## 1 Introduction  
The irrigation of golf courses presents important difficulties due to the heterogeneous distribution of the terrain, the variations in soil composition at different areas, and high water consumption. Furthermore, some areas of the world may present added difficulties due to water scarcity, which may lead to the use of treated wastewater to irrigate the golf course [1]. Therefore, it is necessary to improve the efficiency of the irrigation to both reduce water consumption and increase the quality of the grass at the golf courses. Golf courses are comprised of differentiated areas such as the green, the fairway, or the rough. These areas have different grass lengths, and the activities performed in each area may lead to varied hazards such as uprooting [2]. The differences between these areas in vegetation, soil composition, and terrain lead to different irrigation needs. Nowadays, the popular irrigation methods of golf courses in Spain are comprised of sprinkler systems where the control options allow either the management of sprinkler lines as a group or, in some cases, the individualized management of the sprinklers. However, in order to adjust the amount of irrigation for each area or sprinkler, the soil moisture at each part of the golf course must be monitored. The soil moisture monitoring process can be performed with varied methodologies. The use of sensors is one of the most utilized forms of soil moisture monitoring [3]. The most utilized soil moisture sensors are capacitance sensors. Multiple capacitance soil moisture sensors are available in the market and have been tested for different types of soils to determine their calibration equations [4]. Solid-state resistance soil moisture sensors are also available, but they are less utilized [5]. These sensors are placed at multiple depths to assess the water content in the plant's root zone. The methodology of deploying soil multiple soil moisture sensors is widely used for precision agriculture and has been extended to other types of environments such as urban lawns and golf courses [6]. The staff of the golf course may perform measures by physically accessing the desired area. On the other hand, the sensors may be deployed on the golf courses to obtain soil moisture values periodically. However, this solution presents increased cost as the number of deployed sensors would determine the precision acquired for each area. As it was previously noted, the variations in the terrain lead to areas where the water is accumulated and areas with slopes where the water does not reach the desired depth. The differences in soil moisture content of these different types of areas are difficult to monitor with sensors because it would require a great number of them. Therefore, to obtain a very detailed soil moisture map, countless sensors should be deployed in addition to the network devices necessary to transmit the data to the database. As a result, remote sensing solutions were studied to reduce the cost and difficulties of the sensor deployments. One of the options is the use of drones that obtain images of the fields through devices such as multispectral cameras [7]. These images are then processed to obtain the soil moisture of the fields [8]. Hybrid systems that perform remote sensing through drones and use the drone as a mobile gateway to obtain the data from sensors deployed on the fields are a feasible option as well [9]. The other option is the use of satellites that provide useful data, such as images and microwave data from satellite sensors, and process it to obtain different metrics regarding the soil moisture content and the state of the plants [10]. The advantage of using satellite data is the obtention of a detailed map where the soil moisture is assessed for all the terrain without the difficulties due to the variations in the terrain faced by the sensor deployments. There are different types of available satellites to choose from, such as Sentinel or Landsat.