Chapter 3.1 – Computational Policy Support Systems for Understanding Land Degradation Effects on Water and Food Security for and from Africa

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By Mark Mulligan, King’s College London, London.

This chapter outlines the information needs for land degradation and restoration policy support through identifying which policy makers, policies, and types of support are necessary to understand degradation and restoration, including where and what to restore, how to restore it, and how much to restore. We use Africa as a case study to understand the currently available spatial information in support of land restoration planning. The WaterWorld Policy Support System is used with a range of spatial data sets to understand the areas of Africa subject to recent land degradation (as observed from satellite time series) and the spatial congruence of these areas with intensive croplands, intensive pastures, and deforestation. We indicate that recent land degradation has some, but not a full, association with recent land use. We then examine multi-General Circulation Model (GCM) ensemble climate projections and land use scenarios to indicate which parts of Africa are most at risk of land degradation and the likely impacts of these risks locally and along the agricultural supply chains originating in these areas. Finally, we examine the potential impacts on water and food security of restoring degraded areas in Africa through reforestation and investment in agricultural ecoefficiency. Focusing on Gabon, we indicate that afforestation will have positive impacts on water quality, but negative impacts on water quantity. To mitigate this impact, strategic mixtures of intensive cropland and small-scale afforestation in landscapes provide the greatest potential to reduce degradation (especially soil erosion) and to secure water while minimizing opportunity costs for crop growth. For restoration activities to make an impact at the national scale, huge investments will be required. It is thus critical that these investments have clear economic benefits for water and food security, both locally and downstream.

 

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