This study was conducted in the Hazu River basin which encounters pollution from non-point and point sources. This has led to eutrophication in the downstream Sengari Reservoir due to increased nutrient load mainly phosphorus which is the limiting nutrient for the production of algae. The aim of this study was to apply Soil Water Assessment Tool (SWAT) model to simulate discharge and total phosphorus (TP) load, quantifying phosphorus load from different land-use types and assess the effect of Onsite Wastewater Treatment System (OWTS) such as septic tanks on TP generated in the basin. The simulation period ranged from 2009 to 2015. Sequential Uncertainty Fitting Algorithm (SUFI-2) was used as the optimization tool for model calibration and validation. The model yielded satisfactory performances based on evaluation criteria for both discharge and TP simulation. Paddy fields had the highest TP load per unit area followed by residential areas and forests. From the scenario analysis where all septic tanks are replaced to rural sewage treatment plants, it was shown that the TP load at the basin outlet could be reduced by 617 kg/year. The model can be significant in quantification and management of non-point source and point-source phosphorus load flowing into the Sengari Reservoir to help in the preservation of water quality.

  The objective of this study was to evaluate the ability of a hand-held near-infrared (NIR) sensor and water absorption index to estimate the water content in intact eggplant leaves using a pot experiment. The NIR spectroscopy using a sin-gle wavelength (1940 nm) has already been used to estimate the water content of detached samples in a laboratory. However, it is not known whether this method can be used to estimate the water content of intact leaves of living plants. Therefore, we attempted to compare this method with destructive method by simulating drought stress and analyzing the relationship between leaf water content and soil matric potential. The water content of intact eggplant leaves was predict-ed with a calibration model using NIR reflectance. Both the measured and predicted water content of leaves decreased with decreasing soil matric potential. These results show that both destructive and NIR measurements can be used to estimate the water stress condition. Based on these findings, a hand-held NIR sensor is useful for estimating the water content of intact leaves of living plants.

  We investigated woody vegetation succession and the rate of topsoil development on shallow landslide scars on steep granite slopes in Kagoshima Prefecture, Japan. We used our results to predict the occurrence cycle of shallow landslides. For this study, nine shallow landslide scars of ≥40º were selected. The age of the scars ranged from 2 to 49 years. We installed 5 m × 5 m quadrats in the scars and conducted a field study. The results showed that woody vegetation in the quadrats had a smaller Fisher-Williams index of diversity and the rate of evergreen broad-leaved trees than a climax forest. Accordingly, the succession of woody vegetation in the quadrats was not at the level of a climax forest. The rate of topsoil development, based on the relationship between topsoil depth and the time since the occurrence of the shallow landslide, was 0.25 cm/year. Thus, the occurrence cycle of shallow landslides, based on the topsoil depth needed to generate a shallow landslide and the rate of topsoil development, ranged from 200 to 300 years (average 248 years). Our method was effective for predicting the occurrence of shallow landslides on steep granite slopes.