Deterioration Of Lake Water Quality Research Articles

Water Quality and Environmental Health of Lakes in Coimbatore, India: A Comprehensive Study of the Physicochemical Characteristics

The deterioration of lake water quality is a major national issue, particularly in regions with industrial activity. This study assesses the water quality of five lakes in Coimbatore, India: Krishnampathi, Ukkadam, Kurichi, Sulur, and Singanallur, between December 2016 and April 2017. Twenty physicochemical parameters were analysed following standard procedures outlined by the American Public Health Association. Twelve heavy metal elements concentration in the lakes was analysed using inductively coupled plasma-mass spectroscopy. The results of this study revealed that the values of 17 physicochemical parameters fell beyond the WHO recommended pollution levels in all the study sites, except Sodium, Nitrate, and Sulphate. While, the concentration of 10 heavy metal elements determined were within acceptable limits of WHO-recommended standards for drinking water across all lakes, except Fe and Pb. F-test revealed that the concentration of all the physicochemical parameters varied significantly across all the study sites, except for pH (P = .749). Statistical analysis such as principal component analysis was adopted, and the results were discussed on the multivariate relationships of the physiochemical parameters and heavy metal concentrations of the five study sites. Overall, the findings highlight the urgent need for continuous monitoring and comprehensive management strategies to mitigate the deteriorating water quality in the lakes of Coimbatore district, emphasizing the critical importance of addressing the multitude of factors contributing to this environmental challenge.

Establishing and modeling the causality relationship of hydro-climatic and land cover change variables with water quality over Lake Tana, Ethiopia

Lakes, the most widespread inland water bodies in the globe, are highly susceptible to change in trophic state due to external factors. Changing hydro-climatic conditions and land cover changes (LCC) can cause lake water quality deterioration. This study establishes the quantitative relationship between variability in the water quality index and changes in hydro-climatic and LCC variables. Water quality is represented by the Forel-ule index (FUI) whereas the hydro-climatic variables considered in this study are lake bottom layer temperature (lblt), lake total layer temperature (ltlt), precipitation, runoff, evaporation, lake skin temperature (lskt), surface wind speed and air temperature. The LCC is quantified by lower and higher level leaf area index (Lv-lai and Hv-lai). FUI has a positive relationship with surface wind speed, precipitation, runoff, ltlt, lblt, and LCC and a negative relationship with evaporation, lskt, and air temperature with 95% confidence level over most parts of the Lake. The temporal correlation is also apparent from the long-term trend pattern. A significant decreasing trend is observed in FUI and lake bottom layer temperature (lblt). In contrast, an insignificant increasing trend is observed in air temperature and lake skin temperature (lskt). The changes in LCC, runoff, precipitation, and surface wind speed is insignificant between 2000 and 2020. Moreover, the phase composites of FUI and hydro-climatic and LCC variables derived from multichannel singular spectrum analysis (MSSA) show strong seasonal modulation of water quality by hydro-climatic and LCC variables. The annual cycle represented by the first two eigenmodes (except wind speed which is represented by the second and third eigenmodes) accounts for between 27.41% (wind speed) to 52.32% (precipitation) of the total joint spatiotemporal variability of FUI and the driving variables. The convergent cross-mapping (CCM) analysis shows that cross-map skill (ρ2) is increased with increasing library length (L) and time delay (τ), which suggests significant causal effects of hydro-climatic and LCC variables on FUI and the lagged causation is consistent with maximum values of ρ2. The significant feedback of FUI to changes in hydro-climatic and LCC variables shows the possibility of hindcast/forecast of the historical/future status of water quality from hydro-climatic and LCC variables. As a result, a multivariate nonlinear regression model (MNWQFM) is developed to forecast the lake water quality index from the hydro-climatic and LCC variables. The model has high performance with R2 of 83.6% and root means square error (RMSE) of 0.15 in FUI.

Plateau Lake Water Quality and Eutrophication: Status and Challenges

The continuous and widespread deterioration of lake water quality and eutrophication is not only a local problem, but also a global phenomenon [...]

Analysis of the Interaction between Lake and Groundwater Based on Water-Salt Balance Method and Stable Isotopic Characteristics.

