Kondisi dan Pengelolaan Kawasan Hulu DAS Belawan Hubungannya dengan Tingkat Bahaya Erosi pada Lahan Budidaya di Kabupaten Deli Serdang

The Belawan watershed is located at Deli Serdang Regency and Medan City, with mountainous terrain (70.58%), hills (35.15%), and slopes (20.28%). This study aims to identify the risk of erosion of cropland, especially coffee, corn, and chocolate, to identify more appropriate erosion control measures to achieve regional protection objectives . The research was conducted in the upstream Belawan watershed in the Sibolangit, Bandar Baru, and Kutalimbaru regions from September 2020 to December 2020. The magnitude of the erosion hazard value is analysed using the USLE approach . The USLE method on the amount of erosion is determined by 5 (five) factors, these factors are the rainfall erosion factor (R); soil erodibility factor (K); vegetation factor (C); conservation factor (P) and topography factor (LS). The erosion rate valuefor land use types varies from 95.27 tons/Ha.yr to 232.43 tons/Ha.yr. The amount of erosion that can be tolerated in land use for coffee, corn, and cacao ranges from 19.94 tons/Ha.yr to 39.79 tons/Ha.yr. The risk level for erosion in coffee areas 4.83 and 10.86 with high criteria and very high criteria; in areas of corn event 6.29 and 8.38 with high criteria and in brown areas 5.24 and 3.88 with high criteria and medium criteria.

Criticality Characteristics and Sensitivity Analysis of Fukushima Debris Beds Containing MCCI Products

This study investigates the criticality characteristics of debris beds that may have been formed through the molten–core–concrete-interaction (MCCI) at the pedestal floor of the damaged reactors in Fukushima Daiichi Nuclear Power Station. These were modeled as UO2-concrete systems submerged in water. First, a conservative model was used to evaluate the impact that the presence of concrete has on the neutron multiplication factor (keff) of debris beds. The good moderation capacities of concrete were proved, and it was found that recriticality would be possible under the considered conservative assumptions. Second, a more realistic model was used to perform an uncertainty and sensitivity analysis of a wide range of debris parameters (debris porosity, core meltdown grade, debris size, debris composition, concrete erosion factor, etc.). In this case, the results indicate that the probability of a recriticality event is very remote. It was also found that the presence of boron (B4C) from the control rods within debris has by far the highest influence on keff.

Spatial and temporal estimation of the erosivity factor R based on daily rainfall data for the department of Atlántico, Colombia

<p class="Abstractandkeywordscontent"><span lang="EN-US">Soil erosion caused by rain is the detachment and movement of soil particles caused by the impact of raindrops on the surface. Erosivity factor R is a measure of the rain erosive power used for estimating the erosion rate with the RUSLE method (Revised Universal Soil Loss Equation). Estimating R factor requires rainfall intensity records of storms greater than 12.5 mm or greater than 6 mm but longer than 15 min. However, most of the Colombian rainfall stations have daily rainfall records with which it is not possible to estimate the intensity of each storm and, therefore, makes it difficult to estimate the R factor for a specific area. In this paper a methodology for estimating the erosivity factor R for the department of Atlántico, Colombia from daily records of 16 IDEAM stations is presented. The spatial distribution of the erosivity factor R in the department and its temporal distribution throughout the year are also shown. The results showed a minimum erosivity factor R of 6,894 MJ∙mm∙Ha^-1∙Hr^-1∙yr^-1 and a maximum of 10,925 MJ∙mm∙Ha^-1∙Hr^-1∙yr^-1. The average erosivity factor R for the department of Atlántico was 8,697 MJ∙mm∙Ha^-1∙Hr^-1∙yr^-1. This methodology might be used for estimating the erosion factor R in different Colombian regions where high-resolution precipitation data is limited, but seasonal and orographic conditions should be considered for selecting the rain gages and the area of study.</span></p>

Changes in land use in the region of Grdelica Gorge in the period 1963-2011

A land use is the sole erosion factor that can be controlled and governed by man. Since an inadequate land use can cause intensification of erosive processes, it is possible to reduce their intensity by its change. The paper presents the changes in land use in the region of Grdelica Gorge in the period between 1963 and 2011 and the impact of the changes on the intensity of erosive processes. The identification of wooded land, arable land, meadows, pastures, orchards, vineyards and infertile land performed in 2011 was based on field works and the analysis of high-resolution satellite images. The comparison of the obtained results with the data for 1963 proved that the categories of barren land, forest, meadow and pasture underwent most intensive changes. The above-mentioned changes, along with performance of biological and technical works, resulted in reduction of intensity of erosive processes in the observed period.

