Abstract
Water scarcity has received global attention in the last decade as it challenges food security in arid and semi-arid regions, particularly in the Middle East and North Africa. This research assesses the possible alleviation of water scarcity by reducing the water footprint in crop production through the application of soil mulching and drip irrigation. The study is the first to do so at catchment scale, taking into account various crops, multi-cropping, cropping patterns, and spatial differences in climate, soil, and field management factors, using field survey and local data. The AquaCrop-OS model and the global water footprint assessment (WFA) standard were used to assess the green and blue water footprint (WF) of ten major crops in the Upper Litani Basin (ULB) in Lebanon. The blue water saving and blue water scarcity reduction under these two alternative practices were compared to the current situation. The results show that the WF of crop production is more sensitive to climate than soil type. The annual blue WF of summer crops was largest when water availability was lowest. Mulching reduced the blue WF by 3.6% and mulching combined with drip irrigation reduced it by 4.7%. The blue water saving from mulching was estimated about 6.3 million m3/y and from mulching combined with drip irrigation about 8.3 million m3/y. This is substantial but by far not sufficient to reduce the overall blue WF in summer to a sustainable level at catchment scale.
Highlights
Introduction(Hoekstra et al, 2012), there is increasing interest in the question how to reduce water use and vulnerability to water shortage in agriculture, in irrigated crop production (Jägermeyr et al, 2015; Brauman et al, 2013)
We consider two components: the green water footprint that refers to evapotranspiration of rainwater and the blue water footprint that refers to evapotranspiration of irrigation water (Hoekstra, 2017; Hoekstra et al, 2011)
To assess the possibility of blue water saving in the Upper Litani Basin through alternative agricultural practices, we formulated two scenarios: mulching for all crops (S1), and mulching plus drip irrigation for all summer crops (S2)
Summary
(Hoekstra et al, 2012), there is increasing interest in the question how to reduce water use and vulnerability to water shortage in agriculture, in irrigated crop production (Jägermeyr et al, 2015; Brauman et al, 2013). We focus on soil mulching and drip irrigation as two of the promising agricultural practices that may contribute to increasing water productivity. We further use the concept of blue water scarcity, defined as the ratio of the total blue water footprint in a catchment to the blue water availability, whereby the latter equals natural runoff in the catchment minus the flow that needs to be maintained in support of local ecosystems and communities (Hoekstra et al, 2011)
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