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High nutrient loads are an indicator of pollution sources in a watershed that need to be identified and quantified. These loads in surface and groundwater have been a major concern that impacts water quality in the Midwestern US, including the Great Lakes Basin. To investigate the influence of land use change, especially at urban/rural interfaces, we used the Soil and Water Assessment Tool (SWAT) to model water, sediment, and nutrient export for the St. Joseph River Basin (SJRB), which drains an area of 12,200 km2 in Southwest Michigan/Northwest Indiana and enters Lake Michigan. The SWAT models were built, calibrated and validated for monthly streamflow, groundwater, total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP), nitrate (NO3-N) and dissolved reactive phosphate (DRP; as orthophosphate), using two stream gages (Niles, USGS ID 04101500; Paw Paw, USGS ID 04102500) in Berrien County, MI. We found that monthly hydrology, sediments, and inorganic nutrients were well captured by the model with very good to excellent performance at the Niles gage, and, good to satisfactory performance at Paw Paw. The simulated average annual groundwater was 137 mm and 129 mm for Niles and Paw Paw, respectively, suggesting that on average 57% and 60% of long-term streamflow in the basin comes from groundwater and shallow subsurface flow. For water quality variables, TSS loads were strongly correlated with streamflow with R2 reaching 0.90. Using this model, we investigated how land use change (e.g., agriculture), and the planting of winter cover crops in the fallow season would impact water and nutrient yields from the SJRB. We found that the impact of changing land use and applying cover crops on water quality components was significant and dependent on the selected spatial scale. The simulated outputs indicated that cover crops have no impact on hydrology but significantly reduced DRP and NO3-N export to Lake Michigan by up to 30% and 50%, respectively. Application of this model will assist regional land and water managers in planning for future impacts of land use and climate change and their impacts on water quality and quantity, enabling stakeholders to implement conservation practices to sustain the SJRB and other similar basins in the Great Lakes region.

Humanity’s capacity to live without irreversibly compromising the environmental and biophysical conditions on which it depends is at stake. The expanding societal needs for food and energy add an unsustainable pressure on limited amounts of freshwater resources. In this context, the recent global economic and food security crisis, the adoption of new bioenergy policies, trends of water and land commodification, have been described as the drivers of a fast escalation in transnational land investments. A phenomenon described as a new ‘global land rush’. This process is favoring a strong transformation of the rural landscapes in large parts of Latin America, Southeast Asia and Sub-Saharan Africa, with small-scale farming, the most diffused system of production, being displaced by large-scale commercial intensified agriculture. Such land deals may result in the dispossession of traditional users, subsistence and small-holder farmers by large-scale commercial agriculture, as well as expansion of agricultural land at the expense of savannas, forests, or other ecosystems. Here, we bring together the insights from distinct studies conducted on these different dimensions using the (to our knowledge) largest available sample of georeferenced global transnational land deals. We synthesize these studies with the objective to identify and highlight the interconnectedness of the phenomenon and how different interdependencies and trade-offs play out. Using data from the Demographic and Health Survey Program we then investigate the livelihood, health and food security dynamics associated with this phenomenon. We identified the main archetypes such large-scale transitions and defined their temporal trajectories (e.g., before and after the deals). We found that a significant portion of such deals, especially located in Southeast Asia, showed strong simultaneous increases in deforestation, crop cover and probability of export/trade, severely undermining the food security in such areas. Our approach offers a robust methodology to understand the multi-sectoral implications of the global land rush in a systematic, multi-dimensional and integrated way that we believe is helpful to inform policy.

While the war in Ukraine has dramatically affected global wheat supplies, its food security implications vary substantially across countries, depending on their vulnerability to supply disruptions and ability to access food reserves. New trade data obtained after the onset of the conflict reveal a 75% decrease in wheat export from Ukraine, with the potential to push average calorie intakes below malnutrition thresholds in the most vulnerable countries. Differences in access to international trade determine the impact of supply disruptions and suggest the need for policy measures to defuse the impending food crisis.

A variety of interdisciplinary fields have provided distinct and complementary perspectives on human-water systems over the past few decades. In that context, an important distinctive feature of so...

Millions displaced by conflicts have found refuge in water-stressed countries, where their perceived effect on water availability has shaped local water security discourses. We leverage new annual global data on the water footprint of food production to elucidate the effects of refugee displacement on host countries' water stress. The blue water demand transferred by refugees has nearly doubled between 2005 and 2016. It tends to be transferred towards countries with less water-intensive food provision systems, but more water-intensive dietary habits and comparably scarce water resources. Although minimal in most countries, implications on water stress can be dramatic in vulnerable countries that are already at risk of severe water crises. The 3.3 million refugees in Jordan may have contributed to water stress by up to 60%-points. We find that small changes to current UNHCR refugee resettlement goals can substantially ease the effect of refugee displacement on water stress in vulnerable countries.