INTRODUCTION
Research rationale
As the country advances towards industrialization and modernization, the environment, especially water resources, faces significant challenges Unregulated activities like deforestation, poor agricultural practices, and direct wastewater discharge have led to severe water pollution and a critical shortage of clean water, particularly in arid regions.
During the dry season, water usage significantly increases, particularly for agricultural purposes, as the demand for irrigation rises The total volume of water required for farming during this period is substantial, highlighting the critical role of water management in sustaining crop production.
In 2000, Vietnam's total water supply for the dry season was 70.7 km³, representing 42.4% of the necessary resources, which include river water, spring water, groundwater, and reservoir water Despite government efforts, access to clean water remains limited, with only 46-50% of the urban population and 36-43% of the rural population benefiting from safe drinking water Many communities rely on unhygienic water sources, leading to significant health issues, such as 90% of rural women suffering from gynecological diseases and 95% of children being infected with germs and worms Water pollution poses a serious health risk in these areas (VNCOLD 2014) Bac Kan, a mountainous province in Northern Vietnam, features a dense network of rivers, highlighting the need for improved water management and sanitation in the region.
Bac Kan is home to 3,513 million m³ of water resources, including seven major rivers: Cau, Yen, Phat Dat, Bac Giang, Na Ri, Hien, and Bang Khau The region boasts over 40 mining sites for lead, zinc, gold, and stone However, inadequate management has led to a lack of wastewater treatment systems at most mines, resulting in the direct discharge of polluted wastewater into local rivers and streams, severely contaminating the water in mining areas.
To address the challenges in assessing water quality, utilizing an indicator system like the Water Quality Index (WQI) is essential The WQI provides a comprehensive view of water quality through standardized physical and chemical indicators, making it easy to understand for both professionals and the general public Its simplicity and generalizability allow for effective evaluation of water quality over time and across different locations, serving as a valuable resource for communities and individuals without a background in water management.
"Application of WQI in assessing surface water quality in Bac Kan province, Vietnam”
Research objectives
-Learn about the WQI and hydrographic features in Bac Kan province
-Collection of documentary information: inherit the results available, collected, analyzed through reports, research topics, and reports on environmental impact assessment
-Processing of raw data and through the WQI calculation and assessment of water quality for each river and stream in the Bac Kan city
Significance of study
This study evaluates the surface water quality of large rivers and lakes in the province by analyzing Water Quality Index (WQI) parameters and calculations from all observations The findings aim to inform and propose effective management measures for water quality improvement.
Limitation of study
This study presents updated monitoring and Water Quality Index (WQI) values from the second round of 2017, focusing on the environmental quality changes throughout the year These findings allow for a comparative analysis with previous years, enabling an assessment of the evolving water environment over time.
LITERATURE REVIEW
Study area and water quality in the study area
Bac Kan is a province in the Northeast region of Vietnam, situated north of the capital, Hanoi, at coordinates 22.3033° N and 105.8760° E Covering an area of 4,859.4 square kilometers, Bac Kan had a population of 308,900 as of 2008 The province features a mountainous landscape abundant in natural resources, including minerals and forests, and is home to numerous scenic mountains, rivers, and lakes.
The province, located in the northeast midland mountainous area of Vietnam, boasts the highest altitude among the region's 11 provinces, with over 95% of its land covered by forests This rugged terrain limits water resource development and leads to the overexploitation of forest resources, resulting in significant forest degradation The landscape varies dramatically, ranging from the peak of the Khie Thiouing mountains at 1,640 meters (5,380 ft.) to the lowest point of 40 meters (130 ft.) in Cho Moi District Numerous rivers and streams traverse the province, characterized by steep slopes and short lengths Additionally, approximately 83% of the population relies on agriculture for their livelihood.
