CAJ | 학술논문

黑河中游绿洲集中了全流域95%的耕地，利用了全流域68%的水资源，绿洲农田蒸散是水资源的主要支出项。为了解绿洲生态系统不同景观单元的耗水规律，高效管理区域水资源，该文利用2011年6-8月的7期Landsat TM影像，结合地面气象、物候数据和土地覆盖类型，基于SEBAL-METRIC模型估算了夏季黑河中游样带尺度不同土地覆盖类型蒸散量，并利用涡度观测数据对卫星过境日模型估算的蒸散量进行验证，发现遥感估算值与实测值具有较好的一致性。结果表明：由于土地覆盖类型和灌溉的差异，黑河中游样带尺度内蒸散量空间变化较大，6-8月农田平均总蒸散量是340 mm，林地是328 mm，草地的平均值是214 mm，荒漠区只有97 mm；夏季不同土地覆盖类型蒸散量均保持在较高水平，农田日蒸散量在6月底达到最大值，荒漠日蒸散量于7月中旬达到最大值，草地6月和7月平均日蒸散值较8月大，林地蒸散量月际变化较小。另外，荒漠与绿洲土壤类型差异较大，在荒漠区与绿洲区分别选取“热点”可有效提高模型估算精度。研究对于干旱半干旱区域水资源利用与管理有参考价值。
흑하중유록주집중료전류역95%적경지，이용료전류역68%적수자원，록주농전증산시수자원적주요지출항。위료해록주생태계통불동경관단원적모수규률，고효관리구역수자원，해문이용2011년6-8월적7기Landsat TM영상，결합지면기상、물후수거화토지복개류형，기우SEBAL-METRIC모형고산료하계흑하중유양대척도불동토지복개류형증산량，병이용와도관측수거대위성과경일모형고산적증산량진행험증，발현요감고산치여실측치구유교호적일치성。결과표명：유우토지복개류형화관개적차이，흑하중유양대척도내증산량공간변화교대，6-8월농전평균총증산량시340 mm，임지시328 mm，초지적평균치시214 mm，황막구지유97 mm；하계불동토지복개류형증산량균보지재교고수평，농전일증산량재6월저체도최대치，황막일증산량우7월중순체도최대치，초지6월화7월평균일증산치교8월대，임지증산량월제변화교소。령외，황막여록주토양류형차이교대，재황막구여록주구분별선취“열점”가유효제고모형고산정도。연구대우간한반간한구역수자원이용여관리유삼고개치。
The Heihe River Basin is the second largest inland river basin in the arid area of Northwestern China, and the oasis in its middle reach has 95% of the total arable land and uses 68%of the total water resources in whole basin. Because evapotranspiration (ET) from the oasis is one of the most important components in water consumption, it is very important to study the ET in various land uses for water resource management and allocation in whole basin. The objective of this study was to estimate ET values for different land uses at a spatial scale of 16 km × 20 km in the middle reach oasis of Heihe river basin using remote sensing method. The main challenge of this study was to find a method to extrapolate instant ET values, which were estimated from the remote images, to monthly or seasonal actual ET (AET) values. In this study, a representative transect was selected to analyze the spatial distribution and temporal change of ET for different land cover types in the middle reach of the Heihe river basin. Seven qualified Landsat TM images for the studied transect were obtained during June to August in 2011. The surface energy balance model of SEBAL-METRIC and meteorological data were used to calculate the transient ET and daily reference ET (ET0) when the Landsat passed the studied region. The ratio of instant ET/ET0 was extrapolated to daily value using a sinusoidal function, while the daily ratio of ET/ET0 was assumed to be constant for a short period of 5 to 24 days for estimating a cumulative ET for different land uses in the transect. The comparison of daily ET values obtained by an eddy covariance system and remote sensing method showed the SEBAL-METRIC model combined with Landsat TM image and ET0 can provide reliable estimation of ET for different land cover types with an average relative error of 10.2%. The ET values varied from different land cover types and different irrigation schedules, with the high ET values in water area, farmland and forest, in contrast to low ET values in grassland and desert. The average ET values for farmland and forest during the studied period were 340 mm and 328 mm, respectively. They were higher than that for grassland of 214 mm and desert of 97 mm. ET variation for farmland was closely related to crop growth, and the highest ET value appeared on June 27th when both maize and wheat needed a large amount of water. By contrast, the ET values for desert were greatly influenced by the occurrence of precipitation events, as the vegetation was sparse and the most important limitation factor for evapotranspiration in this area was the low soil water content. Besides, the ET values of forest did not change significantly (p>0.05) during this period, with approximately 4 mm/d in sunny days. This study showed that METRIC hold substantial promise to estimate ET values for different land cover types in the middle reach of the Heihe river basin throughout plant growing periods. Besides, the accuracy of ET estimation in the oasis of Heihe middle reach could be improved when the hot extreme pixels in arable land and desert were respectively chosen due to different soil types.