A new method for estimating water requirement of desert riparian forests and its application in the lower reaches of Tarim River
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 αp and Kb,which reflect the influence of different vegetation types and plant physiology respectively.The values of ap· Kb in 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· Kb in 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 × 108 m3,with the tamarisk forests 4.499× 107 m3 and the P euphratica forests 5.855× 107 m3 in the existing vegetation distribution and coverage conditions.The average water requirement of the riparian forests per unite area was 139.6 mm,the value ofP 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× 107 m3) and in leaf senescence period (0.641 × 107 m3),however,it was 8.244 × 107 m3 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.
the lower reaches of Tarim Riverdesert riparian forestsPopulus euphraticatamariskvegetation water requirement
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维普
