Droplet impact angle and shear stress are important indicators of surface runoff under sprinkler irrigation, and determining the distribution characteristics of these two indicators on sloping land is of great significance for preventing soil surface erosion. Therefore, three slopes (0, 10%, and 20%) and two directions (uphill and downhill) under a Rainbird LF1200 rotary sprinkler were considered in this study. The distribution of droplet impact angles and shear stresses along the radial direction were investigated under various working conditions. The correlations among the droplet impact angle, shear stress, and distance from the sprinkler were also analyzed. These results indicated that the closer to the sprinkler, the larger the droplet impact angle and the smaller the shear stress, and the two indicators gradually decreased and increased with the increase of distance from the sprinkler, respectively. Accordingly, there was a very high potential for soil surface runoff at the spray jet end. It was also observed that the uphill direction generally had a greater impact angle and less shear stress than flat land, while the downhill direction had exactly the opposite result. However, regardless of the direction, an increase in the slope could intensify its effect on the droplet shear stress and impact angle. Therefore, there is an urgent need to focus on the occurrence of surface runoff in soils with larger slopes. In addition, two radial droplet shear stress distribution models were developed, and it was verified that Model 2 had higher accuracy (MAE = 176.6 N m⁻², MBE = 32.8 N m⁻², and NRMSE = 14.4%) and could be used to predict the average droplet shear stresses at different slopes, directions, and distances from the sprinkler. This study contributes to the soil erosion prevention and the sprinkler irrigation system optimization on sloping land.

Knowledge of the response of growth parameters of almond (Badam) trees to different water supply conditions is important for Badam production. To identify growth parameters that are sensitive to water deficit in almond trees, field experiments were conducted during a median water year to monitor the major growth characteristics of almond trees under different irrigation conditions in Shache County, Xinjiang, China. A field (in-situ) monitoring system was also constructed using various sensors for the continuous and non-destructive monitoring of the growth parameters, such as soil water in the root zone, canopy temperature depression, trunk diameter, and fruit diameter of almond trees. The results confirmed the reliability of the monitoring system. Both canopy temperature depression and the diameter shrinkage of the trunk and fruit were significantly negatively correlated (r values ranging from −0.996 to −0.823) with the irrigation water quantity. This correlation was observed from the young fruit stage to the maturation stage of almond trees, under irrigation conditions representing 50–100% of crop evapotranspiration (ETc). These parameters were sensitive (|r| ≥ 0.778) to the water deficit status of almond trees from 14:00 to 18:00 in sunny weather. These results can provide both technical and theoretical support for real-time non-destructive assessment of the water deficit status of almond trees.