To better protect lacustrine ecologies and understand the evolutionary process of lake environments, it is critical to study the interacting mechanisms between lakes and the surrounding groundwater. The Wuliangsu Lake watershed is the largest wetland in the Yellow River basin and is the discharge area of the Hetao Irrigation District (HID), which is one of the three largest agricultural production areas in China. Due to the influence of human activities, the discharge water from the HID has led to the deterioration of the Wuliangsu Lake ecology and the degradation of the lake environment. Based on long-term observation data and water sampling data collected in 2021, a water–salt equilibrium model was used to analyze the recharge rate of groundwater to the lake. The contribution rate of groundwater to lake recharge in the study area was calculated with a Bayesian mixing model by combining D and 18O stable isotope data. Furthermore, the environmental evolutionary process of the lake was also analyzed using the collected water quality data. The results show that channel drainage was the main source of recharge to Wuliangsu Lake, accounting for more than 75%, while groundwater contributed less than 5% of lake recharge. After implementing the ecological water supplement plan, the concentration of various ions in the lake decreased, the concentration of the total dissolved solids (TDS) in the lake decreased from 1.7 g/L in 2016 to 1.28 g/L in 2021, and the ecological environment was improved. The contribution of groundwater to lake recharge was quantitatively analyzed. The results of this study can facilitate the development of vital strategies for preventing the further deterioration of lake water quality and for protecting wetland ecologies.

Impact of spring freshet flooding and summer rainfall flooding on the water quality of an alpine\xa0barrier lake

BackgroundBarrier lakes, formed by river interception, are particularly influenced by the upstream river. As such, spring freshet flooding and summer rainfall flooding due to wet precipitation (e.g. snow and rainfall) may sharply increase the concentrations of nitrogen, phosphorous, and carbon compounds in barrier lakes. Too much nutrients will lead to lake eutrophication. In this study, we used Lake Jingpo, the world’s second largest alpine barrier lake, to examine the impact of spring freshet flooding and summer rainfall flooding on its water quality by building a hydrodynamic water quality model with MIKE 21.ResultsThe MIKE 21 HD hydrodynamic model and MIKE 21 AD convection and diffusion module were calibrated using meteorological data, hydrological data, and water quality data collected in 2018. All errors were in the acceptable range. According to model simulation results, the flow velocity in Lake Jingpo is generally weak (mostly lower than 0.015 m/s), but it increases to 0.045 m/s and above during spring freshet flooding (April–May) and summer rainfall flooding (August–September), which is much higher than in other months. The flow volume of its largest inflowing river reaches 4.81 × 108 m3, 29.77 × 108 m3, and 58.4 × 108 m3 during spring freshet flooding, summer rainfall flooding, and 30-year frequency rainfall flooding period, respectively. The longest diffusion distances from the lake mouth to the downstream way are 16.3 km, 33.1 km, and 43.6 km during the spring freshet flooding, summer rainfall flooding, and 30-year frequency rainfall flooding period, respectively. A larger amount of precipitation leads to longer diffusion distances and increased concentrations of total nitrogen (TN), total phosphorous (TP), chemical oxygen demand (CODMn), and ammonia–nitrogen (NH4-N) in the lake.ConclusionsThe sudden increase in water volume during spring flooding and summer rainfall flooding led to the rapid spread of nutrients and pollutants carried by the water into the barrier lake, resulting in a deterioration of lake water quality. In addition to pollution source control measures, ecological restoration, and the construction of a buffer system in the catchment are very important measures to effectively improve the buffer capacity of barrier lakes in light of spring freshet flooding and summer rainfall flooding.

Urbanization and Industrialization Impact on Surface Water in Coimbatore-Sulur Subwatershed

Industrial pollution and urbanization is a major threat to the water environment.The advent of urbanization and industrialization for economic growth has adversely affected the biological diversity. Lake water quality deterioration has been evident in the lakes surrounding the city of Coimbatore. The growth of industries in the city has led to the increase of population day by day in the city The present study is mainly aimed at studying the nature and impact of water pollution in the sub basins of noyyal river basin in coimbatore-sulur subwatershed which has a major impact on the Environment, Health and Socio-Economic status. To understand the magnitude of the impact, water samples were collected in and around the Coimbatore city namely Sulur lake, Singanallur lake, Valankulam, Ukkadam lake and Noyyal river stream which falls in Coimbatore-Sulur subwatershed and analyzed for physical, chemical and bacterial characteristics. The study showed that the chemical characteristics were relatively higher (TDS-957mg/l), (Cl-439.58mg/l), (NO3-56.28mg/l) than the Bureau of Indian Standard acceptable limits and the presence of Escherichia Coli(60cfu/100ml) and Total Coliform(400cfu/100ml) are menacing in all the water samples leading to major health impact in human beings and also the quality of water is deteriorated.

