Cropland use preferences under land, water and labour constraints— implications for wheat self-sufficiency in the Kabul River basin, Afghanistan

During the past two decades, expanding irrigated land and achieving self-sufficiency in wheat production have been primary focuses of Afghan food security policies. However, the true impacts of these strategies on wheat development are still unknown due to the weak monitoring system. This study was designed to (1) map the spatial dominance of wheat (the main staple crop) and barley (an alternative to wheat) in the Kabul River basin (KRB), (2) examine the exchange of area between the two crops considering the main production constraints of land, water, and labour, and (3) project the likelihood of wheat self-sufficiency in the KRB. For the development of crop dominance maps, the normalized difference vegetation index (NDVI) signatures were used in this study; for the crop area simulations, the dynamics of land system (DLS) model was coupled with the profit maximization model to develop different likely scenarios. The results indicated that from 2000 to 2010, the wheat area increased by 15% (41,075 ha), while the barley area decreased by 9% (-3525 ha), suggesting that improved water management in the KRB has encouraged wheat farming over barley farming. The projected scenarios (for 2030) also showed that the wheat area is likely to expand under all the scenarios, particularly under the business-as-usual (BAU) scenario, in which an annual increase rate of 1.5% is predicted. The economic development under labour constraints (EDL) and the environmental protection under water constraints (EPW) scenarios, on the other hand, showed the lowest increases. The analysis of the predicted wheat area and production values against population growth indicated the unlikeliness of achieving wheat self-sufficiency in the KRB.