INTRODUCTION
Introduction
Vietnam has seen rapid growth in its golf industry, with 35 operational golf courses and an additional 65 projects underway (www.golfasian.com/golf-courses/vietnam-golf-courses/) Despite golf being a relatively new sport in the country, the significant rise in golf course development—mainly foreign-owned—has been unprecedented Proper development and management of golf projects can boost economic growth, create jobs, and contribute to community development Reclaiming fallow or arid lands for golf course development can transform natural landscapes, enhance tourism, and improve local environments when built sustainably Additionally, eco-friendly golf course construction and management can offer environmental benefits, supporting sustainable tourism and community well-being.
Poorly managed and unplanned development of golf courses in Vietnam threatens both socio-economic stability and environmental health Golf courses, as man-made ecosystems featuring streams, turf grasses, and green spaces, can negatively impact water bodies when streams pass through their grounds To maintain optimal playing conditions, golf courses use significantly more pesticides and fertilizers—an 18-hole course employs approximately 1.5 tons of chemicals annually, three times more than agricultural land on the same area—posing risks to surface and ground water quality The frequent application of these chemicals not only jeopardizes the health of workers and golfers but also contaminates nearby water sources, especially in the context of Vietnam’s approval of riverside and seaside golf courses with excessive fertilizer and pesticide use, thereby escalating environmental risks.
According to the Ministry of Agriculture and Rural Development, globally, golf courses are typically constructed away from residential areas or on non-arable, ineffective land In Vietnam, there is a tendency to develop golf courses near rivers, with statistics showing 114 projects, including 10 that pass through rivers or streams The 54-Hole Phoenix Golf Course, located near Bui River, is the largest in Vietnam and the second largest in Asia, highlighting the environmental sensitivity of such sites Due to its proximity to water bodies, environmental issues such as toxic substance runoff and soil leaching pose significant risks to surrounding ecosystems and communities Based on an analysis of existing golf courses and their potential environmental impacts, particularly on stream and water quality, this research focuses on assessing these environmental challenges.
“Evaluating effects of Phoenix Golf Course on water quality at headwater catchment of Bui River in Hoa Binh province.”
Literature Review
Research on the impact of golf courses on water quality has increased significantly since the late 1980s However, these studies often lack public exposure and are rarely compared to identify trends in water quality related to golf course activities Much of the existing research emphasizes the movement of pesticides and fertilizers, highlighting their role in affecting the aquatic environment near golf courses.
A previous study in Cape Cod identified the leaching of eight pesticides and their metabolites into groundwater, demonstrating that pesticide use on golf courses can impact water quality under specific hydrologic conditions (Cohen et al., 1990) Additionally, the U.S Geological Survey reported 27 pesticide degradation products in surface water samples near Portland, highlighting the extent of pesticide runoff into surface waters Multiple studies have shown that the application of fertilizers and pesticides on golf courses adversely affects surface water quality, with excess nutrients contributing to environmental issues such as eutrophication (Antikainen et al., 2004) Phosphorus-based fertilizers, when runoff during watering or storm events, promote algae blooms that deplete oxygen and threaten aquatic life (Ayyappan et al., 2005; Aguila et al., 2004) Furthermore, research by Mallin and Wheeler indicates increased nitrate levels in creeks flowing through golf courses and higher nutrient concentrations in golf course ponds and adjacent coastal areas compared to reference sites, underscoring the environmental impact of golf course runoff on water ecosystems.
Golf has become a significant industry in Southeast Asia, but it poses serious environmental and health risks for nearby communities According to Tourism Concern, an average golf course in tropical countries like Thailand requires 1,500 kilograms of chemical fertilizers and pesticides and consumes water equivalent to that used by 60,000 rural villagers In Vietnam, the Tam Dao Golf Course in Vinh Phuc Province has caused severe local water pollution since its establishment in 2004, due to the discharge of untreated herbicides and pesticides Provincial authorities have neglected to treat these wastes, leading to tensions with local residents and raising concerns about the ecological impact of golf course operations.
