Understanding water availability for irrigation
Availability of water resources is one of the most basic requirements for expanding farmer led irrigation. That’s why a significant part of ILSSI’s efforts is focused on supporting decision-makers to understand where and how water can be sustainably used for irrigation, using state of the art techniques. These efforts include co-designing, employing and strengthening capacity for tools that can reveal competing demands, risks of water insecurity and threats to water quality. ILSSI also trials improved irrigated farming practices that can help safeguard water resources and enable farmers to sustainably increase irrigation.
While water resources are currently underutilized in agricultural production in much of Sub-Saharan Africa, depletion is already occurring in some areas of Southeast Asia. In addition, competition over water resources is increasing around the world between urban and rural, agriculture and industry, domestic and productive users. As small scale irrigation expands with intensified production, it also poses high risks to water quality and therefore, ecosystem and human health. Moreover, farmer led irrigation is often excluded from formal water user groups and other collective management mechanisms, highlighting the gaps in monitoring and governing water and other natural resources.
Identify water availability and use in a basin to expand irrigation sustainably
Water resources in Ethiopia, Ghana, Tanzania, and in areas of Mali, are sufficient to allow farmers to sustainably expand irrigation, which would result in improved incomes and livelihoods for millions. However, water availability differs across space and time. In most areas, surface and groundwater resources need to be used conjunctively and with good tools and practices for on-farm water management. Treating rainfall and groundwater as one interconnected system supports a sustainable expansion of small scale irrigation. Competing water demands, for domestic and productive uses, can be identified and better managed through the use of Water Accounting+. Water Accounting+ is an internationally recognized and standardized framework for allocating available water resources across uses and sectors. Tools such as Water Accounting+ can be central to irrigation planning, enabling identification of potential water insecurity risks under current and future climatic conditions.
Modelling tools, such as ILSSI’s integrated decision support system (IDSS), is used to assess the impacts of farmer-led irrigation at the watershed and field-scale levels. This can help inform plans for expansion of small scale irrigation. ILSSI also works with institutions at multiple levels to build modelling skills in order to evaluate the impacts of farmer-led irrigation on water resource risks, agricultural production, environmental sustainability, household income and nutrition.
Understand shallow groundwater dynamics and enhance recharge
Shallow groundwater represents a valuable resource to smallholders, but must be well managed at the plot level, as well as at watershed and community levels. Farmers can tap into shallow groundwater using manual, diesel or solar-powered pumps. This allows them to irrigate during the dry season and complement rainfed production for one or two seasons (depending on the location).
Spatial information on groundwater depth and aquifer productivity can help in identifying irrigated land potential under current, or climate change, conditions. Such information can also aid in assessing suitability for irrigation technologies such as solar. When planning for small scale irrigation it is important to know how much water is available after the rainy season as this would influence crop and irrigation investment choices. In the Ethiopian Highlands, for example, water levels in shallow wells fluctuate by 2 – 15 meters, as the dry season advances, depending on where they are located in the watershed. The majority of these wells can only provide significant irrigation inputs during the first three months of the eight month-long dry season unless they are located at the bottom of a valley.
Facilitating groundwater recharge, through suitable water and soil management in the watershed, is key to increasing the availability of water for irrigation during the following dry season. For example, employing a newly developed plow – the berken plow – can help farmers break up the hard crust formed below the surface of some soils in the Ethiopian Highlands. This results in reduced rainwater runoff, limits soil disturbance and can lead to increased soil moisture.
Prioritize water quality, while intensifying agricultural production
Intensification of agricultural practices is often associated with expansion of FLI. Increased use of agrochemicals poses a potential risk of water pollution. Institutions should be strengthened alongside irrigation expansion to protect water resources. As agriculture intensifies, national, basin and watershed level institutions should be supported in ways that enable them to identify suitable areas for irrigation development. It is crucial that they are well placed to assess any potential water pollution impacts from agro-chemicals resulting from agricultural intensification facilitated by the irrigation. In some cases, new guidance needs to be created to set allowable levels of chemicals in water bodies.
