Impact of Climate Variability on Blue and Green Water Flows in the Erhai Lake Basin of Southwest China

The Erhai Lake Basin is a crucial water resource of the Dali prefecture. This research used the soil and water assessment tool (SWAT) and the China Meteorological Assimilation Driving Datasets for the SWAT model (CMADS) to estimate blue and green water flows. Then the spatial and temporal change of blue and green water flows was investigated. With the hypothetical climate change scenarios, the sensitivity of blue and green water flows to precipitation and temperature has also been analyzed. The results showed that: (1) The CMADS reanalysis dataset can capture the observed probability density functions for daily precipitation and temperature. Furthermore, the CMADS performed well in monthly variables simulation with relative bias and absolute bias less than 7% and 0.5 °C for precipitation and temperature, respectively; (2) blue water flow has increased while green water flow has decreased during 2009 to 2016. The spatial distribution of blue water flow was uneven in the Erhai Lake Basin with the blue water flow increased from low altitudes to mountain areas. While the spatial distribution of green water flow was more homogeneous; (3) a 10% increase in precipitation can bring a 20.8% increase in blue water flow with only a 2.5% increase in green water flow at basin scale. When temperature increases by a 1.0 °C, the blue water flow and green water flow changes by −3% and 1.7%, respectively. Blue and green water flows were more sensitive to precipitation in low altitude regions. In contrast, the water flows were more sensitive to temperature in the mountainous area.

Download Full-text

Impacts of human activities and climate variability on green and blue water flows in the Heihe River Basin in Northwest China

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-9477-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 9477-9504 ◽

Cited By ~ 15

Author(s):

C. Zang ◽

J. Liu ◽

L. Jiang ◽

D. Gerten

Keyword(s):

Climate Variability ◽

River Basin ◽

Water Flow ◽

Human Activities ◽

Northwest China ◽

Green Water ◽

Heihe River ◽

Blue Water ◽

Water Flows ◽

Green And Blue Water

Abstract. Human activities and climate factors both affect the availability of water resources and the sustainability of water management. Especially in already dry regions, water has become more and more scarce with increasing requirements from growing population, economic development and diet shifts. Although progress has been made in understanding variability of runoff, the impacts of climate variability and human activities on flows of both green water (actual evapotranspiration) and blue water (discharge accumulated in the river network) remain less well understood. We study the spatial patterns of blue and green water flows and the impacts on them of human activities and climate variability as simulated by the Soil and Water Assessment Tool (SWAT) for an inland Heihe river basin located in Northwest China. The results show that total green and blue water flow increased from 1980 to 2005, mainly as a result of climate variability (upward precipitation trends). Direct human activities did not significantly change the total green and blue water flow. However, land use change led to a transformation of 206 million m3 from green to blue water flow, while farmland irrigation expansion resulted in a transformation of 66 million m3 from blue to green water flow. The synchronous climate variability caused an increase of green water flow by 469 million m3 and an increase of blue water flow by 146 million m3 at the river basin level, while the geographical distribution showed an uneven change even with reductions of water flows in western sub-basins at midstream. The results are helpful to benchmark the water resources in the context of global change in the inland river basins in China. This study also provides a general approach to investigate the impacts of historical human activities and climate variability on green and blue water flows at the river basin level.

Download Full-text

Dynamics of green and blue water flows and their controlling factors in Heihe River basin of northwestern China

10.5194/hess-2016-241 ◽

2016 ◽

Author(s):

Kaisheng Luo ◽

Fulu Tao

Keyword(s):