Currently, there is limited research on water quality assessment at the headwater catchment of the Bui River A 2009 study by Hua Thi Yen, Nguyen Thuy Duong, and Tran Van Hung revealed that unplanned development of a golf course led to increased pollution in Bui River's surface water The study found that upstream areas, unaffected by Phoenix Golf Course activities, had low levels of nitrates and phosphates, whereas downstream water exhibited significant increases in total nitrogen and phosphorus Additionally, there is a lack of scientific surveys and reports on the chemical impacts of golf courses in Lam Son commune, with no available documentation to guide further research or policy development.
OBJECTIVES
Objectives
The main objectives of this study include: (1) Evaluating the effect of Phoenix
The Phoenix Golf Course significantly impacts the water quality of the Bui River's headwaters in Lam Son To minimize these environmental effects, implementing sustainable management practices is essential, such as reducing chemical runoff and enhancing water filtration systems Regular monitoring of water quality can help detect contamination early and guide necessary interventions Incorporating eco-friendly landscaping and efficient irrigation techniques can further decrease pollutant load and preserve the natural water ecosystem Effective strategies to mitigate golf course-related water pollution are crucial for protecting the health of the Bui River and ensuring the sustainability of local water resources.
STUDY SITE AND METHODS
Study site
Figure 1 Location of the study site at Lam Son commune
Lam Son commune, located in the western part of Luong Son district in Hoa Binh province, is conveniently situated near Highway 6, which connects Hanoi to the Northwest region, and is approximately 45 km north of Hanoi Geographically, it spans coordinates 20°45’–21°01’ N and 105°24’–105°39’ E, featuring a primarily limestone-rich topography with mountainous terrain aligned northwest-southeast The area's elevation reaches an absolute height of 500 meters above sea level, with a relative elevation of 126 meters, contributing to its diverse landscape.
The area features a humid subtropical climate characterized by extensive summer rainfall, with the rainy season lasting from April to October, bringing warm, wet, and rainy weather In contrast, the dry season occurs from November to March, experiencing colder temperatures with minimal rainfall, creating a distinct seasonal pattern.
Table 1 Climate indicators at Lam Son commune Luong Son district, Hoa Binh province
Month Temperature ( 0 C) Precipitation (mm) Moisture (%)
The study site experiences a mean annual temperature of 23.1°C, with July being the hottest month at 28.2°C and January the coldest at 16°C It receives a total of 1,913 mm of rainfall annually, with the rainy season occurring in July, August, and September, accounting for 95% of the total precipitation with 1,500–1,600 mm during this period December records the lowest precipitation at just 12 mm The area has approximately 146 rainy days each year Additionally, the moisture regime is characterized by high moisture levels that fluctuate throughout the year, with an average of 84%, falling to 82% in October and peaking at 86% in August.
Lam Son commune experiences seasonal wind patterns primarily influenced by atmospheric circulation, with two dominant directions: from April to October, the southeast wind brings hot air and steam, while from November to April, the northeast wind prevails during the dry season The area is rich in rivers, streams, ponds, and lakes, supporting diverse hydrography Over 70% of annual rainfall occurs during the rainy season, often causing floods in the Bui River headwater catchment, whereas the dry season typically brings water shortages affecting local agriculture and daily life.
Methods
4.2.1 Identified catchment boundary of Bui River
This study examines the impact of Phoenix Golf Course on the water quality of the Bui River headwater catchment We identified the catchment boundary of the Bui River and analyzed its characteristics to understand the baseline conditions The headwater catchment boundary was delineated accurately, providing crucial data for assessing potential influences from surrounding land uses These findings contribute valuable insights into how golf course activities may affect water quality in the Bui River's upstream region.
Figure 2 This flow chart represents whole process of doing the analysis in ArcGIS
Step 1: Using application of ArcGIS 10.1 to combine 2 maps of Lam Son commune boundary and Digital Elevation Mode (DEM) image of Lam Son in 2015 We got the map of Lam Son commune DEM image DEM images were downloaded from website http://gdex.cr.gov/gdex/: (1)
Step 2: Create the Flow Direction and Flow Accumulation hydrology layers from
Using ArcGIS 10.1's Spatial Analyst tools—specifically the Fill tool, Flow Direction tool, and Flow Accumulation tool—we generated a flow accumulation layer for the Bui River in Lam Son commune.
