Strategic importance of green water in international crop trade

Virtual water is the volume of water used to produce a commodity or service. By importing agricultural commodities and the virtual water embedded in them, a country saves the water it would have required to produce those commodities domestically. Virtual-water ‘trade’, thus, has the potential to relieve water stress and improve water security. The present research critically evaluates the strategic importance and implications of green water (soil water) in relation to international crop trade. Even if, traditionally, emphasis has been given to irrigation systems, today most global crop production is rain-fed. Besides having a lower opportunity cost, green water use for the production of crops is considered more sustainable than the use of blue water (irrigation). Although green water represents the largest share of virtual water in the international trade of agricultural commodities, with exports going from highly productive rain-fed rich countries towards generally blue water based ones, green water volumes have rarely been estimated. The present study corroborates that green water is by far the largest share of virtual water embodied in maize, soybean and wheat exports from the USA, Canada, Australia and Argentina during the period 2000-2004. Accordingly, green virtual-water flows can play a major role in ensuring water security and saving water in water-deficit economies. The potential of international green virtual-water ‘trade’ for saving water and improving water security, however, is constrained by factors such as technology, the potential for further increases in the productivity, the level of socio-economic development, national food policies and international trade agreements

Green and blue water accounting in the Limpopo and Nile Basins: Implications for food and agricultural policy

Green water, Blue water, Irrigation, Rainfed, Agriculture, technology, Investment, Impact, Climate change, Water resources,

The significance of local water resources captured in small reservoirs for crop production – A global-scale analysis

Rainwater harvesting, broadly defined as the collection and storage of surface runoff, has a long history in supplying water for agricultural purposes. Despite its significance, rainwater harvesting in small reservoirs has previously been overlooked in large-scale assessments of agricultural water supply and demand. We used a macroscale hydrological model, observed climate data and other physical datasets to explore the potential role of small, localized rainwater harvesting systems in supplying water for irrigated areas. We first estimated the potential contribution of local water harvesting to supply currently irrigated areas. We then explored the potential of supplemental irrigation applied to all cropland areas to increase crop evapotranspiration (or green water flow), using locally stored surface runoff in small reservoirs for different scenarios of installed reservoir capacity. The estimated increase in green water flow varied between 623 and 1122 km3 a1 . We assessed the implications of this increase in green water flows for cereal production by assuming a constant crop water productivity in areas where current levels of crop yield are below global averages. Globally, the supplemental irrigation of existing cropland areas could increase cereal production by 35% for a medium variant of reservoir capacity, with large potential increases in Africa and Asia. As small reservoirs can significantly impact the hydrological regime of river basins, we also assessed the impacts of small reservoirs on downstream river flow and quantified evaporation losses from small reservoirs

The effects of cropping intensity and cropland expansion of Brazilian soybean production on green water flows

As land use change alters how green water is appropriated, cropland expansion is instrumental in re-allocating green water towards agriculture. Alongside cropland expansion, agricultural intensification practices modify crop water use and land and water productivity. Particularly, one form of agricultural intensification known as multi-cropping (the cultivation of a piece of land sequentially more than once a year) can result in greater agricultural output per unit of land, as well as more productive use of the available water throughout the annual rainfall cycle. We assess the influence of these two processes, cropland expansion and agricultural intensification, in agricultural green water use in Brazilian agriculture. We applied the biophysical crop model Environmental Policy Integrated Climate (EPIC) to estimate green water use for single and double cropping of soybean (Glycine max) and maize (Zea mays) in Brazil. The first part of our study analyses changes in soybean green water use and virtual water content nationwide between 1990 and 2013, and in a second part we look into the effect of double-cropping on water use for soybean and maize in the Brazilian states of Paraná and Mato Grosso between 2003 and 2013. The results show that cropland expansion plays a more prominent effect in green water use for production of soybean than intensification, and harvested area increase was responsible for the appropriation of an additional 95 km3 of green water in 2013 when compared to 1990, an increase of 155%. We estimate that an additional green water use of around 26 km3 related to second season maize was appropriated through increase of cropping frequency, and without expansion of cropland, in 2013 in the selected states. We discuss the importance of considering multi cropping practices when assessing green water sustainability, and the importance of differentiating green water appropriation through expansion and through cropping frequency changes

Green water in larviculture - An experiment with natural phytoplankton in tanks for first feeding of halibut larvae (Hippoglossus hippoglossus L.)