This thesis just focuss on analaysis the main river and lake in Bac Kan province: Cau river , Nang river , Ba Be Lake , Bac Giang river
Figure 1 Map of Study area (Source: Google Earth pro)
2.1.2 Water quality in the study area
The Cau River in Bac Kan is heavily polluted due to industrial activities, mining, and human actions Additionally, Ba Be Lake faces local pollution from waste oil discharged by numerous tourist motorboats, along with litter such as beer cans and soft drink containers discarded by visitors Notably, oil spills have become evident along the shores of the lake where motorboats operate.
Surface water pollution in the region is primarily localized, with overall quality remaining relatively good Key pollution sources include wastewater from the Cam Giang Cement Plant and Cau Giay Town, which affect the Cau River Basin in Cho Don and Bach Thong districts Additionally, domestic wastewater from households and production facilities, notably the Bac Kan Forest Products Joint Stock Company and Bac A Beer Factory, contributes to pollution in Bac Kan town.
Overview of WQI
The Water Quality Index (WQI) is a composite index derived from various water quality parameters using a mathematical formula, providing a quantitative description of water quality on a standardized scale The concept of using domestic organisms as indicators of cleanliness dates back to 1850 in Germany, marking the inception of WQI studies Today, numerous countries have adopted and adapted WQI methodologies, allowing for the calculation of a single index from diverse parameters This facilitates the comparison of water quality against established indicators, offering a straightforward approach to analyzing a range of biochemical parameters for effective water quality evaluation.
Water Quality Index (WQI) plays a crucial role in decision-making processes, aiding in financial allocation and prioritization of water-related issues It is essential for water quality zoning, guiding standard execution responses, and analyzing water quality variations over time and space Additionally, WQI facilitates the dissemination of information to the community and supports scientific research, including comprehensive studies on the impacts of urbanization on regional water quality and the efficiency of emission control measures.
WQI construction method
2.3.1 Method to build WQI of some countries in the world
There are many countries that have adopted WQI in practice, as well as many scientists studying WQI models The Horton (1965) is the first WQI built on a scale
In the United States, each state has its own Water Quality Index (WQI), primarily following the approach established by the National Sanitation Foundation (NSF, 2004) In Canada, the WQI is based on the methodology developed by the Canadian Environmental Protection Agency (CCME, 2001) Meanwhile, European countries have largely adapted the American WQI framework for their water quality assessments.
Each country or region establishes its own water quality index (WQI) parameters and methodologies While Malaysia and India have developed their WQIs based on the United States model, they can create various WQIs tailored for specific applications such as domestic water supply, agriculture, and industry The overall WQI is derived by calculating the weighted average of these individual indices.
The Belgian method classifies water quality using four key parameters, emphasizing their significance while limiting the number of calculation factors In New Zealand, water quality for recreational use is assessed by identifying the smallest subtraction value Additionally, the Bhargava model from India calculates an individual Water Quality Index (WQI) tailored to specific water use purposes.
2.3.2 Method to build WQI in Vietnam
Dr Ton That Lang from the College of Natural Resources and Environment in Ho Chi Minh City presented an article titled "Building WQI for Assessment of Water Quality Management System of Dong Nai River." This work was featured in the 19th edition of the Scientific Seminar organized by the Institute of Science and Technology of Natural Resources and Environment, highlighting the importance of developing a Water Quality Index (WQI) to evaluate the effectiveness of water quality management in the Dong Nai River.
In the article "WQI Study to Evaluate and Delineate the Quality of the Bassac River," Dr Ton That Lang developed a water quality index for the Hau River system using the Delphi method.
The study titled "Study on Water Quality Zoning under WQI and Assessing the Use of Rivers and Canals in HCMC" by Le Trinh (2008) focuses on the application and enhancement of water quality index (WQI) models from the United States to effectively categorize water quality and evaluate the utilization of rivers in Ho Chi Minh City.
A study conducted on the organic pollution levels in the inner lakes of old Hanoi utilized the Kannel Water Quality Index (WQIkannel) to evaluate the water quality of 22 lakes within the city The WQIkannel was enhanced through the Delphi method, resulting in a comprehensive equation for effective water quality assessment.
