He started his career as a physical geographer, establishing himself as an expert on Libya and remote sensing. His extensive work in the Middle East and North Africa led to exploring the politics and policy of water resources management. His interdisciplinary insight produced important studies on virtual water, which demonstrated the significant role of water embedded in agricultural production. He was the first to point out that trade of food products enabled water-scarce countries to relieve pressure on their water supply, making virtual water an important consideration for water policy. His work exposed the deep flaws in the current systems that produce and supply food and enable its consumption, as they do not value the impacts to water and land. He was recognised for his pioneering work and long-term contributions to research and policy in 2008 with the highly prestigious Stockholm Water Prize. He was also the recipient of the Florence Monito Water Prize and the Monaco Water Prize, both in 2013. The concept of virtual water is now widely adopted in national policies and private sector practices. Virtual water is also taught as part of UK geography A-level syllabus. He valued communicating science and in later years worked on raising awareness of good water stewardship within and beyond the academy.