Search

Among the input data of the watershed model for simulating changes of flowrate in the watershed, weather input data, especially input data related to rainfall, are the most important. Therefore, it is important to ensure the accuracy of rainfall input data to increase the accuracy of the watershed model results. Securing rainfall measurements with finer spatial and temporal resolutions is important in predicting flowrate variations at a sub-catchment, especially as they relate to global and local climate changes in weather conditions such as rainfall depth, rainfall intensity, etc. In this study, adjusted radar-rainfall estimates were suggested as alternative input data for watershed modeling. Through a statistical analysis of the representativeness of a ground rainfall measurement (10 km × 10 km grid), the necessity of radar-rainfall estimates (2 km × 2 km grid) was identified. By applying calibration factors to initial radar-rainfall estimates and comparing adjusted radar-rainfall estimates with ground rainfall measurements, it was proven that adjusted radar-rainfall estimates could be used as input data for watershed simulations (NSE > 0.92; n = 12). Adjusted radar-rainfall estimates and ground rainfall measurements were used as input data of the Soil and Water Assessment Tool model to predict flowrate variations at the outlets of a tributary and the entire watershed. As a result, the accuracies of the simulation results were improved for the outlets of a tributary and the entire watershed (NSE: 0.33 to 0.48 and 0.19 to 0.55, respectively). To obtain more reliable rainfall data, radar images easily accessible to users were applied, and the accuracy of the data was increased by applying simple equations to numerical data extracted from radar image processing. Additionally, the applicability of the adjusted radar-rainfall estimates was demonstrated by comparing the modeling results using the suggested rainfall data and existing ground-based rainfall data. The suggested methodologies are expected to contribute to more accurately predict the possibility of flood disasters in other regions and countries lacking infrastructure related to rainfall measurements and to establish appropriate countermeasures.

Herein, we develop a binder-free copper molybdate nanocone array with a prism-like morphology on nickel foam (Cu3Mo2O9 NCAs/Ni foam) using a single-step hydrothermal method. With an optimal growth time (10 h) under hydrothermal conditions, the prism-like Cu3Mo2O9 NCAs are uniformly decorated on Ni foam with good adhesion and crystallinity. The prepared Cu3Mo2O9 NCAs/Ni foam has been directly used as a binder-free electrode to examine its suitability as a positive electrode in hybrid supercapacitors. In an aqueous 1 M KOH electrolyte, the binder-free Cu3Mo2O9 NCAs/Ni foam showed battery-type behavior with a high areal capacity of 449.5 μAh cm–2 at a discharge current density of 2 mA cm–2 and also exhibited a good cycling stability. In addition, the pouch-type hybrid supercapacitor is assembled using the prism-like Cu3Mo2O9 NCAs/Ni foam as a positive electrode and the activated carbon as a negative electrode in a 1 M KOH electrolyte. The hybrid supercapacitor achieves a maximum cell potential of 1.6 V with ...

Utilizing carbon-based counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) have received much attention in recent times, owing to their low cost, good electrochemical activity, natural abundance and eco-friendly nature. Herein, we have facilely prepared quince leaves derived porous carbon (QLPC) using fallen quince leaves (QLs) and it was used as a cost-effective CE for the fabrication of DSSCs. By means of alkali treatment and pyrolysis process (at different temperatures of 700, 800 and 900 °C), the QLs powder undergoes chemical activation and carbonization, which results in a honeycomb-like QLPC with abundant micro/mesopores and large surface area. Simple and straightforward coating of QLPC samples onto fluorine doped tin oxide glass substrates led to improved electrocatalytic activity and good tri-iodide reduction in DSSCs. When the DSSCs were illuminated under 1 sun condition (AM 1.5; 100 mW cm −2 ), the device assembled with QLPC-based CE (prepared at 800 °C) showed a higher current density of ∼14.99 mA/cm 2 and power conversion efficiency of ∼5.52% among the other QLPC-based CEs, which are comparable with the platinum-based CE in DSSCs. This facile process for the preparation of biomass derived carbon-based CE provides an alternative to the noble metal-free CE in DSSCs.

Honeycomb-like activated porous carbon (HPC) powder with meso/macropore structures was successfully prepared via chemical activation and pyrolysis processes under inert gas atmosphere. Herein, the naturally available pine cone flowers with abundant carbon contents were employed as a biomass to synthesize the HPC sample. The structure and morphology of the HPC powder were characterized by various physicochemical techniques. Moreover, the as-prepared HPC sample was uniformly coated on fluorine doped tin oxide glass using a smooth brush and used as a cost-effective counter electrode (CE) in dye-sensitized solar cells (DSSCs). Under AM1.5G illumination, the fabricated DSSCs with HPC-based CE exhibited a high short-circuit current density (JSC) of 13.51 mA/cm2 and an excellent power conversion efficiency (PCE) of 4.98%, which is attributed to the high specific surface area and hierarchical porous property of the HPC sample. The obtained results were improved compared to the commercially available activated carbon-based CE in DSSCs (JSC = 12.11 mA/cm2 and PCE = 4.45%). This facile fabrication of highly porous activated carbon-based materials from the biomass can be utilized as a high-performance electrode material in DSSCs and energy storage device applications.

