Understanding the groundwater recharge area and discharge processes in forested headwater catchments is crucially important for efficient evaluation of the ability of forested watersheds to decrease storm runoff and to increase baseflow discharge. This similarity evaluation of groundwater and spring water was conducted based on principal component analysis results obtained for dissolved ion concentrations to estimate the groundwater recharge area and discharge processes in forested headwater catchments underlain by sedimentary rock. Results show that upstream spring water in the catchment was significantly influenced by groundwater in headwater slopes. Downstream spring water was significantly influenced by groundwater on side slopes. A similar trend was also observed for an adjacent catchment, which implies the existence of multiple recharge areas in a headwater catchment. Vertical profiles of groundwater quality data further indicated the presence of local groundwater aquifers with ion concentrations similar to spring water. Results demonstrated the detection of the recharge areas of the respective springs in small headwater catchments. Based on the results, complicated groundwater discharge processes were discussed.

　The physical background of a storage-function model was estimated from numerical experiments using the one-dimensional vertical form of Richards equation. Relations between the outflow rate from a soil column and the total storage calculated during the recession stage from a storm event were approximated using a power law equation included in the model. The physical meaning of its exponent was specified from this approximation. Results suggest that the storage function model is not based on the downslope flow, but that it simply parameterizes the vertical unsaturated flow.

　Current status and issues on the management of agricultural ponds were investigated through a case study conducted in Tanbara, Saijo, Ehime. For the target area, 54 agricultural ponds were classified to six categories according to their present situation. Only about 20 % of agricultural ponds play a major role in agriculture, mainly because of abandonment of cultivation caused by depopulation and decreased water demand. Survey results confirmed maintenance and management as very difficult to achieve in 5-10 years. This study revealed clear differences among communities in terms of their management policies and sense of urgency toward disasters, although the survey covered 12 communities in the same town. Furthermore, survey results demonstrated the importance of considering community water use patterns and characteristics.

　Using in situ rainfall data of the Kitahiroshima-chou meteorological monitoring system, which has been functioning in the Chugoku-mountains area since 2008, this study was conducted to evaluate Kaiseki-uryou, which is the estimated precipitation value analyzed at radar-AMeDAS-in situ rainfall stations. The Kaiseki-uryou values at the Kitahiroshima-chou meteorological stations were greater than those of in situ station rainfall. The RMSE values of the hourly rainfall of Kaiseki-uryou of the Kitahiroshima-chou meteorological stations were 0.325 (mm/h) - 1.076 (mm/h), which implies high accuracy of hourly rainfall of Kaiseki-uryou. The values of RMSE and bias in 2018 were remarkably smaller than those in 2008, 2009, and 2010. This fact might result from increased amounts of rainfall and the commencement of observation of dual polarization radar of RCMPR in 2014. The rainfall values of Kitahiroshima-chou and in situ station increased with the height. These study results suggest that Kaiseki-uryou in the mountainous area is useful for predicting and sensing the occurrence of natural disasters because of the great amounts of rainfall in mountainous areas of the Chugoku district.