Hydrological connectivity in large catchments is influenced by natural and human-induced heterogeneities and dynamic processes. In this study, a new aggregated index (AIC) based on topography, ...C-RUSLE factor, RUSLE2 rainfall erosivity, residual topography and soil permeability, was proposed to model structural and functional flow and sediment connectivity (FSC). It was tested in a large Mediterranean catchment (Vero River, NE Spain, 380 km2) with contrasted physiographic and climatic conditions (19 land uses and 15 types of lithology). Twelve weather stations were used and simulations were done at 5 m of pixel resolution using a LiDAR-derived DEM and the D-Infinity algorithm. Structural FSC (FSC-st) was computed with both an updated version of Borselli's index (IC) and the AIC. Values of connectivity with AIC followed a normal distribution with a wider range of values compared with the non-normal distribution obtained with Borselli's approach. The differences in the values of FSC-st between the different land uses were similar with the two indices and in agreement with the soil erosion rates reported in comparable landscapes. The spatial characteristics at sub-catchment scale were better reflected with AIC although values of FSC-st in the river and outlet were similar between both indices. Functional FSC (FSC-fn) was computed with AIC during 96 months (September 2009–August 2017) characterising the spatio-temporal dynamic at catchment scale (18% of coefficient of variation). FSC-fn was higher in September, October, June and July and lower during the period December–February. Variation of connectivity in the stream was higher than in the hillslopes. Modelling testing with river flow was satisfactory between November and March, and during the months with high discharge values and weak during the summer, suggesting different runoff and sediment responses over the year. The new AIC appeared as a suitable tool for geomorphic and hydrological studies at catchment scale.
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•Structural flow and sediment connectivity was mapped in detail with the new AIC.•Values of connectivity with the AIC followed a normal distribution with a wide range.•The new AIC allowed estimating the spatio-temporal dynamic of functional connectivity.•Temporal changes of connectivity in the Vero River were higher than in the hillslopes.•Simulated functional connectivity and river flow dynamics differed during the summer.
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•Good performance on arsenic removal is achieved with composite materials.•Chitosan beads show good mechanical properties both in batch and column experiments.•Magnetic materials are ...obtained with specific metal solution/plant extract ratios.•Magnetic properties are only observed during nanoparticle immobilization in chitosan beads.
New magnetic hybrid materials were developed by the encapsulation of iron oxide nanoparticles into a chitosan matrix. A green synthesis method to obtain metallic nanoparticles was conducted using eucalyptus extract as reducing agent. Well-formed iron oxide nanoparticles were successfully synthesized. Under precise conditions, the encapsulation of the synthesized iron oxide nanoparticles in chitosan beads leads to the formation of magnetic hybrid organic/inorganic materials. The XRD pattern of these materials shows peaks that match with structure similar to maghemite for those materials showing magnetic properties. The new hybrid materials were proved as sorbent in a complete arsenic removal study (pH dependence, kinetic and equilibrium experiments) showing good features and sorption capacity. The large scale sorption capacity of the new material was also successfully proved in a continuous flow study using a column filled with beads of the hybrid magnetic material.
Forest fires and post-fire management practices (PFMP) cause changes in the hydrological response of a hillslope. This study evaluates the effect of log erosion barriers (LB) and Easy-Barriers® (EB) ...on the spatial patterns and values of structural sediment connectivity (SC) in a Mediterranean mountainous pine forest affected by an arson fire in August 2017. A drone flight was done in July 2019 (23 months after the fire and 11 months after the PFMP) to obtain a high-resolution orthomosaic and DEM (at 0.05 m). Two contrasted areas, with and without PFMP, were selected along the same hillslope and 26 small basins were identified: 16 in the treated area (mean area, slope and vegetation recovery of 916 m2, 60% and 25%; with 94 LB and 39 EB) and 10 in the untreated area (1952 m2, 75% and 20%). The aggregated index of sediment connectivity (AIC) was chosen to compute SC in three temporal scenarios: Before and just after the fire and when all PFMP were implemented including the incipient vegetation recovery. Output normalization allowed the comparison of the non-nested basins among them. After accounting the intrinsic differences among the basins and areas, and the temporal changes of SC between the three scenarios, the contribution of the barriers was estimated in 27% from the total decrease of SC in the treated area (−8.5%). The remaining 73% was explained by the vegetation recovery. The effectiveness of the LB (11.3% on average) and EB (13.4%) did not diminish with increasing slope gradients. These percentages become relevant considering the small area affected by the LB (2.8%) and EB (1.3%). Independent metrics (convergence index, flow width, flat areas and LS factor) also reported clear differences between the two areas –higher soil erosive intensity in the untreated area– and in accordance with the AIC results.