Hierarchical copper oxide (CuO) nanostructures (NSs) with caterpillar-like morphologies were facilely integrated onto a highly flexible conductive woven textile substrate (CWTs) by a drop-casting approach. Initially, the CuO NSs were synthesized via a simple and green wet-chemical method in 30 min and the obtained colloidal solution of CuO was easily dropped onto well-cleaned CWTs. By virtue of their interesting structural features, the caterpillar-like CuO NSs on CWTs were employed as binder-free electrodes for supercapacitors and their electrochemical properties were investigated in 1 M KOH solution. Additionally, a small portion of redox-additive potassium ferricyanide (K3Fe(CN)6) was added to the 1 M KOH solution, which led to efficient enhancement of energy storage performance with superior cycling stability for the caterpillar-like CuO NSs on CWTs. Furthermore, the fabricated asymmetric supercapacitor (SC) with CuO NSs on CWTs and activated carbon with an operating potential window of 1.5 V simultaneously exhibited excellent energy density and power density values. Such a simple and low-cost approach to easily construct metal oxide nanomaterials on flexible textiles with redox-additive electrolyte may be useful for several potential applications in high-performance energy storage devices.

Using a simple electrochemical deposition (ECD) method, β-nickel hydroxide (β-Ni(OH)2) nanosheets (NSs) are facilely integrated on non-woven conductive textile substrate (NWCTs). The NWCTs with copper-plated polyethylenterephthalate (Cu/PET) fibers serves as a highly conductive and low-cost working substrate for the ECD method. With an aid of direct current voltage in the growth solution, the β-Ni(OH)2 NSs well adhere to NWCTs fibers with good uniformity. The surface morphology and crystallinity properties of the synthesized β-Ni(OH)2 NSs on NWCTs are characterized by various physicochemical techniques. Furthermore, the hierarchical β-Ni(OH)2 NSs on NWCTs reveal superior energy storage performance in 1 M KOH electrolyte solution as a binder-free electrode for pseudocapacitors. Compared to the conventional conductive foil-based electrode, the pseudocapacitive electrode in this work exhibit a relatively high electrochemical performance (specific capacitance of 2185.6 F g–1 at 5 A g–1) and stable capacitance...

Manganese dioxide nanosheet arrays with interconnected arrangements are easily synthesized on vapor grown carbon fibers (MnO2 NSAs@VCFs) by a simple wet-chemical method at low temperature. The conductive nature of the VCFs serves as a scaffold and easily reduces potassium permanganate species for the formation of hierarchical MnO2 NSAs@VCFs. When utilized as an electroactive material for pseudocapacitors, the sophisticated configuration of the nanocomposite provides an effective electrochemical activity and an electron pathway for higher electrochemical performance in 1 M Na2SO4 aqueous solution. The hierarchical MnO2 NSAs@VCFs exhibit a maximum specific capacitance of 115.3 F g−1 at a current density of 0.5 A g−1 with an excellent cycling stability of 85.6% after 2000 cycles at a current density of 5 A g−1. Such facile and cost-effective fabrication of a metal oxide nanocomposite with improved electrochemical performance allows it to be considered as a promising electroactive material for energy storage devices.

Coastal erosion, a worldwide social issue, has garnered substantial attention. Numerous methods have been implemented to control coastal erosion problems, however, the presence of rigid structures limits erosion mitigation, thereby causing various challenges. For instance, in the case of submerged breakwaters, local scour in front of the structure and scour caused by the flow occurring in open inlets affect the subsidence and stability of the structure and can also cause structural failure. To solve these problems, this paper proposes a hybrid method of using a submerged breakwater with an artificial coral reef installation, further, this study evaluates the attenuation of waves and mitigation of sediment transportation through large-scale 3D hydraulic experiments. We found that the hybrid method with an artificial coral reef installed in the open inlet shows excellent wave control and plays a clearly beneficial role in the advancement of the shoreline. The artificial coral reef method reduced the return flow generated by the drag force at the breakwater shoulder and open inlet. In addition, scour at the breakwater shoulder was inhibited by collecting the sand escaping offshore. Simultaneously, scour at the open inlet was also mitigated. The application of the hybrid method compensated for the problems caused by local scour and erosion in the submerged breakwater, thereby leading to the improvement of its function. Therefore, the hybrid method proposed in this paper was determined to be applicable not only for submerged breakwaters, but also for various structures for controlling coastal erosion.

