Carbon dynamics and export from flooded wetlands: A modeling approach

Described in this article is development and validation of a process based model for carbon cycling in flooded wetlands, called WetQual-C. The model considers various biogeochemical interactions affecting C cycling, greenhouse gas emissions, organic carbon export and retention. WetQual-C couples carbon cycling with other interrelated geochemical cycles in wetlands, i.e. nitrogen and oxygen; and fully reflects the dynamics of the thin oxidized zone at the soil-water interface. Using field collected data from a small wetland receiving runoff from an agricultural watershed on the eastern shore of Chesapeake Bay, we assessed model performance and carried out a thorough sensitivity and uncertainty analysis to evaluate the credibility of the model. Overall, model performed well in capturing TOC export fluctuations and dynamics from the study wetland. Model results revealed that over a period of 2 years, the wetland removed or retained equivalent to 47 ± 12% of the OC carbon intake, mostly via OC decomposition and DOC diffusion to sediment. The study wetland appeared as a carbon sink rather than source and proved its purpose as a relatively effective and low cost mean for improving water quality

Wild pig removal reduces pathogenic bacteria in low-order streams

Invasive wild pig populations have undergone enormous increases in the United States and particularly across the southern U.S. in recent years. High fecundity rates and abilities to adapt quickly to varied habitats have enabled pig populations to become entrenched and difficult to eliminate. The pigs cause many negative impacts on ecosystems including degradation of water quality through infusion of fecal contamination and other non-point source pollutants. Our goal was to determine the effects of pig removal on water quality in streams that were known to be significantly polluted by pig activity Bolds (J Environ Qual 50: 441–453, 2021). We compared e. coli and fecal coliform concentrations and loads in streams between a pre-removal period with those that occurred during the removal activities. Results suggest that e. coli and fecal coliform concentrations were reduced by 75 and 50% respectively through pig removal efforts. Questions remain concerning the longevity of the reduction especially once pig removal activities decrease in intensity

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Sediment source area identification over watersheds: Influence of spatial scale and sediment travel times

Sediment yield from a watershed has important implications for water quality and water resources, especially from agricultural areas. Water quality issues arise because sediments serve as carriers for various pesticides, radioactive materials and nutrients. Therefore, it is crucial to identify sediment source areas to design proper abatement strategies and develop TMDL initiatives accordingly. A physically-based watershed-scale surface flow and erosion model, KINEROS was utilized as the modeling tool in this study. A GIS interface of the KINEROS model was employed to automate the channel extraction and watershed delineation. An important issue of geomorphologic detail was examined here because it influences model predictions of water flow and sediment discharges. The effect of geomorphologic resolution over peak runoff, peak sediment discharge and total sediment load was investigated. It was shown that the required geomorphologic detail is a function of quantity of interest. Empirical relationships were developed relating these quantities to optimal resolution, watershed characteristics and nature of the storm. Following the study on geomorphologic resolution, two methodologies were developed to identify the source areas and their relative strengths for sediment generation. Both methods rely on hydrograph and sedimentograph data collected at the mouth of the watershed. The first method used a modified unit sedimentograph approach, while the second method relied on optimization techniques. Data over several events were examined over two small watersheds, and a statistical procedure was utilized to assess the erosion vulnerability of different regions in the watersheds. These results were presented in the form of maps to obtain a spatial picture of sediment generating areas. Results from these two independent methods showed good agreement. Because of parameter non-uniqueness that typically confounds the results from these methods, it was suggested that the resolution utilized for source identification be smaller than the one indicated by the study on geomorphologic resolution

An Integrated Approach for Modeling Wetland Water Level: Application to a Headwater Wetland in Coastal Alabama, USA