Using SWAT to Evaluate Streamflow and Lake Sediment Loading in the Xinjiang River Basin with Limited Data

Soil erosion and lake sediment loading are primary concerns of watershed managers around the world. In the Xinjiang River Basin of China, severe soil erosion occurs primarily during monsoon periods, resulting in sediment flow into Poyang Lake and subsequently causing lake water quality deterioration. Here, we identified high-risk soil erosion areas and conditions that drive sediment yield in a watershed system with limited available data to guide localized soil erosion control measures intended to support reduced sediment load into Poyang Lake. We used the Soil and Water Assessment Tool (SWAT) model to simulate monthly and annual sediment yield based on a calibrated SWAT streamflow model, identified where sediment originated, and determined what geographic factors drove the loading within the watershed. We applied monthly and daily streamflow discharge (1985–2009) and monthly suspended sediment load data (1985–2001) to Meigang station to conduct parameter sensitivity analysis, calibration, validation, and uncertainty analysis of the model. The coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS), and RMSE -observation’s standard deviation ratio (RSR) values of the monthly sediment load were 0.63, 0.62, 3.8%, and 0.61 during calibration, respectively. Spatially, the annual sediment yield rate ranged from 3 ton ha−1year−1 on riparian lowlands of the Xinjiang main channel to 33 ton ha−1year−1 on mountain highlands, with a basin-wide mean of 19 ton ha−1year−1. The study showed that 99.9% of the total land area suffered soil loss (greater than 5 ton ha−1year−1). More sediment originated from the southern mountain highlands than from the northern mountain highlands of the Xinjiang river channel. These results suggest that specific land use types and geographic conditions can be identified as hotspots of sediment source with relatively scarce data; in this case, orchards, barren lands, and mountain highlands with slopes greater than 25° were the primary sediment source areas. This study developed a reliable, physically-based streamflow model and illustrates critical source areas and conditions that influence sediment yield.

Impact of External Conditions on Water Quality of Kamencové (Alum) Lake in Chomuto v and Proposal of Revitalizing Measures

Abstract Kamencové Lake (also called Alum Lake) located in Chomutov (North Bohemian Brown Coal Basin, Czech Republic) is a worldwide unique for its lake water chemical composition (K Al (SO4)2 12 H2O) that naturally prevents algae growth. The region used to be a centre of heavy industry based on brown coal burning, with a crucial impact on the environment (especially acid rain) in 1980s. This fact was considered the key aspect influencing the lake water quality deterioration in the past, besides the growing popularity of the area for recreational purposes (increased risk of eutrophication) and the significant changes in the lake maintenance (increased risk of eutrophication, excessive bottom sedimentation). Due to the real threat of gradual losing the lake water unique characteristics, scientifically-based systematic measures reducing the potential risk of eutrophication need to be implemented. The present study builds on the results of previous surveys by Geofyzika Brno, Povodí Ohře, s.p. or Hydroprojekt Praha. Its aim is to assess the potential risk of eutrophication in Alum Lake and to propose remedial measures.

Investigation of spatio-temporal variations of selected water quality parameters and trophic status of Lake Tana for sustainable management, Ethiopia

