scholarly journals Supplementary material to "Dynamics of green and blue water flows and their controlling factors in Heihe River basin of northwestern China"

Author(s):  
Kaisheng Luo ◽  
Fulu Tao
2012 ◽  
Vol 16 (8) ◽  
pp. 2859-2870 ◽  
Author(s):  
C. F. Zang ◽  
J. Liu ◽  
M. van der Velde ◽  
F. Kraxner

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.


2016 ◽  
Author(s):  
Kaisheng Luo ◽  
Fulu Tao

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.


2012 ◽  
Vol 9 (3) ◽  
pp. 3311-3338 ◽  
Author(s):  
C. F. Zang ◽  
J. Liu ◽  
M. van der Velde ◽  
F. Kraxner

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 in these has mainly focused on blue water but ignored green water. Here we report on spatial and temporal patterns of both blue and green water flows 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 22.09 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 large areas of glaciers in upstream. Green water flows are distributed more homogeneously among different sub-basins. The green water coefficient was 88.0% in the 2000s for the entire river basin, varying from around 80–90% in up- and mid-stream sub-basins to above 95% in downstream sub-basins. This is much higher than reported green water coefficient in many other river basins. The spatial patterns of green water coefficient were closely linked to dominant land covers (e.g. glaciers in upstream and desert in downstream) and climate conditions (e.g. high precipitation in upstream and low precipitation in downstream). There are no clear consistent historical trends of change in green and blue water flows and green water coefficient at both the river basin and sub-basin levels. This study provides insights into green and blue water endowments for the entire Heihe river basin at sub-basin level. The results are helpful for formulating reasonable water policies to improve water resources management in the inland river basins of China.


2015 ◽  
Vol 7 (6) ◽  
pp. 6741-6762 ◽  
Author(s):  
Yunbo Bi ◽  
Hongjie Xie ◽  
Chunlin Huang ◽  
Changqing Ke

2013 ◽  
Vol 10 (7) ◽  
pp. 9477-9504 ◽  
Author(s):  
C. Zang ◽  
J. Liu ◽  
L. Jiang ◽  
D. Gerten

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.


2015 ◽  
Vol 6 (4) ◽  
pp. 800-815 ◽  
Author(s):  
Chuanfu Zang ◽  
Junguo Liu ◽  
Dieter Gerten ◽  
Luguang Jiang

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.


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