Achieve greater yields and reduced water use through conservation agriculture
Conservation agriculture practices contribute to a range of farmer benefits, while also improving soil health and reducing negative environmental impacts. Benefits include: increased crop yields, reduced yield variability, increased profit from agricultural activities, and enhanced nutritional outcomes. For example, in one test site in Ethiopia, onion production through conservation agriculture achieved 35% higher yields compared to conventional agriculture. The application of soil cover on onion plots reduced soil evaporation by 26% compared to conventional tillage, while it also added organic matter to the soil. Conservation agriculture with drip irrigation in Ethiopia and Ghana has been found to reduce water use by between 18-45%, depending on the crop type, resulting in a range of crop yield increases (in some cases almost double), compared to conventional tillage. Soil moisture after irrigation was also higher under conservation agriculture.
Adapt irrigation practices through irrigation learning tools
Irrigation learning tools, such as wetting front detector systems, enable farmers to achieve higher water productivity, increased yields, and improvements in the quality of produce. For example, in Dangishta, Ethiopia, these tools resulted in a doubling of onion yields when farmers used manual water lifting devices. In cases where motorized pumps were used, irrigation learning tools helped farmers achieve crop yield increases of up to 21%, while reducing water use by up to 44%.
Govern shared resources at the community level for adaptability and resilience
At the community level, participant games can improve local understanding of groundwater-related interdependences, for strengthened management of shared resources. In addition, ILSSI examines the use of pumped water for multiple purposes. This emphasizes the need for adaptive community and watershed level governance of conjunctive water use.
DOWNLOAD: ILSSI brief on water resources
Contributing to solutions
Providing information on water resources for sustainable irrigation investments
Water resources in Ethiopia, Ghana, Tanzania, and areas of Mali, are sufficient to allow farmers to sustainably expand irrigation; shallow groundwater offers potential for irrigation in many countries. Facilitating groundwater recharge is therefore, key to increasing the availability and sustainability of water for irrigation. ILSSI uses Water Accounting, an Integrated Decision Support System suite of models, and Agent Based Modelling, among others, to examine water availability, potential for irrigation adoption, risks to water scarcity and climate scenarios. At the same time, we develop the capacity of public and research sectors to assess, monitor and plan resource use toward enhanced sustainability. To support the private sector, ILSSI has developed suitability mapping tools that enable decision-making about new markets for solar irrigation.
Providing evidence for sustainable water and land interventions
Conservation agriculture practices contribute to a range of farm-level improvements, including greater yields and reduced water usage. ILSSI with North Carolina A & T and local partners quantified and modeled the benefits of CA for both farmers and natural resource sustainability. ILSSI research partners are also assessing the impact of water and land management techniques – such as bunding, contouring and in situ agriculture water management – on livelihoods.
Testing approaches to improve water use at multiple scales
Misuse of water at field level can have suboptimal effects on production. For example, over-irrigating causes problems with soils, nutrients and water quality. However, managing water at field level is complex and new irrigators often lack information specific to their farms. ILSSI research on farm water management is contributing to materials for training and guidance, as well as identification of practical tools to aid farmers. Our evidence shows that irrigation learning tools, enable farmers to achieve higher water productivity, and often higher quality of produce, benefitting farmers, market actors, and the environment.
Contributing to tools and guidance for water governance
Shallow groundwater represents a valuable resource to smallholders, but must be well managed at the plot as well as community and watershed levels. ILSSI partners are developing and piloting participant games that can improve local understanding of groundwater-related interdependencies for strengthened management of shared water resources. ILSSI has also developed and analyzed data with public agencies as inputs to guidance and monitoring systems for water quality and sustainable land management interventions.
- Water resource assessment, gaps, and constraints of vegetable production in Robit and Dangishta watersheds, Upper Blue Nile Basin, Ethiopia
- Assessing potential land suitable for surface irrigation using groundwater in Ethiopia
- Effect of climate change on land suitability for surface irrigation and irrigation potential of the shallow groundwater in Ghana
- Suitability mapping framework for solar photovoltaic pumps for smallholder farmers in sub-Saharan Africa
- Establishing irrigation potential of a hillside aquifer in the African highlands
- Experimental evaluation of conservation agriculture with drip irrigation for water productivity in sub-Saharan Africa
- Compendium on climate-smart irrigation (FAO)
- Water Accounting+
- Integrated Decision Support System