization. The root systems of riparian plants on regulated rivers may suffer from lower soil moisture due to lack of natural flow variability. This study aimed to evaluate how soil moisture influences the root system of a herbaceous riparian plant. Plants of Juncus amabilis were dug out along a soil moisture gradient, corresponding with positions close to or distant from the water margin and low or high relative bank elevation. Root depth, belowground space occupation, root mass fraction, and mean fractal dimension were used to evaluate root structural dynamics in relation to bank position and soil moisture. The ratio between root and aboveground dry weights of sampled plants was constant over the elevation range sampled. Plant root systems tended to grow deeper, occupy more belowground space, and have fewer branches as soil moisture declined. These findings indicate that lower soil moisture levels and reduced river flows may significantly influence herbaceous riparian plant growth and survival. Riparian plant health and function will likely be promoted by flow regimes that provide adequate and timely water delivery.

Soil erosion is one of the most serious environmental concerns as it threatens the sustainable agriculture and poses a grave threat to global food security. It is important to adopt the appropriate soil conservation measures to reduce the erosion hazard. In the present study, SWAT model has been applied to study the impact of various best management practices (BMPs) on sediment yield and nutrient losses from a Lower Sutlej River Basin, India. The impact of agricultural and structural BMPs was assessed both individually and in combinations to evaluate the best possible combination of BMPs. Three scenarios, viz., CT1-BMP-1 + CF-BMP-2 + CD-BMP-5 + Fertilizer level 1 (Scenario-1), CT1-BMP-1 + CF-BMP-2 + CB-BMP-3 + CD-BMP-5 + CT2-BMP-8 + Fertilizer level 2 (Scenario 2) and CT1-BMP-1 + CF-BMP-2 + CB-BMP-3 + BT-BMP-4 + CD-BMP-5 + GSS-BMP-6 + SBSS-BMP-7 + CT2-BMP-8 + Fertilizer level 3 (Scenario 3) were developed to study their impact on sediment yield and nutrient losses. The average annual sediment yield from watersheds ranges from 3.08 to 21.63 ton/ha/yr for the base scenario (without BMPs), 1.97 to 13.94 ton/ha/yr in scenario 1, 1.66 to 10.77 ton/ha/yr in scenario 2, and 1.04 to 7.78 ton/ha/yr in scenario 3. At the watershed level, the greatest decrease in sediment yield was obtained from check dam (28.72%), followed by bench terracing (25.62%), grade stabilization structures (22.74%), contour bunding (20.88%), stream bank stabilization structures (10.02%), contour trenching (8.99%), conservation tillage (6.66%) and contour farming (4.54%). The use of structural BMPs at the watershed level reduced sediment yields more effectively than agricultural BMPs. The implementation of all the potential BMPs in Scenario 3 minimized sediment yields to the extent of 66.25%. Model simulation demonstrated that a 30% reduction in fertilizer application under fertilizer scenario 3 resulted in the highest reduction in total nitrogen (24.04%), nitrate nitrogen (8.97%), and total phosphorus (11.75%). The study findings may be useful for promoting sustainable land and water resource management at the river basin level.

The authors of the article studied the rivers and lakes of the Leningrad region of the North-West region of the Russian Federation for the total iron content and analyzed the results obtained. This chemical indicator is being investigated due to the fact that it can have an adverse effect on the environment and human health. The main goal of the work was to analyze the most polluted water bodies of the Leningrad region in terms of excess of the maximum permissible concentration (MPC) for total iron and to develop a way to reduce its concentration. A colorimetric analysis method was used to obtain the data. Exceeding the maximum permissible concentration for total iron was found in more than 80% of samples. A detailed analysis of the three most polluted water bodies was carried out. The results obtained showed that the water bodies of the Leningrad region are heavily contaminated with common iron. In this regard, it is required to develop special measures to reduce its concentration. The authors suggest the use of gabion structure with a special filler for bank stabilization and reduction of the concentration of total iron to the most polluted rivers of the Leningrad region.