Development of Flow Duration Curves and Eco-Flow Metrics for the Tawi River Basin - (Jammu, India)

Abstract

A Flow duration Curve (FDC) and eco-metrics are one of the principal techniques employed to study the changes in flow regimes and flow discharge in any river basin. Stream flows vary widely over a year and this variability can be assessed by using FDC’s which is a curve plotting stream flows (Q) on the vertical axis and the percent of time the flow is equalled or exceeds (P) a critical discharge threshold on the horizontal axis for a particular river basin. Flow Duration curves (FDCs) are imperative instruments which are fundamental for water asset distribution and administration, which can further be analysed to get a great deal of hydrological data to understand the impact of climate changes on water asset frameworks. Results got from the flow duration curves are required by hydrologists and specialists associated with various water asset ventures such as assessing the hydropower capabilities of a waterway, stream health, surge control examines such as recurrence outlines, runoff estimations, figuring the dregs stack and broken down solids of a stream, and contrasting the adjacent catchments. Apart from these classical uses, the FDCs can also be used to survey the health status of the streams in terms of its ecological status. The present study has been undertaken with an objective to identify the ecological health status of the Tawi River, based on ecoflow metrics. Eco-surplus and eco-deficit are known as the indicators of Hydrologic Alteration (IHA) and are used to study intra and inter annual variations in river flows. The daily stream flow data at Gulab Singh Bridge, Jammu from the Hydrological Data Centre of the Central Water Commission (CWC), Jammu has been used to develop the Flow Duration Curve (FDCs) for the different periods like daily, monthly, annual etc. Finally, 10- daily time series have been used to identify the ecosurplus and the ecodeficit years and their respective magnitudes. Further, an eco-flow metric for the Tawi River was prepared for the 30 years daily discharge data from the period 1977 to 2007. The results of the study conclude that Tawi River is an ecosurplus river, in most of the years of the study period. The ecology of Tawi River is at par for the study period except for the years 1999 and 2000. Although the ecology is under sustaining conditions, but the metric has been falling in course of time, which can be a signal of ecological deterioration in the future.