Water Resources ◽

River Basin ◽

Water Flow ◽

Heihe River Basin ◽

Green Water ◽

Heihe River ◽

Blue Water ◽

Water Flows ◽

Green And Blue Water ◽

County Scale

Abstract. Climate variation will affect hydrological cycle, as well as the availability of water resources. In spite of large progresses have been made in the dynamics of hydrological cycle variables, the dynamics and drivers of blue water flow, green water flow and total flow (three flows), as well as the proportion of green water (GWC), in the past and future at county scale, were scarcely investigated. In this study, taking the Heihe River basin in China as an example, we investigated the dynamics of green and blue water flows and their controlling factors during 1980–2009 using five statistical approaches and the Soil and Water Assessment Tool (SWAT). We found that there were large variations in the dynamics of green and blue water flows during 1980–2009 at the county scale. Three flows in all counties showed an increasing trend except Jiayuguan and Jianta county. The GWC showed a downward trend in the Qilian, Suzhou, Shandan, Linze and Gaotai counties, but an upward trend in the Mingle, Sunan, Jinta, Jiayuguan, Ganzhou and Ejilaqi counties. In all the counties, the three flows and GWC had strong persistent trends in the future, which are mainly ascribed to rainfall variation. In the Qilian and Shandan counties, rainfall was the major controlling factor for the three flows and GWC. Rainfall controlled the green water and total flows in the Mingle, Linze and Gaotai counties; green water flow and GWC in the Suzhou county; green water flow, total flow and GWC in the Jinta and Ejilaqi counties. Our results also showed that the "Heihe River basin allocation project" had significant influences on the abrupt changes of the flows above-mentioned. Our results illustrate the status of the water resources at county scale, providing a reference for water resources management of inland river basins.

Download Full-text

A step forward toward the high-resolution assessment of virtual water flows at the company’s scale

10.5194/egusphere-egu21-14900 ◽

2021 ◽

Author(s):

Elena De Petrillo ◽

Marta Tuninetti ◽

Francesco Laio

Keyword(s):

Water Management ◽

High Resolution ◽

Water Resources ◽

Virtual Water ◽

The State ◽

Green Water ◽

Blue Water ◽

Food Trade ◽

Water Flows ◽

Final Consumer

Through the international trade of agricultural goods, water resources that are physically used in the country of production are virtually transferred to the country of consumption. Food trade leads to a global redistribution of freshwater resources, thus shaping distant interdependencies among countries. Recent studies have shown how agricultural trade drives an outsourcing of environmental impacts pertaining to depletion and pollution of freshwater resources, and eutrophication of river bodies in distant producer countries. What is less clear is how the final consumer &#8211; being an individual, a company, or a community- impacts the water resources of producer countries at a subnational scale. Indeed, the variability of sub-national water footprint (WF in m3/tonne) due to climate, soil properties, irrigation practices, and fertilizer inputs is generally lost in trade analyses, as most trade data are only available at the country scale. The latest version of the Spatially Explicit Information on Production to Consumption Systems model&#160; (SEI-PCS) by Trase provides detailed data on single trade flows (in tonne) along the crop supply chain: from local municipalities- to exporter companies- to importer companies &#8211; to the final consumer countries. These data allow us to capitalize on the high-resolution data of agricultural WF available in the literature, in order to quantify the sub-national virtual water flows behind food trade. As a first step, we assess the detailed soybean trade between Brazil and Italy. This assessment is relevant for water management because the global soybean flow reaching Italy may be traced back to 374 municipalities with heterogeneous agricultural practises and water use efficiency. Results show that the largest flow of virtual water from a Brazilian municipality to Italy -3.52e+07 m3 (3% of the total export flow)- comes from Sorriso in the State of Mato Grosso. Conversely, the highest flow of blue water -1.56e+05 m3- comes from Jaguar&#227;o, in the State of Rio Grande do Sul, located in the Brazilian Pampa. Further, the analysis at the company scale reveals that as many as 37 exporting companies can be identified exchanging to Italy; &#160;Bianchini S.A is the largest virtual water trader (1.88 e+08 m3 of green water and 3,92 e+06 m3 of blue water), followed by COFCO (1,06 e+08 m3 of green water and 6.62 m3 of blue water) &#160;and Cargill ( 6.96 e+07 m3 of green water and 2.80 e+02 m3 of blue water). By building the bipartite network of importing companies and municipalities originating the fluxes we are able to efficiently disaggregate the supply chains , providing novel tools to build sustainable water management strategies.

