Abstract
This paper studied the impacts of small-scale irrigation (SSI) interventions on environmental sustainability, agricultural production, and socio-economics using an Integrated Decision Support System (IDSS). The IDSS is comprised of a suite of models, namely the Soil and Water Assessment Tool (SWAT), Agricultural Policy/Environmental eXtender (APEX), and Farm Income and Nutrition Simulator (FARMSIM). The IDSS was applied in Dimbasinia watershed in northern Ghana using irrigation water from shallow groundwater. The watershed has a modest amount of shallow groundwater resources. However, the average annual irrigation water requirement exceeded the average annual shallow groundwater recharge. It was found that the current crop yield in Dimbasinia watershed was only ~40% of the potential crop production. This is mainly related to climate variability, low soil fertility, and land-management practices. For example, application of 50 kg/ha urea and 50 kg/ha DAP doubled maize and sorghum yield from the current farmers’ practices. Better income was obtained when irrigated vegetables/fodder were cultivated in rotation with sorghum as compared to in rotation with maize. Investment in solar pumps paid better dividends and also supplied clean energy. The socio-economic analysis indicated that having irrigated dry season vegetables will improve household nutrition. Since shallow groundwater recharge alone may not provide sufficient water for irrigation in a sustainable manner, surface water may be stored using water-harvesting structures to supplement the groundwater for irrigation. Integrated use of the water resources will also reduce depletion of the shallow groundwater aquifer. We conclude that IDSS is a promising tool to study gaps and constraints as well as upscaling of SSI.
Highlights
The number of malnourished people in the world has dropped substantially [1,2]; there are still more than 1 billion poor people [3]
Soil and Water Assessment Tool (SWAT) analyzes biophysical impacts of intensification at the watershed scale, Agricultural Policy/Environmental eXtender (APEX) analyzes the impacts of interventions at the individual fields, and Farm Income and Nutrition Simulator (FARMSIM) assesses economic feasibility and nutritional impacts at the household level
This study was conducted in the Dimbasinia watershed in Ghana, which is located at 10◦55 14.60 N, 1◦02 14.78 W in the Upper East Navrongo Region (Figure 1)
Summary
The number of malnourished people in the world has dropped substantially [1,2]; there are still more than 1 billion poor people [3]. In Ghana, agriculture employs more than half of the population on a formal and informal basis and contributes a quarter of gross domestic product (GDP) and export earnings [8] This suggests that investment in agriculture can contribute to food security and poverty reduction for the majority of the rural poor [5,7]. There is limited research that shows the holistic impacts of small-scale irrigation (SSI) interventions like adopting irrigation technologies, proper use of fertilizer and improved seed varieties on environmental indicators in terms of soil erosion and sediment loadings as well as on family income and nutrition in small watersheds in drought-prone areas. SWAT analyzes biophysical impacts of intensification at the watershed scale, APEX analyzes the impacts of interventions at the individual fields, and FARMSIM assesses economic feasibility and nutritional impacts at the household level
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