Monitoring of Irrigation Schemes by Remote Sensing: Phenology versus Retrieval of Biophysical Variables
Monitoring of Irrigation Schemes by Remote Sensing: Phenology versus Retrieval of Biophysical Variables
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DOI：
10.3390/rs6065815
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Nadia Akdim;S. Alfieri;A. Habib;Abdeloihab Choukri;E. Cheruiyot;K. Labbassi;M. Menenti
中科院分区：
文献类型：
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作者：
Nadia Akdim;S. Alfieri;A. Habib;Abdeloihab Choukri;E. Cheruiyot;K. Labbassi;M. Menenti
作物需水量评估（CWR）对于水资源管理至关重要，特别是在干旱和半干旱地区，如摩洛哥西部的Doukkala地区，在这些地区，灌溉是最大的用水户。CWR的估算采用了简单的（半）经验方法：第一种方法是基于归一化植被指数（NDVI）与作物系数（Kc）的相关性，称为Kc-NDVI方法；第二种是直接应用Penman-Monteith方程的分析方法，基于反射率估算冠层生物物理变量，如地表反照率(r)、叶面积指数（LAI）和作物高度（hc）。利用2012/2013年农业季节的高空间分辨率RapidEye （REIS）、SPOT4 （HRVIR1）和Landsat 8 （OLI）影像序列，对作物蒸散等和生物物理变量的时空变化进行了评估。双作物系数法（Kcb）的验证表明，基于卫星的每日ETc估算值与地面ETc的估算值一致，即R2 = 0.75, RMSE = 0.79，而Kc-NDVI的R2 = 0.73, RMSE = 0.89，分别为分析方法。从需水量和分配水量之间的充分性角度对灌溉绩效进行评估，结果表明，整个地区的CWR远远大于分配的地表水，这种差异在生长季节开始时很小。在整个灌溉季节，地表水分配和灌溉需水量（IWR）之间的差异更小。地表水分配与净灌溉需水量（NIWR）相当接近。
The appraisal of crop water requirements (CWR) is crucial for the management of water resources, especially in arid and semi-arid regions where irrigation represents the largest consumer of water, such as the Doukkala area, western Morocco. Simple and (semi) empirical approaches have been applied to estimate CWR: the first one is called Kc-NDVI method, based on the correlation between the Normalized Difference Vegetation Index (NDVI) and the crop coefficient (Kc); the second one is the analytical approach based on the direct application of the Penman-Monteith equation with reflectance-based estimates of canopy biophysical variables, such as surface albedo (r), leaf area index (LAI) and crop height (hc). A time series of high spatial resolution RapidEye (REIS), SPOT4 (HRVIR1) and Landsat 8 (OLI) images acquired during the 2012/2013 agricultural season has been used to assess the spatial and temporal variability of crop evapotranspiration ETc and biophysical variables. The validation using the dual crop coefficient approach (Kcb) showed that the satellite-based estimates of daily ETc were in good agreement with ground-based ETc, i.e., R2 = 0.75 and RMSE = 0.79 versus R2 = 0.73 and RMSE = 0.89 for the Kc-NDVI, respective of the analytical approach. The assessment of irrigation performance in terms of adequacy between water requirements and allocations showed that CWR were much larger than allocated surface water for the entire area, with this difference being small at the beginning of the growing season. Even smaller differences were observed between surface water allocations and Irrigation Water Requirements (IWR) throughout the irrigation season. Finally, surface water allocations were rather close to Net Irrigation Water Requirements (NIWR).