In Japan, debris disasters often took place caused by intense rainfall that intensity is more than 70～80 mm/hr. Other characteristics of these intense rainfalls are as follows; 1) affected areas was small within limited areas, and 2) continued period was very short such as 1～5 hours. From 2010 to 2015 years, many debris flows took place by these intense rainfalls and many lives were killed by these debris flows. In order to save human lives from these debris disasters, evacuation is very important in addition to construct check dams. Such evacuation may be achieved by the risk information about for hazardous site and time. For the purpose to mitigate debris disasters, three wears, hard (to construct disaster prevention structures), soft (to delineate hazard area and to push risk information) and human (to participate in evacuation training and to evacuate), are pointed as important measures.

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 In this article some fundamental issues in hydrologic modeling are discussed, and some emerging methods toward their solutions are presented. The issues discussed are i) the physically-based, distributed modeling of hydrologic processes in the face of climate change, ii) the coupled modeling of hydrologic and atmospheric processes in ungauged or sparsely-gauged watersheds, iii) modeling of hydrologic processes in the face of land heterogeneity, iv) estimation of the design flood for large structures under a changing future climate, and v) modeling uncertainty and long range dependence in hydrologic processes.

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 Large-scale flood damage caused by abnormal weather has occurred frequently in recent years. To mitigate such damage, some method is necessary to estimate the runoff and water level at any time and location. As a tool for doing so, the runoff calculation solver iRIC SRM, which is useful without complicated procedures, was developed. The SRM has a function for optimizing the model parameters for a given storage function method by inputting the rainfall and discharge. It also has a function for calculating the discharge by inputting the rainfall and model parameters. Regarding basins for which measured discharge data are not available, optimization of model parameters is not possible. Therefore, verification of the propriety of the calculated runoff is not possible. This study examined a method for estimating the necessary parameters by extracting the borders of drainage basins and the geological data of the land surface layer and by estimating the average rainfall for the basin, based on GIS data. The discharge calculated using the optimized parameters was compared to the discharge calculated using the geologically set parameters based on a multiple regression function in which the geological surface ratio was used as a variable. A comparison showed that runoff calculation with accuracy of the Nash coefficient of about 0.7 is possible using the geologically set parameters. Results show that runoff calculation can be accomplished easily at any location in Japan using the method presented in this report.

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 Radio-controlled electric-powered multicopters have become extremely useful as low-cost unmanned aerial vehicle (UAV) with a camera or sensor for proximity remote sensing. Crop growth management is an important use of remote sensing. Particularly for rice, a key crop in Japan, remote sensing is useful to support management for increased yields, optimum harvest time forecasting, and improved eating quality. Observation and prediction have been conducted for wide areas using aircraft and satellite remote sensing. We used a small UAV for growth monitoring of rice: details of growth were monitored using high temporal-spatial resolution images. Then we produced rice growth estimation models. Additionally, structure from motion and multi-view stereo (SfM-MVS) software was used to create ortho mosaic image and crop surface models (CSMs). We used it to monitor rice growth.Observation results revealed details of rice growth differences, which derive from cultivation conditions. Rice growth estimation models yielded good results. We infer that rice production management of techniques such as fertilization can be done using methods used for this study.

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 Numerous research projects examining urban surface flux have been conducted during the last two decades.Direct measurements of surface flux using the eddy covariance method facilitated the advancement of quantitative elucidation of the heat balance and CO₂ exchange between urban surfaces and the atmosphere. Results show that the heat balance in cities has unique features differing from those of bare ground, vegetation, and forests. This report addresses the following topics: selection of an appropriate observation site for the flux measurement over urban areas, recommendation of instrumentation height in the urban surface layer, and the “surface” concept in cities. Moreover, fundamental examination is made of urban heat balance and CO₂ flux in Tokyo, obtained mainly based on the author’s experiments. Some recent research trends of flux measurements over urban areas are described, with introduction of the “Urban Flux Network,” launched as a flux community network.

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 Applaud of Contribution to Hydrological Research Letters starts from 2015 to highly evaluate articles contributing to Hydrological Research Letters.

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 This report provides the current status of Hydrological Research Letters in 2015 based on the number of citations, the number of web page accesses, and the number of PDF downloads.

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