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Field experiments were conducted for two consecutive years (2013-2014 and 2014-2015) to study the effects of straw mulching on microclimate characteristics, energy flux, soil evaporation (E s) and evapotranspiration of winter wheat (Triticum aestivum L.) under adequate drip irrigation in North China Plain (NCP). The results revealed that straw mulching affected air temperature (T a) and dew point temperature (T d) near the soil surface but had little effect on relative humidity (RH) compared with non-mulched fields. Straw mulching increased the turbulent exchange coefficient (K), and K within the canopy was higher than that above the canopy. Straw mulching clearly increased the sensible heat flux (H) distribution in April-June, and part of the energy needed for evapotranspiration was provided by transfer from the warmer air aloft. There was a linear functional relationship between H and T a measured above and within the canopy. The straw mulching decreased E s but increased crop transpiration (T). Mulched treatment (TM) can decrease the total irrigation amount by about 7%-15% compared with the non-mulched treatment (TN). There were no significant differences (p>0.05) in cumulative crop evapotranspiration (ET c) between TM and TN treatments under adequate drip irrigation, and the use of mulch may need to be combined with an optimal deficit drip irrigation schedule for managing the declining water table in NCP.

Study on eco-environmental water requirement was of great significance in the planning and regulation of ecological water system, and the regional optimization of water resources. The river ecological water requirement is the core of the study. In this paper the meaning of eco-environmental water requirement and ecological status of lake are discussed. Based on the environmental flow of natural ecosystem, the water quantity model is built referring to the Montana law and year guarantee setting method; on basis of the analysis of the relationship among environmental flows of river requirements, the efficiency of water resource usage, the consumption coefficient, and the concentration of waste water elimination, the water quantity and water quality calculation method of the environmental flows river requirements in social and economic system is developed by reference to the controlled object inversion model (COIM). With the two models, the river ecological situation and the corresponding water demand were investigated. Results shows that, to achieve the goal which the river eco-environmental situation is safe for Zhengzhou city, the river ecological water requirement is 52.6, 57.9, 60.5, and 63.1 million m3 in 2005, 2010, 2015 and 2020, respectively; to achieve the target which the river's eco-environmental situation is healthy for Zhengzhou city, the river's ecological water requirement is 287, 300, 313 million m3 in 2010, 2015, and 2020, respectively. Considering the water resources condition in the planning years for Zhengzhou city, it is necessary to increase external water of 160, 124, 155 million m3 to get healthy river in 2010, 2015 and 2020, respectively.Keywords-river ecological water requirement; water quantity model; water quality model; water resource allocation