Groundwater level
During the experiment, there are a few days are cloudy and rainy, and the PV pumping system could not work well. Therefore, data in days that PV pumping system worked regularly are stimulated in this paper. When the solar radiation is ample in a day, the well dried up in the afternoon due to the slow recharge rate of the well. Imagine that in each hour the flow is sustainable and steady. Data of four days are used to validate the model, 23rd. June, 29th. June, 1st. July and 2nd. July respectively.
The measured data and modeled data are shown in Fig. 4. The figure shows that groundwater level keeps decreasing during the pumping process. It would stop working if the groundwater level is lower than pump. The PRMSE. is as low as 1.40%, and Nash Sutcliffe. efficiency is 0.80, which indicates that the model of groundwater level is reliable.