Step 3: Create the contour map of Lam Son commune by using Spatial Analyst tool in ArcGIS 10.1 “Spatial Analyst Surface Contour” (3)
Step 4: From Flow accumulation layer was created from step 3, using “Map algebra tool” in Spatial Analyst to identify streams Then using “Stream order and stream to feature tools” to display all stream orders into map (4)
Step 5: We had already the coordinate points of outlet catchment by using GPS device in the field Determine the outlet point of headwater catchment of Bui River in map by importing the coordinate point into ArcGIS and using Editor tool bar to place the outlet point in map
Step 6: Run the Watershed Tool, with the inputs are “Flow direction” and Pour point is the outlet point to identify the catchment area and boundary By combining with the map “Contour map of Lam Son commune”, we got the finally map of catchment boundary of Bui River
To assess the impact of Phoenix Golf Course on the water quality of Bui River, water samples were collected from three strategically located points along the stream: upstream, within the golf course, and downstream These sampling points enable a comprehensive evaluation of potential pollution or water quality changes caused by the golf course's proximity The analysis aims to determine how the golf course influences water parameters and overall river health, providing valuable insights for environmental management and sustainable golf course practices.
Figure 3 Map of water samples in Bui River
* Sampling period: To evaluate the effect of Phoenix golf course to water quality of Bui River, we take water samples in three periods at three different locations:
- Day 1: Before raining and applying fertilizer, pesticide on golf course: 8h – 10h,
- Day 2: After applying fertilizer and pesticide on golf course: 8h – 10h, 18 August 2015
* Number of water samples: As figure shows, the red arrow indicate location on
Bui Rivers the we sampled at, at three locations such as upstream, Phoenix golf course, downstream where we collected water samples in three days Total water samples are 9
Water samples were collected in the field following the standard Vietnam TCVN 5996-1995: Water Quality – Sampling – Guidance on Sampling on Rivers and Streams, ensuring accurate and representative data for water quality assessment.
During the reparation process, approximately nine clean plastic bottles were used to collect samples, ensuring they were thoroughly cleaned to prevent contamination Essential equipment for the task included a black box, a layout map of Phoenix Golf Course, a pen and notebook for recording data, a GPS device for precise location tracking, and additional tools such as a phone, camera, and other necessary equipment Proper cleaning and careful handling of the plastic bottles are crucial to maintain sample integrity throughout the project.
Water samples are collected by dipping bottles into surface water at a depth of 30-50 cm, following the direction of water flow to ensure representative sampling The bottles must be capped immediately underwater to prevent oxygen from entering and altering the sample Labels should be handwritten or pre-printed and securely affixed to the bottles for proper identification During transportation, samples are stored in black boxes to protect them from sunlight, which can affect the activity of organisms in the water After sampling and preservation in the field, the samples are transported to the laboratory for analysis of water quality indicators, ensuring accurate assessment of water conditions.
4.2.4 Method of analyzing water samples in laboratory:
The water quality analysis encompassed key parameters such as temperature, pH, dissolved oxygen (DO), chemical oxygen demand (COD), total suspended solids (TSS), biochemical oxygen demand (BOD5), total nitrogen (N-NO3), total phosphorus (P-PO4), and total Coliforms Samples were collected and analyzed following Vietnam's TCVN 5996-1995 standards for water sampling, ensuring data reliability pH levels were measured directly in the field using a Hana pH meter for accuracy, while total suspended solids were determined through standardized weight analysis methods, providing comprehensive insights into water quality conditions.
1 Taking about 100 ml water samples to filter by filter paper
2 The weight of filter paper before and after the filter must be dried in an oven to constant mass at a temperature of 150 0 C and then weighed on an analytical weight with the bias ± 0,1mg
3 From this total suspended solid is calculated by formula:
Total Suspended Solids (TSS) are calculated using the formula: TSS = (m2 – m1) / V (mg/l), where m1 is the weight of the filter paper at 150°C before filtering, m2 is the weight after filtering, and V is the volume of the water sample passed through the filter paper To determine dissolved oxygen (DO), the modified Winkler method is employed, providing accurate measurements essential for water quality assessment.
