China's food production under water and land limitations

[摘要] The future availability of the natural resources (water and land) needed for food production is highly uncertain. Evidence shows diminishing natural resources and growing food demand throughout many parts of the world. China is one of the countries that face the challenge of managing its finite water and land resources to support their population. Difficulties mainly arise from: (1) the geographic mismatch between the location of water resources and available land; (2) a large and growing number of population; and (3) limited natural resources per capita. This thesis presents a systematic approach to evaluate the effects of water and land constraints on food production and applies it to China as a case study. Based on the basic principle of water and land balance, crop resource requirements, and per capita consumption, the assessment of natural resources limitations on food production can be formulated into an optimization model, with the objective function maximizing the number of people fed subject to resource constraints. This formulation makes it possible to systematically and efficiently evaluate the effects of natural resource constraints for such a complex and large scale study regions such as China. Even though our approach is based on the basic principle, we incorporate several significant features into the model to realistically represent the spatial and temporal heterogeneity in climate, land use, and crop requirements. Our analysis is conducted at a detailed spatial resolution of 0.5;; by 0.5;;, includes water movement at the same resolution, accommodates the mixture of crops in people;;s diet, and distinguishes irrigated from rain-fed agriculture. Our optimization model presents an average long term analysis. The model is developed and calibrated to reproduce long-term observed conditions during the nominal period of 1990- 2000. We then use the model together with globally and locally available data to make future predictions of China;;s food production capacity during the future period of 2046-2065. These future predictions include the impacts of the South-to-North Water Diversion project and projected climate change. The future climate scenarios are taken from the general circulation model predictions and represent diverse seasonal and regional patterns. Regionally, land is a limiting factor in the south, while water is a limiting factor in the north. Our results suggest that irrigation and multiple-cropping are keys in enhancing China;;s food production capacity to support increasing population. The spatial and seasonal distribution of rainfall changes is critical for agriculture in meeting future food requirements under climate change.

[发布机构] Massachusetts Institute of Technology