scholarly journals Influence of Riverbed Incision and Hydrological Evolution on Water Quality and Water Age Based on Numerical Simulation: A Case Study of the Minjiang Estuary

2021 ◽  
Vol 18 (11) ◽  
pp. 6138
Author(s):  
Peng Zhang ◽  
Lanyimin Li ◽  
Yishu Wang ◽  
Chengchun Shi ◽  
Chenchen Fan
Keyword(s):  
Water Quality ◽  
Dilution Effect ◽  
Scientific Basis ◽  
Low Oxygen ◽  
Quality Model ◽  
Water Age ◽  
Offshore Water ◽  
Minjiang River ◽  
Open Sea ◽  
Pollutant Discharge

In recent years, problems such as water quality deterioration, saltwater invasion, and low oxygen have appeared in estuaries all over the world. The Minjiang River in Fujian, as a typical tidal estuary area, is facing these thorny problems. In this paper, the effects of topography and hydrologic evolution on the water age and water quality of the lower reaches of the Minjiang River were simulated by building a hydrodynamic and water quality model. The results show that: (1) It was found that the riverbed incision of the lower reaches of the Minjiang River led to the overall decline of river water level, the increase of river volume, and the increase of downstream water age, which eventually led to the decrease of dissolved oxygen (DO) and the deterioration of water quality in the downstream from Shuikou to Baiyantan. However, the decline of topography led to the increase of tidal volume in the estuary, the enhancement of the dilution effect of oxygen-rich water bodies in the open sea, and the increase of DO in the lower reaches of Baiyantan. (2) Under no tidal action, the concentration of pollutants in the water of the North Channel increased, the DO decreased, and the DO decreased from Baiyantan to the offshore water. After the enhancement of tidal action, the dilution of oxygen-enriched water from the offshore water increased, and the DO increased. (3) The hydrological and water quality characteristics of the upper part of the lower reaches of the Minjiang River were mainly controlled by topography, runoff, and pollutant discharge, which were more affected by the tidal current transport operation and pollutant discharge near the open sea. In recent decades, the deterioration of water quality and the aggravation of saltwater intrusion in the Minjiang River were closely related to the serious topographic downcutting. The results provide a scientific basis for revealing the deterioration of estuary water quality and long-term management of the estuary.

scholarly journals Assessment of water quality modelling capabilities of EPANET multiple species and pressure-dependent extension models

2013 ◽  
Vol 13 (4) ◽  
pp. 1161-1166 ◽  
Author(s):  
Alemtsehay G. Seyoum ◽  
Tiku T. Tanyimboh ◽  
Calvin Siew
Keyword(s):  
Water Quality ◽  
Distribution Systems ◽  
Operating Conditions ◽  
Quality Analysis ◽  
Future Research ◽  
Operating Pressure ◽  
Quality Model ◽  
Water Age ◽  
First Order ◽  
Multiple Species

The need for accurately predicting water quality through models has increasingly been crucial in meeting rigorous standards and customer expectations. There are several endeavours on developing robust water quality models for water distribution systems. In this paper, two variants of the EPANET 2 water quality model have been assessed to inform future research. The models are the multiple species extension EPANET-MSX and the pressure-dependent extension EPANET-PDX. Water quality analysis was conducted on a hypothetical network considering various operating pressure conditions. Different kinetic models were employed to simulate water quality. First order, limited first order and zero order models were used for predicting chlorine residual, disinfection by-products (DBPs) and water age respectively. Generally, EPANET-MSX and EPANET-PDX provided identical water quality results for normal operating conditions with adequate pressure but different results for pressure-deficient networks. Also, a parallel first order model with fast and slow reacting components was used for chlorine decay and DBPs using the EPANET-MSX model for a network operating under normal pressure conditions.

scholarly journals Traceability and Emission Reduction of Dissolved Inorganic Nitrogen in Minjiang Estuary, China

2021 ◽  
Vol 18 (19) ◽  
pp. 10017
Author(s):  
Chenchen Fan ◽  
Peng Zhang ◽  
Gangfu Song ◽  
Huaru Wang ◽  
Bingyi Wang
Keyword(s):  
Water Quality ◽  
Inorganic Nitrogen ◽  
National Standards ◽  
Dissolved Inorganic Nitrogen ◽  
Quality Model ◽  
Model Calculations ◽  
Minjiang River ◽  
Global Environmental ◽  
Near Shore ◽  
Coefficient Method

The accumulation of dissolved inorganic nitrogen (DIN) in estuaries has become a global environmental problem. A two-dimensional, hydrodynamic water quality model was constructed in this study to investigate the sources of DIN pollution in the Minjiang Estuary. The concentration response field between the stream input and DIN in the estuary was established by using the surveyed source data of the study area. A sharing coefficient method was used to calculate the contribution percentage of each outfall to derive and propose a reasonable nitrogen reduction plan. The results showed that the input of land-based nitrogen into the Minjiang River contributed more than half of the DIN in the near-shore sea; the middle and upper reaches of the Minjiang River largely influenced the estuary area (38.57%). Conversely, the estuary and the coastline accounted for a smaller proportion of only 5.24%, indicating that an integrated DIN reduction should be implemented in the estuary area of the whole river basin. The model calculations showed that the reduction results, after remediation according to the current national standards for wastewater discharge in rivers, were not satisfactory. Thus, a new scheme is proposed in this paper—the total nitrogen (TN) input from land-based sources into the Minjiang Estuary and from the Shuikou Dam to the Min’an section should be reduced to below 31.64%; simultaneously, the DIN concentration discharged from the Shuikou Dam should be controlled and maintained below 0.5 mg·L−1 (TN = 0.8 mg·L−1). These results will provide guidelines for developing strategies for the improvement of DIN and water quality in similar estuaries.

