摘要
This paper quantified irrigation water consumption according to vegetation cover changes in the Nile Delta using remote sensing data. Soil in the Nile Delta is clay, so the common irrigation system is tradition surface irrigation with less than 60 % irrigation efficiency. Agricultural field consumes more than 80 % of water resources under surface irrigation. In the previous decades, vegetation cover decreased in old lands because of urbanization. Vegetation cover changing studied at years 2002, 2007 and 2013 using Landsat 7, Landsat 8 and SPOT 4 satellite data. Monthly MODIS evapotranspiration (ETa) data were used to estimate the quantity of water consumed by vegetation cover in the Nile Delta. MODIS products land surface temperature (LST) and Normalized Difference Vegetation Index (NDVI) were used to estimate water deficit index (WDI). The FAO-Penman-Monteith (FPM) model was used to calculate reference evapotranspiration (ETo). The crop coefficient (Kc) was estimated according to NDVI. WDI and potential crop evapotranspiration (ETc) were used to calculate actual crop evapotranspiration (ETa). A linear relation between ETa based on MODIS product and ETa based on estimated method was established with R 2 as high as 0.86. The Nile Delta agricultural water consumption changed as a result of vegetation cover changing. The vegetation cover changing were 691,870, 698,510 and 693,340 (ha), and it consumed 3.78*109, 4.21*109 and 3.78*109 (m3/year) at years 2002, 2007 and 2013 respectively according to MODIS ETa product. On the other hand, vegetation water consumption according to estimated ETa changed and the results were 4.7*109, 5.3*109 and 4.8*109 (m3/year) at years 2002, 2007 and 2013 respectively. Keywords Water deficit index (WDI) Normalized Difference Vegetation Index (NDVI) Vegetation cover Actual evapotranspiration (ETa) Landsat SPOT 4 and MODIS