Map of Thuong River Section Through Bac Giang City

* Diagram of sampling locations

Figure: 3.1. Sampling diagram of Thuong River section through Yen The - Tan Yen

Figure 3.2. Diagram of Thuong River section through Bac Giang City

Figure 3.2. Sampling diagram of Thuong River section through Yen Dung

Figure 3.3. Description of sampling locations for monitoring the quality of sources directly affecting the Thuong River and the water quality of the Thuong River.

- Sample analysis method:

Samples of surface water and wastewater quality analysis are in the laboratory of the Center for Environmental Monitoring and Modeling Research - University of Natural Sciences, address 334, Nguyen Trai Ward, Thanh Xuan District, Hanoi, with specific indicators and analysis methods in the following table:

Table 3.2. Indicators and methods for analyzing wastewater and surface water quality

Analysis parameters	Unit	Analytical method
1	pH	-	TCVN 6492:1999 – Determination of pH by pH meter
2	COD	mg/l	SMEWW 5220D- Determines chemical oxygen demand by oxidizing organic compounds with a mixture of dichromate and sulfuric acid in a closed cuvette at 150 O C for 2 hours, then measuring the absorbance at 420nm.
3	BOD5	mg/l	TCVN 6001-1:2008 – Determination of biochemical oxygen demand after 5 days (BOD5) by the inoculation and dilution method
4	TSS	mg/l	TCVN 6625:2000- Determination of suspended solids by filtration through a glass fiber filter paper of known mass. Dry the filter paper and residue at 103 – 105 O C. Weigh the dried filter paper. The difference in the mass of the filter paper before and after filtration and drying gives the TSS value.
5	DO	mg/l	TCVN 5499:1995- Determination of dissolved oxygen – Winkler method.
6	Fe	mg/l	TCVN 6177:1996- Determination of iron by spectrometric method using 1,10-phenanthroline reagent.
7	NO3-(N)	mg/l	Optical measurement method
8	PO43- (P)	mg/l	Optical measurement method
9	Cl-	mg/l	Determined by Mohr salt titration method.
10	Coliform	MPN /100ml	TCVN 6187-2:1996 – Detection and enumeration of coliform bacteria, thermotolerant coliform bacteria and presumptive Escherichia coli by membrane filtration method.

Maybe you are interested!

- Comparison and evaluation method:

+ For the results of industrial wastewater quality analysis samples evaluated according to QCVN 40:2011/BTNMT (M 04; M 07);

+ For domestic wastewater quality, evaluate according to standard QCVN 14:2008/BTNMT (M 13);

+ For sample analysis results at the input locations, evaluate according to QCVN 08:2008/BTNMT (M 01; M 02; M 03; M 06; M 09);

+ For sample analysis results at wastewater pumping stations, evaluate according to QCVN 14:2008/BTNMT standards (M 05; M 08; M 10; M 11; M 12).

3.4.2. Determining the flow and water quality characteristics of the Thuong River in the study area:

* Criteria to achieve results on:

- Assessment of water flow changes of Thuong River;

- Assessment of Thuong River water quality at the time of study;

- Water quality changes of Thuong River.

* Implementation method:

a. Assessment of water flow changes of Thuong River:

To evaluate the flow of water on the Thuong River, the project calculates the flow of the Thuong River at the Cau Son hydrological station over the years, specifically as follows:

* Calculation of flow data on Thuong River at Cau Son hydrological station

TTV Cau Son

Figure 3.4. Hydrological station network at the river

Thuong, Bac Giang province

Figure 3.5. Self-recording well of Thuong River water level of Cau Son Hydrological Station

On the main stream of the Thuong River, there are two hydrological stations, Cau Son station and Phu Lang Thuong station, which are still in operation. Cau Son hydrological station is a level I hydrological station, however, the station stopped measuring water flow since 1974, currently the station only measures water level data of the Thuong River. Phu Lang Thuong hydrological station is a level III station, only measuring river water level and located in the downstream of the Thuong River. Therefore, Cau Son hydrological station was chosen to calculate and extend flow data on the Thuong River at water quality monitoring locations.

Cau Son hydrological station is located on the upper stream of the Thuong River in Huong Son commune, Lang Giang district, Bac Giang (controlling the water volume of the Thuong River before flowing into Bac Giang), built in 1960, measuring the flow and water level from 1961 -1973, from 1974 to present the station only monitors H, however the relationship Q = f (H) at Cau Son is quite tight. To ensure reliability, the topic will extend the flow data series at Cau Son station using the correlation method Q = f (H).

Correlation method Q = f(H)

Using the actual measured values Q and H from 1962-1973 to construct the correlation lines Q ~ H. From there, a table of actual measured documents Q ~ H can be constructed. The specific steps are as follows:

Step 1) From the measured Q, H value series, extract the series of H max , Q max , H TB , Q TB and H min , Q min values of each month. Then, arrange the data series in order from smallest to largest.

Step 2) Divide the data series Q, H above into 4 value ranges (according to Q) as follows:

Value range 1: Q < 30 m 3 /s

Value range 2: 30 m 3 /s < Q < 100 m 3 /s Value range 3: 100 m 3 /s < Q < 400 m 3 /s Value range 4: Q > 400 m 3 /s

Draw the correlation lines Q ~ H (lines passing through the center of the point group) corresponding to the above value ranges.

3) Based on the Q~H correlation lines constructed corresponding to the above value ranges, a Q~H actual measurement document declaration table can be established.

From the data H; Q of Cau Son station from 1962-1973 (Appendix 2), the correlation relationship Q = f (H) was determined. Based on the correlation curves Q~H constructed corresponding to the value ranges and data H of Cau Son station in 2004-2016 (Appendix 2), the flow Q of Cau Son station in 2004-2016 was determined.

b. Changes in water quality of Thuong River:

- Field sampling method and sample analysis method

Because the water quality of the Thuong River is affected by many different factors, the project selected 13 locations for sampling the surface water of the Thuong River corresponding to the sampling locations for assessing water quality at the main sources of impact and ensuring that they meet the standards for representing the water quality of the river in the study area. The implementation methods are similar to those presented in section 3.4.1 above.

- Data synthesis method:

To assess the changes in water quality of the Thuong River flowing in Bac Giang province over space and time, the project has synthesized the results of monitoring the quality of the Thuong River by the Department of Environmental Protection, Department of Natural Resources and Environment of Bac Giang province conducted in October 2016 (including 47 surface water points on the Thuong River) and the results of analyzing 13 surface water samples of the Thuong River conducted in May 2017.

- The current water quality status of Thuong River is assessed from the results of river water quality analysis obtained by comparison with Vietnamese Standards and assessment according to WQI.

- The change in water quality of Thuong River over time is assessed based on the pollutants measured in October 2016 by the Department of Environmental Protection, Department of Natural Resources and Environment of Bac Giang and the analysis results in May 2017 of the project.

3.4.3. Research on the current status of water resources management of Thuong River in Bac Giang province.

* Implementation method:

Synthesis method – document inheritance

The topic will collect and research documents on the management and protection of Thuong River water resources in Bac Giang province and from there evaluate and draw the most general solutions to protect Thuong River water resources.

3.4.4. Proposing solutions to protect water resources of Thuong River in Bac Giang province.

* Criteria to achieve results on:

- Policy and management solutions;

- Technology solutions (with specific technology models).

* Implementation method: