一个新的荒漠河岸林需水量估算方法及其在塔里木河下游的应用

A new method for estimating water requirement of desert riparian forests and its application in the lower reaches of Tarim River

通过检验一个使用气象数据和植被参数实现逐日计算不同植物种需水量,并能反映其空间变化的荒漠河岸林需水量估算模型,并基于2013年的气象和遥感数据,分析了塔里木河下游荒漠河岸林需水量的时空动态特征。结果表明:在现有植被分布和盖度下,塔里木河下游河岸林年总需水量为1.035×10~8m^3,其中柽柳群落需水4.499×10~7m^3,胡杨群落需水5.855×10~7m^3;单位面积河岸林平均需水量为139.6 mm,胡杨群落需水量比柽柳群落多63.0 mm;河岸林展叶期和落叶期需水量较少,而生长盛期每天大约需水75×10~4m^3。模型强调植被空间分布对需水量的影响,能够动态描述需水量的时空变化,为内陆河水资源管理提供更丰富的信息和准确的结果。

In this paper,an estimation model for water requirement of desert riparian forests was proposed. The model could achieve the target of daily calculation and reflect spatial variation of water requirement for different vegetation species by using normal meteorological data and vegetation parameters. Then,spatial and temporal distribution of water requirement of riparian forests in the lower reaches of Tarim River was analyzed using this model. The most important part of the model is αpand Kb,which reflect the influence of different vegetation types and plant physiology respectively. The values of αp·Kbin different growing periods in a vibrant growing Tamarix spp.stand and a Populus euphratica Oliv stand were acquired by fitting the data of measured ET and calculated ET0 and fitting the data of ET/ET0 and inversed leaf area index（LAI）. Then,based on the meteorological data and remote sensing images of 2013 in the lower reaches of Tarim River,the spatio-temporal dynamics of riparian forests water requirement in the lower reaches of Tarim River was analyzed. Results showed as follows：（1）values of ET/ET0 had a good correlation with the LAI in the germination and leaf expansion period and the leaf senescence period,and ET had a good correlation with ET0 in the vibrant growing season,which indicated that the values of αp·Kbin the three different growing stages for tamarisk stand and P. euphratica stand were reasonable;（2）model checking based on observed data from the tamarisk stand indicated that this model could estimate water requirement and its daily dynamics of tamarisk stand with relatively high accuracy（NSE=0.780,RMSD=0.677）;（3）the annual total water requirement of the riparian forests was 1.035×108m3,with the tamarisk forests4.499×107m3and the P. euphratica forests 5.855×107m3in the existing vegetation distribution and coverage conditions. The average water requirement of the riparian forests per unite area was 139.6 mm,the value of P. euphratica forests was 63 mm more than tamarisk forests;（4）the whole riparian forests water requirement was relatively little in leaf expansion period（1.469×107m3）and in leaf senescence period（0.641×107m3）,however,it was 8.244× 107m3 in vibrant growing season. The distribution of water requirement was connected with vegetation types and its coverage,the denser of the vegetation the more water it required. The model presented in this paper emphasized the impact of spatial variability of distribution of the desert riparian forests to water requirement,described time-space transformation and enhanced the estimation accuracy of water requirement and could provide more information and more accurate results for inland river resources management.