## 3 Results
### Main Outcomes of the Top 20 Highly Cited Articles from Each Thematic Area
#### 3.2.2 Water  
The main focus of the 20 most highly cited articles in the thematic area of water (Table 4) is on groundwater potential mapping (10 articles) and on groundwater quality (7 articles Most of the EMMENA countries suffer from water scarcity because of the semi-arid and arid climate which, combined with the population growth and the growing demand for water, creates an urgent need to further explore the potential groundwater resources as an alternative [53; 54; 55; 56; 57; 58; 59; 60; 61; 62]. Existing groundwater resources in EMMENA countries (e.g., Iran, Egypt) have significantly declined, both in terms of quality and quantity [63; 64; 65; 60; 66; 67; 68]. Due to anthropogenic activities and mismanagement, groundwater bodies in the EMMENA region face many threats such as brackish water [63; 64; 65], poor water quality index [66], fluoride and nitrate contamination [67; 68], and high levels of total dissolved solids (TDS) [60]. According to [PERSON] et al. [54], due to the constant technical advancements in the field of groundwater potential mapping, there is no current agreement or reference on which approach is more suitable to predict high groundwater potential. However, all studies have in common the use of GIS and geostatistical methods, including different models and algorithms. The studies used various sources of data (e.g., ALOS PALSAR, ASTER, Landsat, ground-based) related to water quantity, land use/land cover, soil and geology, digital elevation, and morphological (e.g., slope, aspect) and hydrological data (e.g., river network). The choice of the input data depends on the site-specific characteristics of each region. All these studies highlighted that the results will be useful for better water and land management practices and policies. The remaining studies in the water thematic area focus on dam site selection [69], quantification of irrigation water [70], and on evapotranspiration estimates [71]. [PERSON] et al. [69] conducted a comparative analysis of the analytic hierarchy process (AHP) and the technique for order of preference by similarity to ideal solution (TOPSIS) for the optimum dam site selection in Sistan and Baluchestan Province (Iran), with the use of GIS. Their comparison was made based on geographic (geology, land use, sediment, erosion, slope, groundwater, and discharge) and water quality (soluble sodium percentage, total dissolved solids, potential of hydrogen, and electrical conductivity) criteria. The authors reported that the TOPSIS method is better suited to the problem of dam site selection for this study area. [PERSON] et al. [70] used the SM2 RAIN algorithm for the estimation of irrigation water use at the southern Urmia Lake catchment (Iran) based on satellite soil moisture observations obtained from Advanced Microwave Scanning Radiometer 2 (AMSR2). They found that the simulated quantities of the irrigation water were consistent with the observed data with an average R = 0.86 and RMSE = 12.89 mm/month. [PERSON] and [PERSON] [71] applied three different models (Surface Energy Balance Algorithm for Land (SEBAL), Mapping Evaportranspiration with Internalized Calibration (METRIC), Surface Energy Balance System (SEBS)) to estimate the amount of evapotranspiration over the region of the Amirkabir dam reservoir (Iran). Sixteen Landsat 5 and Landsat 8 satellite images from 2011 to 2017 were used in these models to compute evapotranspiration and the results were validated with ground truth pan evaporation data. The authors found good performance of the SEBS (R2: 0.62, RMSE: 0.93) and METRIC (R2: 0.57, RMSE: 2.02 mm) models. On the contrary, the SEBAL model showed poor performance (R2: 0.36, RMSE: 5.1 mm).