Channel morphological change monitoring using high-resolution LiDAR-derived DEM and multi-temporal imageries.

Natural processes and human activities both cause morphological changes in channels. Remote sensing products are often used to assess planform changes, but they tend to overlook vertical changes. However, considering both planform and vertical changes is crucial for a comprehensive evaluation of morphological changes. Using spatiotemporal aerial imagery and topographic data, remote sensing plays a vital role in evaluating channel morphological changes and flood-carrying capacity. This study aimed to investigate the morphological changes of a creek in an urban catchment using very high-resolution remote sensing products. In this study, we developed a new framework for investigating overall channel morphology change by employing very high-resolution aerial imagery and a LiDAR-derived digital elevation model (DEM). By digitizing channel boundaries using ArcGIS Pro 3.0, and analyzing various morphological parameters, erosion, and deposition patterns, we examined the impact of urban expansion and infrastructure development on channel adjustments. Channel adjustments have been performed in the case study catchment (Dry Creek, South Australia, Australia) due to urban expansion and development of infrastructure in the downstream reaches. Our findings revealed a significant southwest shift in the planform of the channel, with a maximum shift of 478 m and an average shift of 217 m since 1998. This alteration resulted in an increase in the sinuosity index reaching 1.2. Over the period from 2018 to 2022, the channel experienced a net deposition depth of 3.4 cm to 3.6 cm in downstream reaches. The annual deposition volume in the downstream reaches was 1963 m3, necessitating regular desilting to prevent channel capacity loss and flooding in the surrounding environment. This study also highlights the incremental growth of riparian vegetation within the channel, which affects surface roughness, channel slope, and carrying capacity. These findings provide a valuable baseline for future investigations into stream channel morphology changes and emphasize the importance of implementing appropriate measures such as desilting and vegetation management to mitigate deposition levels, reduce flood risks, and enhance the overall health and functionality of Dry Creek. The framework used in this study can be applied to other case studies employing reliable and high-resolution remote sensing data products.

Neutral electrolyzed oxidizing water is effective for pre-harvest decontamination of fresh produce.

Pre-harvest sanitization of irrigation water has potential for reducing pathogen contamination of fresh produce. We compared the sanitizing effects of irrigation water containing neutral electrolyzed oxidizing water (EOW) or sodium hypochlorite (NaClO) on pre-harvest lettuce and baby spinach leaves artificially contaminated with a mixture of Escherichia coli, Salmonella Enteritidis and Listeria innocua (~1 × 108 colony-forming units/mL each resuspended in water containing 100 mg/L dissolved organic carbon, simulating a splash-back scenario from contaminated soil/manure). The microbial load and leaf quality were assessed over 7 days, and post-harvest shelf life evaluated for 10 days. Irrigation with water containing EOW or NaClO at 50 mg/L free chlorine significantly reduced the inoculated bacterial load by ≥ 1.5 log10, whereas tap water irrigation reduced the inoculated bacterial load by an average of 0.5 log10, when compared with untreated leaves. There were no visual effects of EOW or tap water irrigation on baby spinach or lettuce leaf surfaces pre- or post-harvest, whereas there were obvious negative effects of NaClO irrigation on leaf appearance for both plants, including severe necrotic zones and yellowing/browning of leaves. Therefore, EOW could serve as a viable alternative to chemical-based sanitizers for pre-harvest disinfection of minimally processed vegetables.

Comparative antibacterial activities of neutral electrolyzed oxidizing water and other chlorine-based sanitizers.

There is increasing demand for safe and effective sanitizers for irrigation water disinfection to prevent transmission of foodborne pathogens to fresh produce. Here we compared the efficacy of pH-neutral electrolyzed oxidizing water (EOW), sodium hypochlorite (NaClO) and chlorine dioxide (ClO2) against single and mixed populations of E. coli, Listeria and Salmonella under a range of pH and organic matter content. EOW treatment of the mixed bacterial suspension resulted in a dose-dependent (<1 mg/L free chlorine), rapid (<2 min) and effective (4-6 Log10) reduction of the microbial load in water devoid of organic matter under the range of pH conditions tested (pH, 6.0, 7.0, 8.4 and 9.2). The efficacy of EOW containing 5 mg/L free chlorine was unaffected by increasing organic matter, and compared favourably with equivalent concentrations of NaClO and ClO2. EOW at 20 mg/L free chlorine was more effective than NaClO and ClO2 in reducing bacterial populations in the presence of high (20-100 mg/L) dissolved organic carbon, and no regrowth or metabolic activity was observed for EOW-treated bacteria at this concentration upon reculturing in rich media. Thus, EOW is as effective or more effective than other common chlorine-based sanitizers for pathogen reduction in contaminated water. EOW's other characteristics, such as neutral pH and ease of handling, indicate its suitability for fresh produce sanitation.

A field and laboratory investigation of kerb side inlet pits using four media types.