Freshwater resources are of critical importance to both natural ecosystems and human development. The health of aquatic ecosystems is dependent on right proportions and required succession of major nutrients in the water and sediment. Surface water pollution by agrochemicals has become a growing threat to the human society and natural ecosystems in the recent decades. Lake Tana is the largest fresh water body in Ethiopia, located at an altitude of 1786 m above sea level. The lake has an average depth of 9 m and maximum depth of 14 m with surface area of 3150 km2. The lake is an economically important shallow lake in the country and is threatened by anthropogenic and climatic factors. Excess agrochemicals input from agricultural activities and industrial effluent around Lake Tana watershed can pose a serious threat on the lake ecosystem by expansion of water hyacinth. The study was made to investigate the spatio-temporal variations of selected water quality parameters and trophic status of Lake Tana for sustainable management options for sustainable use of the lake. Different environmental samples such as water and sediment were collected from fourteen representative sampling sites of the lake for the measurement of physicochemical parameters and nutrients in both dry and wet seasonal basis. The physicochemical parameters were measured in-situ with portable multimeter and nutrients and chlorophyll a were determined by following the standard procedures outlined in the American Public Health Association (APHA) using UV/Visible spectrophotometer. The trophic status of the lake was determined using trophic state variable and Carlson model. The lake water quality level was also evaluated using comprehensive evaluation index model. There were spatio-temporal variations in the physico-chemical parameters and nutrients in the lake ecosystem during the study period. Higher concentrations of nutrients, electrical conductivity (EC) and total dissolved solid (TDS) were recorded in sampling sites of effluents of the some resort and the major feeding rivers in all seasons. The values of the comprehensive pollution index ranged from 0.68 to 1.01 and 0.91 to 1.69 during dry and wet seasons respectively. According to the values of comprehensive pollution index, the lake is moderately and slightly polluted in dry and wet seasons, respectively. The values for SRP, and TP distributions were higher in the wet season in most of the sampling sites. Carlson trophic state model showed the average values of Carlson Trophic State Index (CTSI) of Lake Tana were found to be 69.77 and clearly indicated Lake Tana TSI value lies well above the minimum value for eutrophic condition. In order to stop further deterioration of lake water quality and to eventually restore the beneficial uses of the lake, management of agrochemicals in the lake watershed should be given urgent priority. It is mandatory to prepare guidelines for the trophic status of the Ethiopian freshwater bodies in the country by making bottom-up-down discussion.

Coupled long‐term limnological data and sedimentary records reveal new control on water quality in a eutrophic lake

AbstractHuman impacts on freshwater ecosystems are pervasive, but the short and discontinuous nature of most datasets limits our ability to understand the controls on water quality and effectively manage freshwater resources. We examine change in Lake Mendota (Madison, Wisconsin) over the last two centuries by pairing analyses of a sedimentary archive with the site's > 100 yr limnological record. We show that eutrophication of the lake, evident as an abrupt shift in sediment composition, began in the late 19th century following the intensification of urban and agricultural land use in the watershed. Efforts to address deterioration of lake water quality, including the removal of point‐source pollutants and biomanipulation, have had a measurable influence on sediment composition and water clarity. Since the early 1980s, quasi‐seasonal cycles of phytoplankton blooms have induced calcite precipitation, leaving distinct laminations in the sedimentary record. These “whiting events” evidently did not accumulate in lake sediments until the late 20th century, indicating that efforts to remediate water quality have shifted the lake to a new ecosystem state. Calcite whitings can improve water quality in eutrophic lakes by coprecipitation with phosphate, increasing phosphorus (P) burial in lake sediments. Using long‐term limnological records, we report negative correlations between calcite saturation indices and P in lake surface waters and show that calcite whitings could partially explain recent P decline in Lake Mendota surface waters. Our study reveals a previously uncharacterized potential control on water quality in this eutrophic lake and demonstrates the benefit of coupling long‐term limnological data with sedimentary records.

Long-term change in the trophic status and mixing regime of a deep volcanic lake (Lake Bolsena, Central Italy)

Lake Bolsena, the fourth Italian lake for volume (9.2 × 109 m3), must be considered as highly sensitive to eutrophication for its extremely long water renewal time. In this paper, temperature and chemical characteristics of the lake measured in the period 2003–2017 are used to discuss the mixing pattern and the variation in the oxygen and algal nutrient concentrations, as indicators of the trophic level. In the analysed period the lake showed oligomictic characteristics, reaching the full overturn, with homogenization of the chemical profile over the whole water column, only in 4 out of the 15 considered years. A regular decrease of oxygen and increase of phosphorus concentrations in the deepest layers has been observed in the non-circulating multi-year periods. The mean total phosphorus concentration showed a regular increase, reaching values close to 16 μg P L−1 in early spring 2017, mostly because of the urban discharge from the watershed, not adequately collected from an existing sewage pipe. Chemical and mixing patterns are discussed in relation with a previous study, carried out in 1966–1971, confirming the recent increase of phosphorus concentrations and the lower frequency of full circulation. The progressive deterioration of lake water quality indicates the need of prompt actions to reduce the external nutrient load and of further studies on the physical and biological characteristics of the lake, still strongly missing.