The water quality index (WQI) is calculated using the sum of normalized parameters (Ci) weighted by their corresponding importance (Pi), where values range from 1 to 4, with 4 indicating critical factors for aquatic life, such as dissolved oxygen, and lower values for less significant parameters like chloride content The subjective constant (K), ranging from 0.25 to 1, helps differentiate between highly polluted and less polluted waters Various methods, including the United States WQI (NSQ-WQI), India's Bharavara, and Canada's WQI-CCME, have been adapted for regional water quality assessments For this study, the Vietnam Environment Administration (VEA) method from 2011 was selected to accurately reflect the surface water pollution situation in Bac Kan province, aiding in the assessment, zoning, and management of water quality.
Pollution zoning involves dividing geographical areas into regions with varying degrees of environmental pollution National environmental quality standards, established in many countries, set limits on air, surface water, and coastal water quality to ensure human health and prevent illness An environment is considered contaminated when pollutant concentrations exceed these established limits Pollution levels are assessed based on the ratio of actual pollutant concentrations to permissible levels Specific quantitative criteria are used to identify polluted areas, delineating boundaries based on different pollution levels The Environmental Quality Index (EQI) is commonly used to classify environmental quality, with specific indices such as the Water Quality Index (WQI) for surface water, Sea Water Quality Index (SWQI) for seawater, and Soil Quality Index (SoQI) for soil.
METHODS
Stages of research
Research is divided into two stages
The application of the Quality Water Index (QWI) for assessing surface water quality was conducted at 40 monitoring sites across major lake basins, including the Cau River, Nang River, Ba Be Lake, Pho Day River, and Bac Giang, as detailed in Table I.
Statistical methods and aggregation of secondary data
In April and June 2017, monitoring data for DO parameters, temperature, BOD5, COD, N-NH4+, P-PO4 3-, TSS, turbidity, total coliform, and pH were collected from the Department of Natural Resources and Environment of Bac Kan province This data was used to calculate the Water Quality Index (WQI) values for each monitoring position across the two observation periods, allowing for comprehensive comparisons.
Table 1 List of monitoring stations (Report on environmental monitoring results of Bac Kan province-2017)
No Name of the monitoring point
Description of the monitoring point
2.450.870 430.019 - Location: Cau River water at Duong Quang Bridge
- Purpose, meaning: Current status and the impact of the development of Cau River area to water quality from the upstream to Bac Kan city
2 Nam Co stream water NMTX-4 Background monitoring
- Location: Downstream of Nim Cut stream, before confluence with Cau river
- Purpose and meaning: Current status and quality of Nam Cau stream water before entering Cau river
Stream flows through Quang Son residential area, Doi
- Location: Nong Thuong stream before confluence with Cau river
- Purpose, meaning: Assess the level of pollution in the Nong Thuong stream running through the Quang Son residential area, Doi Ky
4 Pa Danh stream NMTX-6 Environmental impact monitoring
- Purpose, meaning: Assess the level of pollution in Pa Danh stream
Kien and Duc Xuan wards
105 o 49 ’ 969 22 o 09 ’ 144 - Purpose, meaning: Assess the level of pollution in the stream running through Phung Chi Kien ward and Duc Xuan ward