Download Full-text

Water saving through international trade of agricultural products

Hydrology and Earth System Sciences ◽

10.5194/hess-10-455-2006 ◽

2006 ◽

Vol 10 (3) ◽

pp. 455-468 ◽

Cited By ~ 250

Author(s):

A. K. Chapagain ◽

A. Y. Hoekstra ◽

H. H. G. Savenije

Keyword(s):

Water Resources ◽

Water Use ◽

Virtual Water ◽

Water Saving ◽

Agricultural Products ◽

Green Water ◽

Blue Water ◽

Water Flows ◽

Global Water ◽

National Water

Abstract. Many nations save domestic water resources by importing water-intensive products and exporting commodities that are less water intensive. National water saving through the import of a product can imply saving water at a global level if the flow is from sites with high to sites with low water productivity. The paper analyses the consequences of international virtual water flows on the global and national water budgets. The assessment shows that the total amount of water that would have been required in the importing countries if all imported agricultural products would have been produced domestically is 1605 Gm3/yr. These products are however being produced with only 1253 Gm3/yr in the exporting countries, saving global water resources by 352 Gm3/yr. This saving is 28 per cent of the international virtual water flows related to the trade of agricultural products and 6 per cent of the global water use in agriculture. National policy makers are however not interested in global water savings but in the status of national water resources. Egypt imports wheat and in doing so saves 3.6 Gm3/yr of its national water resources. Water use for producing export commodities can be beneficial, as for instance in Cote d'Ivoire, Ghana and Brazil, where the use of green water resources (mainly through rain-fed agriculture) for the production of stimulant crops for export has a positive economic impact on the national economy. However, export of 28 Gm3/yr of national water from Thailand related to rice export is at the cost of additional pressure on its blue water resources. Importing a product which has a relatively high ratio of green to blue virtual water content saves global blue water resources that generally have a higher opportunity cost than green water.

Download Full-text

Water budget fluxes in catchments under grassland and Eucalyptus plantations of different ages

Canadian Journal of Forest Research ◽

10.1139/cjfr-2020-0156 ◽

2020 ◽

Author(s):

Decio Ferreto ◽

José Miguel Reichert ◽

Rosane Barbosa Lopes Cavalcante ◽

Raghavan Srinivasan

Keyword(s):

Water Resources ◽

Water Flow ◽

Water Budget ◽

Development Stage ◽

Livestock Grazing ◽

Green Water ◽

Canopy Interception ◽

Planted Forests ◽

Water Flows ◽

Eucalyptus Plantations

The area with planted forests increased in the last decades and they have an important role in programs to sequester carbon. However, the effects of eucalyptus plantations on water resources in the Southern Grasslands biome are largely unknown, and we herein address water budget fluxes including green and blue flows. We evaluated green (canopy interception and evapotranspiration) and blue (discharge) water flows in three watersheds; two predominantly covered with Eucalyptus, either in the first years after planting or at the end of the rotation, and one with livestock-grazing grassland. We used field measurements of rainfall, streamflow and throughfall, and estimated canopy interception and evapotranspiration by water balance. Water flows in the monitored watersheds with eucalyptus plantations were influenced by forest development stage. Annual canopy interception and transpiration were always higher in the watersheds with eucalyptus than in the one with grassland, except for the transpiration in the first year after plantation in watershed with young eucalyptus. Increase in evapotranspiration (green water flow) and the consequent decrease in streamflow (blue water flow) should be considered in local water resources management. Studies on catchment hydrology and forest management for improved water use efficiency and streamflow regulation are required, particularly in understudied regions.

Download Full-text

Green Water

Oxford Research Encyclopedia of Environmental Science ◽

10.1093/acrefore/9780199389414.013.368 ◽

2017 ◽

Author(s):

Garrison Sposito

Keyword(s):

