In many OECD countries, water allocation between competing users has remained a bargaining process that is often characterised by a strong political dimension. One reason is that second-best solutions might in some cases provide a more effective (albeit more costly) way to solve the water competition problem, while at the same time addressing issues of fairness and food security. Not only will this ensure a higher probability of their participating in the programme (trades are always voluntary), but the market design will also benefit from local knowledge of the geographical and social characteristics of the water basin. Its advantages - notably its relative insulation from climatic events and its accessibility to farmers - have led to its intensive use in areas with limited or unstable surface water supplies.