Analysis of water resources variability in the Yellow River of China during the last half century using historical data

Abstract

[1] The river discharges have decreased continuously during the last half century in the Yellow River, the second-largest river basin in China. In particular, a drying up of the main river along the lower reach has occurred since 1972, and the situation has become more and more serious during the 1990s. Using 50 years of meteorological data from 108 stations together with a collection of irrigation data, the long-term changes in the river discharge have been investigated with a view to identifying the reason for the drying up of the Yellow River. It was found that the annual precipitation generally decreased (À45.3 mm/50 yr) while the air temperature generally increased (+1.28°C/50 yr). From the 1960s to the 1970s the precipitation decreased by 29.6 mm/10 yr, the evaporation increased by 7 mm/10 yr (for pan evaporation), and the irrigation water usage increased by 10.5 mm/10 yr. As a consequence the drying up of the Yellow River has occurred since 1972. Irrigation was developed continuously in the 1980s, but the drying-up situation maintained at the same level as during the 1970s. The reason for this was the increase in precipitation (by 10.3 mm/10 yr) and the sharp decrease in the evaporation (by 133 mm/10 yr for pan evaporation). During the 1990s the irrigation was maintained at a level similar to that during the 1980s, but the drying-up situation was greatly aggravated. The reason for this was found to be a result of the decrease in precipitation (by 38.2 mm/10 yr) and the increase in evaporation (by 52 mm/10 yr for pan evaporation).

Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

“…Since the GBHM model has been successfully applied in the Yellow River (Yang et al, 2004;Cong et al, 2009) and the Yangtze River (Xu et al, 2007(Xu et al, , 2008, it is chosen as a bottom-up tool to simulate the hydrological processes and the evapotranspiration in the Luan River basin. As shown in Fig.…”

“…The bottom-up approach in hydrology generally uses "process based" or "physically based" distributed hydrological models, which can predict overall catchment's water balance components based on process simulation at smaller spatial and temporal scales. In order to understand the hydrological processes at a local scale and to analyze the temporal and spatial variability of water resources at a watershed scale, a number of distributed hydrological models have been developed: SHE model (Beven et al, 1980;Abbott et al, 1986;Bathurst et al, 1995;Refsgaard and Storm, 1995), IHDM model (Morris, 1980), SLURP model (Kite, 1995), SWAT model (Arnold et al, 1998), GBHM model (Yang et al, 1998(Yang et al, , 2002(Yang et al, , 2004Cong et al, 2009), WEP (Jia et al, 2001), VIC (Liang, 1994) etc. These and many other models have been developed and have been applied to interpret and predict the impacts of land-use change and climate variability.…”

Modeling the crop transpiration using an optimality-based approach

“…[34]. The missing meteorological data were gap-filled by the space interpolation of nearby meteorological stations, using an angular distance weighting method [2] .…”

“…Much of this is a reflection of poor water-use efficiency in irrigation practices, which has led to serious environmental problems in this region, such as river dry-up and groundwater overdrafts [2] . Water conservation, based on improving the water use efficiency in agriculture, is recognized as a feasible and promising way to solve this problem.…”

“…Taking the Yellow River basin (the drainage area is 753000 km 2 ) as an example, the mean annual precipitation is only 570 mm, whereas the mean annual runoff is 58 billion m 3 , with about 60% concentrated in the wet season. A further cause of water stress results from the ever-increasing and excessive water demand due to population growth, with concomitant demands for water for food production and industrial and municipal development [1] .…”