Energy Balance ◽

Water Flow ◽

Land Surface ◽

Green Water ◽

Richards Equation ◽

Blue Water ◽

Global Flow ◽

Catchment Scale ◽

Rooting Zone ◽

Visualization Techniques

Precipitation falling onto the land surface in terrestrial ecosystems is transformed into either “green water” or “blue water.” Green water is the portion stored in soil and potentially available for uptake by plants, whereas blue water either runs off into streams and rivers or percolates below the rooting zone into a groundwater aquifer. The principal flow of green water is by evapotranspiration from soil into the atmosphere, whereas blue water moves through the channel system at the land surface or through the pore space of an aquifer. Globally, the flow of green water accounts for about two-thirds of the global flow of all water, green or blue; thus the global flow of green water, most of which is by transpiration, dominates that of blue water. In fact, the global flow of green water by transpiration equals the flow of all the rivers on Earth into the oceans. At the global scale, evapotranspiration is measured using a combination of ground-, satellite-, and model-based methods implemented over annual or monthly time-periods. Data are examined for self-consistency and compliance with water- and energy-balance constraints. At the catchment scale, average annual evapotranspiration data also must conform to water and energy balance. Application of these two constraints, plus the assumption that evapotranspiration is a homogeneous function of average annual precipitation and the average annual net radiative heat flux from the atmosphere to the land surface, leads to the Budyko model of catchment evapotranspiration. The functional form of this model strongly influences the interrelationship among climate, soil, and vegetation as represented in parametric catchment modeling, a very active area of current research in ecohydrology. Green water flow leading to transpiration is a complex process, firstly because of the small spatial scale involved, which requires indirect visualization techniques, and secondly because the near-root soil environment, the rhizosphere, is habitat for the soil microbiome, an extraordinarily diverse collection of microbial organisms that influence water uptake through their symbiotic relationship with plant roots. In particular, microbial polysaccharides endow rhizosphere soil with properties that enhance water uptake by plants under drying stress. These properties differ substantially from those of non-rhizosphere soil and are difficult to quantify in soil water flow models. Nonetheless, current modeling efforts based on the Richards equation for water flow in an unsaturated soil can successfully capture the essential features of green water flow in the rhizosphere, as observed using visualization techniques. There is also the yet-unsolved problem of upscaling rhizosphere properties from the small scale typically observed using visualization techniques to that of the rooting zone, where the Richards equation applies; then upscaling from the rooting zone to the catchment scale, where the Budyko model, based only on water- and energy-balance laws, applies, but still lacks a clear connection to current soil evaporation models; and finally, upscaling from the catchment to the global scale. This transitioning across a very broad range of spatial scales, millimeters to kilometers, remains as one of the outstanding grand challenges in green water ecohydrology.

Download Full-text

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

Hydrology and Earth System Sciences ◽

10.5194/hess-16-2859-2012 ◽

2012 ◽

Vol 16 (8) ◽

pp. 2859-2870 ◽

Cited By ~ 90

Author(s):

C. F. Zang ◽

J. Liu ◽

M. van der Velde ◽

F. Kraxner

Keyword(s):

River Basin ◽

River Basins ◽

Heihe River Basin ◽

Green Water ◽

Heihe River ◽

Blue Water ◽

Natural Conditions ◽

Water Flows ◽

Inland River ◽

Green And Blue Water

Abstract. In arid and semi-arid regions freshwater resources have become scarcer with increasing demands from socio-economic development and population growth. Until recently, water research and management has mainly focused on blue water but ignored green water. Furthermore, in data poor regions hydrological flows 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 and 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.

Download Full-text

Limits to the world’s green water resources for food, feed, fiber, timber, and bioenergy

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1817380116 ◽

2019 ◽

Vol 116 (11) ◽

pp. 4893-4898 ◽

Cited By ~ 53

Author(s):

Joep F. Schyns ◽

Arjen Y. Hoekstra ◽

Martijn J. Booij ◽

Rick J. Hogeboom ◽

Mesfin M. Mekonnen

Keyword(s):