Kerb side inlets with adjacent leaky wells are an emerging tool to harvest stormwater and to reduce runoff volumes and peak flow rates. This is achieved by collecting the first flush runoff into kerb side storages and infiltrating this water into the surrounding soil, thereby also reducing stormwater pollutant loadings. The hydraulic performance of the kerb side inlet, filter media and surrounding soil are key factors in the performance of these systems. However, no field or laboratory data are currently available for the hydraulic performance of a kerb side tree inlet pit. In this study, 12 tree inlet pits were constructed and filled with various media types including gravel, water treatment solids (a recycled waste product), sandy loam and clay to examine (1) leaky well infiltration rates (2) emptying times of the wells and (3) the well capacity (runoff storage volume) before and after runoff filtering through the wells. Using a laboratory model, the water harvesting performance of the kerb side inlet plate was also examined for various road longitudinal slopes. Using the field and laboratory data, simulation of the well performance was undertaken using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) to assess the capacity of these systems to reduce runoff volumes at the residential street scale. It was hypothesised that the type of filter media used in leaky well systems has a significant impact on the infiltration rate, regardless of the native soil type through which the stormwater eventually infiltrates. The results showed that the infiltration rates of systems filled with gravel were significantly higher than for the other media types, and this was followed by water treatment solids, sandy loam and clay. The results of the MUSIC modelling indicated that 2.8% of the mean annual runoff volume in the catchment could be harvested by the systems at the case study site. It was found that selection of high infiltration rate media and regular maintenance are the key factors for maintaining long-term performance of these systems.

Performance of a kerb side inlet to irrigate street trees and to improve road runoff water quality: a comparison of four media types.

The TREENET inlet is an emerging water-sensitive urban design technology that consists of a novel kerb side inlet coupled with a leaky well infiltration system. The inlets have been retrofitted to existing roads since 2006; however, there is currently little information available on the effectiveness of these inlet and leaky well systems. This study investigated the performance of the kerb side inlets and leaky well system for water quality improvement prior to infiltration to native soil. The leaky wells included four filter media types, namely gravel, water treatment solids, sandy loam and clay. To compare the performance of the four filter media types, batch and column studies were performed in the laboratory. The best performance was observed using the sandy loam as a filter media, followed by clay, water treatment solids and then gravel. The selection of effective media for removal of heavy metals is important as each media type has different pollutant removal capacity, infiltration and clogging performance.

Potential of combined Water Sensitive Urban Design systems for salinity treatment in urban environments.

Water sensitive urban design and similar concepts often recommend a 'treatment train' is employed to improve stormwater quality. In this study, the capability of a combined permeable pavement and bioretention basin was examined with a view to developing a permeable pavement reservoir that can supplement the irrigation needs of a bioretention system in semi-arid climates. Salinity was a key study parameter due to published data on salinity in permeable pavement storage, and the potential to harvest water contaminated with de-icing salts. To conduct experiments, roofwater was collected from a roof in Adelaide, South Australia. Water was amended with NaCl to produce a control runoff (no added salt), a medium (500 mg/l) and a high (1500 mg/l) salinity runoff. Water was then run through the pavement into the storage reservoir and used to irrigate the bioretention system. Samples were collected from the roof, the pavement reservoir and the bioretention system outflow to determine whether significant water quality impacts occurred. Results show that while salinity levels increased significantly as water passed through the pavement and through the bioretention system, the increase was beneficial for irrigation purposes as it was from Ca and Mg ions thus reducing the sodium absorption ratio to levels considered 'good' for irrigation in accordance with several guidelines. Permeable paving increased pH of water and this effect was prominent when the initial salt concentration increased. The study shows that permeable pavements with underlying storage can be used to provide supplementary irrigation for bioretention systems, but high initial salt concentrations may present constraints on beneficial use of stormwater.

Introducing a water quality index for assessing water for irrigation purposes: A case study of the Ghezel Ozan River.

Rivers are one of the main water resources for agricultural, drinking, environmental and industrial use. Water quality indices can and have been used to identify threats to water quality along a stream and contribute to better water resources management. There are many water quality indices for the assessment and use of surface water for drinking purposes. However, there is no well-established index for the assessment and direct use of river water for irrigation purposes. The aim of this study was to adopt the framework of the National Sanitation Foundation Water Quality Index (NSFWQI) and, with adjustments, apply it in a way which will conform to irrigation water quality requirements. To accomplish this, the NSFWQI parameters for drinking water use were amended to include water quality parameters suitable for irrigation. For each selected parameter, an individual weighting chart was generated according to the FAO 29 guideline. The NSFWQI formula was then used to calculate a final index value, and for each parameter an acceptable range in this value was determined. The new index was then applied to the Ghezel Ozan River in Iran as a case study. A forty five year record of water quality data (1966 to 2010) was collected from four hydrometery stations along the river. Water quality parameters including Na+, Cl-, pH, HCO-3, EC, SAR and TDS were employed for water quality analysis using the adjusted NSFWQI formula. The results of this case study showed variation in water quality from the upstream to downstream ends of the river. Consistent monitoring of the river water quality and the establishment of a long term management plan were recommended for the protection of this valuable water resource.