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There is an obvious gap between China's current irrigation water use efficiency and the world's advanced level for that of China is only 0.50, whereas that of world's advanced level reaches 0.7-0.8. Therefore, saving water resources, improving agricultural irrigation water efficiency, and ensuring the irrigation efficiency will be a long-term strategic task in the future of China. The purpose of this paper was to make a comprehensive evaluation for water use efficiency of Yellow River irrigation area based on flow-tracing and multiple weights method. In order to make a good comprehensive evaluation for water using efficiency, an open index-evaluation system including 19 deterministic index and 3 sub-systems based on irrigation flow-tracing method. Then, the improved fuzzy evaluation model was constructed based on multiple layer-weight determination method by making use of multi-objective and multi-level system. In the first layer (input layer), the index weight was confirmed by calculating entropy-weight-vector, and in the second layer (criterion layer), the sub-system weight was confirmed by the entropy-weight-vector method, equal-weight method and experience weight method, respectively for multi-layer weights. Finally, obtaining data and comparing different weights from the evaluation results was carried out by the fuzzy evaluation model. The paper took Sanyizhai Irrigation Area in lower reaches of the Yellow River as a case study. Sanyizhai Irrigation Area is located in the eastern plain of Henan Province (34°52N, 144°44E), north of the Yellow River. Sanyizhai Irrigation Area was founded in 1958, and it involves 18 counties scattered in Kaifeng, Shangqiu and Heze in Henan Province, and Shandong Provinces as well. Up to now, the water-diverting capacity of Sanyizhai Irrigation Area is about 150 m3/s, and irrigation area covers 9 counties(districts) mainly in the eastern part of Henan province, that is: Kaifeng, Lankao and Qi counties of Kaifeng City, Minquan County, Ningling County, Suiyang District, Liangyuan District, Sui County and Yucheng County of Shangqiu City respectively. The total land area of Sanyizhai Irrigation Area reaches 4 344.2 km2 and the total cultivated area is 2 701.42 km2. The paper took 10 years data from 2005 to 2014 of Sanyizhai Irrigation Area as a case study to make a comprehensive evaluation for water use efficiency. The 3 kinds of weight was used for the calculation. The results showed that: the first entropy-weight-vector weight was 0.307, 0.348, 0.345, the second equal-weight was 0.333, 0.333, 0.334, and the third subjective weight was 0.400, 0.200, 0.400. The evaluation result presented a general identical trend and showed that weight-influence was very limited for the evaluation result. According to the evaluation result, the irrigation water effect in 2013 was optimal among 10 years with average value 0.993 by comprehensive evaluation. Meanwhile, this evaluation results were in conformity with the actual situation of Sanyizhai Irrigation Area. In 2013 the rainfall and groundwater is relatively small, whereas the practical diverted irrigation intake and irrigation area has kept high level, which has ensured irrigation effect of and crop-harvest. According to the evaluation value of second layer, the dynamic variation process about engineering factors and management factors could be seen clearly, which showed that it kept a low-level development before 2007 and entered into a higher level development after 2009, so it could help us find the existing problems in irrigation process and provides data basis and technical support for the scientific planning and sustainable development of Yellow River Irrigation Area. [ABSTRACT FROM AUTHOR]

Summary: In this paper, the trends of the annual streamflow and precipitation and cross correlations between them were analyzed in nine large river basins of China during 1956–2005. The results indicate that: (1) the annual mean streamflow decreases in arid and semi-arid regions of north China; however, increasing trends occur in south and Southwest China; (2) the annual streamflow and precipitation exhibit reasonable correlation in nine large river basins except those located in inland areas. The annual streamflow over most areas of China is fed by precipitation; however, the decline in streamflow is faster than the decreases of precipitation since 1970s in the arid and semi-arid regions of north China. The relationship between the annual precipitation and streamflow presents a non-stationary state in north China. This non-stationary relationship is strongly influenced by both human activities and precipitation changes; (3) a significant increase of water use might be the major factor responsible for the steeper decline in streamflow than in precipitation in Haihe River, Yellow River and Songliao River basins in north China. In inland river areas, increase of water use and actual evapotranspiration might result in decline in streamflow although precipitation has an increase tendency. This paper sheds light on the non-stationary relationship between annual precipitation and streamflow and possible underlying causes, which will be helpful for a better understanding of the changes of precipitation and streamflow in China at large scale and in other regions of the world. [Copyright &y& Elsevier]

Abstract: Long-term changes to the Yellow River delta in China have received considerable attention not only because of the growing economic importance of the delta region but also because they provide a clear example of the dominant role played by anthropogenic effects upon a large dynamic river delta. This paper presents a detailed study on the morphological consequences of reduction in river sediment load and influence of human activities based on sediment load data at three gauging stations in the upper, middle and lower reaches of the Yellow River basin from 1950 to 2007. The results indicate that sediment loads at all three gauging stations display a gradually decreasing trend over the past 58years. The primary reason for this decrease is shown to be due to various human activities, including the construction of Longyangxia and Liujiaxia reservoirs in the upper reaches, water–soil conservation practices and the commissioning of Sanmenxia and Xiaolangdi reservoirs in the middle reaches. It is estimated that water–soil conservation practices which are a major factor to the decrease of sediment load at Huayuankou gauging station account for 40% of the total amount of reduction, sediment trapping by Sanmenxia and Xiaolangdi reservoirs account for 30% of the total amount of reduction and the 10% decrease is caused by human activities in the upper reaches. The remaining 20% decrease is attributed to precipitation decrease. The reduction of sediment load has directly impacted on the lower Yellow River and the delta region, causing alternate changes between siltation and scouring in the lower river channel along with an increased rate of erosion over the whole Yellow River delta. [Copyright &y& Elsevier]

Abstract: The purpose of the paper is to extract and make the best use of rainfall information contained in the Chinese historical archives of Qing Dynasty, and reconstruct the precipitation series during 1736–1911. The study followed the Yu-Fen-Cun (rainfall infiltration depth) observation method in Qing Dynasty, to conduct soil infiltration experiment under the natural rainfall conditions during 2004–2006. The related parameters, such as precipitation, intensity, initial soil moisture content and infiltration depth have been measured at 10 stations (east of 105°E, 30°–40°N) with representative climatic conditions and soil physical texture in the middle and lower reaches of the Yellow River and Yangtze-Huaihe River Valley. The statistical results indicate that precipitation is the primary influencing factor to infiltration depth and is positively correlated with the infiltration depth. Additionally, the effects of every factor on infiltration depth are significantly different between the middle and lower reaches of the Yellow River and Yangtze-Huaihe River Valley. Finally, the relationship equations of precipitation and infiltration depth are established for each site, most of which can pass over 60% of the variance explanations and provide quantitative models to reconstruct the precipitation series using Yu-Fen-Cun records in Qing Dynasty. [Copyright &y& Elsevier]