Background
Cambodia is among the countries most vulnerable to the impacts of climate change, with increasing drought frequency, erratic rainfall patterns, rising temperatures, and more frequent extreme weather events significantly affecting water availability and agricultural productivity. As agriculture remains predominantly rain-fed, with only a limited proportion of farmland served by reliable irrigation, rural communities are highly exposed to climate risks. Existing irrigation and rural water storage infrastructure is often outdated, poorly maintained, and insufficient to address prolonged dry periods, resulting in declining crop yields, reduced household incomes, and heightened food insecurity.
Recognizing these challenges, Cambodia has identified rainwater harvesting as a national adaptation priority under its Technology Needs Assessment and other climate strategies. However, many existing ponds and reservoirs suffer from high seepage losses, evaporation, sedimentation, and water quality degradation, limiting their effectiveness and long-term storage capacity. While a range of technical options, including improved pond and reservoir designs, seepage reduction technologies, evaporation control measures, sediment management, and water quality protection, are available, their technical performance, economic feasibility, and suitability under Cambodia's diverse climatic, hydrological, and socio-economic conditions remain insufficiently assessed.
A further constraint is the lack of reliable and comprehensive data to support planning and investment. Information on the location, condition, storage capacity, water demand, seasonal use, and management of existing rural water storage systems is fragmented, making it difficult to prioritize interventions, compare technology options, estimate investment needs, or prepare bankable proposals for climate finance. Strengthening the evidence base is therefore essential to guide policy, improve investment planning, and support the scale-up of climate-resilient rainwater harvesting systems across Cambodia.
CTCN Support
Through the CTCN technical assistance, Cambodia will undertake a comprehensive assessment of improved rainwater harvesting technologies for decentralized rural water storage. The support will evaluate technical options to enhance water retention, reduce seepage and evaporation losses, control sedimentation, and improve water quality protection under different local conditions. The assessment will consider technical performance, economic feasibility, environmental sustainability, scalability, and suitability across different agroecological regions, while identifying the most appropriate technology packages for rural communities.
The technical assistance will also strengthen the evidence base for decision-making by assessing existing water storage infrastructure, identifying data and institutional gaps, and developing recommendations for planning, operation, maintenance, and stakeholder coordination. The results will provide practical guidance to national and sub-national authorities for prioritizing investments, strengthening policy and institutional frameworks, and preparing investment-ready proposals to mobilize financing from climate funds and development partners.
Expected Outcome
The proposed technical assistance will deliver an evidence-based roadmap for scaling up improved rainwater harvesting systems in Cambodia, including prioritized technology options, feasibility assessments, and recommendations for implementation and investment. By strengthening technical knowledge, planning capacity, and financing readiness, the project will support informed policy decisions, improve climate resilience of rural water resources, and contribute to sustainable agricultural production, enhanced water security, and long-term adaptation to climate change.
Seeking experts
The CTCN invites qualified experts and firms to submit Expressions of Interest (EOI) to participate in this initiative. For further information on this opportunity, visit the UN Global Marketplace (UNGM) or the UN website. Deadline for applications: 20 July 2026.
If you are not yet a member of the CTCN Network, you can apply to join here.
