Evaluating policy options for integrated and cost effective river management in the tidal Ouse
The River Ouse forms a significant part of the Humber river system, which drains about one fifth of the land area of England and provides the largest fresh water input to the North Sea from the UK. The tidal Ouse has suffered from a sag of dissolved oxygen (DO) during the last few decades, caused by effluent discharges from industries and Sewage Treatment Works (STWs). Poor water quality during the summer prevents the return of salmon, which is regarded by the Environment Agency (EA) as a key indicator of rivers' ecological health. The EA proposed to increase water quality in the Ouse by implementing more stringent environmental policies. This conventional management option, however, usually offers less flexibility in compliance and incurs excessive costs of pollution abatement to industries and STWs. This thesis explores the potential to improve water management by adopting an integrated and cost effective river policy, which allows for variation in the assimilative capacity of river water. Various options to improve water quality are considered in a comprehensive framework for river policy. Reduction in both effluent discharges and water abstraction are considered together with choice of location for effluent discharge. Different instruments of environmental policy, tax-subsidy scheme (TSS) and tradable pollution permits (TPP) systems are compared with the command and control (CAC) approach. A hydrological model from the EA is combined with an economic model to identify the least cost solution for water quality management in the river system. This thesis provides a theoretical discussion of this problem in both static and dynamic settings. This framework is then applied to the empirical case of the tidal Ouse for particular water quality targets. To achieve the water quality target at least cost is a constrained optimisation problem, solved by computing software. The integrated river policy is able to achieve a significant improvement in water quality at lower cost than is currently incurred. This thesis also compares the different policy instruments for delivering this water quality improvement in the tidal Ouse.