| Summary: | Thesis (Ph. D.)--Boston University === Croplands are essential to human welfare. In the coming decades , croplands will experience substantial stress from climate change, population growth, changing diets, urban expansion, and increased demand for biofuels. Food security in many parts of the world therefore requires informed crop management and adaptation strategies. In this dissertation, I explore two key dimensions of crop management with significant potential to improve adaptation pathways: irrigation and crop calendars.
Irrigation, which is widely used to boost crop yields, is a key strategy for adapting
to changes in drought frequency and duration. However, irrigation competes with
household, industrial, and environmental needs for freshwa t er r esources. Accurate
information regarding irrigation patterns is therefore required to develop strategies
that reduce unsustainable water use. To address this need, I fused information
from remote sensing, climate datasets, and crop inventories to develop a new global
database of rain-fed, irrigated, and paddy croplands. This database describes global
agricultural water management with good realism and at higher spatial resolution
than existing maps.
Crop calendar management helps farmers to limit crop damage from heat and
moisture stress. However, global crop calendar information currently lacks spatial
and temporal detail. In the second part of my dissertation I used remote sensing to
characterize global cropping patterns annually, from 2001-2010, at 0.08 degree spatial
resolution. Comparison of this new dataset with existing sources of crop calendar
data indicates that remote sensing is able to correct substantial deficiencies in available data sources. More importantly, the database provides previously unavailable
information related to year-to-year variability in cropping patterns.
Asia, home to roughly one half of the Earth's population, is expected to experience
significant food insecurity in coming decades. In the final part of my dissertation,
I used a water balance model in combination with the data sets described above to
characterize the sensitivity of agricultural water use in Asia to crop management.
Results indicate that water use in Asia depends strongly on both irrigation and crop
management, and that previous studies underestimate agricultural water use in this
region. These results support policy development focused on improving the resilience
of agricultural systems in Asia.
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