The Yamuna River is the largest tributary of the Ganga River and one of the most important and sacred rivers in India. Millions of people in the country depend on the 1,376 km long river for domestic, industrial and agricultural uses. Over the years, however, the river has experienced severe degradation of its water quality.

The discharge of domestic sewage is the main cause of river’s pollution. There is a large gap between the amount of wastewater generated and the amount of wastewater treated in the cities and urban centres throughout the basin. Increasing urbanisation is further widening this gap. Treating sewage before it is discharged is not enough to restore the ecological integrity of the river.

To help water officials combat this problem, we conducted an Integrated Water Resources Management (IWRM) and water quality modelling study. As part of this study, we developed a Decision Support System (DSS) that uses baseline information on:

• topography
• land use
• river flow
• water quality
• wastewater discharges
• less water intensive crops

MIKE BASIN was used to describe the catchment’s hydrology, examine abstractive uses (such as irrigation and domestic water use) and their return flows, and estimate pollution load. MIKE 11 and MIKE ECO Lab were used to conduct river hydrodynamic and water quality modelling.

Our DSS takes into account different wastewater loading and water availability situations – as well as management options and future changes – to predict water quality scenarios. We utilised the DSS to generate water quality scenarios based on different actions aimed at:

• controlling wastewater discharges to the basin
• increasing the availability of water resources in the basin by using less water intensive crops

These scenarios will enable government planners to make sound decisions in order to help restore the quality of the Yamuna River and manage its pollution levels.