Mathematical modeling — A tool for coastal water quality management

Presence of various types of uncertainties in water quality management problems has been recognized as one of the major challenges in water quality modeling. Vagueness, lack of adequate data and nonlinearity of cost and/or benefit functions in most of water quality and waste load allocation management problems have reduced the capability of direct inclusion of uncertainty analysis in the management models. This study presents a fuzzy waste load allocation model in which cost function and the water quality standards or the goals of dischargers and pollution control agencies are expressed with appropriate linear and/or nonlinear and nondecreasing and/or nonincreasing membership functions. QUAL2E and Classified Population Genetic Algorithm (CPGA) were coupled to develop the optimum strategy resulting in maximum value of the minimum nonzero membership values, which represent the optimum satisfaction level of the conflicting goals. Number of constraint violations was used to penalize the fitness function in order to eliminate the infeasible solutions at the final results. The model was applied to a hypothetical case example. Results show a very suitable convergence of the proposed algorithm to good of possibility to the near global optima. Effects of linear and nonlinear membership functions are examined and the results are analyzed.

Spatial-temporal patterns and drivers of coastal water quality dynamics: Insights from explainable machine learning and PLS-SEM analysis in Xiamen Bay, China.

Navel gazing at remote sensing of inland and coastal waters from space Environmental monitoring from space The remote sensing definition of water quality The plight of remotely monitoring case 2 water quality The irony of remote sensing End-users of aquatic remote sensing products 1.6 Aquatic remote sensing products What went wrong with the great potential? Models, models, models, models The inevitable compromise of aquatic remote sensing Some concluding comments Remote sensing of inland water quality: a science primer Remotely sensing the Earth from space Remotely sensing aquatic color from space Remotely sensing inland and coastal water quality from space The scientific methodology (forward and inverse models) Concluding remarks The science of remotely sensing case 2 water quality Aquatic optics and water color Case 1 and case 2 waters Inherent optical properties (optical cross section spectra) Forward and inverse optical modeling Trans-spectral processes Remote sensing reflectance The status of remote sensing science Applications of water quality products to environmental monitoring What do environmental end-users want? What do environmental end-users need? What can environmental end-users be given? Benefits of incorporating remote estimates of water quality into environmental monitoring protocols: value-added remote sensing Inland and coastal (case 2) water quality products Providers and users: a marketplace reality check Applications of inland and coastal water color products Mapping water clarity Mapping chlorophyll concentrations (and primary production) of mid-oceanic (case 1) waters Mapping chlorophyll concentrations (and primary production) of optically complex inland and coastal (case 2) waters Monitoring the extent and progress of blue-green algae blooms and red tides Delineating the presence of inorganic turbidity in inland and coastal waters Monitoring the extent and progress of marine and inland oil spills Delineating the regional groundwater discharge, recharge, and transition areas (and temporal changes therein) Monitoring inland and coastal water quantity Recording natural and anthropogenic changes in shoreline/coastal features Recording changing configurations of continental ecozones Seagrass meadows: location and spatial distribution of substrate and substrate vegetation A lost opportunity to present an environmental manager with a compromise between science and usage of science Some comments on water quality monitoring Crystal-ball gazing at remote sensing of inland and coastal waters from space The United States, Canada, and space Addressing the chasm between Canadian inland and coastal water quality products and their potential end-users EOADP and GRIP The compact airborne spectrographic imager (CASI) Directions taken at CSIRO Suspended sediments recognized as independent CPAs? Back to the future with red wavelengths? Truth in advertising of remote sensing products Environmental science and the vagaries of populism Three examples of controversial environmental issues Quality science emergent from fear-instilling rhetoric Ground-level ultraviolet radiation and natural waters Environmental monitoring from space and controversy

Eco-hydrological modelling in a highly regulated lowland catchment to find measures for improving water quality

Explainable and causal machine learning to investigate the spatiotemporal dynamics patterns of coastal water quality in Hong Kong.

