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Renewable & Alternative Power Technologies
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
While the famous massive hydropower plants draw the most attention, the majority of hydropower plants are much smaller. Many are similar in concept and design, but at a scale of one tenth or one hundredth the size. Projects of much smaller capacity and with rated heads of about 65 ft (20 m) or less are termed low-head plants. These can still be sizable systems of 20 MW or more, though many are under 1 MW of capacity. Low-head dams may often be located closer to where the real electric loads are, reducing the power lost in transmission. They may also be designed as run-of-the river plants, which use power in the river water as it passes through the plant without causing appreciable change in the river flow. These systems generally impound very little water and, in some cases, do not require a dam or reservoir. This reduces the likelihood of water quality changes, such as higher temperature, lower oxygen, increased phosphorus and nitrogen, and increased siltation.
Special Address
Published in C.V.J. Varma, B.S.K. Naidu, A.R.G. Rao, Silting Problems in Hydro Power Plants, 2020
Hydro and water resource projects located in remote and inaccessible sites involve high cost structures. Remedial measures during the operation & maintenance stages can often be time consuming, laborious and expensive. With the increasing pace of Hydro Power development, the greater need of having thorough understanding of Environmental and Economic Aspects of Silt Management is eminent to ensure smooth operation of Hydro plants. Siltation, a natural process in any river system is due to continuous soil erosion, entrainment, transportation, deposition and the compaction of sediments. The present landscape of our river basins is the result of such natural siltation process over the years. In any river system, erosion & siltation processes are closely related to the natural conditions of the river basin, such as, its topography, geology, climate, hydrology, vegetation, sediment characteristics etc. These natural processes are greatly influenced and sometime aggravated by human activities. If water resource projects are not planned with the proper knowledge of siltation processes in different river environment, the nature may bring in radical changes in natural conditions of river thereby affecting the projects. Needless to say siltation plays an important role in water resource projects both from the Environmental as well as Techno-Economical angle. Problem of sedimentation has been globally felt and therefore is a matter of concern in every part of the world. We can not afford to ignore sedimentation and its impact on the operation of Hydro Power plant besides on the lives of people.
Steps towards the sustainable management of sediment in ports and harbours
Published in C. Patrick Heidkamp, John Morrissey, Towards Coastal Resilience and Sustainability, 2018
Amélie Polrot, Jason R. Kirby, Jason W. Birkett, Ian Jenkinson, George P. Sharples
Among the different coastal environments, ports and harbours hold an important place. Dominating the local economy, they permit trade, fishing and tourism or can shelter a naval base. A well-known challenge in world ports and harbours is to maintain their navigability. Indeed, sediments accumulate with time and activities, which creates significant problems for shipping as sedimentation decreases nautical depth. The most widespread method to tackle siltation problems is dredging, which consists of sediment excavation from the site, followed by its transport and disposal in a designated area. Dredging is a significant industry with a global turnover estimated as €5.02 billion (IADC, 2016). However, dredging is also associated with many detrimental issues including the fundamental non-sustainability of the practice, sediment loss from the coastal system (Manap & Voulvoulis, 2015) and the presence of contaminants in the targeted sediments (Birkett et al., 2002). Indeed, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, heavy metals, dioxin or organotin compounds coming from industry, agriculture and urban run-off are commonly found in sediments in the world’s ports and harbours (United States, 1999) in concentrations exceeding sediment quality standards (Al Sawai, 2015; Buruaem et al., 2012; Nasr et al., 2006; Sany et al., 2013).
Small baselines techniques of time series InSAR to monitor and predict land subsidence causing flood vulnerability in Sidoarjo, Indonesia
Published in Geomatics, Natural Hazards and Risk, 2022
Noorlaila Hayati, Amien Widodo, Akbar Kurniawan, I Dewa Made Amertha Sanjiwani, Mohammad Rohmaneo Darminto, Imam Satria Yudha, Josaphat Tetuko Sri Sumantyo
The reseachers also recorded the change of morphology. Silting of river had been detected in two villages as shown in the Figure 11. Comparing to another village, Kalidawir-Putat, the change of river depth located in Kedungbanteng and Banjarasri was 78.3 cm and 75 cm, respectively. Siltation is mostly contributed by deposition of fine sediment and sediment movement due to extreme floods. Yet at a certain depth, the layer of riverbed matrix might change during catastrophic events e.g., subsidence as a result of the decrease in surface elevation. Moreover, the drainage of Kedungpeluk and Gedangrowo was distracted by the backwater effect. When rain fell on the land and could not quickly discharge the cumulative rainwater into the main channel, large floods were unavoidable. These two villages suffering from inundation water for many months was believed due to an impact of the backwater. The tributaries received water from the main river channel due to overcapacity. It made this water back up the tributaries and was not able to drain properly. The water had no place to flow and just inundated since those villages rellied on them for drainage.
Impacts of combined and separate land cover and climate changes on hydrologic responses of Dhidhessa River basin, Ethiopia
Published in International Journal of River Basin Management, 2022
Gizachew Kabite Wedajo, Misgana Kebede Muleta, Berhan Gessesse Awoke
Overall, the hydrological processes of the Dhidhessa River basin have undergone significant changes during the last three decades in response to the land cover and climate changes observed in the basin. The changes in hydrologic regimes are indicators of changes in watershed conditions (Welde & Gebremariam, 2017). The increase in surface runoff and decrease in groundwater recharge in the Dhidhessa River basin indicate deterioration of land resources of the basin and the downstream areas. Increased surface runoff aggravates soil erosion and reservoir siltation, and deteriorates water quality. As such, we believe changes in land cover and climate could result in a negative effect on water resource availability and agricultural production in the Dhidhessa River basin and the downstream areas. The problem could be more severe as the trend continues (Kabite et al., 2019; Kabite et al., 2020).
A new criterion for critical suspension of nonuniform sediment
Published in Coastal Engineering Journal, 2022
Zhilin Sun, Lixia Sun, Yun Gao, Haolei Zheng, Wengang Xiang, Yimeng Gao
(4) Sediment transport capacity is a key solution to the problem of siltation and erosion in rivers, estuaries and coastal waters. In several previous formulas, however, the relationship between sediment transport capacity and critical suspension condition is cut off. Combination of Eq. (13) with Eq. (5) makes it possible that sediment transport capacity links to critical suspension conditions.