An integrated modelling and multicriteria analysis approach to managing nitrate diffuse pollution: 1. Framework and methodology.

As trade-off relationships between the agronomy and the environment are common over land uses within a catchment, one of major concerns of catchment management plans is how to balance the trade-offs over land uses at the catchment-scale. In this two-part paper, an integrated modelling and multicriteria analysis (MCA) methodology is presented which can be used to evaluate a set of land use alternatives and to identify an 'ideal' compromise between economic return and environmental pollution. This 'ideal' compromise here is achieved by land use optimisation of which the objective is to minimise the environmental pollution (nitrate leaching rate) and to maximise the economic return (agronomic gross margin), considering both environmental and economic potential across the catchment in a site-specific manner. The suggested methodology can be used to produce a site-specifically optimised land use scenario that is an 'ideal' compromise between nitrate diffuse pollution and agronomy at the catchment-scales. Some issues on the actual application of the methodology are also discussed.

An integrated modelling and multicriteria analysis approach to managing nitrate diffuse pollution: 2. A case study for a chalk catchment in England.

The site-specific land use optimisation methodology, suggested by the authors in the first part of this two-part paper, has been applied to the River Kennet catchment at Marlborough, Wiltshire, UK, for a case study. The Marlborough catchment (143 km(2)) is an agriculture-dominated rural area over a deep chalk aquifer that is vulnerable to nitrate pollution from agricultural diffuse sources. For evaluation purposes, the catchment was discretised into a network of 1 kmx1 km grid cells. For each of the arable-land grid cells, seven land use alternatives (four arable-land alternatives and three grassland alternatives) were evaluated for their environmental and economic potential. For environmental evaluation, nitrate leaching rates of land use alternatives were estimated using SHETRAN simulations and groundwater pollution potential was evaluated using the DRASTIC index. For economic evaluation, economic gross margins were estimated using a simple agronomic model based on nitrogen response functions and agricultural land classification grades. In order to see whether the site-specific optimisation is efficient at the catchment scale, land use optimisation was carried out for four optimisation schemes (i.e. using four sets of criterion weights). Consequently, four land use scenarios were generated and the site-specifically optimised land use scenario was evaluated as the best compromise solution between long term nitrate pollution and agronomy at the catchment scale.

Deriving robust operating rules for the interim control of the Kirazdere reservoir.

A methodology is developed for deriving robust operating rules for the interim control of a multipurpose reservoir. The methodology includes the generation of policies using optimisation models, the derivation of robust operating rules using artificial neural networks and the evaluation of the identified policies through simulation. The approach developed is demonstrated through an application to the Kirazdere Reservoir located on the Kiraz River in Turkey.