Tradeoffs, inequalities, and asymmetries of cooperative smallholder irrigation in dryland environments

Abstract

Smallholder farms play an important role in food production throughout the developing world but face threats from decreased water availability due to land grabs and climate change. In some regions smallholders may gain access to irrigation water through community water projects (CWPs). Although CWPs provide a valuable service, the benefits they offer involve tradeoffs and vary over time and space. To understand the limits of smallholder irrigation it is necessary to consider this variability at multiple scales.

The models in Chapters 1, 2, and 3 simulate CWP irrigation in a dryland environment based on the Laikipia region of Central Kenya. The study presented in Chapter 1 investigates the effect of crop choice and irrigation availability on farming outcomes in Laikipia using an ecohydrological model of irrigation and plant growth. The results demonstrate that access to irrigation water allows risk-averse smallholders to farm higher-value market crops instead of drought-resistant subsistence crops.

The study presented in Chapter 2 investigates the effects of CWP functioning on member outcomes through an expansion of the model from Chapter 1 to include streamflow generation, water distribution, and dues collection. The results show that the effect of irrigation norms on member benefits is dependent on water costs and household characteristics. Additionally, disparities in member returns are minimized when CWPs apply by-volume fee assessment.

Chapter 3 features a study that investigates the impact of CWP withdrawal position and inter-CWP withdrawal restrictions on average outcomes. The model simulates discharge from multiple sub-catchments — each with a CWP intake— that are networked together within a larger catchment. The results show that imposing a lowflow limit reverses the usual pattern of upstream predominance, while a two-day rotation ensures relatively equal results but allows less water to leave the catchment.

Lastly, the study in Chapter 4 evaluates the polycentric governance of multiple communities sharing an asymmetric resource such as a river. It uses an agent-based model to investigate cooperation within and among communities. The results demonstrate that the initial level of intra-communal cooperation has a positive impact on inter-communal cooperation. Additionally, increasing resource availability leads to greater inter-communal cooperation but lower intra-communal cooperation.