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•Vegetation recovery in the treated area was 24% larger than in the untreated area.•Barriers caused 27% of the total decrease of connectivity in the treated area (−8.5%).•Vegetation recovery caused 73% of the decrease of connectivity in the treated area.•The effectiveness of the log-barriers and Easy-Barriers was of 11.3% and 13.4%.•The effectiveness of both types of barriers remains regardless the slope gradient.
The role of soils in regulation and provision of blue and green water Keesstra, Saskia; Sannigrahi, Srikanta; López-Vicente, Manuel ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
09/2021, Letnik:
376, Številka:
1834
Journal Article
Recenzirano
Odprti dostop
The United Nations Sustainable Development Goal 6 aims for clean water and sanitation for all by 2030, through eight subgoals dealing with four themes: (i) water quantity and availability, (ii) water ...quality, (iii) finding sustainable solutions and (iv) policy and governance. In this opinion paper, we assess how soils and associated land and water management can help achieve this goal, considering soils at two scales: local soil health and healthy landscapes. The merging of these two viewpoints shows the interlinked importance of the two scales. Soil health reflects the capacity of a soil to provide ecosystem services at a specific location, taking into account local climate and soil conditions. Soil is also an important component of a healthy and sustainable landscape, and they are connected by the water that flows through the soil and the transported sediments. Soils are linked to water in two ways: through plant-available water in the soil (green water) and through water in surface bodies or available as groundwater (blue water). In addition, water connects the soil scale and the landscape scale by flowing through both. Nature-based solutions at both soil health and landscape-scale can help achieve sustainable future development but need to be embedded in good governance, social acceptance and economic viability.
This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.
•Effects of root morphological characteristics on soil water infiltration rates was studied.•Root length density and root surface area were negatively correlated with infiltration rate.•Root length ...density (5−30 cm) and root surface area (10−20 cm) influence infiltration rates.•It provide insights for plant root morphological characteristics on the infiltration processes.
Surface water infiltration is an important process to meet plant water needs and an important part of the hydrological cycle via groundwater recharge, with special relevance in semi-arid regions. This study evaluated the relationships between grassland plant root morphological characteristics and soil water infiltration rates (IR: initial, steady and average). For this purpose, five artificial homogeneous grasslands (Melilotus suaveolens, Medicago sativa, Panicum virgatum, Bromus inermis and Miscanthus sinensis) without irrigation or fertilization were studied in the Loess Plateau. The observed steady IR were significantly different between the 1-year grasslands: M. suaveolens >M. sativa >P. virgatum >B. inermis >M. sinensis. The root length density and root surface area were negatively correlated with the average, initial and steady IR at different soil depths (p < 0.05). However, the root volume did not significantly influence IR. The stepwise multiple regression determined that the main factors controlling IR were the root length density at the depth of 5−30 cm and root surface area at the depth of 10−20 cm. Our results provide insight into the influence of grassland root morphological characteristics on water infiltration in drylands and are of interest for soil water supply programs in forage production.
Land use composition and patterns influence the hydrological response in mountainous and forest catchments. In plantation forest, management operations (FMO) modify the spatial and temporal dynamics ...of overland flow processes. However, we found a gap in the literature focussed on modelling hydrological connectivity (HC) in plantation forest under different FMO. In this study, we simulated HC in two steep paired forest subcatchments (K2 and K3, 33.2ha), composed of Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) plantations (59% of the total area) against a tree thinning intensity of 50% at different time. Additionally, construction of new skidding trails and vegetation recovery was simulated on five thinning-based scenarios that covered a 40-month test period (July 2010 – October 2013). As a future scenario, six check-dams located in the main streams were proposed to reduce sediment and radionuclide delivery. An updated version of Borselli's index of runoff and sediment connectivity was run, using the D-infinity flow accumulation algorithm and exploiting three 0.5-m resolution digital elevation models. On the basis of the pre-FMO scenario, HC increased at catchment scale owing to tree thinning and the new skidding trails. This change was more noticeable within the area affected by the FMO, where HC increased by 11.4% and 10.5% in the cypress and cedar plantations in K2 respectively and by 8.8% in the cedar plantation in K3. At hillslope plot and stream scales, the evolution in the values of HC was less evident, except the increment (by 5.4%) observed in the streams at K2 after the FMO. Progressive vegetation recovery after the FMO triggered a slight reduction of connectivity in all compartments of both subcatchments. Forest roads and especially skidding trails presented the highest values of HC, appearing as the most efficient features connecting the different vegetation patches with the stream network. The spatial and temporal evolution of HC over the five past scenarios correlated well with the observed changes in runoff yield, as well as with the available values of rainfall interception and throughfall before, during, and after the FMO. The simulation of the proposed scenario recommends the construction of check-dams as effective landscape features to somewhat reduce HC and thus to decrease the sediment and radionuclide delivery rates from the two subcatchments.
