جستجوی مقالات مرتبط با کلیدواژه « metric » در نشریات گروه « آب و خاک »

Irregular development of agricultural areas, crops planting with high water need in the Urmia Lake Basin and also low irrigation efficiency have caused a significant reduction in the lake surface in recent years, so estimating water consumption in agriculture can be efficient in both accurate agriculture management and water resources management. In this context, by using METRIC algorithm and Landsat 8 and MODIS satellite images, the actual evapotranspiration have been estimated for a part of the Urmia Lake basin - Hasanlu dam downstream - in the year 2015 and 2016. Therefore, by considering the percipitation at Naghadeh station as the representative of percipitation in the study area, the valoum of irrigation water used in the agricultural area downstream of Hasanlu Dam was estimated. Then, the valoum of water allocated to this dam and estimation water volume was compared to the WaPOR product. The estimated values for Landsat 8 are 468 and 315 mm and for MODIS, 240 and 208 mm for 2015 and 2016, respectively. The estimated usage of the METRIC algorithm is significantly different from the allocated values and the WaPOR system. The estimated values are far higher than the ground statistics and the WaPOR system for nearly all months of the two years. The difference between METRIC and ground statistics and WaPOR product in the study area is calculated equal 23 and 26.6 million cubic meters, respectively.

In arid and semi-arid regions, water resource management and optimization of applying irrigation water are particularly important. For optimization of applying irrigation water, the estimated values of actual evapotranspiration are necessary for avoiding excessive or inadequate applying water. The estimation of actual crop evapotranspiration is not possible in large areas using the traditional methods. Hence, it is recommended to use remote sensing algorithms for these areas. In this research, actual evapotranspiration of wheat fields was estimated using METRIC algorithm (Mapping EvapoTranspiration at high Resolution with Internalized Calibration), using ground-based meteorological data and satellite images of Landsat8 at the Faculty of Agriculture, Shiraz University, in 2016-2018. In the process of METRIC execution, cold pixels are located in well-irrigated wheat fields where there is no water stress and maximum crop evapotranspiration occurred. The estimated maximum values of evapotranspiration using the METRIC algorithm were validated favorably using the obtained values by the AquaCrop model with NRMSE (Normalized Root Mean Square Errors) equal to 0.12. Finally, the values of water productivity (grain yield per unit volume of evapotranspiration) and irrigation efficiency were estimated using the values of predicted actual evapotranspiration using remote sensing technique. The values of measured irrigation water and produced wheat grain yield in 179 ha were estimated at 0.86 kg m-3 and 75%, respectively.