The Water-Food Nexus: A Data-driven, Interdisciplinary Approach to Inform Decision Making in Sri Lank

My dissertation research aims to improve management of water resources for agriculture, which accounts for 70% of global freshwater withdrawals and 90% of global water consumption. Using Sri Lanka as a case study, we constructed Palmer Drought Severity Index (PDSI) and Standardized Precipitation Index at a 9-month scale (SPI-9) agricultural drought indices. We then analyzed these indices for: 1) spatiotemporal patterns of drought in the country from 1880 to 2010 and 2) utility as drought monitoring tools. Our findings show that although the two indices exhibited similar physical patterns, with a strong, negative association between the Northeastern monsoon and El-Ni˜no in recent decades. Important zonal distinctions were present between the indices concerning correlations to local metrics of drought impacts; PDSI correlated best with the intermediate zone districts, SPI-9 correlated best with dry zone districts, but neither index correlated well with the wet zone districts.;The drought analysis indicated that the northeast portion of the island (an important agricultural region) was becoming drier during the minor growing season, when water resources are already scarce. So we quantified and assessed patterns in irrigation water requirements (IWRs) for rice (the staple food of the country) over 20 years. Comparing IWRs with actual planting records indicates that shifting planting dates to earlier in the season is a low-cost adaptation that could yield IWRs savings of up to 6% in parts of the country. These potential water savings are particularly important given emerging climate change research of less water being available for irrigation during the minor growing season.;In certain parts of the country, however, water stress is already significant enough to warrant diversification away from rice production, a water-intensive process. Given that crop selection decisions are influenced by myriad factors besides weather, I led an interdisciplinary team of researchers (with backgrounds in hydrology, social psychology, human geography, and behavioral economics) to assess whether provision of seasonal forecasts to farmers could inform their crop selections and lead to improved net agricultural incomes. For this mixed methods study, we compiled and analyzed data from numerous sources including meteorological assessments, games in the field, household surveys, interviews, and government reports. Our empirical findings were rolled into a single-agent system dynamics model, with which we explored the combined impact of a changing climate and varying crop economics on agricultural income. Our results indicate that, when water resources are scarce, farmer incomes could become stratified, potentially compounding existing disparities in farmers' financial and technical abilities to use forecasts to inform their crop selections. This analysis highlights that while policies and programs that promote production of certain crops may ensure food security in the short-term, the long-term implications of these dynamics need careful evaluation.;Beyond water and food, the convergence of limited supply and growing demand issues has prompted much needed conversations about interactions with other critical resources such as energy. For example, treatment of nitrates (a common agriculture-related water quality issue) requires energy investments, which depend on the same scarce water resources upon which agriculture also depends on in Sri Lanka. Given the complex physical and social factors (including governance shifts, climate change, population growth, and technology developments) govern these resource interactions, interdisciplinary research will become increasingly important for and all nations (including Sri Lanka) to help inform policies and strategies that efficiently manage resource use.