In July 2018, a large number of landslide disasters occurred in the southwestern part of Ehime Prefecture, resulting in enormous damage and many casualties. Firstly, this paper summarized the characteristics of the rainfall event and the landslide disasters throughout the prefecture. The statistics revealed that the numberand the types of landslidesstrongly depended onthe geology. Secondly, the rainfall characteristics that caused landslides in the southwestern part of the prefecturewere analyzed byusing the coordinates of each slope failure and the localrainfall databased on the radar/raingauge-analyzed precipitationand XRAIN. The discriminant analysis of the relationship between the hourly rainfall and the soil water index showed a significant bias in the distribution of the rainfall indices in response to the occurrence of the slope failures, and that each rainfall index had a boundary value at which the number ofslopefailures increased rapidly. It was also revealed that the density of slope failure beyond the boundary value of each rainfall index clearly differs depending on the geology.

In-situ tracer test has been carried out to examine the appropriate procedure and evaluation methods in sandy gravel aquifer. It is essential to understand the hydrogeological characteristics of the aquifer by applying an iterative approach in order to conduct a tracer test. The specific gravity of groundwater in the vicinity of the test section could be different from that of pumped groundwater used as tracer solution. It is found that test results have been affected by this difference. It is necessary to conduct a preliminary tracer test to determine the optimal specific gravity of tracer solution with characteristics of the tested aquifer in order to obtain appropriate results.

Attenuation layers are considered to be installed beneath the excavated soils and rocks which contain geogenic contaminants, preventing contaminants from reaching the groundwater. In this study, breakthrough curves which are assumed to be obtained from column sorption tests are simulated using numerical analysis. Four different methods to obtain partition coefficients from breakthrough curves are discussed to investigate the evaluation of attenuation layer. The one-dimensional advection-dispersion analysis was conducted considering attenuation layer of 30 cm thickness using these obtained partition coefficients. Partition coefficients were determined within approximately 40% differences. The partition coefficient obtained using inverse analysis to fit numerical solution provided the lowest determination, and earlier breakthrough than the parameters determined by Freundlich parameters.

In order to investigate the preparation of calibration curve for the measurement of calcium carbonate content using a gasometric method, at first, we summarized the outline of various calcium carbonate content tests. Then we investigated the factor of fluence on the results of calcium carbonate content test. As the results, we could prepare the calibration curve under the following the test conditions instead of the test methods that was left to the judge of the tester.: (1) “small dolly” was used for shaking, (2) hydrochloric acid concentration was “3mol/L”, (3) added hydrochloric acid volume was “30mL”, (4) shake direction was “perpendicular to the diaphragm surface of the pressure gauge”, (5) shake speed was “3 times per second”, (6) shake time was “50 seconds”, (7) pressure measurment time was “60 seconds” after shaking starts.