WorkBlock 2 - Population and land use change

Co-ordinator: Gunther Fischer, International Institute for Applied Systems Analysis
Deputy co-ordinator: David Wiberg International Institute for Applied Systems Analysis

The main objective of Workblock 2 is to provide gridded estimates of population, land use and water requirements for the 20th and 21st centuries for use in the other Work Blocks.

This work block focuses on the human demand side of the water cycle, the driving forces of anthropogenic feedbacks to the water cycle, development of scenarios of future changes to these driving forces, and the uncertainties, risks and vulnerabilities of human water demand. It has a key role in providing spatially detailed data on the anthropogenic driving forces for common use in other WorkBlocks. In order to provide spatially explicit datasets, this work block will assimilate state-of-the-art available geographical information to produce a consistent global coverage of data, develop and assemble scenarios of future changes in driving forces, refine and apply methodologies for downscaling existing statistical data and scenarios to a grid, and assess the uncertainties in the data and scenario development. Agricultural modelling is needed for the spatially detailed estimation of agricultural water consumption and withdrawals, as well as for providing land use change feedbacks to the climate system.

WATCH requires consistent global data and global scenarios for 200 years, information that may necessarily be less specific and refined, but covers the globe at a longer time scale than in other EU projects such as SCENES and CLIMPACT. The gridded datasets developed in WB2 will be made available to other WATCH WB’s. For instance projected changes in cultivated land are necessary inputs for assessing the water resources of a region (see below).

Figure courtesy of: International Institute for Applied System Analysis (IIASA)

This work block is structured into 3 work packages:

  • WP2.1 will provide gridded distributions of past, as well as scenarios of future, urban and rural populations. Starting from databases of current population distribution, it will apply downscaling techniques to available aggregate national population statistics and scenarios to quantify past and projected urban and rural populations.
  • WP2.2:  in this work package, past land cover and land use will be obtained from: synthesising current spatial data, datasets available from past land use/cover change research efforts, and through downscaling of historical agricultural production statistics. Projected land cover and land use distributions will be derived on the basis of aggregate land use scenarios, reflecting trajectories of the key driving forces. In addition, this WB will provide new datasets of soil/terrain conditions and vegetation to WB1 and WB5.
  • WP2.3 will analyse, in collaboration with WB6, the past and future demand of water for agriculture, domestic use and industry, including the size and location of dams and areas of irrigation. Future water use will take into account changes in population, demography, rural/urban sectors, projected economic growth and changes in economic structure, new water-saving technologies, competition for water, and changes in water requirements due to climate change. 

Work Performed and Results achieved during Year 2 (February 2008 – 31 January 2009)
The focus of Work Block 2 in the second year has been to further assemble and develop datasets on past and future land use and sectoral water demands as well as supporting datasets. Global future land use datasets were developed for SRES A2 and B1 scenarios out to 2100. A spatial dataset and report have been completed on the Preliminary Spatially Explicit Estimates of Past and Present Domestic Water Use. In order to better assess water demands by agriculture, a new Harmonized World Soil Database has been developed and provided to WATCH partners. Other supporting agriculture water
demand datasets include global crop water deficits and potential increases in production with irrigation have been calculated and developed. Further achievements during the year include:

  • links with GranD (the Global Reservoir and Dam (GRanD) Database) to provide an update of the global lakes and wetlands database, when GRanD becomes available.
  • A website was set up at IIASA to hold WB2 data and documentation in a single location.