Operation & Maintenance of Tailings Earth En Dam Specially For Disposal of Fly Ash from Thermal Power Stations
Several tailings earthen dams have failed during monsoon. Due to failure of tailings dam, stored tailings waste gets release in downstream area causing environmental hazard. Ash produced by combustion of coal in thermal power stations are stored in ash pond. No well-defined provision of operation and maintenance exists for ash pond. Therefore, this paper describes various issues related to operation and maintenance of ash pond.
DESIGN AND MAINTENANCE OF ASH POND FOR FLY
Thermal Power Plants using coal is chief source of energy in our country and it is likely to remain so in near future. The total production of fly ash per annum has already crossed 100 million tones and the disposal of the fly ash is causing several challenges. Utilization of fly ash has picked up but till the percentage utilization is far below satisfaction and power plants are no option but to dispose the fly ash in ash pond. No well defined design procedure or codal provision exist for the ash pond construction and maintenance. Fly ash being a waste product, power plants do not always pay much attention on maintenance of the ash pond. There are number of serious failures in ash pond which resulted in escape of ash slurry into the surrounding areas, including water bodies and created environmental hazard. This paper describes various issues related to the design and maintenance of ash pond.
Impacts of climate and land use changes on flood risk management for the Schijn River, Belgium
Abstract Flooding is the most common natural disaster in Europe. Modern flood risk management relies not only infrastructure development but also on governmental and non-governmental actors applying legal, economic and communicative water management instruments. Within the European Union (EU), flood management closely relies on policy set at the EU and national levels. It is now recognized that a sound understanding of climate change is required in addition to current management by taking into account land use change and socio-political context, as climate and land use changes have major impacts on hydrological responses. This paper investigates the hydrological behavior due to urbanization under current and future climate scenarios of high summer and high winter rainfall for 20 sub-catchments of the Schijn River, located in the Flanders region near Antwerp, Belgium. As urbanization increases and existing rainfall-runoff models neglecting the specific behavior of urban runoff, a hydrological model was developed based on a basic reservoir concept and applied to the existing rainfall-runoff model (PDM) flow to examine the specific urban contribution. Results revealed that peak flow for urban runoff and the total peak flow (i.e. rural and urban runoff) were significantly higher (i.e. ranges from 200% to 500%) than the existing rainfall-runoff model (PDM) flows, because of faster and more peaked urban runoff response. The impact of climate change on current and future conditions was also assessed by estimating peak flows with respect to return periods from the flood frequency curve. The predicted peak flow of high summer future climate scenario was significantly higher (i.e. ranges from 200% to 250%) than that of the current climatic condition for this region. Furthermore, hourly peak flow and daily volume ratios of 100-year return period for the highest, lowest and average impervious area were projected for the time horizon of the year 2100. It is concluded that climate change impacts contribute the most in producing peak flow in coming years, while increased urbanization takes the second place for both hourly and daily values. Results on urbanization effect and climate change impact assessment are useful to the water managers for spatial planning, emergency planning and insurance industry.