We used Winkler method to determine the amount of dissolved oxygen present in the sample There are 12 steps in laboratory:
1 Collect the sample to be tested in a 300 mL BOD bottle taking special care to avoid adding air to the liquid being collected Fill bottle completely and add stopper
2 Remove bottle stopper and add 1 mL of the manganous sulfate solution at the surface of the liquid
3 Add 1 mL of the alkaline potassium iodide sodium azide solution at the surface of the liquid
4 Replace the stopper, avoid trapping air bubbles and shake well by inverting the bottle several times Repeat shaking after floc has settled halfway Allow floc to settle a second time
5 Add 1 mL of concentrated sulfuric acid by allowing the acid to run down the neck of the bottle above the surface of the liquid
6 Restopper, rinse the top of the bottle to remove any acid and shake well until the precipitate has dissolved
7 Titrate a volume of treated sample which corresponds to 200 mL of the original sample This volume calculated using the formula: mL of sample to titrate = 200 x [300/(300 2)] = 201 mL
8 Pour 201 mL of sample from the BOD bottle into an Erlenmeyer flask NOTE: Since variations occur in the actual volume of each BOD bottle, do not pour 99 mL of sample out of the BOD bottle and assume that 201 mL will be left
9 If the solution is reddish brown in color, titrate with 0.025N sodium thiosulfate or 0.025N PAO until the solution is a pale yellow (straw) color Record the amount of titrant used Add a small quantity of starch indicator and proceed to step 11
RESULTS AND DISSCUSION
Characteristic of catchment headwater of Bui River
By using Digital Elevation Model map of Lam Son in 2015 and “Hydrology” tools of ArcGIS, I determined the map catchment boundary of Bui River in Lam Son commune:
Figure 4 Catchment boundary of headwater Bui river in Lam Son commune
Characteristics of catchment headwater of Bui River were conducted by supporting of ArcGIS 10.1software:
Table 2 Characteristics of catchment headwater of Bui River
Number Characteristics of catchment Values
7 The perimeter of catchment 26.778 (km)
8 The area of catchment 30.548 (km 2 )
11 The length of stream 26.88 km 2
Located in Lam Son commune, Luong Son district, Hoa Binh province, northern Vietnam, this catchment covers an area of 30.548 square kilometers The Bui River watershed features an elevation range of 30 to 800 meters, with slopes varying from almost flat to mountainous terrain, influencing local hydrology and land use.
The catchment has a shape index (Kc) of 1.35 and a total stream length of 26.88 km Water flows downhill from high-elevation areas toward lower elevations, following the natural gradient The catchment features small streams that discharge into larger streams and ultimately lead to the outlet, with stream channels trending in a northwest-southeast direction It includes both permanent streams that flow year-round and temporary streams that dry up during the dry season.
Maintenance and operation of Phoenix golf course
The Phoenix Golf Course, established in 2005 following Vietnam government permission number 2417/GP, features 54 holes designed by renowned international golf course designers Mr Ronald Fream from the USA along with Korean and Japanese experts, reflecting each country's unique style Covering an expansive area of 315 hectares, the course is situated in a scenic valley surrounded by hills and mountains, with some areas used for farming, offering breathtaking views often called "Ha Long Bay inland." Recognized as "The biggest and most beautiful golf resort" in Vietnam, it is listed in the Vietnam Guinness Book of World Records The course features challenging fairways and greens with undulating terrain and clever routing through distinctive limestone cliffs, making it a unique golfing destination The facility includes 17 hectares dedicated to the golf club and hotel, with an additional 250 hectares allocated for turf grass systems.
Figure 5 Operation mechanism of using chemical Phoenix golf course
Table 3 Parts of the Phoenix golf course
Parts of the Phoenix Golf course Description
1 Tees This is the starting point of each hole and has a small device for setting the ball up above the ground Average 1180 m 2 per holes, normally mowed short and often, fertilized as needed, over seeded and top- dressed to replace divots and maintain smoothness
2 Greens This is the most closely mown and smooth area on the course where the holes are located Grasses are achieved generally by daily mowing, seasonal coring, light frequent topdressing, regular fertilization, consistent frequent irrigation, and insect and disease control as needed to maintain near perfect turf
3 Fairway They are the closely mown area between the tee and green, normally annual insecticide sprays, and repeated fungicide treatments during the growing season
4 Roughs Roughs are longer grass, thicker grass or naturally growing adjacent to fairways, greens and perhaps tees, normally maintained at a low level of intensity Fertilization is minimal, often being limited to overthrow from fairway fertilizer applications
5 Practice greens Practice green is separate from the golf course; designated for practicing putting only
6 Driving range This is an area, separate from the golf course, designated for hitting practice balls
7 Water hazard This is a pond, lake, river which is designed to add both beauty and difficulty to a golf course The area about 15 ha
Phoenix Golf Course utilizes high-quality turf grasses such as Tifeagle for greens and Wintergreen Bermuda for fairways to ensure optimal playing conditions These areas demand superior turf quality, requiring significant nutrients, fertilizers, and pesticides to maintain their lush appearance and playability Hybrid grasses are selected for their aesthetic appeal and durability, making them ideal for golf course lawns Although these grasses thrive in hostile tropical climates like Vietnam, they necessitate frequent watering and meticulous management to sustain their growth and performance standards.