At 232 day degrees, halibut larvae were transferred from indoor tanks to 1.7 m^3 outdoor tanks for first feeding. The number in each tank was approximately 750. Three tanks were continuously given algal suspension ("green water") and supplied nonenriched Artemia instar II. Six tanks were given filtered deep water ("clear water"). Three of the six were supplied nonenriched Artemia, and three were supplied Artemia prefed in green water. Feeding incidence at day 3 was 47 % in green water and 0 % in clear water. Larval growth was significantly higher in green water compared to clear water, while no significant difference was found between the clear water groups given prefed and nonenriched Artemia. The mean myotome heights for all groups were 0.75 - 0.78 mm at day 7. At day 14 and 21, the mean heights were 1.49 and 1.86 mm in the green water group and 0.84 and 1.05 mm in the clear water groups. The survival rates were also much higher in green water. Out of a total of approximately 2250 halibut larvae in the green water tanks, 684 larvae were found alive at the end of the experiment. Corresponding numbers for the clear water tanks were 57 out of 4500. Preliminary results indicate no nutritional effect of the algae

The water footprint of olives and olive oil in Spain

This paper evaluates the water footprint of Spanish olives and olive oil over the period 1997-2008. In particular, it analyses the three colour components of the water footprint: green (rainwater stored in the soil), blue (surface and groundwater) and grey (freshwater required to assimilate load of pollutants). Apparent water productivity and virtual water embedded in olive oil exports have also been studied. Results show more than 99.5% of the water footprint of one liter of bottled olive oil is related to the olive production, whereas less than 0.5% is due to the other components such as bottle, cap and label. Over the studied period, the green water footprint in absolute terms of Spanish olive oil production represents about 72% in rainfed systems and just 12% in irrigated olive orchards. Blue and grey water footprints represent 6% and 10% of the national water footprint, respectively. It is shown that olive production is concentrated in regions with the smallest water footprint per unit of product. However, the increase of groundwater consumption in the main olive producing region (Andalusia), from 98 to 378 Mm3 between 1997 and 2008, has added significant pressure in the upstream Guadalquivir basin. This raises questions about the sustainability of irrigated olive orchards for export from the region. Finally, the virtual water related to olive oil exports illustrate the importance of green water footprint of rainfed olives amounting to about 77% of the total virtual water exports

Assessment of spatial and temporal patterns of green and blue water flows under natural conditions in inland river basins in Northwest China

In arid and semi-arid regions freshwater resources have become scarcer with increasing demands from socioeconomic development and population growth. Until recently, water research and management has maily focused on blue water but ignored green water. Furthermore, in data poor regions hydrological low under natural conditions are poorly characterised but are a prerequisite to inform future water resources management. Here we report on spatial and temporal patterns of both blue and green water flows that can be expected under natural conditions as simulated by the Soil and Water Assessment Tool (SWAT) for the Heihe river basin, the second largest inland river basin in Northwest China. Calibration ad validation at two hydrological stations show good performance of the SWAT model in modelling hydrological processes. The total green and blue water flows were 22.05-25.51 billion m3 in the 2000s for the Heihe river basin. Blue water flows are larger in upstream sub-basins than in downstream sub-basins mainly due to high precipitation and a large amount of snow and melting water in upstream. Green water flows are distributed more homogeneously among different sub-basins. The green water coefficient was 87%-89% in the 2000s for the entire river basin, varying from around 80%90% in up-and mid-stream sub-basins to above 90% in downstream sub-basins. This is much higher than reported green water coefficients in many other river basins. The spatial patterns of green water coefficients were closely linked to dominant land covers (e.g. snow cover upstream and desert downstream) and climate conditions (e.g. high precipitation upstream and low precipitation downstream). There are no clear consistent historical trends of change in green and blue water flows and the green water coefficient at both the river basin and sub-basin levels. This study provides insights into green and blue water endowments under natural conditions for the entire Heihe river basin at the sub-basin level. The results are helpful to benchmark the natural flows of water in the basin as part of improved water resources management in the inland river basins of China

Fiegel, Kurt H. (SC 1257)

Finding aid only for Manuscripts Small Collection 1257. Paper, “Historic and Archival Photographic Documents of the 1869 Bowling Green Water Works Engine/Boiler Room, Repair Shop and Pump House: A Contributing Element of WA-B-3, the Bowling Green Water Works, Warren County, Kentucky” by Kurt H. Fiegel, Frankfort, Kentucky. Includes historical narrative, construction details, maps and photographs. This project documented the structure prior to its demolition