**10. Concluding remarks**

**Figure 16.** Temperature measurements coming from MSN.

48 Remote Sensing of Environment: Integrated Approaches

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**9. Smart management of evapotranspiration using 3G telephony**

As ETc is calculated each night based on that day's both weather readings and satellite images using the previously described method, the ETc results from these calculations are sent to farmers each morning giving them the water balance (Crop water require‐ ments) for their area for the irrigation season until the previous day. Using the existing method by combining satellite-derived crop coefficients and the 3G telephony with SMS delivery service, now offers the potential to provide low cost, site specific and personal‐ ised (for crop type and management conditions) irrigation water management informa‐ tion to individual famers across an irrigation region (Papadavid et al., 2012). Automatically triggered text messages can be generated by server-based software that combine data and formatting and then send the message out to mobile phones via an In‐ ternet cellular network gateway services. 3G phones can not only send SMS but can also As a key component in water resources management, it is essential to estimate evapo‐ transpiration accurately for water resources evaluation, drought monitoring and crop pro‐ duction simulation. Accurate estimates of ETc are needed for numerous agricultural and natural resource management procedures. However, this is difficult to achieve in practice because actual evapotranspiration cannot be measured directly and varies considerably in time and space.

Satellite images are collected across Mediterranean areas with frequencies ranging from dai‐ ly to monthly. The clear skies enable the gathering of good quality information and it is now possible to use satellite remote sensing to estimate the rates of ETc as shown in this chapter. Research has shown that there is a direct relationship between vegetation cover such as indi‐ ces and ETc. This means that the standard approach of using static crop water requirement look-up tables can be improved by using the more dynamic and customised information provided by satellite imagery. Satellite Remote sensing can assist in improving the estima‐ tion of ETc, and consequently water demand in cultivated areas for irrigation purposes and sustainable water resources management.

In this Chapter remotely sensed data along with meteorological data, modeling techni‐ ques and surface energy balance algorithms were combined. All these procedures com‐ bined can provide the spatial distribution of ETc in maps where users can derive the value of ETc for each crop in mm/day. The methodology followed can be applied for any place since it can be considered as 'algorithm adaptation' to local conditions. The parameters that are required in the empirical equations can be easily evaluated using re‐ mote sensing techniques and field spectroscopy. Modeling techniques (for example, re‐ gression analysis) are used to correlate and evaluate measured crop canopy factors, such as Leaf Are Index (LAI) and Crop Height (CH), to remotely sensed data uring the entire phenological cycle of each crop. The intention is to create semi-empirical models describ‐ ing LAI and CH, which are indispensible parameters in almost all ETc algorithms, using remotely sensed data. Using these models, users can avoid direct measurements of these parameters every time there is an application of an ETc algorithm.

The methodology as described in this chapter can support decision makers of Water Au‐ thorities. The methodology was applied for Landsats' images but it can easily be adapted for other satellite sensors. The use of field-spectroradiometer can facilitate the procedure since it provides a spectrum which can be adapted to satellites' bands by simple transformation, us‐ ing relative spectral response (RSR) filters of each satellite.
