Effects of Climatic Change on Evapotranspiration in Zhalong Wetland,Northeast China

Evapotranspiration (ET) process of plants is controlled by several factors. Besides the physiological factors of plants, height, density, LAI (leaf area index), etc., the change of meteorological factors, such as radiation, temperature, wind and precipitation, can influence ET process evidently, thus remodeling the spatial and temporal distribution of ET. In order to illuminate the effects of meteorological factors on wetland ET, the ET of Zhalong Wetland was calculated from 1961 to 2000, the statistical relationships (models) between ET and maximum temperature (Tmax), minimum temperature (Tmin), precipitation (P) and wind speed at 2m height (U2) were established, and the sensitivity analysis of the variables in the model was performed. The results show that Tmax and Tmin are two dominating factors that influence ET markedly, and the difference of rising rate between Tmax and Tmin determines the change trend of ET. With the climatic scenarios of four General Circulation Models (GCMs), the ET from 2001 to 2060 was predicted by the statistical model. Compared to the period of 1961-2000, the water consumption by ET will increase greatly in the future. According to the scenarios, the rise of Tmax (about 1.5℃ to 3.3℃) and Tmin (about 1.7℃ to 3.5℃) will cause an additional water con- sumption of 14.0%-17.8% for reed swamp. The ecological water demand in Zhalong Wetland will become more severe.

Heavy Metal Emission Characteristics of Urban Road Runoff

Pavement runoff sampling points were set up on the main roads of Chengdu city.Six rainfall-runoff events from July to September in 2017 were sampled by synchronous observation of rainfall,runoff and pollution.The concentration changes of copper,lead,zinc,chromium and cadmium in the runoff process were monitored,and the pollution emission regularity and initial scouring effect were studied.The results show that the emission regularity of pavement runoff pollution is closely related to rainfall characteristics and pollutant occurrence,and the concentration of dissolved heavy metals reaches its peak at the initial stage of runoff.The peak time of particulate heavy metal concentration lagged slightly behind that of rainfall intensity.There is a big difference between the strength of initial scouring degree and dissolved heavy metals the stronger the initial scouring degree of total heavy metals,the weaker the dissolved heavy metals.Reducing pavement runoff in the early stage of rainfall is an effective means to control heavy metal pollution.

Partitioning of vertical water loss in reed swamp wetlands:Theory,research and application

This paper proposes an on-site monitoring system for evaporation(Ew) and evapotranspiration(ET) in wetlands called the Compensation Evapotranspiration Observation System.Considering the characteristics of wetlands environment and emergent plants,the vertical flux of water loss in wetlands can be separated using the system based on compensation principle.A comparison research on water loss through ET in reed(Phragmites australis) stands between Zhalong wetland and Baiyangdian wetland was carried out in 2004-2009.In Baiyangdian wetland,the ET rates from three reed stands with different leaf area indexes were measured.The results show that annual ET in Zhalong wetland was 739-886 mm during study period.Comparatively,annual ET of the three reed stands in Baiyangdian wetland was 970-1117 mm,1261-1452 mm and 1759-2035 mm,respectively.The ET rates in Baiyangdian were stronger than in Zhalong because of the effects of geography and climate characteristics.Moreover,seasonal dynamic changes and influence factors of transpiration-acting factor from the two wetlands were also analyzed.It is indicated that the transpiration-acting factor can be affected by geographic location,aboveground biomass,plant growth and climate conditions.