Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 2022

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

An experiment of energy dissipation on USBR IV stilling basin - Alternative in modification

Bantacut Alfiansyah Yulianur, Azmeri Azmeri, Jemi Faris Zahran, Ziana Ziana, Muslem Muslem

Journal of Water and Land Development

2022

no. 53

68--72

Previous researchers have been widely studied the equation for calculating the energy dissipation in USBR Type IV, applied in the stilling basin structure as an energy dissipator. However, inefficient energy dissipating basins are commonly found in the field due to the large discharge and high water head, potentially damaging the bottom of the energy dissipating basin and its downstream river. Therefore, an energy dissipator plan fulfilling the safe specifications for the flow behaviour that occurred is required. This study aimed to determine the variation of the energy dissipators and evaluate their effect on the hydraulic jump and energy dissipation. For this purpose, a physical model was undertaken on the USBR Type IV spillway system. The novelty of this experiment showed that combination and modification dissipation features, such as floor elevation, end threshold and riprap lengthening, could effectively dissipate the impact of energy downstream. The final series exhibited a significantly higher Lj/y1 ratio, a favourable condition due to the compaction of the hydraulic jump. There was also a significant increase in the downstream tailwater depth (y2) during the jump formation. Therefore, the final series energy dissipator was better in the stilling basin design for hydraulic jump stability and compaction. The increase in energy dissipation for the final series type was the highest (98.4%) in Q2 and the lowest (84.8%) in Q10 compared to the original series. Therefore, this type can better reduce the cavitation risk damaging to the structure and downstream of the river.

Distribution of Mercury in Soil, Water, and Vegetable Fern in a Former Gold Mining Area – Evidence from Nagan Raya Regency, Aceh Province, Indonesia

Nisah Khairun, Muslem Muslem, Ashari Tengku Muhammad, Afkar Majral, Iqhrammullah Muhammad

Journal of Ecological Engineering

2022

Vol. 23, nr 8

30--39

The mercury contamination associated with the former intense illegal gold mining activities is suspected in the watershed of Krueng Cot Satu, Nagan Raya Regency, Aceh Province, Indonesia. The aim of this study was to evaluate the mercury contamination residue in the water, soil, and vegetable fern (Pityrogramma calometanos (L)) The samples were collected from locations in the already closed artisanal gold mining sites. The sampling locations were purposively determined by considering their closeness to the previous gold mining activities sites. The content of mercury was analyzed using flow injection for atomic spectroscopy – atomic absorption spectroscopy. The method used was validated by linearity, Limit of Detection (LoD), Limit of Quantification (LoQ), Relative Standard Deviation (RSD), and recovery. The validation test showed that this method is well linear, sensitive, accurate, and precise with a correlation coefficient, LoD, LoQ, RSD and recovery of 0.9999, 0.0477 μg/L, 0.1447 μg/L, 2.96% and 95–105%, respectively. Herein, it was found that the concentrations of mercury contents in the water samples were below the detectable range. However, a high range of mercury concentration of 0.236 – 0.328 μg/g was found in soil, with the highest concentration obtained in the sample collected from the riverbank. The fern sample collected near the riverbank contained mercury in all its parts and concentrated in the root (0.408 μg/g in the leaves, 0.276 μg/g – stalks, and 9.994 μg/g – roots). Meanwhile, the absence of mercury contamination was obtained in the leaves and stalks of the fern samples collected far from the riverbank. The roots, however, were detected with mercury contamination with the highest concentration reaching 27.660 μg/g. Despite its disappearance in the water, mercury contamination residue from the former artisanal gold mining activities still could be traced in the soil and heavy metal accumulating plant – P. calometanos (L).