Research and Application of Risk Assessment Methodology for Power Station Boiler Superheaters

Risk-based inspection (RBI) has been applied to good effect in relation to pieces of equipment and pipelines in the petrochemical industry worldwide, but to the best of our knowledge application of RBI to power station boilers has not hitherto been reported. The tubes of the four key components, namely, the economizer, the water-cooling wall, the superheater, and the reheater, are prone to blast due to direct fire heating. Such a blast always causes unplanned shutdown and has severe safety implications. Based on the “API 581-2000” code (Risk-Based Inspection Base Resource), the failure mechanisms of power station boilers have been studied, and the high-temperature smoke erosion factor and high-temperature creep factor have been calculated. Then, considering specific situations in China, such as material quality and extended service, a failure modification factor based on remaining life has been proposed. Finally, two risk assessment projects have been carried out; after delineating the risk levels of the tubes, appropriate management suggestions have been proposed. The obtained data should provide some technical support for the application of RBI to power station boilers.

Catchment process affecting drinking water quality, including the significance of rainfall events, using factor analysis and event mean concentrations

To ensure the protection of drinking water an understanding of the catchment processes which can affect water quality is important as it enables targeted catchment management actions to be implemented. In this study factor analysis (FA) and comparing event mean concentrations (EMCs) with baseline values were techniques used to asses the relationships between water quality parameters and linking those parameters to processes within an agricultural drinking water catchment. FA found that 55% of the variance in the water quality data could be explained by the first factor, which was dominated by parameters usually associated with erosion. Inclusion of pathogenic indicators in an additional FA showed that Enterococcus and Clostridium perfringens (C. perfringens) were also related to the erosion factor. Analysis of the EMCs found that most parameters were significantly higher during periods of rainfall runoff. This study shows that the most dominant processes in an agricultural catchment are surface runoff and erosion. It also shows that it is these processes which mobilise pathogenic indicators and are therefore most likely to influence the transport of pathogens. Catchment management efforts need to focus on reducing the effect of these processes on water quality.

Influence of climate conditions on the intensity and spreading of wind erosion

The influence of climate conditions on the intensity and spreading of wind erosion was considered in the area of South Moravia. For this purpose, 16 meteorological stations were selected on the basis of accessibility of required data, their adequate representativeness, homogeneity, and position of the stations. It was necessary to make the database of climatological factors (such as wind velocity, precipitation and air temperature) of the period of 1961–2003 for the analyses of climatological data. The climatological data was then evaluated for the periods of 1961–2003, 1961–1990, 1991–2000, and 1971–2000. Clima- tic erosion factor, which explains potential erodibility of soil by wind, was determined through the analyses of factors influencing the wind erosion. The assessment of influence of expected climate change on the intensity and spreading of wind erosion consists in the selection of suitable climatological model and climate change scenarios on the basis of ability to model the three climatological factors (wind velocity, precipitation and air temperature). Climate change scenarios were then applied on the data of the selected climatological stations and the assessment of changes in data sets and the comparative analysis of the outputs of the scenarios with measured data from the normal period of 1961–1990 were done. The climatic erosion factor was also determined from the altered data of the scenarios.

A CFD Based Correlation for Erosion Factor for Long-Radius Elbows and Bends

A model for predicting sand erosion in 90 degree elbows and bends has been developed based on computational fluid dynamics (CFD), particle tracking and erosion data. After the flow field was obtained from the flow (CFD) model, particles were introduced into the flow and particle trajectories were computed using a Lagrangian approach. A model was also implemented that accounts for the interaction between the particles and the target material. Based on predicted particle impingement velocities, erosion rates and penetration rates were predicted using the empirical equations for erosion ratio. The predicted penetration rates are compared with available experimental data for several different elbows. The agreement between the predicted penetration rates and the experimental data is good. In addition, based on many predictions and erosion rate results, a new CFD based correlation is developed that can be used for an approximate engineering calculation to account for effects of elbow radius on erosion in long-radius elbows. This equation is for computing the ratio of the wall thickness loss (or the penetration rate) in a long-radius elbow to the penetration rate of a standard (short-radius) elbow. The results from the correlation agree well with the trend of available data in the literature.