Introducing reservoir sustainability indexing to investigate reservoir operations and piloting it at the basin of Lake Urmia with sparse data

Reservoir sustainability indexing/estimation is introduced in this paper, capable of handling sparse data. It innovates by interconnecting a set of three variables: estimating Environmental Water Requirements (EWRs) by conceptual rules; estimating Reliability, Resilience and Vulnerability (RRV) criteria by using EWRs; and thereby calculating Sustainability Indexes (SI), which are either satisfactory or unsatisfactory. These together transform reservoir studies into an innovative capability , implemented by a strategy at three levels: Level 1 scopes critically the research direction setting up a rule engine. Level 2 calculates the EWRs, RRV and SI metrics. Level 3 addresses the defensibility of the results. The capability is piloted on 9 major reservoirs with available data out of 44 in the basin of Lake Urmia for a proof-of-concept. The subsequent knowledge discovery uncovers that: (i) Of 5.3 Billion Cubic Metres (BCM/Annum) lake inflows, 3.1 BCM/annum is required to maintain the lake, but cut off unwarrantedly, instigated the catastrophe. (ii) SI-values verify that the basin is fragile against unwarranted operations; conversely, evidence is given that restoring Lake Urmia is feasible by overhauling reservoir management. (iii) The emerging retrospective explanation is that reservoir operations are the single root cause instigating the catastrophic disappearance of Lake Urmia. • Attributing Lake Urmia catastrophe to climate change instigates fait accompli . • Reservoir Sustainability Indexing is introduced to examine the cause under sparse data. • A sample of 9 main reservoirs out of 44 is piloted for knowledge discoveries . • They provide evidence that neglecting Environmental Flow instigated the catastrophe. • Thus, overhauling unwarranted operations is the key to restoring the Lake.