2.2.4 Soil water storage variation in the rainfall process and growing season
In our study, we defined the absolute increase in SM (AIM , vol.%) at each measurement location as follows:
AIM = SMe - SMs (4)
where SMe (vol.%) and SMs(vol.%) are the SMs at the end time of the soil wetting process and at the start time of rainfall, respectively. Additionally, we calculated the soil water storage variation at the 100 cm soil depth (SWS0-1m , mm) after each rainfall process:
SWS0-1m =\(\sum_{i=1}^{5}{\text{AIM}_{i}\times D_{i}}\times 10\) (5)
where AIMi represents the absolute increase in SM at layer i. Di is the thickness of each depth interval. Then, the rainfall transformation rate (RTR , %) was calculated as follows:
RTR = SWS0-1m / R1-13 × 100% (6)
Where R1-13 is the total rainfall amount from the P1 to P13 rainfall processes. Additionally, we compared the averaged SM profile and total soil water storage variation (SWStotal ) for the 6 months among the study sites:
SWStotal=\(\sum_{i=1}^{5}{\text{AVM}_{i}\times D_{i}}\times 10\) (7)
where AVMi represents the absolute variation in SM across the entire monitoring period at layer i.