6 Khuoi Cuong spring water NMTX-8 Environmental impact monitoring
2.442.552 436.007 - Location: Khuoi Cuong spring water
- Purpose, meaning: To assess the level of pollution in Cuoi Cuong spring water flowing through Xuoc Hoa commune
Water of Nang river at Tin Don Bridge
2.484.080 419.883 - Location: Water of Nang river at Tin Don Bridge
- Purpose, meaning: Current status and evolution of Nang River water quality from the upstream to Cho Ra town
8 Water of Nang River at Buoc Lom (wharf) NMBB-2 Background monitoring
2.484.180 414.816 - Location: Nang River water at Buoc Luom
- Purpose, meaning: The status and development of the quality of Nang River from Cho Ra town to Khang Ninh commune
9 Water of Ba Be lake
2.478.907 409.169 - Location: Ba Be Lake Water (Lake 1)
- Purpose, meaning: Status and development of water quality in Lake 1
10 Water of Ba Be lake
2.482.717 408.491 - Location: Ba Be Lake water (lake 3)
- Purpose, meaning: The current state and evolution of water quality in Lake 3 near the position with the Nang River
Cho Lon spring water (Pac Ngoi suspension bridge)
2.476.636 411.518 - Location: Cho Leng spring water at Pac Ngoi suspension bridge
- Purpose, meaning: Status and development of Cho Leng spring water quality before flowing into Ba Be Lake
Ta Han stream (at Background
- Location: Ta Han stream at Coc Toc village
River at Pu Cham suspension bridge in
- Location: Ha Hieu River water at Pu Cham suspension bridge in Bach Trach commune
- Purpose, meaning: Assess the quality of Ha Hieu river before confluence with Nang River
Giang commune) NMBT-1 Environmental impact monitoring
2.456.688 435.846 - Location: Na Co stream at Cam Giang bridge
- Purpose, meaning: Assessment of Na Cam stream quality from Phu Thong town to Cam Giang commune (Na Cu bridge) The impact of the operation of Cam Giang Gang
(at Suoi To bridge) NMBT-2 Background monitoring
2.462.019 435.603 - Location: Phu Thong stream water at To stream bridge
- Purpose, meaning: Current status and development of Phu Thong stream water quality after flowing through the town area
2.450.986 436.639 - Location: Na Cu stream in Nguyen Phuc commune
- Purpose, meaning: Current situation and quality of Na
Cu stream before confluence with Cau river
My Thanh commune NMBT-4 Environmental impact monitoring
2.450.515 439.457 - Location: Sy Binh spring water in My Thanh commune
- Purpose, meaning: Assessment of Na Cu stream quality from Phu Thong town to Cam Giang commune (Na Cu bridge) The impact of the operation of Cam Giang Gang
Ngoc Phai commune NMCĐ-1 Background monitoring
- Location: Na Tum stream, Ngoc Phai commune- Purpose, meaning: Current status and quality of Na Trom stream, Ngoc Phai commune
105 o 34 ’ 484 22 o 10 ’ 353 2.436.038 402.822 commune) 105 o 33 ’ 524 22 o 01 ’ 182 - Purpose, meaning: Current status and evolution of water quality in the river
- Location: Quang Bich - Nam Cuong waterfall
- Purpose, meaning: Current status and quality of Quang Bach - Nam Cuing spring water
- Location: Ban Thi stream near the hospital 50 beds
The objective of this study is to evaluate the pollution levels of the This Stream stream, focusing on the impact of mining activities by Cho Dien and the influence of local residents in Ban Thi commune.
River in Bang Lang commune (Tum To bridge)
2.447.626 403.910 - Location: Water of Pho Day River in Bang Lang commune
The objective of this study is to evaluate the pollution levels in the water of the Pho Day River's first branch, primarily caused by mineral exploitation and processing activities occurring at the river's headwaters.