•Hydrological connectivity clearly increased due to tree thinning and skidding trails.•Incipient vegetation recovery slightly decreased connectivity.•The location of tree thinning influenced the magnitude of the connectivity changes.•Temporal changes of connectivity correlated well with available data of runoff yield.•Check-dams appeared as a promising strategy to reduce connectivity and delivery rates.
Even during the continuing world pandemic of severe acute respiratory syndrome coronavirus 2 (SARS CoV‐2), consumers remain exposed to the risk of getting infected by existing, emerging, or ...re‐emerging foodborne and waterborne viruses. SARS‐CoV‐2 is different in that it is transmitted directly via the airborne route (droplets and aerosols) or indirect contact (surfaces contaminated with SARS‐CoV‐2). International food and health organizations and national regulatory bodies have provided guidance to protect individuals active in food premises from potential occupational exposure to SARS‐CoV‐2, and have recommended chemicals effective in controlling the virus. Additionally, to exclude transmission of foodborne and waterborne viruses, hygiene practices to remove viral contaminants from surfaces are applied in different stages of the food chain (e.g., food plants, food distribution, storage, retail sector, etc.), while new and enhanced measures effective in the control of all types of viruses are under development. This comprehensive review aims to analyze and compare efficacies of existing cleaning practices currently used in the food industry to remove pathogenic viruses from air, nonfood, and food contact surfaces, as well as from food surfaces. In addition, the classification, modes of transmission, and survival of food and waterborne viruses, as well as SARS‐CoV‐2 will be presented. The international guidelines and national regulations are summarized in terms of virucidal chemical agents and their applications.
Forest fires and post‐fire practices influence sediment connectivity (SC). In this study, we use the ‘aggregated index of connectivity’ (AIC) to assess SC in five Mediterranean catchments (198–1090 ...ha) affected by a wildfire in 2012 in south‐eastern Spain. Two temporal scenarios were considered, immediately after the fire and before post‐fire management, and 2 years after the fire including all practices (hillslope barriers, check‐dams, afforestation, salvage logging and skid trails). One LiDAR (light detection and ranging)‐derived digital elevation model (DEM, 2 m × 2 m resolution) was generated, per scenario. The five catchment outlets were established as the computation target (AICOUT), and structural and functional SC were calculated. Index outputs were normalized to make the results of the non‐nested catchments comparable (AICN‐OUT). The output analysis includes the SC distribution along the catchments and at local scale (929 sub‐catchments, 677 in the burned area), the hillslope and channel measures' effect on SC, and a sedimentological analysis using observed area‐specific sediment yield (SSY) at 10 new (built after post‐fire practices) concrete check‐dams located in the catchments (SSY = 1.94 Mg ha−1 yr−1; σ = 1.22). The catchments with more circular shapes and steeper slopes were those with higher AICN‐OUT. The structural SC maps – removing the rainfall erosivity influence – allowed evaluating the actual role played by the post‐fire practices that reduced SC (
x¯= − 1.19%; σ = 0.41); while functional SC was linked to the actual change of SC (
x¯= + 5.32%; σ = 0.62). Hillslope treatments resulted in significant changes on AICN‐OUT at sub‐catchment scale with certain disconnectivity. A good and positive correlation was found between the SSY and the changes of AICN‐OUT. However, the coarse DEM resolution explained the lack of effect of the rock check‐dams – located on the secondary channels – on AICN‐OUT. AICN‐OUT proved to be a useful tool for decision making in post‐fire restoration, but an optimal input data is still necessary to refine calculations.
Sediment connectivity has been studied in a burned area in two temporal scenarios, Pre‐management scenario (AIC 2012; just after wildfire) and post‐management (AIC 2014; after the application of post‐fire mitigation measures). The AIC index was calculated for 5 catchments with a structural and a functional approach. Differences between scenarios and approaches were observed and a positive relationship between the temporal AIC changes and the Specific sediment yield (SSY) measured in the catchments.
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