Flow Verification

Test results of the efficiency model was evaluated by Nash-Sutcliffe index for observed and calculated data in Ba Tha hydrology station. Nash-Sutcliffe index = 85.57% for Ba Tha station shows that the results of the model calculations achieved enough credibility.

Figure 6. A comparation between calculated flow and observed flow with the frequency of 85% at Ba Tha station

Water quality verification

Proceed compare results of water quality simulation of the model with observed data in October and December 2010 at locations sampled on Day River mainstream, we realized that error lies in the permitted limits (not more than 10%) so that the calculated results of the model are reliable

The verification of water quality at Ba Tha, Hong Phu bridge and Doan Vi bridge are showed in these figures below:

3. THE SIMULATION RESULTS OF WATER QUALITY CHANGES UNDER THE CONTROL OF WASTEWATER PLANS

Forecasting trends of water quality changes in 2020 relevant to 3 senarioes to control discharge of wastewater into water sources as follows

3.1 Scenario 1

With this scenario, the wastewater flow inevitably increased due to the socio-economic development and related activities, but the wastewater before discharge into river systems in the region that have been partly processed in order to limit the impact of waste water to the river (level of treatment given is 60%). The purpose of the scenario 2 is to: (i) forecast the water quality in river basins with plans for social-economic development and human action on the environment; (ii) assess the level of impact of wastewater on water quality in the river Nhue - Day River. This scenario is based on the increase in the economic livelihood activities entail an increase in the amount of waste water in the basin. However, there have been some actions to prevent uncontrolled discharge into rivers. Wastewater quality compared to scenario 1 were processed in part (60%) as mentioned above. Our results showed that the concentration of BOD5, which vary in space, namely with the point concentration decreased but also the point of concentration has increased because waste is not much handled while not many wastewater flow still rising. On Day river in some stations such as Mai Linh, Van Dinh, Hong Phu Bridge, BOD concentration still exceeded the QCVN 08/2008 standard B1 ranged between 18 - 25 mg / l, besides, there are some stations met the water quality standard A2 QCVN 08/2008 (Tan Lang, Kien Khe pontoon), on downstream water quality tends to be better.

3.2 Scenario 2

Wastewater flow increased due to the development of socio-economic and related activities, but the wastewater before discharge into river systems in the region have been partly processed (higher than scenario 1) aimed at limiting the influence of wastewater to rivers and assess the degree of influence of waste sources for river water quality (level of treatment given is 80%). In this scenario, the amount of wastewater is treated more than scenario 1, the calculated results show that the concentration of BOD has decreased compared to scenario 1. The highest BOD on Day River is still in section flowing through Ha Dong territory only reach levels of 20 mg/l.

3.3 Scenario 3

In this scenario, the amount of waste water is treated completely. This is the optimal scheme but plans to comply with the conditions currently in our country is not feasible, calculation results showed that levels of BOD almost in the position attained water quality standard QCVN 08/2008 Category A2. Input water quality data into the model, the obtained results are showed in these figures from Figure 10 to Figure 12. Calculation results forecast in 2020 showed that water quality has improved considerably in case the flow of treated waste water before discharge to the river is higher than the flow of untreated waste water. BOD on Day river for treatment scenario is 80% and 100% are mostly met the water quality standard QCVN 08/2008 type A2.

Through the above review and analysis, it shows that the development of socio - economic in parallel with the increasing of the pollutant concentration in the mainstream of Day river. Obviously in 2015 and 2020 if there are no drastic measures to control pollution sources, Day River water quality is no longer eligible to supply water for domestic and industrial purposes. Therefore to ensure the flow of water quality in future Day river eligible for daily life and production, it is require now to have timely solutions to solve this problem.

4. CONCLUSION

The study “Applicaton of WEAP model in forecasting water quality for water resources protection master plan with pilot study in day river basin” shows that with the strength of developing scenarios as well as the ability to rapidly changing the reference parameters, therefore WEAP is suitable in making rapid assessments in forecasting the change trend of water quality as a base for managers, planners to propose optimal methods for water resources development as well as protection. Besides, the pilot study on Day River basin indicates that the river water quality is now seriously degraded under pressures of the economic and livelihood activities. This study has initially succeeded in applying WEAP model to forecast trends in water quality on the mainstream of Day river under the socio-economic development planning in 2015 and 2020. Our calculation results give some initial comments relatively overall on the trend in quality mainstream of Day river. According to our results, the organic pollution in Day river becomes serious in the year 2020 caused by the impact of industrialization, as well as human activities in the basin. The research results show that wastewater control and treatment are very important and effective in protecting water resources. To achieve these purposes of using water resources, it now needs to control at least 60% of the total volume of wastewater treated up to environmental standards.

REFERENCES

Nguyen Tat Dac (2005), Mathematical model for water flow and water quality on canal and river systems, Agricultural Publishing House;

Statistical Office of Hanoi, Statistical Yearbook 2010;

Bureau of Statistics of Ha Nam Province, Statistical Yearbook 2010;

Bureau of Statistics of Hoa Binh Province, Statistical Yearbook 2010;

Report on status and socio-economic development orientations till 2010 and orientations towards 2020, "Surveying project on Irrigation Planning for Day river basin", Institute for Water Resources Planning;

"A report on the National Environment 2006, Report on Environmental Status of 3 river basins Cau, Day and Dong Nai", Ministry of Natural Resources and Environment, 2007;

Reporting the results of water quality monitoring of Nhue-Day river, Environmental Protection Agency, in 2005 - 2010;

Status report  of Nhue - Day river basin, Water Resources Management Department, 2007;

Manual for  WEAP, KS. Ngoc Anh Trieu.a