The coastal area of the Western Province is faced with an acute environmental problem due to undesirable pollution of its waters from various wastes. The overall objective of this research was to determine the present status of water quality along the coastal line in the Western Province. In addition, an attempt was made to suggest recommendations to mitigate the pollution levels. The study was carried out from November 2011 to April 2012 and sampling was done on a monthly basis from Bentota to Negombo in selected coastal area. Dissolved oxygen (DO), water temperature, pH, turbidity, conductivity, total dissolved solids (TDS) and salinity were determined in situ and water samples were subjected to laboratory analysis using standard methods. Coastal water quality results revealed that, the average ammonia concentration (0.22 ± 0.16) mg/L and water temperature (30.0 ± 3.8) 0C were below the maximum permissible limits of the proposed ambient water quality standards for Sri Lankan coastal waters. Average pH (7.91 ± 0.34) was within the ideal pH range for above standards whereas the mean concentration of DO was below the saturation level. An average value determined for Biochemical Oxygen Demand (12.08 ± 4.47) mg/l was much higher than the permissible threshold limit (>5 mg/l) which indicates the gross organic and inorganic pollution in all selected sampling locations in western coast. Proposed ambient coastal water quality standards should be modified using coastal water quality monitoring data and expert views and comments. Further studies needed to determine heavy metal concentration and bacteriological parameters to obtain clear picture of the pollution status. DOI: http://dx.doi.org/10.4038/jepsl.v3i2.7843 Journal of Environmental Professionals Sri Lanka: 2014 Vol. 3 No. 2: 12-24

Coastal water quality in Hawaii: the importance of buffer zones and dilution

The scarcity of water resources in Egypt has necessitated the use of various types of lower quality water. Agricultural drainage water is considered a strategic reserve for meeting increasing freshwater demands. In this study, a novel model series was applied to a drainage basin in the Nile Delta to optimize integrated water quality management for agriculture and the aquatic environment. The proposed model series includes a waste load allocation model, an export coefficient model, a stream water quality model, and a genetic algorithm. This model series offers an optimized solution for determining the required removal levels of total suspended solids (TSS), the chemical oxygen demand (COD) at point and non-point pollution sources, and the source flows that require treatment to meet a given water quality target. The model series was applied during the summer and winter to the El-Qalaa basin in the western delta of the Nile River. Increased pollutant removal and treated fractions at point and non-point sources reduced violations of the TSS standards from 732.6 to 238.9 mg/L in summer and from 543.1 to 380.9 mg/L in winter. Likewise, violations of the COD standards decreased from 112.4 mg/L to 0 (no violations) in summer and from 91.7 mg/L to no violations in winter. Thus, this model is recommended as a decision support tool for determining a desirable waste load allocation solution from a trade-off curve considering costs and the degree of compliance with water quality standards.

The resolution of digital elevation model (DEM) used for watershed delineation and data extracted from the delineated watershed relevant to hydrography plays an important role in the calibration of hydrological models. The effect of DEM resolution on the drainage length, watershed area and average slope are studied in many earlier works. DEM resolution can have impact on hydrologic modeling parameters, water quality simulation results. The impacts of DEM resolution on results of the watershed response and water quality modeling are studied using HSPF (Hydrologic Simulation Program Fortran) model applied to a watershed in Kentucky in this study. Three major streams in this watershed are impaired due to pathogen pollution according to the current state of Kentucky water quality standard set for recreation. The effects of DEM resolution on water quality modeling and calibration for fecal coliform bacteria are studied using a HSPF model. Results from this study indicate that the DEM resolution affects hydrography parameters of the delineated watershed, influence the calibration process, and the non-point and point source loadings to the streams in the watershed.

Integration of multi-source data for water quality classification in the Pearl River estuary and its adjacent coastal waters of Hong Kong

Long-term characteristics of water quality around the Guangdong-Hong Kong-Macau Greater Bay Area: Spatiotemporal variations and meteorological effects

Marine water quality is one of the priorities among contemporary Black Sea environmental issues. Its major importance and complex implications are evinced by international and national concerted concern and actions, such as the control of eutrophication and the financing of nutrient reduction supported by the Global Environment Facility (GEF), the continued European Union (EU) commitment to the Black Sea, the Strategic Action Plan for the Rehabilitation and Protection of the Black Sea with related National Action Plans for the entire region. Coastal water quality along the Romanian Black Sea coast will be considerably improved by the full operation of four wastewater treatment plants at Constantza Nord, Constantza Sud, Eforie Sud and Mangalia until the end of 2008: following main achievements are expected from the modernization of mentioned facilities: – conformity of wastewater quality parameters with European Economic Community (now EU) Directives, –improvement of quality control and ecological protection of coastal waters, – fulfillment of one of Romania's obligations as EU admission candidate country.

It is of great significance to analyze the threshold relationship between landscape pattern and water quality for watershed water environment treatment. However, previous studies did not consider the influence of spatial scale on threshold. Therefore, this study proposed the idea of the relationship between landscape pattern and water quality threshold considering the spatial scale effect to solve the above problems. Firstly, the percentage of landscape composition area under 9 spatial scales (riparian buffer zone and sub-basin) of 20 rivers entering the lake in Dianchi Lake Basin was extracted to identify the optimal spatial scale of landscape pattern and water quality by redundant analysis (RDA). Then, a variety of nonlinear regression models such as power regression, exponential regression, quadratic regression, and segmented regression are used to quantitatively detect the thresholds of landscape pattern and water quality. The results show that (1) the spatial scale has a significant influence on the threshold relationship between landscape pattern and water quality, and the total interpretation rate of landscape pattern on water quality is the largest at the buffer scale of 1100m riparian zone, which is an effective buffer for river governance. (2) Different spatial scales have different effects on the threshold relationship between landscape pattern and water quality. In the nonlinear regression model of landscape pattern and water quality in the buffer zone of 1100m riparian zone, the significance and R2 of the equation are better than those of the sub-basin. (3) From the nonlinear relationship between landscape pattern and water quality, it is found that the landscape threshold can be quantitatively identified when the water quality changes abruptly or reaches the I ~ V water quality standard. Among them, the type-1 landscape threshold at the water quality mutation point can be used as the long-term goal of water quality protection in Dianchi Lake Basin, and the type-2 landscape threshold can be used as the short-term goal of water quality adjustment. The research results can provide a scientific basis for the governance of water environment and the rational planning of landscape pattern in Dianchi Lake Basin, and have practical significance for guiding the sustainable development of cities.

In water quality management, pollution control strategies have been sought to accord with the assimilative capacity of water bodies so as to preserve water quality. The waste load allocation (WLA) is a useful approach to determine the allowable loading of pollution sources in water quality management. For any WLA, a particular water body condition is needed as a basic scenario under which the relevant parameters are fixed. The particular flow rate is known as design flow and usually set at low flow in order to be protective. The design flow is traditionally a particular deterministic value, such as Q (75), implying that it is expected that the probability of water quality violation is 25% in the long run. However, this long-term expectation might not be realized in individual years due to variability of natural flow. The flow variability will make a WLA plan overoptimistic or over-conservative in different years, suggesting that the deterministic design flow without uncertainty consideration might lead to an ineffective or inefficient decision-making. To address the problem, we explicate the relationship between flow variability, design flow and water quality with different flow distributions to facilitate the understanding of the process of a WLA. In order to manifest the uncertainty effects of design flow, the results from the annual flow duration curve (AFDC) is compared with the conventional flow duration curve (FDC). The AFDC approach is capable of obtaining the uncertainty level of the design flow by generating the confidence interval rather than a fixed value. The effect of different record lengths on design flow determination is estimated as well. Finally, a refined WLA process is proposed with a re-examination of water quality violation to improve the allocation decision under uncertainty. TaHan River Basin in northern Taiwan is used as a case study.

This study analyzed the water quality dynamics in the coastal zone of Boracay Island in relation to anthropogenic activities and natural factors. Seven sites were studied where possible sources of nutrient inputs on spatial and temporal basis were identified. Water samples were evaluated using the Philippine Department of Environment and Natural Resources (DENR) regulatory standards. The coastal water quality was generally influenced by nutrient loading coming from untreated and partially treated waste water from households and commercial establishments not connected to the sewerage system of the island. Natural cleansing mechanisms attributed to activities of autotrophs in the coastal water and biogeochemical processes of mangrove swamps are operational. Coastal waters adjacent to mangrove swamp impoverished of mangrove trees showed poor water quality, while coastal water adjacent to mangrove swamp with relatively good mangrove cover exhibited good water quality. The months of February to June with highest number of tourist arrival proved to be the critical periods. Lugotan Cove close to Mangrove Swamp 6 impoverished of trees was the critical area in the Island. Puka Beach close to Mangrove Swamp 1 with good mangrove cover showed the cleanest water quality, followed by Long Beach with most of the commercial establishments connected to the sewerage system.