- Location: Cau River water in Dong Vien commune
- Purpose, meaning: Status and development of Cau River water quality Impacts by nature, agro-forestry activities, etc
River of Yen Nhuan commune (second branch) monitoring 105 o 35 ’ 073 22 o 01 ’ 728 commune (second branch)
- Purpose, meaning: Status and development of infection in the water of Pho Day River (second branch) due to activities of people's livelihood, agriculture and forestry
Nong Ha (after waste water discharge of B & H paper factory)
- Location: Cau River water in Nong Ha
- Purpose and significance: To assess the level of water pollution in the Cau river after the waste water discharge position of the B & H paper factory
2.426.197 427.284 - Location: Cau River water in Thanh Binh
- Purpose, meaning: Status and development of water quality of Cau River from Nong Ha to Thanh Binh
Yen Dinh bridge) NMCM-3 Background monitoring
2.422.391 426.984 - Location: Cau River water at the
- Purpose, meaning: Current status and development of Cau River water quality from Thanh Binh to Yen Dinh bridge
Water (O Ga Bridge) NMCM-4 Background monitoring
- Location: Cho Chu Spring water at the bridge O Ga
Tham temple NMCM-5 Background monitoring
2.420.392 425.669 - Location: Cau River water at Tham temple
- Purpose, meaning: Current status and development of water quality of Song Cau river from Yen Dinh bridge to Tham
Bac Giang river water (Luong
2.462.637 456.321 - Location: Bac Giang river water (Luong Thuong commune)
- Purpose, meaning: Status and progress of water quality in Bac Giang river from upstream to Luong Thuong commune
Bac Giang river water (Tan An suspension bridge)
2.461.096 458.201 - Location: Bac Giang river water (Tan An suspension bridge)
- Purpose, meaning: Current status and development of water quality in Bac Giang river from Luong Thuong commune to Lang San commune
Bac Giang river water (Pac Cap I dam)
- Location: Bac Giang river water (Pac Cap I dam)
- Purpose, meaning: Current status and development of water quality in Bac Giang river before confluence with
34 Water of Na Ri river
(Pac Cap II dam) NMNR-4 Background monitoring
2.457.301 461.836 - Location: Na Ri River (Pac Cap II dam)
- Purpose, meaning: Current status and evolution of water quality Na Ri River from Hao Nghia Bridge to Pac Cap II Dam
Bac Giang river water (Hat Deng bridge)
2.460.226 467.468 - Location: Bac Giang river water (Hat Deng bridge)
- Purpose, meaning: Status and development of water quality in Bac Giang River from Pac Tra to Hat Deng Bridge
2.445.493 458.962 - Location: Na Ri River (Hao Nghia Bridge)
- Purpose, meaning: Current situation and quality of Na
Ri river water from upstream to Hao Nghia bridge
Van Tung stream water (Van Tung NMNS-1 Background
2.481.422 447.983 - Location: Van Tung stream water
- Purpose, meaning: Current situation and quality of
Na Phac bridge) NMNS-2 Background monitoring
- Location: Na Phac stream (at Na Phac bridge)
- Purpose, meaning: Current status and quality of Na Phac stream water
2.490.830 450.758 - Location: Coc Dan stream water - Thuong An (at Na
- Purpose, meaning: Status and evolution of Canh Dan- Thuong An stream water quality
(Ban Giang Bridge) NMNS-4 Background monitoring
2.471.578 449.858 - Location: Thuan Mang Stream (Ban Giang Bridge)
- Purpose, meaning: Status and development of Thuan Mang spring water quality
WQI calculation method
The Water Quality Index (WQI) is determined using the formula outlined in the technical manual provided in Decision No 879/QD-TCMT, issued on July 1, 2011, by the Director General of the Vietnam Environment Administration.
* Calculate WQI parameters (WQI SI )
- Calculated WQISIfor some parameters: BOD5, COD, N-NH4 +, P-PO4 3-, TSS, Turbidity, Total coliform By Equation 1:
BPi: Lower limit concentration of the monitored parameter values is given in the following table, corresponding to level i
The upper limit concentration of monitored parameter values is represented by BPi+1, as detailed in the accompanying table for level i + 1 The Water Quality Index (WQI) value at level i is indicated by qi, while the WQI value at level i + 1 is denoted as qi+1, both corresponding to their respective BPi values in the table.
Cp: The value of the monitoring parameter
Table 2 Table regulated for qi, BPi values
- Calculate the WQI value for DO (WQIDO): Calculated through the DO value of the saturation percentage DO saturation value:
DO value of the saturation percentage:
Dissolved DO: DO value was monitored (Calculated by mg/l)
BPi, BPi+1, qi, qi+1: are values corresponding to i, i + 1 in Table 3 i qi
BPi values regulated for each parameter BOD 5
Table 3 Regulated BPi, qi values for DO% saturation i 1 2 3 4 5 6 7 8 9 10
In the case, the Cp value of parameter matches the BPi value given in the table; the WQI of parameter is equal with corresponded qi value
If DO% saturationvalue ≤ 20 then WQIDO equals to 1
If 20 < DO% saturation value