Evapotranspiration And Water Balance Of Subalpine Meadows In The Qilian Mountains

Water is the necessary to sustain life and health and water is an important part of earth's ecological system which can not be replaced,water is also an indispensable important resources for economic development.Water cycle is a contact of land surface processes and atmospheric,the reasonable use of water resources has important meaning,and rainfall and evapotranspiration process is the main parts among water cycle.Subalpine meadows is an important component,it can keep water conservation,reduce water loss,regulate climate,sequestrate carbon,promote the ecological balance and improve the level of local economic development,it is also important to the survival of the nomads resources.What is the water cycle characteristic of subalpine meadows in the Qilian Mountains? What is profit and loss of water of subalpine meadows in the Qilian Mountains? Based on these two questions,we choose Tianlaochi basin in the upstream of Heihe River as our study area,and use eddy covariance observation data,synchronous meteorological data and infiltration system data to study the evapotranspiration and water balance of subalpine meadows,and study the ecological system dynamic variation and distribution characteristics of water cycle elements.At the same time,we use five classic evapotranspiration simulation models to simulate the evapotranspiration.We are trying to reveal process of water balance of the subalpine meadow ecosystem in the study area for the evaluation of regional water balance condition.Main results were as follows:1)From change rule of precipitation,we can see that precipitation occurs mainly in the growing season,annual rainfall of 2014 is 714.25 mm/year,followed by 2015 and 2016,respectively 503.68 and 518.23 mm/year,and then the year 2018(433.53 mm/year),annual rainfall of 2017 is the least.2)Wind speed change trend increases firstly,then decreases,and then increases again in one year,the wind speed is small in the growing season and sharp in the non-growing season(winter).The variation trend of air temperature increases firstly and then decreases,which is the normal distribution.3)The change trend of relative humidity and atmospheric pressure is similar,increasing firstly and then decreasing,which is normal distribution.4)Evapotranspiration occurs mainly in the growing season and it is few in the non-growing season,evapotranspiration of July and August are mainly the most.The order of the annual evapotranspiration is 2015>2014>2016>2018>2017.5)Combined with meteorological data,we use the Penman,the FAO Penman,the FAO Penman Monteith,Priestley Taylor and FAO Radition five models to simulate the evapotranspiration.The FAO Radition model simulation values is much bigger than the actual evapotranspiration which is not suitable for simulate simulation of subalpine meadow in the study area,other four models simulation values are slightly bigger than actual evapotranspiration,and the other four models make adjustment coefficient,after adjustment,the four models can be used as simulation models to simulate the evapotranspiration of subalpine meadows in the study area.6)Soil infiltration capacity mainly concentrates in the growing season,which is from May to October,the change of soil infiltration is different in different years.There is no runoff of subalpine meadows in different slope surface in the study area7)?SWC changes greatly in the growing season and both positive and negative value occur.The value of?SWC is positive in 2014 and negative in other four years.As a whole,the value of?SWC is negative in the five years.8)The change trend of Soil moisture in different soil depth difference and?SWC are similar,but differ in the change of positive and negative value.