石羊河流域天然植被生态需水量估算及预测

运用ARCGIS9.0对2008年石羊河流域遥感影像土地利用覆盖图统计分析,得出各种天然植被的覆盖状况,利用潜水蒸发法对研究区内各县区的天然植被生态需水量进行了估算,并根据石羊河重点治理规划对未来的天然植被生态需水量进行了预测分析。结果表明,石羊河流域现状天然植被最低生态需水量为1.9536亿m3,最高生态需水量为6.3425亿m3,其中,永昌县的天然植被生态需水量为0.6855～2.5141亿m3,凉州区天然植被生态需水量为0.4693～1.3135亿m3,古浪县天然植被生态需水量为0.4152～1.2391亿m3,民勤县天然植被生态需水量为0.3743～1.2435亿m3,金川区的天然植被生态需水量为0.0093～0.0323亿m3;2015年石羊河流域天然植被生态需水量预测为2.1495～6.9811亿m3;2020年石羊河流域天然植被生态需水量预测为2.3644～7.6792亿m3。

Evaluation and Prediction of Ecological Water Requirement of Natural Vegetation in Shiyang River Basin

Data of natural vegetation coverage in Shiyang River basin in 2008 was obtained by statistical analysis on remote sensing imageries using ArcGIS 9.0 software,then the ecological water requirement(EWR) of natural vegetation in each county in the study area was evaluated by phreatic evaporation method,and the prediction of the EWR in the future was made on the basis of Key Management Program of Shiyang River basin.Results showed that the minimum EWR of natural vegetation was 195.36 million m3 presently in Shiyang River basin,and the maximum one was 634.25 million m3.EWR of natural vegetation ranged from 68.55 to 251.41 million m3 in Yongchang County,from 46.93 to 131.35 million m3 in Liangzhou District,from 41.52 to 123.91 million m3 in Gulang County,from 37.43 to 123.45 million m3 in Minqin County and from 0.93 to 3.23 million m3 in Jinchuan District.It was predicted that the lowest EWR of natural vegetation and the highest one would be 214.95 and 698.11 million m3 respectively in Shiyang River basin in 2015,and the lowest one and the highest one would be 236.44 and 767.92 million m3 respectively in 2020.