Water pollution from agriculture: a global review. Executive summary

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More people, more food, worse water? a global review of water pollution from agriculture

Water quality models are important in predict- ing the changes in surface water quality for environmental management A range of water quality models are wildly used, but every model has its advantages and limitations for specific situations The aim of this review is to provide a guide to researcher for selecting a suitable water quality model Eight well known water quality models were selected for this review: SWAT, WASP, QUALs, MIKE 11, HSPF, CE-QUAL-W2, ELCOM-CAEDYM and EFDC Each model is described according to its intended use, development, simulation elements, basic principles and applicability (eg, for rivers, lakes, and reservoirs and estuaries) Currently, the most important trends for future model development are: (1) combination models—indivi- dual models cannot completely solve the complex situations so combined models are needed to obtain the most appropriate results, (2) application of artificial intelligence and mechanistic models combined with non- mechanistic models will provide more accurate results because of the realistic parameters derived from non- mechanistic models, and (3) integration with remote sensing, geographical information and global position systems (3S) —3S can solve problems requiring large amounts of data

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A review of hydrological/water-quality models

Dissolved oxygen, stream temperature, and fish habitat response to environmental water purchases.

Although access to clean and potable water is a requirement for healthy living, the constant release of non-point source pollutants into water bodies has resulted in water quality degradation. In a bid to curb this situation, water quality models are used as a tool. This study reviews 10 non-point source models, namely: AGNPS, ANSWERS, CREAMS, SWRRB, HSPF, SWAT, EPD RIV1, DMA, CMBA, and MA, giving consideration to their nature, components, area of use, strengths, and limitations. Our review indicated that hydrological processes and mechanisms involved in the movement of non-point source pollutants have not been completely developed in these models. However, HSPF and EPD RIV1 models (which have in-stream process components) are limited due to limitations in their operations and computational difficulties. Further research would seek to develop a non-point source pollutant model that would not only adequately and effectively simulate non-point source pollutants in water bodies, but would also be easy to assess, user-friendly, and time-efficient.

http://www.pjoes.com/pdf-76497-26092?filename=Assessing Non_Point.pdf

Assessing Non-Point Source Pollution Models:a Review

Surface water quality models can be useful tools to simulate and predict the levels, distributions, and risks of chemical pollutants in a given water body. The modeling results from these models under different pollution scenarios are very important components of environmental impact assessment and can provide a basis and technique support for environmental management agencies to make right decisions. Whether the model results are right or not can impact the reasonability and scientificity of the authorized construct projects and the availability of pollution control measures. We reviewed the development of surface water quality models at three stages and analyzed the suitability, precisions, and methods among different models. Standardization of water quality models can help environmental management agencies guarantee the consistency in application of water quality models for regulatory purposes. We concluded the status of standardization of these models in developed countries and put forward available measures for the standardization of these surface water quality models, especially in developing countries.

https://downloads.hindawi.com/journals/tswj/2013/231768.pdf

A review of surface water quality models.

A case study of the Caofeidian oil refining project is conducted. A two-dimensional convective dispersion mathematical model is established to simulate the increase in the concentration of pollutants resulting from the wastewater discharge from the Caofeidian oil refining project and to analyze the characteristics of the dispersion of pollutants after wastewater is discharged and the effect of the wastewater discharge on the surrounding sea areas. The results demonstrate the following: (1) The Caofeidian sea area has strong tidal currents, which are significantly affected by the terrain. There are significant differences in the tidal current velocity and the direction between the deep-water areas and the shoals. The direction of the tidal currents in the deep-water areas is essentially parallel to the contour lines of the sea areas. Onshore currents and rip currents submerging the shoals are the dominant currents in the shoals. (2) The pollutant concentration field in the offshore areas changes periodically with the movement of the tidal current. The dilution and dispersion of pollutants are affected by the ocean currents in different tidal periods. The turbulent dispersion of pollutants is the most intense when a neap tide ebbs, followed by when a neap tide rises, when a spring tide ebbs and when a spring tide rises. (3) There are relatively good hydrodynamic conditions near the project's wastewater discharge outlet. Wastewater is well diluted after being discharged. Areas with high concentrations of pollutants are concentrated near the wastewater discharge outlet and the offshore areas. These pollutants migrate southwestward with the flood tidal current and northeastward with the ebb tidal current and have no significant impact on the protection targets in the open sea areas and nearby sea areas.

Simulation of the effect of an oil refining project on the water environment using the MIKE 21 model

Two types of water allocation scenarios were proposed for reasonably utilizing water resources and improving water quality in a two-river network in Tongzhou District. Water circulation and quality were selected as two important indexes to evaluate the two scenario. Meanwhile, one-dimensional water amount and quality model was set up on the basis of the MIKE11 model to compare the two scenarios in terms of improving water environment. The results showed that both scenarios changed the hydrodynamic conditions, and consequently the river flow reached 0.05 m/s or higher in the central part of river stream. In addition, we also found that the two plans have similar effects on water quality, with first scenario producing larger area of water class III and IV than the second scenario.

Impact assessments of water allocation on water environment of river network: Method and application

In order to investigate the motion feature of alien phytoplankton in the Bohai Bay area, this paper combines the biological characteristics of phytoplankton in the Bohai Bay to build a two-dimensional tide hydrodynamic and particle tracking coupling model to simulate the phytoplankton at different specific growth rates. The characteristics of the movement trajectory of the three major ports in the Bohai Bay (Caofeidian Port, Tianjin Port, and Huanghua Port) and the diffusion processes. The results show that the movement of alien phytoplankton is mainly affected by the tidal circulation near the port. The diffusion trend is basically consistent with the residual flow field in the Bohai Bay, and its distribution density is directly affected by the specific growth rate of the population and is positively related to the specific growth rate; the release of alien phytoplankton at the three major ports is all concentrated around the ports, with the largest distribution density in Tianjin Port, and the possibility of red tide disasters is also greatest compared to the other two major ports; it is necessary to strengthen the monitoring of alien organisms in the port area and actively prevent alien phytoplankton from entering Bohai Bay through ship ballast water.

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Qinggai Wang

Papers

A review of surface water quality models.

Simulation of the effect of an oil refining project on the water environment using the MIKE 21 model

Impact assessments of water allocation on water environment of river network: Method and application

Numerical Simulation on the Diffusion of Alien Phytoplankton in Bohai Bay