Phoenix golf course's maintenance practices can impact water quality in Bui River, as chemicals from turf management may runoff into water bodies The course uses Delta-Coated fertilizer for greens at a rate of 1.5 kg per 100 m² every 2 to 3 months, resulting in approximately 3.75 tons of fertilizer for the 10% green area spanning 25 hectares Fairway grass, covering about 60% of the total 150 hectares, receives regular Delta-Top applications at 1–2 kg per 100 m² monthly, totaling around 22.5 tons annually, along with 7 tons of NPK fertilizer each application Additionally, chemical pesticides such as Chlorpyrifos, Diazinon, and Isazofos are used to maintain green turf, although specific quantities are not disclosed These maintenance chemicals pose potential risks to water quality in the surrounding environment.
In 17-Augst, 2015 Phoenix golf course using Delta-Top and NPK fertilizers for maintaining turf grass systems to be root grow well, deep thick root systems and leaf color and texture still good in shape and green, with the average amount of fertilizer is 25 tons/ha
The quality of a golf course is primarily determined by the landscape, which is challenging to maintain due to intensive chemical fertilizer and pesticide use Consistent and uniform irrigation is essential for turf health, requiring water to be quickly absorbed and rapidly drained to prevent waterlogging During summer, golf courses typically need to water at least twice a week, with approximately 15,000 m³ of water per session, as noted by Phoenix Golf Course Located near the Bui River, which serves as a key irrigation source with a series of interconnected ponds and streams, the golf course faces significant concerns over the deteriorating water quality of the Bui River.
Characteristics water quality of Bui River
The graph in Figure 6 illustrates pH fluctuations across three different locations—upstream, golf course, and downstream—during three distinct periods pH is a crucial indicator of free hydrogen ion concentration in water, and maintaining it within an optimal range is vital for the health of humans and aquatic life Analysis reveals that pH values at these sites range from 7.4 to 7.9, exhibiting minimal fluctuation Importantly, all measurements remain within the permissible limits set by the QCVN 08:2008/BTNMT Column B1 regulation, indicating the water quality is within safe standards.
The highest pH value was recorded 7.9 at downstream sample in 20-August (rainy day) and the lowest pH value was recorded 7.4 at golf course samples The pH of water affects the solubility of many toxic and nutritive chemicals Golf course activities in watershed may affect pH, increased leaching of soils, and runoff nutrient from grasses during heavy precipitation affect pH downstream b) Total Suspended Solid (TSS)
Figure 7 The changing amount of TSS is in three periods at three different locations Total suspended solids (TSS) are a measure of sediment concentration which is the dry weight after filtering a water sample Suspended silt and clay, organic matter and plankton can contribute to turbidity and high concentrations of suspended solids can lower water quality by absorbing light From the figure, we can see slightly increase of TSS from upstream to downstream samples At upstream, TSS is the lowest values and ranges from 7.5 to 16.1 mg/L At the stream which part flow through golf course, TSS level ranges from 10.8 to 18.6 mg/L but at downstream the amount of TSS is much higher than the others All the TSS concentration at 3 locations meets the permitted values of standard B1 (which need to below 50 mg/L)
TSS at golf course and downstream samples is slightly increased after spraying fertilizer one day Spraying fertilizer of golf course is used a large amount of water so that flow is from golf course and particles transported to stream and water body In 20-August, heavy rains and fast-moving water are erosive They pick up and carry enough dirt and debris to stream So, heavy rainfall may cause higher TSS, this lead to upward trend of
Following rainfall, Total Suspended Solids (TSS) levels ranged from a low of 16.1 mg/L upstream to a high of 30 mg/L downstream, indicating increased sedimentation after rain events TSS concentrations between 7.5 and 30 mg/L suggest moderate water quality in the headwater catchment of the Bui River Additionally, dissolved oxygen (DO) levels are a critical parameter for assessing water health, highlighting the overall quality of the river post-rainfall Monitoring these parameters provides insights into the impact of rainfall on sediment load and water quality in the Bui River catchment area.
