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Comprehending the characteristics of infiltration is essential for conserving spring recharge areas, particularly on hillslopes of a Quaternary volcanic landscape. Quantitative investigations were carried out to identify soil physical properties and morphological features related to infiltration behavior. We used 15 transects with 70 sampling points in total to collect soil samples, observed morphological characteristics, and measured the infiltration. Data analysis employed statistical methods, including principal component analysis (PCA) and K-means cluster analysis. PCA revealed that infiltration was strongly correlated with slope, slope length, surface curvature, and slope position and that it was a function of soil physical properties, i.e., soil moisture, particle size distribution, and bulk density. The K-means cluster analysis classified the sampling points into four clusters that corresponded to three slope positions, namely upper slope, middle slope, and footslope. The high infiltration rate in the middle slope was caused by the relatively steep slope, sandy soil texture, low soil moisture, and low bulk density. On the contrary, the relatively flat slope, high clay content, high soil moisture, and high bulk density of the footslope created a low infiltration rate. According to these infiltration parameters, the preferred area for spring water catchment conservation was the middle slope. [ABSTRACT FROM AUTHOR]

Springs are a vital source of water supply in Quaternary volcanic environments, such as Rinjani Volcano on Lombok Island, and yet little is known about their emergence and recharge areas. Knowledge of spring recharge area can substantially support further spring analysis and management. This study was performed in two spring zones on the southern flank of Rinjani Volcano. It combined the available morphological, lithological, and hydrological datasets to build a conceptual model of the spring recharge areas. According to the analysis results, the conceptual model allowed to describe the flow medium, the aquifer type, and the characteristics of the flow system. The local morphology controlled the direction and gradient of groundwater flow to the springs. The analysis also revealed that the spring water in the study area was meteoric water, which mainly came from rainwater infiltration. Therefore, the boundaries of the spring recharge areas were represented by the morphological divides. [ABSTRACT FROM AUTHOR]