RESTORATION OF DEGRADED URBAN RIVERS

Abstract

The present study is undertaken with an aim to find the possibilities in restoring the severely polluted Hindon River in India. The feasibility of restoration activities is typically analysed for Hindon Basin by comparing with Thames Basin in the United Kingdom, where apparently the Thames River has been restored. By comparing the two basins, the study tries to understand the catchment-scale properties and basin wide management remedies that can assist in restoring a river and improve the water quality. On comparing, it is found out that the two basins tends behave quite differently in different aspects. Thames basin is able to maintain the organic pollution to a very minimal level owing to its geomorphological, climatic, hydrogeological phenomena and strategic management practices by large. Conversely, Hindon River suffer from extreme water quality condition and this is mainly attributed to poor management practices within the basin. The drainage density and the areal extent of the Thames basin is relatively higher than Hindon Basin, rendering it to accumulate more surface water during any event of precipitation and thereby increasing the assimilative capacity of the river. Further, due to continuous rainfall throughout the year in Thames basin, it further increase the availability of surface water, which eventually increases the assimilative capacity of the river. On the other hand, Hindon basin receives maximum rainfall only during July and August and receives little or no rainfall for rest of the month, rendering the river to suffer from extreme water quality condition during low flow season. Most importantly, the Chalk aquifer in Thames basin plays a major role in maintaining flow regime within the river system. In addition, recharge structures built along the Thames River helps in continuous recharge of the aquifer. The study also focuses on water quality analysis for the Hindon River so as to understand the spatial and temporal variation of water quality. The water quality data from 1994 to 2012 for the various monitoring station were acquired for the analysis. Non parametric tests along with post hoc interaction test were performed so as to understand the variation in water quality. The study found the presence of spatial and temporal variance of water quality at 5 percent significance level within the basin. Besides water quality analysis, the pollution load was also estimated for both the point and non-point sources within Hindon basin. ii Further the study undertook the water quality modeling using Water quality analysis and simulation programme (WASP8). The model was calibrated and validated prior to any scenario analysis was performed. Using the validated model attempt has been made to generate the feasible scenarios of restorative measure, like load reduction, flow augmentation, instream reaeration and reduction sediment oxygen demand within the river system and to assess how these restorative scenarios help abate the pollution of the river. From the scenario analysis, it was found that although the scenarios developed help in improving the water quality condition, it do not meet the requirements as requested by the CPCB for the propagation of wild life and fisheries and further restorative strategies like nutrient stripping from the treatment plant and riparian management along the river is deemed necessary for improvement in water quality. Further, in order to minimise the excessive pumping effect of water from aquifer, efforts should also be made to artificially recharge the aquifer within the basin.