Comparing actual evapotranspiration estimations by METRIC to in-situ water balance measurements over an irrigated field in Turkey

Developing a New ANN Model to Estimate Daily Actual Evapotranspiration Using Limited Climatic Data and Remote Sensing Techniques for Sustainable Water Management

“…The research area that has gained popularity under the name Akarsu Irrigation District (hereafter, AID, A = 9495 ha ≈ 95 km 2 , Figure 1) in the studies carried out so far is located in the Lower Seyhan Plain (LSP) in the southeastern part of the Mediterranean region of Turkiye. The LSP shows typical characteristics of a deltaic plain with a rather flat topography (a slope of 1% or less) and a large-scale irrigation and drainage network [5,7]. The Mediterranean climate, characterized by warm and rainy in the winter season, whereas dry and hot in the summer season, prevails utterly in the LSP and, in turn, in the study area.…”

“…Therefore, accurately estimating ETa is of the utmost importance, as well as a critical issue in water-balance methods and agricultural water management at the irrigation scheme level. In this regard, the remote sensing (RS)-based surface energy balance models are one of the indirect methods to estimate spatially ETa over large-scale irrigation catchments with a high spatial and temporal resolution [7].…”

“…Several researchers have estimated ETa based on the RS-based surface energy balance models, such as the "Surface Energy Balance Algorithm for Land" (SEBAL) [8,9], "Mapping EvapoTranspiration at High Resolution and with Internalized Calibration", i.e., METRIC [10,11], and "Surface Energy Balance System" (SEBS) [12]. These models normally use Landsat satellite imagery or Moderate Resolution Imaging Spectroradiometer (MODIS) which include more required RS data alongside weather parameters [7,10], among others. However, as pointed out by Bachour et al [13], among others, RS technology has some limitations.…”

“…In addition, H calculation in the METRIC model is based on the anchoring pixels, i.e., hot and cold, so there are complexities involved in sensitivity selecting anchor pixels for improved estimation of H and LE fluxes [14]. Moreover, Landsat satellite data with a 30 m by 30 m spatial resolution are normally available every 16 days for satellite scenes [7]. As such, the methodology obtained by Allen et al [10] has been used to estimate ETa based on the METRIC model for each pixel during the satellite image overpass date.…”

“…The novelty of this study is to establish a new methodology for generating daily actual evapotranspiration (ETa) series based on the ANN model using some of the parameters of MODIS data coupled with availably daily moderate spatial and less input of weather variables as compared to the existing methods of ETa-based surface energy balance models estimation. Therefore, this study aims to use an artificial neural network (ANN) approach to estimate daily ETa values in large-scale irrigation catchments using two parameters of MODIS data, i.e., NDVI and LST, coupled with limited site-specific climatic variables at a large-scale irrigation scheme located in the Lower Seyhan Plain irrigation project area with >210,000 ha of land [7]. Furthermore, this paper is the first attempt to generate a new model using the ANN algorithm as an alternative to the existing methods of actual evapotranspiration estimation in a largescale irrigation district in the Eastern Mediterranean Region of Turkiye.…”