Figure 8 The changing of DO concentration is in three periods at three different locations
Dissolved oxygen (DO) measures the amount of oxygen dissolved in water and is a crucial indicator of water quality It significantly influences aquatic life, as adequate oxygen levels are essential for the survival of aquatic organisms Both excessively high and low DO levels can be harmful, disrupting ecosystems and threatening the health of aquatic species Monitoring DO is vital for assessing water health and maintaining a balanced aquatic environment.
The Dissolved Oxygen (DO) levels in Bui River ranged from 3.7 to 5.1 mg/L, exhibiting a declining trend from upstream to downstream Across three sampling locations, DO levels varied, but overall, most measurements exceeded the standard B1 requirement of greater than 4 mg/L The mean DO concentration in the samples ranged from 4.2 to 4.8 mg/L, with upstream sites consistently showing higher DO levels compared to downstream locations, indicating better water quality upstream.
The dissolved oxygen (DO) levels in other locations have a mean value of 4.8 mg/L, primarily due to the rapidly moving water with an upstream velocity of 0.34 m/s, which enhances oxygen content In comparison, the golf course samples show a slightly lower mean DO of 4.5 mg/L, while downstream samples have an average DO of 4.2 mg/L, indicating a gradual decrease in oxygen levels downstream.
In 14-August, it is sunny day and the golf course was not application fertilizers, the
The DO levels of three samples were similar initially, and one day after fertilizer application on August 18th, there was minimal change in their DO concentrations However, following the rain on August 20th, upstream DO levels increased, while DO levels at the golf course and downstream sites showed a decreasing trend due to rainfall Rainwater transported organic matter from the soil into the stream, leading to elevated nutrient levels such as phosphorus, nitrogen, and ammonia from fertilizer runoff This nutrient influx stimulated algae and aquatic plant growth, impacting dissolved oxygen levels downstream.
DO level in downstream can drop to below the allowable limit 3.7 (mg/L) it means stressful to aquatic life d) Biological oxygen demand (BOD)
Figure 9 Values for BOD are in three periods at three different locations
The biochemical oxygen demand (BOD) test measures the amount of oxygen consumed by microorganisms, such as bacteria, during the oxidation of organic matter in water Data indicate an increasing trend of BOD5 concentrations from upstream to downstream, with values at both the golf course and downstream locations exceeding the permissible limit of 15 mg/L In contrast, water samples taken upstream, unaffected by the golf course, showed BOD5 levels below the standard, ranging from 3.5 to 4.5 mg/L, highlighting the impact of the golf course on water quality.
BOD 5 values also changes when golf course sprayed fertilizers for turf grass Concentration of BOD5 at golf course sample increased 3.1 mg/L and at downstream sample increased too 4.2 mg/L after applying fertilizers one day The BOD can increase due to an increase in nutrient such as nitrogen and phosphorous loads to a water body and organic matter decomposes it will use up dissolved oxygen This is reason why BOD values increased significantly after rain event at both golf course sample and downstream sample, otherwise, BOD value at upstream sample decrease after raining with values 3.5 mg/L When BOD levels are high, dissolved oxygen (DO) levels decrease because the oxygen that is available in the water is being consumed by the bacteria Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive Thus, generally, the water quality of headwater catchment was influenced by maintained grass of Phoenix golf course, poor and large amount of organic matter in water and it can threat to living organism in water body e) Chemical oxygen demand (COD)
Figure 10 The changing COD concentration is in three periods at three different locations
Chemical Oxygen Demand (COD) measures the oxygen required for the chemical oxidation of organic and inorganic substances, such as ammonia and nitrite, in water Low COD values indicate minimal organic pollution, with upstream water samples showing the lowest levels ranging from 8.6 to 15.8 mg/L, well below the standard B1 limit of 30 mg/L In contrast, water from the golf course exhibits significantly higher COD levels, ranging from 38.4 to 51.5 mg/L—over three times higher than upstream levels—and both golf course and downstream samples exceed permissible limits This suggests that upstream areas unaffected by golf course activities have low organic pollution, while sections flowing through the golf course experience elevated COD concentrations due to its operations.