Central America ◽

Water Scarcity ◽

Water Footprint ◽

Limited Resource ◽

Green Water ◽

Human Society ◽

Blue Water ◽

Water Requirements ◽

Water Flows ◽

The Cost

Green water––rainfall over land that eventually flows back to the atmosphere as evapotranspiration––is the main source of water to produce food, feed, fiber, timber, and bioenergy. To understand how freshwater scarcity constrains production of these goods, we need to consider limits to the green water footprint (WFg), the green water flow allocated to human society. However, research traditionally focuses on scarcity of blue water––groundwater and surface water. Here we expand the debate on water scarcity by considering green water scarcity (WSg). At 5 × 5 arc-minute spatial resolution, we quantify WFg and the maximum sustainable level to this footprint (WFg,m), while accounting for green water requirements to support biodiversity. We then estimate WSg per country as the ratio of the national aggregate WFg to the national aggregate WFg,m. We find that globally WFg amounts to 56% of WFg,m, and overshoots it in several places, for example in countries in Europe, Central America, the Middle East, and South Asia. The sustainably available green water flows in these countries are mostly or fully allocated to human activities (predominately agriculture and forestry), occasionally at the cost of green water flows earmarked for nature. By ignoring limits to the growing human WFg, we risk further loss of ecosystem values that depend on the remaining untouched green water flows. We emphasize that green water is a critical and limited resource that should explicitly be part of any assessment of water scarcity, food security, or bioenergy potential.

Download Full-text

Influence of human activities and climate variability on green and blue water provision in the Heihe River Basin, NW China

Journal of Water and Climate Change ◽

10.2166/wcc.2015.194 ◽

2015 ◽

Vol 6 (4) ◽

pp. 800-815 ◽

Cited By ~ 9

Author(s):

Chuanfu Zang ◽

Junguo Liu ◽

Dieter Gerten ◽

Luguang Jiang

Keyword(s):

Climate Variability ◽

River Basin ◽

Water Flow ◽

Human Activities ◽

Heihe River Basin ◽

Green Water ◽

Heihe River ◽

Blue Water ◽

Green And Blue Water ◽

Water Provision

Human activities and climate simultaneously affect water cycling and provision. Here, we study the impacts of climate variability and human activities on green and blue water provision (or the flows of both green water and blue water) in the inland Heihe River Basin as simulated by the Soil and Water Assessment Tool (SWAT). The results show that total green and blue water flow varied significantly from 1980 to 2010. Direct human activities did not significantly change the sum of green and blue water flow volumes. However, land use change led to a transformation of 206 million m3/year in the entire river basin from green to blue water flow, while farmland irrigation expansion resulted in a transformation of 66 million m3 from blue to green water flow. The synchronous climate variability, with an upward precipitation trend, caused an increase of green water flow by 469 million m3/year and an increase of blue water flow by 146 million m3/year at the river basin level over the study period. The results provide a general approach to investigate the impacts of historical human activities and climate variability on water provision at the river basin level.

Download Full-text

A Spatial and Temporal Study of the Green and Blue Water Flow Distribution in Typical Ecosystems and its Ecosystem Services Function in an Arid Basin

Water ◽

10.3390/w11010097 ◽

2019 ◽

Vol 11 (1) ◽

pp. 97 ◽

Cited By ~ 3

Author(s):

Chuanfu Zang ◽

Ganquan Mao

Keyword(s):

Water Flow ◽

Assessment Tool ◽

Model Simulation ◽

Swat Model ◽

Flow Distribution ◽

Green Water ◽

Heihe River ◽

Corn Yield ◽

Blue Water ◽

Green And Blue Water

Research on relationship between green and blue water flow and ecosystem service functions has great significance for improving water resources management and for ecological protection. In this study, the distribution patterns and service functions of green and blue water flow in different ecosystems were analysed by Soil and Water Assessment Tool (SWAT) model simulation and Correlational Analysis. In the entire basin, the amount of green and blue water flow in the grassland was greater than that in the cropland, and that in the cropland was larger than that in the forest. The corn yield per hectare of cropland was highest in the Heihe River Basin, followed by wheat, and the lowest yield was the oil yield from 2000 to 2010. The mutton yield in the grassland ecosystem was greater than the beef yield from 2000 to 2010, which shows that the beef production would consume more water flow. Results show an obvious positive correlation between green or blue water flow and wheat and corn yields. Beef and mutton had a significant correlation with blue water flow, whereas mutton had a stronger correlation with green water flow.

Download Full-text