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Among all the environment-conservation related project investments, river action plans have got a major impetus. River Yamuna (as a part of Ganga Action Plan) is dominant in terms of investments and infrastructure development. The river covers 10.7% of the country’s area and traverses through seven states, including the capital city of India.
The river is highly polluted and 85% of the pollution is contributed by domestic waste. Delhi has only 0.4% share in terms of the total river’s catchment area but in terms of pollution, the capital contributes maximum pollutant load to the river. In order to clean the river, the Government of India started Yamuna Action Plan (YAP) Phase I in 1993 with Delhi stretch of the river as the main focus. Thereafter, the plan was extended to Phase II in 2004. In 2011, the government approved the financial assistance for Phase III. The present research aims to integrate the concept of water-quality index and water-quality model in formulating a methodological framework for an effective river-quality restoration plan. The study mainly endeavours towards the identification, evaluation, and application of regulatory river-quality model(s) on the Delhi stretch of River Yamuna and propose different scenarios to control the pollution levels in the river. It seeks to find iteratively the best possible way to achieve the river-water quality objective and also question whether the river stretch can ever attain the desired water-quality class without flow augmentation. The identification of water-quality model is based on a comparative analysis of various river-quality models from literature and in the process, it highlights the errors and uncertainties associated with river-quality modelling. The applicability of the selected model in the study region is methodologically established. Possible options for pollution reduction are explored through stakeholder participation.
The pollution inventory of point and non-point sources of pollution is made through primary monitoring and secondary sources of information. YAP is evaluated using CCME water-quality index. QUAL2Kw river quality model is calibrated, validated, and applied for four monitoring stations for a period of 1999-2009 for four critical water quality parameters viz. dissolved oxygen, biochemical oxygen demand, nitrogenous compounds, and total coliforms. Thereafter, the model is used to simulate the future scenarios under various interventions for the horizon year 2021. Feasible interventions identified include completion of existing initiatives, drain diversions, tertiary treatment, and recycling and reuse options that are envisaged to reduce river pollution load significantly. Both flow and wastewater characteristics have been projected and used as an input for intervention analysis.
An evaluation of the river-action plan reveals that there is neither improvement nor deterioration in the river quality during YAP. This means that YAP projects have failed to bring water quality in Delhi stretch anywhere near the desired river class. At the same time, YAP projects are successful in preventing further deterioration in water quality, although the region has witnessed phenomenal population and economic growth during the same period. Pollution data analysis shows that point sources are major contributors of organic load to the river and in comparison, the contribution of non-point sources is negligible. QUAL2Kw model has performed satisfactorily for BOD, coliforms, and nitrogenous compounds with a high value of coefficient of determination (R2). For DO, the model shows less R2 value for all the periods and at all the monitoring stations. However, the river itself has very low observed values of DO. The results obtained from other statistical indicators, such as root mean square error, mean bias error and standard deviation bias error, show that the difference between observed and simulated DO is low, indicating satisfactory results. Therefore, QUAL2Kw is used for water quality prediction in intervention analysis. It is seen that current projects under YAP will not provide any noticeable improvement in the water quality. The results of intervention analysis show that adopting the tertiary treatment and recycling options will be the best strategy with almost 40% improvement in the water quality when compared to the present status. However, in the scenario of best intervention, the river doesn’t meet the required standard and thus, it becomes imperative to augment the freshwater flow in order to attain the desired river class “C”. Subsequently, the freshwater flow required to achieve the desired river class is calculated iteratively and found to be 3.46 BLD.
The result of the research shows that in order to achieve the desired river class, it is important to treat, recycle, reuse, and augment the freshwater flow into the system. Given the existing scenario, the first three options are feasible and the last one to augment the flow is difficult due to the existing structure of interstate water allocation in the basin.
The research demonstrates to objectively evaluate the impact of various interventions for river action plan. This is done by verifying the applicability of a water quality model and by collecting and measuring different water-quality variables. Finally, it came out that there is a need to revisit the river classification of the study stretch to come out with an economic justification of the investments under YAP
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