Changes in COD levels at the golf course clearly demonstrate the impact of fertilizer application and rainfall events; for instance, the COD increased from 48.6 mg/L on August 18th following fertilizer application, and heavy rain on August 20th (80.9 mm) caused nutrient runoff that elevated COD concentrations to 51.5 mg/L, adversely affecting water quality Rainfall initially contributed to nutrient leaching but also diluted COD levels, highlighting how golf course activities and weather patterns influence downstream water quality The elevated COD levels indicate that the water quality in this catchment is poor for human uses such as aquaculture, emphasizing the environmental impact of turf management practices.
Figure 11 The total nitrogen values change in three periods at three different locations
Higher nitrogen concentrations in water bodies lead to increased pollutant and nitrate reactions, which can cause oxygen depletion in freshwater environments Data indicates a significant rise in nitrogen levels from upstream to downstream along the Bui River, with sampling sites showing notable differences The upstream site exhibits the lowest nitrogen concentration, ranging from 1 to 2 mg/L, while samples from the golf course and downstream areas consistently present higher nitrogen levels due to fertilizer and pesticide runoff from Phoenix Golf Course This gradient highlights the impact of agricultural and recreational activities on water quality and underscores the importance of monitoring nitrogen pollution to protect aquatic ecosystems.
Applying fertilizers to lawns can lead to nitrate runoff into water bodies, especially when grass uptake is insufficient Monitoring shows that nitrogen levels increase downstream and after pesticide application at golf courses, indicating fertilizer runoff; for example, one day after pesticide spraying, stream nitrogen concentrations rose from 4.3 mg/L to 5.35 mg/L Heavy rains on August 20th further exacerbated this issue, causing nitrogen-rich runoff with total nitrogen reaching up to 7.1 mg/L downstream The maintenance practices at Phoenix Golf Course significantly impact Bui River’s water quality by elevating total nitrogen levels due to fertilizer use However, all measured nitrate levels remain below the EPA standard of 10 mg/L (Standard B1), ensuring the water remains suitable for domestic use.
Figure 12 The changing of total phosphorous is in three periods at three different locations
CONCLUSIONS 40 REFERENCES
The catchment headwater of the Bui River covers an area of 30.548 km² with a total stream length of 26.88 km, serving as a vital water source Water flows downhill from high-elevation areas to lower elevations, ensuring a natural water movement essential for the region This catchment plays a crucial role in supplying water for domestic use and irrigation, supporting local communities and agricultural activities.
Phoenix Golf Course is strategically built around the Bui River, enhancing its scenic beauty and ecological significance Covering a total of 250 hectares, the course features extensive turf grass systems that require significant maintenance To maintain the lushness and quality of the turf, the course utilizes large quantities of fertilizers and pesticides, with an average of nearly 30 tons of fertilizers applied monthly.
Water quality assessment of Bui River reveals that upstream locations unaffected by golf course activities show the lowest levels of key parameters As water flows from upstream to downstream, especially near golf courses, there is a noticeable increase in TSS, COD, BOD, total nitrogen, and total phosphorus, particularly after rainfall This trend indicates that excess fertilizers from golf courses potentially runoff into the river, contributing to nutrient loading Generally, parameters such as pH, TSS, DO, total nitrogen, and total coliforms remain within permitted limits according to QCVN 08:2008 regulations; however, total phosphorus, BOD, and COD concentrations at golf course and downstream sites frequently exceed permissible levels.
The maintenance and operation of Phoenix golf course have negatively impacted the water quality of Bui River, with data indicating significant increases in total nitrogen and phosphorus levels both at the golf course and downstream Excessive fertilizer use on the golf course has been identified as a primary source of nitrogen and phosphorus enrichment in the river This deterioration in water quality renders it unsuitable for human consumption, though it can still be used for irrigation, traffic, or other purposes with specific requirements.
To minimize the effect of golf course suggesting that utilizing riparian buffer zones and avoiding using fertilizer before rain
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