scholarly journals Research on Control Method of Pollutant Total Amount of Water Quality based on Fuzzy Mathematics

2020 ◽  
Vol 24 (2) ◽  
pp. 191-199
Author(s):  
Rui Liu
Keyword(s):  
Water Quality ◽  
Control Method ◽  
Comprehensive Evaluation ◽  
Water Environment ◽  
Pollution Source ◽  
Source Control ◽  
Fuzzy Mathematics ◽  
Quality Model ◽  
Control Framework ◽  
Pollutant Discharge

With the increase of pollutants discharged into the water, it is difficult to control the water environment pollution via reducing part of pollutant discharge. Therefore, the control method of pollutant total amount of water quality based on fuzzy mathematics is proposed. Firstly, a control framework and process of the pollutant total amount was built. The total amount of pollutant discharged into this region was controlled within a certain amount to achieve the predetermined environmental objective. Then, water pollution of different regions was evaluated via water quality model based on the fuzzy mathematics in the region or key protection domain with severe pollution and a concentrated pollution source, which makes the comprehensive evaluation of the water quality pollution more scientific. Finally, the control of pollutant total amount was completed via the optimized combination of point source control and unit control of total amount. Experimental results show that the method is scientific, objective and reasonable during controlling the pollutant discharge. It controls the pollutant total amount excellently.

Characteristic and Influential Factors of Pollution Zone in the Lower Reach of Minjiang Tidal River

2011 ◽  
Vol 403-408 ◽  
pp. 2437-2440
Author(s):  
Mei Bing Liu ◽  
Xing Wei Chen
Keyword(s):  
Water Quality ◽  
Influential Factors ◽  
Tidal River ◽  
Two Dimensional ◽  
Lower Reach ◽  
Quality Model ◽  
Longitudinal Diffusion ◽  
Pollutant Load ◽  
Minjiang River ◽  
Tidal Area

The lower reach of Minjiang River, which passes through the Fuzhou city, is in the tidal area. A Two-Dimensional hydrodynamic and water quality model is developed. Taking Wukong sewage outfall as an example, the characteristic of pollution zone which is visualized by the contour of concentration is investigated, and the influential factors are also analyzed. It shows that the longest upstream pollution zone appears near the fastest flood moment, the longest downstream one appears near the ebb moment, the widest pollution zone occurs near the high or low water stand moment. The factors such as pollutant load, pollutant decaying coefficient and longitudinal diffusion coefficient are sensitive to the range of the pollution zone.

Mixed Layer Models and Their Application to Water Quality Problems

1994 ◽  
Vol 29 (2-3) ◽  
pp. 221-232
Author(s):  
M.J. McCormick
Keyword(s):  
Water Quality ◽  
Mixed Layer ◽  
Thermal Structure ◽  
Mass Conservation ◽  
Eddy Diffusion ◽  
Rate Of Change ◽  
Surface Mixed Layer ◽  
Storm Events ◽  
Quality Model ◽  
Mixing Processes

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.

Applying the Soil Water Assessment Tool to 5th Canadian Division Support Base Gagetown

2014 ◽  
Vol 49 (4) ◽  
pp. 372-385
Author(s):  
Shawn Burdett ◽  
Michael Hulley ◽  
Andy Smith
Keyword(s):  
Water Quality ◽  
Soil Water ◽  
Land Management ◽  
Management Practices ◽  
Assessment Tool ◽  
Anthropogenic Activities ◽  
Quality Model ◽  
Sediment Yields ◽  
Soil Water Assessment Tool ◽  
Water Assessment

A hydrologic and water quality model is sought to establish an approach to land management decisions for a Canadian Army training base. Training areas are subjected to high levels of persistent activity creating unique land cover and land-use disturbances. Deforestation, complex road networks, off-road manoeuvres, and vehicle stream crossings are among major anthropogenic activities observed to affect these landscapes. Expanding, preserving and improving the quality of these areas to host training activities for future generations is critical to maintain operational effectiveness. Inclusive to this objective is minimizing resultant environmental degradation, principally in the form of hydrologic fluctuations, excess erosion, and sedimentation of aquatic environments. Application of the Soil Water Assessment Tool (SWAT) was assessed for its ability to simulate hydrologic and water quality conditions observed in military landscapes at 5th Canadian Division Support Base (5 CDSB) Gagetown, New Brunswick. Despite some limitations, this model adequately simulated three partial years of daily watershed outflow (NSE = 0.47–0.79, R2 = 0.50–0.88) and adequately predicted suspended sediment yields during the observation periods (%d = 6–47%) for one highly disturbed sub-watershed in Gagetown. Further development of this model may help guide decisions to develop or decommission training areas, guide land management practices and prioritize select landscape mitigation efforts.

Application of Expert Systems Technology in Water Quality Modeling

1989 ◽  
Vol 21 (8-9) ◽  
pp. 1045-1056 ◽  
Author(s):  
Thomas O. Barnwell ◽  
Linfield C. Brown ◽  
Wiktor Marek
Keyword(s):  
Water Quality ◽  
Expert Systems ◽  
Knowledge Engineering ◽  
Stream Water ◽  
Environmental Modeling ◽  
Water Quality Modeling ◽  
Stream Water Quality ◽  
Quality Model ◽  
Knowledge Based ◽  
Available Technology

Computerized modeling is becoming an integral part of decision making in water pollution control. Expert systems is an innovative methodology that can assist in building, using, and interpreting the output of these models. This paper reviews the use and evaluates the potential of expert systems technology in environmental modeling and describes elements of an expert advisor for the stream water quality model QUAL2E. Some general conclusions are presented about the tools available to develop this system, the level of available technology in knowledge-based engineering, and the value of approaching problems from a knowledge engineering perspective.

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