Experiment on water surface evaporation rule in typical area of Haihe River basin

Water surface evaporation is an important indicator of hydrological cycle in specific watershed.Based on the principle of main component analysis and statistical correlation analysis method,the water surface evaporation data was analyzed in the central plain of Haihe River basin.The results showed that air temperature and wind speed were the dominated factors effecting water surface evaporation in this area.In monthly scale,there was significant positive correlation between daily mean water surface evaporation and air temperature,however in daily scale,the correlation between daily mean water surface evaporation and air temperature was not marked.In time scale of either month or day,there was significant positive correlations between water surface evaporation and wind speed.Meanwhile,the effect of wind speed on evaporation is depended on the initial value of water surface evaporation,the bigger the value is,the greater the effect of wind speed on evaporation is.At last,according to the diurnal evaporation and nightly evaporation data,a conclusion is drawn that there is no distinct difference in the proportions of diurnal evaporation(52.2%) and nightly evaporation(47.8%) in total daily evaporation.