Monitoring & Evaluating Water Productivity in Irrigation [Mozambique]
Irrigation interventions hold tremendous potential to help farmers cope with increasing climate variability and to ensure food security in many poorer regions of the world. Globally, irrigated land accounts for only 17 percent of cultivated land, but 40 percent of total food production. Yet, failure to properly manage irrigation schemes often leads to lack of investments in this sector. Empirical research in the field of water management is key in responding to these operational challenges, but has been limited in this context.
Together with researchers from IFPRI, a team from the World Bank and specialists from the Ministério de Agricultura, Instituto Nacional de Irrigação as well as from the Eduardo Mondlane University, hydrosolutions ltd. has implemented a low-cost, high-tech real-time crowd-sensing approach for measuring field water availability in new smallholder irrigation schemes in Mozambique. Despite progress in the beginning of this decade, poverty reduction in Mozambique has stagnated with 55 percent of the population still living in poverty. In addition, the poverty rate in the rural areas, where two-thirds of the population lives, has been increasing. In the central part of the country, agriculture is dominated by smallholder rain-fed farms which have experienced significant harvest losses as a result of extreme weather like droughts and floods. Promoting sustainable irrigation and drainage is essential in making smallholder farmers resilient to these intensifying climate variations and the government of Mozambique has made the development of irrigation a priority for agriculture growth and rural development.
The Figure above shows the selection of smallholder schemes in Manica Province in Central Mozambique where water productivity assessment work was carried out.
Contrary to traditional monitoring approaches that do not scale well due to prohibitive costs and that are prone to vandalism and normally cause significant O&M requirements, the technology used d deployed and instrument by hydrosolutions ltd. lies entirely on user-reported data that are recorded at specific intervals. All monitoring protocols have been thoroughly discussed with the communities under consideration and agreed upon. The designated persons in charge of data collection were given a contract that clearly specifies their roles and responsibilities with regard to the site- and technology-specific daily data collection and the modalities for the remuneration of operational expenses and salaries.
For irrigation canals, measurement sites were calibrated using the propeller method for the establishment of water height-discharge relationships. Assuming normal conditions for flow, this allows for translating simple water depth measurements (i.e. with a ruler) into discharge values. For sprinklers and hydrants, average yield values were calculated with repeated measurements through volumetric dosing. The Figure below shows sample collected data for the discharge at the intake in Nhamandeme Scheme.
The designated data collectors were given a notebook with pre-printed forms to fill out. Data on irrigation canals flows are collected three times daily and averaged over the day. Through the determination of the sub-scheme level catchment of a particular irrigation canal, supplies can be calculated on a per hectare basis on daily scales. For fields that are irrigated by sprinklers and hydrants, the number of active units is recorded twice daily. Multiplying these numbers with average yields, daily water supplies can easily be calculated.
For each scheme, a designated extension officer is collecting the data on a weekly basis and types in the information in a spreadsheet table. This information can then automatically be uploaded to a web-based scheme-specific accounting and data management system. The extension officer will also be monitoring the data collection on a weekly basis for QA/QC. The officer will also follow-up in case of questions and report back to INIR as well as designated university people that are the local project leaders.