Suspended sediment and phosphorus budget and trophic status of Bukit Merah Reservoir, Perak, Malaysia

Abstract Bukit Merah Reservoir (BMR) is one of the 51 impoundments in Malaysia. BMR is the oldest reservoir built in the early 1900s originally to store water for irrigation, but nowadays its functions include also flood control and water supply. Nowadays, it is threatened by land use change in the upper catchments and surrounding activities, which feeding eroded material and chemicals into the reservoir. Suspended sediment, as well as, nutrient fluxes into BMR are becoming an increasing threat to the reservoir, as its sedimentation and eutrophication accelerate. This paper discusses our study on the BMR carried out between March 2008 and April 2009 to assess the water quality status, and to determine the sediment and Total Phosphorus (TP) influx into the south pool lake. An estimated amount of suspended sediment fluxes of about 2,900 t year−1 came from the north pool lake (18%) and 12,900 t year−1 from the main Kurau River inlet (82% of the total input to the BMR). Of these total sediment input (nearly 15,800 t) about 5,600 t (36%) of the total sediment influx was trapped in the BMR. TP influx was about 18.8 t year−1 and about 7 t (37%) was trapped in the reservoir. The amount sediment and TP stored in the BMR affect the water quality of the lake, therefore the mean trophic state of the lake is eutrophic (TSI of 54.4) related to high productivity. Increasing sediment input into the reservoir has affected the reservoir volume and frequent flooding down-stream of the reservoir during rainy seasons, while eutrophication has caused the lake water quality deterioration.

Influence of changes in watershed landuse pattern on the wetland of Sultanpur National Park, Haryana using remote sensing techniques and hydrochemical analysis

Change in water supply and drainage patterns of surface and subsurface moisture zones are greatly enhanced due to anthropogenic activities. Monitoring changing wetland ecosystems helps to determine their tolerance to such anthropogenic activities.Sultanpur National Park, a wetland ecosystem located in Gurgaon district of Haryana state is such an ecosystem, harbouring plant and animal biodiversity. Increase in agriculture and builtup area in the surrounding region along with artificial deepening of the lake area for rainwater accumulation has led to the degradation of the central lake both in terms of quantity and quality. The anthropogenic influence was validated by landuse landcover mapping (through K-means unsupervised classification) of LANDSAT data within the wetland catchment for year 2000 and 2015 having an overall accuracy of 89.45% for 2000 and 80.48% for 2015.A declining trend in the total area under water cover in postmonsoon with a final area reduction of ~66% was observed from the year 1995–2015. Rampant agriculture and builtup land adjacent to the lake as well as artificial pumping of groundwater are major reasons for the deterioration of the lake water quality further posing major threats to the wetland ecosystem.Siltation from erosion and surface runoff due to mining and agriculture have led to the input of ionic components resulting in lake water quality deterioration as well as reduction in the depth of the lake available for rainwater accumulation. It has been inferred that high concentrations of nitrate (50% of samples above permissible limit (> 45ppm)) and phosphate (50% of samples above permissible limit (> 0.1ppm)) ions within the lake water is due to input from surface run off from the surrounding agricultural cropland within the lake catchment further leading to lake eutrophication and habitat loss suitable for plant and animal biodiversity.

The impact of changed river discharge on water quality deterioration in a prairie lake revealed by the sedimentary evidence

Abstract In order to investigate the historical water quality state and identify the factors causing modern environmental degradation in a prairie lake, total organic carbon (TOC), total nitrogen (TN), stable carbon isotopes of organic matter and total phosphorus (TP) from lake sedimentary core with high resolution age frame were analyzed. The results show that the values of proxies (TOC, TN, TP, δ13C, C/N) increased significantly after 2000 compared with before, which indicates Lake Hulun has heightened nutrient level and pollution extent, thus induced growth of algal bloom and water quality deteriorated after 2000. Since the event of decreased river discharge and lowered water level began in 2000 corresponds extremely well with our sedimentary records that nutrients pollution and eutrophication occurred in Lake Hulun at the same moment, the change of river discharge can be seen as the primary and direct reason of lake water quality deterioration in this period. In addition, the increased wind and water erosion as a result of serious and widespread destruction of grassland in Lake Hulun basin is the potential factors for changing the nutrients concentration in Lake Hulun.

Causes of polytrophism of three lakes in the Wdzydze Landscape Park

Causes of polytrophism of three lakes in the Wdzydze Landscape ParkIn the lakes Cheb and Słupino, located in the Wdzydze Landscape Park the quality of waters has been deteriorating in recent years. In the hydrologic year 2009 the quality of water was examined three times. Monthly measurements on the lake inflows and outflows were carried out 12 times to determine biogenic loads. In 2010 the supplementary measurements of biogenic loads were taken in the streams five times. According to Vollenweider's criterion, the loads of nitrogen and phosphorus compounds are too big, the heaviest to Lake Cheb. The discharge from the new sewage treatment plant is directed by the inflows into this lake. A similar situation takes place in the inflow to Lake Schodno. Paradoxically, in some catchments the construction of the sewage treatment plant may result in the deterioration of lake water quality.

