1. Assessing the dynamics of private smallholder irrigation using sand river aquifers in semi-arid lands: A Case Study of different farming systems along the ephemeral Olkeriai River in Kajiado, Kenya

Conceptual framework and research methodology:

• Identification of shallow alluvial aquifer based farm system typologies and their characteristics through baseline surveys and GIS mapping
• In-depth study of farmers’ life histories and trajectories of development for each of the systems through semi structured interviews

Main finding/ knowledge insights:

Three types of farming systems were identified:

• Three main drivers for farmer-led development of irrigation systems were found to be: availability and ease of access to water in the sand river bed, land arability along the river and proximity to major markets
• Key risks faced by farmers include: pest attacks, exploitation by brokers, lack of support networks, water shortage in some parts, conflicts with landowners and financers and crop damage by wild animals
• Farmer coping mechanisms include: dynamically downgrading/upgrading between farm systems, diversification of crops and incomes and shifting farms

Relevance for development:

The drivers and challenges to enable irrigated farming in sand rivers is a crucial learning to develop the portfolio of investments required to enable different farming systems and achieve development and sustainability goals (SDG 2.4)

2. Mapping Small-scale Informal Irrigation using Time Series of High Resolution Data from Sentinel 2A/2b Satellite: A case Study from Kenya

Conceptual framework and research methodology:

• Satellite data acquisition and processing
• Ground truthing by primary data collection
• Classification of images as small holder irrigated farms using machine learning
• Validation and accuracy assessment

Main finding/ knowledge insights:

• On a 75% small-scale Irrigated farms found within a buffer of 250m from the sand river (Olkeriai River)
• Small-scale Irrigation rose from 742.57ha in 2017 to 1555.3ha in 2019
• Small-scale irrigation fragmentation has increased. There are many irrigated plots once used which are now abandoned in favour of new plots. These impact the riparian forest and the resulting ecosystem

Relevance for development:

Mapping small holder irrigation farms provides insight into farmer-led development of irrigation practices. It helps to assess the resilience of smallholder irrigation to climate change. This is crucial to meet develop sustainable food production systems, resilient agricultural practices and increased productivity (SDG 2.4)

3. Understanding the Hydrogeology of Kajiado and the Role of Sand River on Groundwater Storage and Abstraction

Conceptual framework and research methodology:

• Meteorological and land use data from FAO Wapor, Soil data (SOTER) and DEM, satellite images were used
• Field work – In-situ measurements such as probing, slug tests and VES measurements to ascertain the alluvial aquifer depth and characteristics, water and sand sample collection for lab testing

Main finding/ knowledge insights:

Estimate of the storage capacity of the sand river aquifer:

• Sand depth by probing found to be >3m in all probes
• Average porosity of 34.5% of Olkeriai sand river
• Hydraulic conductivity of about 150 m/day
• Conceptual model of the alluvial aquifer as shown in below image.

Relevance for development:

Developing enhanced insight into the potential of natural sand river storage systems is essential for development of the water resource and agriculture in these regions contributing to increased agricultural productivity and resilient agricultural practices while ensuring resource sustainability