Estimating agricultural water productivity using remote sensing derived data

Abstract

AbstractThe 2030 Agenda aims at ending extreme poverty, inequality, injustice and climate change. Progress is evaluated through a set of Sustainable Development Goals (SDGs), targets and indicators. However, there are various challenges affecting regular and timely reporting. Remote sensing (RS) derived data has been shown to provide a valuable complementary data source in reporting SDGs. This study focuses on how RS derived data could support SDG 6 related to water, and in particular SDG indicator 6.4.1 - change in Water Use Efficiency (WUE) over time presented in USD per m3 of water withdrawn. Although water withdrawals cannot be monitored through RS, water use in agriculture, globally withdrawing the largest amount of water, can be monitored through RS based evapotranspiration.Two approaches were modelled to compute the progress of SDG 6.4.1 in the agricultural sector. The first approach uses the standard equation of SDG 6.4.1, replacing water withdrawal with blue evapotranspiration in the irrigation sector. The second approach distributes the gross value added to the gross domestic product by irrigated agriculture according to the land productivity in irrigated agriculture as observed by RS. The results of these two approaches were compared to the standard way SDG 6.4.1 is calculated. The analyses were carried out for Lebanon, which faces critical water challenges while experiencing a difficult economic and political situation.The results for Lebanon show that the different approaches to estimate Awp show similar trends as Awe, initially showing an increasing trend followed by a sharp decline in 2019 due to the deteriorating economic situation in the country. However, the absolute values differ substantially, largely due to discrepancies between the estimated irrigated area from RS data and the static data reported in AQUASTAT. The results illustrate the spatial variability of Awp in Lebanon, with the area that contributes significantly to the agricultural production nationally (Bekaa and Baalbek) shows lower land and water productivity compared to irrigated areas in other governorates. The contribution of agriculture to the overall SDG 6.4.1 indicator was relatively small, although agriculture is a major consumer of water.