Response of sediment chemistry and accumulation rates to recent environmental changes in the Clear Lake watershed, California, USA

The Clear Lake watershed, California, USA has been modified for agriculture since the arrival of Europeans in the early 1800s, and this has led to the deterioration of lake water quality. To assess the response of Clear Lake wetland sediments to recent environmental changes caused by watershed modifica- tion, physical and chemical properties of sediment cores at the inlet (Rodman Slough) and outlet (Anderson Marsh) were analyzed. 210 Pb dating showed increases of sedimentation rate for Anderson Marsh in the 1930s and 1980s, and those increases corresponded to algal blooms and the increase of P input into Clear Lake, respectively. Ranges of recent sedimentation and mass accumulation rates in Anderson Marsh were 0.41- 0.52 cm/yr and 1070-1380 g m 22 yr 21 . Accumulation rates of P, Ca, Mg, K, and Pb were slightly higher in Rodman Slough than in Anderson Marsh. Sediment analyses showed that the excess P originating from agricultural activities reach Clear Lake through Rodman Slough and were removed in the lake. 210 Pb dating

Modelling the Effects of Inflow Parameters on Lake Water Quality

A one-dimensional lake water quality model which includes water temperature, phytoplankton, phosphorus as phosphate, nitrogen as ammonia, nitrogen as nitrate and dissolved oxygen concentrations, previously calibrated for Lake Calhoun (USA) is applied to Uokiri Lake (Japan) for the year 1994. The model simulated phytoplankton and nutrient concentrations in the lake from July to November. Most of the water quality parameters are found to be the same as for Lake Calhoun. To predict probable lake water quality deterioration from algal blooming due to increased nutrient influx from river inflow, the model was run for several inflow water conditions. Effects of inflow nutrient concentration, inflow volume, inflow water temperatures are presented separately. The effect of each factor is considered in isolation although in reality more than one factor can change simultaneously. From the results it is clear that inflow nutrient concentration, inflow volume and inflow water temperature show very regular and reasonable impacts on lake water quality.

Forecasting the changes in lake water quality in response to climate changes, using past relationships between meteorological conditions and water quality

In order to forecast the effects of global warming on the water environment, the relationship between meteorological conditions and lake water quality was investigated statistically using 17 years of monitoring data obtained from a shallow eutrophic lake, Lake Kasumigaura. The usefulness of the DPY (difference from the previous year) method was confirmed for removing the watershed change (e.g. land cover, population, etc.). From the analysis of the relationships between air temperature and water temperature on a monthly basis, the delay of time was seen to be negligible, but the gain was reduced due to the high frequency of change. As the amount of precipitation affected their relationship on a yearly basis, the slopes of 1·0–1·2 °C water temperature/ °C air temperature were determined with the DPY method by excluding the combinations of the years having large difference in annual precipitation. The deterioration of lake water quality, such as increases in COD (chemical oxygen demand) and decreases in transparency, was quantitatively assessed as corresponding to an increase in air temperature. In addition, we found that higher precipitation led to high nitrogen concentrations on a monthly basis, as well as on a yearly basis, probably induced by both the runoff of soilwater having high concentrations and the lowering of residence times of lake water. Copyright © 2000 John Wiley & Sons, Ltd.

The Monthly Impact of Nonpoint Sources to Hoedong Lake, Korea

Lake Hoedong, located in the south of Korea peninsula, is a small, shallow, eutrophic lake, which is an important water supply source for the city of Pusan. Although point sources are discharged after secondary treatment, there has beena steady deterioration of lake water quality. Removal of point sources alone mayproduce no measurable improvement in the lake condition because of nonpoint sources. So the objectives of this paper are to quantify the nonpoint sources and to assess theimpact to the lake. Nutrient inputs from point sources are unlikely to have been alteredsignificantly, but nonpoint nutrient inputs have great monthly variation. Contributionof nonpoint sources to the external input of total phosphorus is almost 67% in the wet season and 19% in the dry season. Assuming that a substantial nonpoint source reductionis made by the Hoedong Lake basin, we attempt to estimate the effect of the lake waterquality by mass balance equation. The nonpoint source impact to Hoedong Lake waterquality is more than 60% in the wet season.