Headwater wetlands provide many benefits such as water quality improvement, water storage, and providing habitat. These wetlands are characterized by water levels near the surface and respond rapidly to rainfall events. Driven by both groundwater and surface water inputs, water levels (WLs) can be above or below the ground at any given time depending on the season and climatic conditions. Therefore, WL predictions in headwater wetlands is a complex problem. In this study a hybrid modeling approach was developed for improved WL predictions in wetlands, by coupling a watershed model with artificial neural networks (ANNs). In this approach, baseflow and stormflow estimates from the watershed draining to a wetland are first estimated using an uncalibrated Soil and Water Assessment Tool (SWAT). These estimates are then combined with meteorological variables and are utilized as inputs to an ANN model for predicting daily WLs in wetlands. The hybrid model was used to successfully predict WLs in a headwater wetland in coastal Alabama, USA. The model was then used to predict the WLs at the study wetland from 1951 to 2005 to explore the possible teleconnections between the El Niño Southern Oscillation (ENSO) and WLs. Results show that both precipitation and the variations in WLs are partially affected by ENSO in the study area. A correlation analysis between seasonal precipitation and the Nino 3.4 Index suggests that winters are wetter during El Niño in Coastal Alabama. Analysis also revealed a significant negative correlation between WLs and the Nino 3.4 Index during the El Niño phase for spring. The findings of this study and the developed methodology/tools are useful to predict long-term WLs in wetlands and construct more accurate restoration plans under a variable climate

Investigation of flow properties in natural streams using the entropy concept

This paper examines the discharge and velocity distributions in natural open channel flows using the entropy theory. Flow measurements were carried out at four different cross-sections in central Turkey. The mean and maximum velocities at these stations exhibited a linear distribution and the entropy parameter was calculated to be M=1.31. Using this value, discharges for all flow conditions were calculated as a function of the measured maximum velocities (umax). It was observed that the umax/H and zmax/H ratios remained relatively constant when 0.2=y/T=0.8, especially for the wider channels. Using these constant values for each station, umax and zmax could be determined solely as a function of the water depth H. Although the calculated velocities were higher than those measured at some verticals, the entropy-based approach presents an attractive alternative to the traditional flow-measurement techniques for the determination of flow properties because of its simplicity and quick application

Potential impacts of land use change on streamflow and groundwater resources under changing climate in the Flint River Basin, Georgia, United States

This study ascertains the factors affecting streamflow and irrigation water demand under different land use/cover (LULC) changes and future climate scenarios in the Flint River Basin, Georgia, United States, using the seemingly unrelated regression (SUR) panel model. An advantage of using the SUR model is that it accounts for cross-hydrological correlation, which is important due to the cross-sectional dependence between streamflow and pumpages. A set of streamflow, ground/surface water withdrawal, climatic, and LULC data used in this study was gathered from publicly available data sources and state agencies. Furthermore, the results show that a 10% increase in corn acreage in the watershed could lead to a significant rise in surface water and groundwater pumpings demands, respectively at 124% and 168%. This study identifies potential evapotranspiration (PET) threshold, which may lead to a water deficit in the region. For various LULC scenarios involving corn and urban area expansion, the probability of facing water scarcity at least once from 2025 to 2060 is estimated to range from 0.2% to 3.8% and 0.7% to 2.6% under RCP 4.5 and RCP 8.5 scenarios, respectively. These findings underscore the trade-off between water scarcity and food security in the context of changing climate, highlighting a need to design appropriate incentives to enhance water-use efficiency and adopt climate-smart strategies. The study’s significance extends to other similar watersheds worldwide that face similar challenges arising from changing land use and climate, which impact the sustainability of water resources, particularly groundwater resources, over time

Radar remote sensing reveals potential underestimation of rainfall erosivity at the global scale

Rainfall kinetic energy (RKE) constitutes one of the most critical factors that drive rainfall erosivity on surface soil. Direct measurements of RKE are limited, relying instead on the empirical relations between kinetic energy and rainfall intensity (KE-I relation), which have not been well regionalized for data-scarce regions. Here, we present the first global rainfall microphysics–based RKE (RKEMPH) flux retrieved from radar reflectivity at different frequencies. The results suggest that RKEMPH flux outperforms the RKE estimates derived from a widely used empirical KE-I relation (RKEKE-I) validated using ground disdrometers. We found a potentially widespread underestimation of RKEKE-I, which is especially prominent in some low-income countries with ~20% underestimation of RKE and the resultant rainfall erosivity. Given the evidence that these countries are subject to greater rainfall-induced soil erosion, these underestimations would mislead conservation practices for sustainable development of terrestrial ecosystems