## 3 Results and Discussion  
### The Spatiotemporal Changes in Climate Variables (2001-2020)  
Weather conditions play a crucial role in managing water resources, with their fluctuations being observed over the period from 2001 to 2020 (Figure 3). The range of temperatures varied significantly during this time, with the lowest recorded for maximum temperature (Tmax) in 2014 at 36.83 \({}^{\circ}\)C and the highest in 2015 at 38.40 \({}^{\circ}\)C, averaging at 37.53 \({}^{\circ}\)C. Similarly, the lowest and highest values for minimum temperature (Tmin) were noted in 2018 (25.06 \({}^{\circ}\)C) and 2010 (26.0 \({}^{\circ}\)C), respectively, with an average of 25.49 \({}^{\circ}\)C (Figure 3A).  
The maximum relative humidity (RH) valued ranged from 40.85% in 2015 to 50.52%, which was recorded in 2019, with an average value over the time period equal to 46.03%. While the trend of wind speed (WS) values has the maximum value in 2017 of 5.02 ms\({}^{-1}\), the lowest value of wind speed was recorded in 2007 with 4.39 m s\({}^{-1}\) having a mean value of 4.66 m s\({}^{-1}\) (Figure 3B).  
The highest values of effective precipitation were observed in 2007 at 120.45 mm and in 2019 (75.04 mm), while the lowest value was recorded in 2015 at 23.94, with an average value equal to 48.0 mm, where the rainfall season extends from May to October, while the sugarcane growing season extends from May to November, and there was no rainfall in November recorded through the time series 2001-2020. In the same context, the lowest and highest ETo values were reported in 2007 with 5.01 mm d\({}^{-1}\) and in 2017 with 6.16 mm d\({}^{-1}\), having an average of 5.60 mm d\({}^{-1}\) (Figure 3C).  
The variations in ETc, yield, and GWFP values related to sugarcane growing seasons over the time series from 2001 to 2020 were highly related to the climate changes which have a great impact on climatic parameters and so on crop evapotranspiration, yield, and subsequently, the GWFP, where the maximum ETc was achieved in 2017 at 64.72 m\({}^{3}\) ha\({}^{-1}\) followed by 60.11 m\({}^{3}\) ha\({}^{-1}\) in 2015, while the lowest value was recorded in 2007 at 47.30 m\({}^{3}\) ha\({}^{-1}\) with a mean value equal to 55.36 m\({}^{3}\) ha\({}^{-1}\). Consequently, the maximum yield was achieved in 2008 at 48.40 ton ha\({}^{-1}\) m\({}^{3}\) ha\({}^{-1}\) followed by 48.20 ton ha\({}^{-1}\) in 2004, while the lowest value was recorded in 2016 at 34.60 ton ha\({}^{-1}\) with a mean value equal to 42.71 ton ha\({}^{-1}\). Accordingly, the GWFP had the maximum in 2007 of 25.46 m\({}^{3}\) ton\({}^{-1}\) m\({}^{3}\) ha\({}^{-1}\) followed by 19.19 m\({}^{3}\) ton\({}^{-1}\) in 2019, while the lowest value was recorded in 2017 at 5.90 m\({}^{3}\) ton\({}^{-1}\) with a mean value equal to 11.27 m\({}^{3}\) ton\({}^{-1}\) (Figure 4).  
\begin{table}
\begin{tabular}{c c c c} \hline
**NSE** & **Classifications** & **SI** & **Classifications** \\ \hline NSE = 1 & Perfect & SI \(<\) 0.1 & Excellent \\ NSE \(>\) 0.75 & very good & 0.1 \(<\) SI \(<\) 0.2 & Good \\
0.74 \(>\) NSE \(>\) 0.64 & Good & 0.2 \(<\) SI \(<\) 0.3 & Fair \\
0.64 \(>\) NSE \(>\) 0.5 & Satisfactory & SI \(>\) 0.3 & Poor \\ NSE \(<\) 0.5 & Unsatisfactory & & \\ \hline \end{tabular}
\end{table}
Table 3: The range of NSE and SI.  
Figure 3: The climatic parameters and reference evapotranspiration from 2001 to 2020 in the study area are (**A**) Tmax and Tmin, (**B**) relative humidity and wind speed, and (**C**) effective precipitation and reference evapotranspiration.