When stormwater runoff flows into a constructed wetland, the water level changes inside, and the volume of the wetland changes accordingly. In this study, the relationship between pollutant removal and water depth flowrate changes was analyzed with velocity phase analysis, using the concepts of horizontal velocity and vertical velocity. A constructed wetland located in an agricultural area was used for the velocity phase analysis. Analysis results revealed that all four ponds and Phases I and III accounted for over 90% of the pollutant load. In particular, Phase III, where vertical and horizontal velocities were reduced, was responsible for approximately twice the load on average. The reason for the highest load in Phase III was due to the inflow of contaminants into the constructed wetland through the first flush effect occurred at the time when the flow rate decreased due to the difference in runoff strength. Therefore, it is necessary to maximize Phases I and III in the velocity phase when designing multi-stage wetlands to make the flow of water more natural. Furthermore, considering pollutant load levels, a design review is needed to expand the size of downstream wetlands, so that they can optimize water quality management functions.

Three-dimensional hierarchical honeycomb-like activated porous carbon pillared ultrathin Ni(OH)2 nanosheets (Ni(OH)2 NSs@HAPC) for use as supercapacitor materials were facilely synthesized. With an aid of pine cone flowers as a biomass source, HAPC conducting scaffolds were prepared by the alkali treatment and pyrolysis methods under an inert gas atmosphere. Subsequently, the Ni(OH)2 NSs were synthesized evenly on the surface of HAPC via a solvothermal method. The resulting HAPC and Ni(OH)2 NSs@HAPC composite materials offered free pathways for effective diffusion of electrolyte ions and fast transportation of electrons when employed as an electrode material. The Ni(OH)2 NSs@HAPC composite electrode exhibited excellent electrochemical properties including a relatively high specific capacitance (Csp) value of ~ 916.4 F/g at 1 A/g with good cycling stability compared to the pristine HAPC and Ni(OH)2 NSs electrodes. Such bio-friendly derived carbon-based materials with transition metal hydroxide/oxide composite materials could be a promising approach for high-performance energy storage devices because of their advantageous properties of cost effectiveness and easy availability.

To characterize fluorescent dissolved organic matter (FDOM) in Yeongsan River in Korea, 110 water samples were acquired from March 2008 to November 2009 around the watershed. Excitation emission matrix data of fluorescence was obtained using spectrophotometric analysis and parallel factor (PARAFAC) model was used to characterize FDOM. The spatiotemporal variation and effect on FDOM were studied using an exploratory analysis and analysis of variance (ANOVA). According to the spatial and seasonal characteristics, we used post hoc analysis to identify significantly different sites and season. The PARAFAC results identified three most important PARAFAC components explaining 95.32% of total variance of original data-set. Seasons and sites had a significant effect on PARAFAC Components I and II (p ≤ 0.05), whereas season had a significant effect on Component III (p ≤ 0.05). There was no significant interaction between seasons and sites for all the three PARAFAC components (p > 0.05). For Components I and II, summer season was significantly different from other seasons (p ≤ 0.05), whereas for Component III, the fall season was significantly different from winter and summer seasons (p ≤ 0.05). These results indicate that ANOVA and post hoc analysis in our study not only confirmed the results of previous studies, but also revealed differences in seasons and sites for identified FDOMs as a new information. The methodology proposed in this paper can be a useful tool for finding sources and sinks of FDOMs in a riverine system influenced by natural organic matter impairment.

Highly flexible and conductive fabric (CF)-supported cauliflower-like nickel selenide nanostructures (Ni3Se2 NSs) are facilely synthesized by a single-step chronoamperometry voltage-assisted electrochemical deposition (ECD) method and used as a positive electrode in supercapacitors (SCs). The CF substrate composed of multi-layered metallic films on the surface of polyester fibers enables to provide high electrical conductivity as a working electrode in ECD process. Owing to good electrical conductivity, high porosity and intertwined fibrous framework of CF, cauliflower-like Ni3Se2 NSs are densely integrated onto the entire surface of CF (Ni3Se2 NSs@CF) substrate with reliable adhesion by applying a chronoamperometry voltage of −1.0 V for 240 s. The electrochemical performance of the synthesized cauliflower-like Ni3Se2 NSs@CF electrode exhibits a maximum specific capacity (CSC) of 119.6 mA h g−1 at a discharge current density of 2 A g−1 in aqueous 1 m KOH electrolyte solution. Remarkably, the specific capacity of the same electrode is greatly enhanced by introducing a small quantity of redox-additive electrolyte into the aqueous KOH solution, indicating the CSC≈251.82 mA h g−1 at 2 A g−1 with good capacity retention. Furthermore, the assembled textile-based asymmetric SCs achieve remarkable electrochemical performance such as higher energy and power densities, which are able to light up different colored light-emitting diodes.