Water science and engineering 

About: Water science and engineering is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): Flood myth & Water resources. It has an ISSN identifier of 1674-2370. It is also open access. Over the lifetime, 703 publications have been published receiving 7789 citations. The journal is also known as: Shui kexue yu shui gongcheng.

A simple formula for predicting settling velocity of sediment particles

Abstract: Based on the general relationship described by Cheng between the drag coefficient and the Reynolds number of a particle, a new relationship between the Reynolds number and a dimensionless particle parameter is proposed. Using a trial-and-error procedure to minimize errors, the coefficients were determined and a formula was developed for predicting the settling velocity of natural sediment particles. This formula has higher prediction accuracy than other published formulas and it is applicable to all Reynolds numbers less than 2×105.

Adsorption of Cr(VI) in wastewater using magnetic multi-wall carbon nanotubes

Abstract: Magnetic multi-wall carbon nanotubes were prepared with wet chemical treatments and characterized by a transmission electron microscope (TEM) and X-ray diffraction (XRD). They were used as adsorbents for the removal of Cr(VI) in aqueous solutions. The effects of adsorbent dosage, the concentration of Cr(VI) in aqueous solution, temperature, and pH value on the removal efficiency were studied. Results showed that the adsorption capacity of the magnetic multi-wall carbon nanotubes increased with the initial Cr(VI) concentration, but decreased with the increase of adsorbent dosage. The adsorption amount increased with contact time. The adsorption kinetics were best represented by the pseudo second-order kinetic model, and the adsorption isotherms indicated that the Langmuir model better reflected the adsorption process. The obtained calculation results for the Gibbs free energy revealed that the adsorption was a spontaneous and endothermic process. The enthalpy deviation was 3.835 kJ·mol−1. The magnetic multi-wall carbon nanotubes showed significant potential for application in adsorption of heavy metal ions.

Compensation and benefit sharing: Why resettlement policies and practices must be reformed

Abstract: Many public and private sector projects, such as hydropower dams or mines, trigger forced population displacement but fail to resettle people sustainably and instead cause their impoverishment Social science research has found that one root cause of such failures and of impoverishment is asset dispossession and the insufficient financing of resettlement Most governments, however, state that (1) compensation alone is sufficient for restoring the income and livelihood of those displaced, and (2) resources to supplement compensation with additional financing are not available The author critiques and rejects these positions He offers a theoretical analysis of the limits and flaws of compensation payments for expropriated assets, and argues that resources are available for supplementing compensation with financial investments for resettlers' development The sources for supplementary financing are the economic rent (windfall profits) generated by natural resource projects such as hydropower or mining and the regular stream of benefits generated by all projects that require resettlement Further, the author argues that financial investments in resettlers' welfare are indispensable and that benefit sharing is feasible Therefore, both should become basic principles of resettlement legislation and practice In addition to theoretical analysis, the author documents with empirical evidence that some countries (China, Brazil, Canada, Columbia and Japan) already make investments additional to compensation for post-displacement reconstruction The author sums up his argument in these key points: (1) Compensation alone cannot prevent the impoverishment of resettlers and cannot in itself restore and improve their livelihoods; (2) Additional financing is needed for direct investments in resettlement with development; (3) Compensation levels must be increased; (4) Financing resources are available in most cases for investing in resettlers' development, but allocation of investments depends on the political will of governments and project owners; (5) Firm opposition to displacement and under-compensation is growing in many countries and the strength of resettlers' demands and political opposition does influence allocation levels; (6) Mechanisms for benefit sharing and transfer are known and effective and these mechanisms can be adjusted to different country and economic sector conditions; (7) The introduction of benefit-sharing rules requires legislative enactment for robust application

Fluoride Levels in Surface and Groundwater in Africa: A Review

Abstract: Fluoride has been reported to be among natural pollutant of water in Africa. High fluoride levels beyond the recommended World Health Organization limit of 1.5 mg/l has been observed in various Africa countries. However, the information is scattered in different publication medium. Therefore, objective of this work was to put together the information on fluoride levels in surface and groundwater in Africa, and describe the status and distribution of fluoride in water among African countries. This study assembled the secondary data of fluoride concentrations in surface and groundwater from the various literatures in African countries. Such countries represent southern, northern, eastern and western Africa. Descriptive statistics was used and results showed that elevated fluoride concentration occurred in countries such as Tanzania, Kenya, Algeria, Nigeria, Ghana, Malawi, Sudan, Uganda, the Republic of South Africa and Ethiopia. The highest fluoride concentration reported was 2,800 mg/l in Lake Nakuru in Kenya. The high fluoride concentrations in water can be linked to volcanic activities, presence of thermal waters especially those with high pH, gases emitted from earth’s crust, granitic and gneissic rocks. The high fluoride in water is severe in countries located in East African Rift Valley like Kenya, Tanzania and Ethiopia. However, all the incidences of highest fluoride levels in water in the Rift Valley countries were found in surface water bodies. This is contrary, as it is expected groundwater to be more concentrated as compared to surface water due to more water rock interaction than in surface water bodies. There was no single study among many studies has reported the long term trend of concentration of fluoride in water with time. Thus, the effort to establish long term trend of fluoride concentration in water should be taken in consideration. This helps to predict future concentration of fluoride and possibility to minimize future risks. Also, fluorosis has also been reported to be endemic in fluoritic areas of Africa though, little is known on other fluoride negative effects. Therefore, more efforts should concentrate on finding appropriate defluoridation techniques to be applied while considering the cost of operation, efficiency, practicability, easy application and environmental friendly.

Application of HEC-HMS for flood forecasting in Misai and Wan'an catchments in China

Abstract: The hydrologic model HEC-HMS (Hydrologic Engineering Center, Hydrologic Modeling System), used in combination with the Geospatial Hydrologic Modeling Extension, HEC-GeoHMS, is not a site-specific hydrologic model. Although China has seen the applications of many hydrologic and hydraulic models, HEC-HMS is seldom applied in China, and where it is applied, it is not applied holistically. This paper presents a holistic application of HEC-HMS. Its applicability, capability and suitability for flood forecasting in catchments were examined. The DEMs (digital elevation models) of the study areas were processed using HEC-GeoHMS, an ArcView GIS extension for catchment delineation, terrain pre-processing, and basin processing. The model was calibrated and verified using historical observed data. The determination coefficients and coefficients of agreement for all the flood events were above 0.9, and the relative errors in peak discharges were all within the acceptable range.