Economics of reservoir sedimentation and sustainable management of dams

Accepted practice has been to design and operate reservoirs to fill with sediment, generating benefits from remaining storage over a finite period of time. The consequences of sedimentation and project abandonment are left to the future. This 'future' has already arrived for many existing reservoirs and most others will eventually experience a similar fate, thereby imposing substantial costs on society. Such costs could be avoided if sedimentation was minimized and dams were allowed to live forever. The fact that the world's inventory of suitable reservoir sites is limited provides an additional reason for encouraging the sustainable management of dams. This paper provides a framework for assessing the economic feasibility of sediment management strategies that would allow the life of dams to be prolonged indefinitely. Even if reduced accumulation or removal of sediment is technically possible, its economic viability is likely to depend on physical, hydrological and financial parameters. The model presented incorporates such factors and allows a characterization of conditions under which sustainable management would be desirable. The empirical implementation of the model draws upon the substantial amount of technical information available. We analyze the sustainability of reservoirs, with a focus on the trade-off between such sustainability and the short to medium term benefits which a reservoir is expected to produce. The results show that, for a very wide range of realistic parameter values, sustainable management of reservoirs is economically more desirable than the prevailing practice of forcing a finite reservoir life through excessive sediment accumulation.     

Flood regime and leaf fall determine soil inorganic nitrogen dynamics in semiarid riparian forests.

Flow regulation has reduced the exchange of water, energy, and materials between rivers and floodplains, caused declines in native plant populations, and advanced the spread of nonnative plants. Naturalized flow regimes are regarded as a means to restore degraded riparian areas. We examined the effects of flood regime (short [SIFI] vs. long [LIFI] inter-flood interval) on plant community and soil inorganic nitrogen (N) dynamics in riparian forests dominated by native Populus deltoides var. wislizenii Eckenwalder (Rio Grande cottonwood) and nonnative Tamarix chinensis Lour. (salt cedar) along the regulated middle Rio Grande of New Mexico. The frequency of inundation (every 2-3 years) at SIFI sites better reflected inundation patterns prior to the closure of an upstream dam relative to the frequency of inundation at LIFI sites (> or =10 years). Riparian inundation at SIFI sites varied from 7 to 45 days during the study period (April 2001-July 2004). SIFI vs. LIFI sites had higher soil moisture but greater groundwater table elevation fluctuation in response to flooding and drought. Rates of net N mineralization were consistently higher at LIFI vs. SIFI sites, and soil inorganic N concentrations were greatest at sites with elevated leaf-litter production. Sites with stable depth to ground water (approximately 1.5 m) supported the greatest leaf-litter production. Reduced leaf production at P. deltoides SIFI sites was attributed to drought-induced recession of ground water and prolonged inundation. We recommend that natural resource managers and restoration practitioners (1) utilize naturalized flows that help maintain riparian groundwater elevations between 1 and 3 m in reaches with mature P. deltoides or where P. deltoides revegetation is desired, (2) identify areas that naturally undergo long periods of inundation and consider restoring these areas to seasonal wetlands, and (3) use native xeric-adapted riparian plants to revegetate LIFI and SIFI sites where groundwater elevations commonly drop below 3 m.     

Decarbonization of Vietnam’s economy: decomposing the drivers for a low-carbon growth

Environmental Science and Pollution Research - Vietnam has witnessed a rapid increase in national-level CO2 emissions due to rising urbanization, economic expansion, export growth, and industrial...     

Regional disparities in Preventive measures of COVID-19 pandemic in China. A study from international students’ prior knowledge,perception and vulnerabilities

Environmental Science and Pollution Research - The COVID-19 pandemic needs immediate solution before inflicting more devastation. So far, China has successfully controlled transmission of COVID-19...     

Mapping farmers’ vulnerability to climate change and its induced hazards: evidence from the rice-growing zones of Punjab,Pakistan

Environmental Science and Pollution Research - In developing countries like Pakistan, agriculture constitutes the primary source of support for the majority of rural and the adjacent urban...     

Quantification of triazine herbicides in soil by microwave-assisted extraction and high-performance liquid chromatography

A method for the determination of herbicides residues, triazine (atrazine, metribuzin, ametryn, and terbutryn), in soil samples with high-performance liquid chromatography (HPLC)?CUV detection is described. The proposed method is based on microwave-assisted extraction (MAE) of soil samples for 4 min at 80% of 850-W magnetron outputs in the presence of mixture of solvents (methanol/acetonitrile/ethylacetate). Related important factors influencing the MAE efficiency, such as the solvent type and volume, irradiation energy, and time, were optimized in detail. Calibration curve ranges established using HPLC for metribuzin, atrazine, ametryn, and terbutryn are 1.0?C19.0, 0.9?C18.0, 0.6?C11.0, and 0.7?C11.0 µg mL^???1, respectively. The limits of detection of metribuzin, atrazine, ametryn, and terbutryn are 0.30, 0.24, 0.16, and 0.20 µg mL^???1 while limits of quantification are 1.0, 0.80, 0.50, and 0.60 µg mL^???1, respectively. A Plackett?CBurman factorial design was used as a screening method in order to select the variables that influence MAE extraction. The recoveries of the method at three different spiked levels were assessed by analyzing real soil samples and were found to be in the range of 83.33 ± 0.12?C96.33 ± 0.23 with good precision (<8%).     

Impacts of continuously regenerating trap and particle oxidation catalyst on the NO2 and particulate matter emissions emitted from diesel engine

Two continuously regenerating diesel particulate filter (CRDPF) with different configurations and one particles oxidation catalyst (POC) were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO₂, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO₂/NO_x significantly. The results of smoke emissions and particle number (PN) emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter (PM) and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO₂/NO_x. The PN emission results from two CRDPFs indicated that more NO₂ generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO₂ exposure in atmosphere.     

Exploring the potential effect of Achnatherum splendens L.–derived biochar treated with phosphoric acid on bioavailability of cadmium and wheat growth in contaminated soil

Environmental Science and Pollution Research - Biochar remediation efficiency could be enhanced through numerous treatments such as acids treatment. Still, there has little work done on...     

Agricultural factor endowment differences and relative poverty nexus: an analysis of macroeconomic and social determinants

Environmental Science and Pollution Research - Poverty is a significant global ongoing issue that influences a substantial amount of people despite all efforts to eliminate or lessen it. Although...