Final Technical report: Establishing and Operating a Near East and North Africa Regional Network for Evapotranspiration (NENA-ETNet)

Abstract

Actual Evapotranspiration (ETa) is the main component required to understand both hydrological and ecological processes between the land surface and the atmosphere. Reliable spatiotemporal measurements of ET are important for water resources planning, management and monitoring, efficient irrigation scheduling, and climate change mitigation scenarios development. Virtually no existing coordinated measurements and initiatives to validate various estimates of ETa are systematically carried out in the NENA Region although the region is extremely water scarce and vulnerable to climate change. Therefore, the Water Scarcity Initiative (WSI) of FAO for the Near East and North Africa, conceived and promoted the coordination of ETa field measurements as vital in the region with a consistent protocol established through this ET-Network project, which could effectively be used to validate and calibrate the remotely sensed estimations. The overarching objective of this project (named NENA-ETNet) was to establish and operate a NENA Regional Network of specialized institutions, within the countries of reference, to conduct field measurements of actual ET, over selected crops and for at least four seasons, in order to evaluate the accuracy of existing RS-based ET estimates. The idea was to build a common regional understanding on ETa measurements (ETa) in the field and through RS, on accuracy assessments of RS ETa data of different databases and on their analyses and use for agriculture-related applications (e.g., water accounting, water productivity, water management, etc.). Therefore, ICARDA was called upon, in collaboration with FAO and five countries in the region, to establish such a regional ET network to obtain reliable source of ground measurements of ET with the multiple goals of calibrating and validating RSbased ETa retrievals, calibrating and validating crop models and to do regional synthesis using the measured data in a multi-location, multi-season manner, in the context of regional water scarcity. The NENA-ETNet had a special focus on comparing CORDOVA-ET system using other field ETa methods of determination in order to decide if CORDOVA-ET method could be used as a regional standardized validation protocol. The participating countries were Egypt, Jordan, Lebanon, Morocco and Tunisia. The participating countries now have good capacity and facilities for ET measurements using energy balance and micro-meteorological methodologies, lysimeter and gravimetric methods. This report briefly summarizes all the project research results, learnings, challenges, recommendations and strategies on the way forward.