The Noyyal sub-basin, which is 3510 sq km in area, is part of the Cauvery basin that lies in the state of Tamil Nadu. It is a rapidly urbanizing sub-basin that includes the Class I cities of Coimbatore and Tiruppur as well as 84 smaller urban settlements. Water issues in this basin have been the focus of much public debate and action over the last two decades. Most of the debate, triggered by farmer agitations and court cases, has focused on the question of water pollution; water scarcity and sustainability issues have received relatively little attention. Recent bans on industrial...

The first question we address is whether there is sufficient water to meet the current needs of water users in Noyyal sub-basin, which users experience water scarcity, where and when. In trying to understand whether there is sufficient water, there are two considerations. In defining whether users get enough water to meet their present needs, it would be useful to clarify what it means to say that users get ‘enough’ water to ‘meet’ their present needs.

First, defining ‘enough’ is a challenging task. In the case of domestic needs, clear norms exist. TWAD has norms that vary from 40 LPCD...

In the previous section, we examined the issue of whether current water availability is adequate to meet current needs. However, current use affects future availability also, particularly in the case of groundwater. Moreover, variations in year-to-year availability (of rainfall and surface water) are high and therefore resilience against drought years also needs to be considered. Thus, both sustainability of average use under average conditions and resilience against major droughts are of concern. There is also a question of whether pollution levels affect usability of water.

There are various sources of data and several studies that have looked at these issues,...

The third dimension on which the water situation may be assessed is the fairness of water allocation. Unfortunately, there are no objective or broadly accepted criteria for us to judge how water ought to be allocated across users/uses. We therefore talk about quantitative equity only when it comes to allocations within a particular sector or user group. On the other hand, allocation between sectors or user groups, such as domestic versus industrial versus agriculture, or upstream versus downstream, is judged in terms of fairness. Since there is no clear criterion for fairness, we examine the fairness in the process of...

Since the mid-1990s, water quality and the impact of industrial pollution have been the most debated aspect of water resource management in the Noyyal basin. The intense debate and public interest in water quality issues in the Noyyal have generated vast literature — including government-commissioned, academic and non-governmental — on the types and distribution of contaminants in the region.

However, as described in Section 1, the series of court cases that sparked this debate have culminated in the High Court passing a ZLD order in 2011. Due to this, and other factors mentioned earlier, by 2013 almost half the textile...

We have attempted to review and summarise the current state of knowledge on water issues in the Noyyal sub-basin. We defined water ‘problem’ using a four-dimensional framework of water scarcity, fairness, sustainability and water quality.

We find that there are significant issues on all fronts. Water scarcity is not immediately apparent to many domestic users because they are primarily dependent on inter-basin imports from the Bhavani basin to the north. However, anecdotal evidence suggests that there is also considerable dependence on local groundwater, which may be depleting. Industrial water scarcity has not been a problem, at least in the Tiruppur...