Formulation of ranfall interception and transpiration processes and evaluation of the alleviation functions of forest for flood and drought

根据作者的雨水事故模型，中断率由雨水强度和潜在蒸发率的产品产生，然后在雨水事件结果中，中断损失和雨水损失之间的关系与恒定强度的雨水损失和雨水损失之间的关系：I = a ·h_I· R + c，在我是干扰损失的地方， R是雨水事件中的雨水，H_I潜在的蒸发率，以及a和c是协同和恒定的更远的地方，考虑到干扰-雨水关系的非线性特性，提出了一种统计表格。在日常传输被确认几乎可以通过使用大量观测数据的净辐射或潜在蒸发，但也是世界各地，转化和潜在蒸发之间关系的可能关联性被公式化为蒸汽压力失效和失效的一个功能。这与土壤湿度有关。可以使用每日雨水、径流、排水量、空气温度和相对湿度来识别的模型参数。Sarukawa和Tatsunokuchi，“森林土壤层的调节功能”，对于洪水和洪水可以被评估，这意味着使用雨水。runoff模型能够将溢出流组件从观察到的排泄物中分离出来，并使用对雨天和非雨天的每日传输速率估计，以及这些干扰、传输和森林土壤层的特性对于评估洪水和洪水的适应功能非常重要。

Based on the rainfall inception model by the authors, the interception rate is given by the product of rainfall intensity and potential evaporation rate, and then the relation between the interception loss and gross rainfall with a constant intensity for a rainfall event results in : I = a ・ h_I ・ R + c, where I is the interception loss , R the rainfall in a rainfall event, h_I the potential evaporation rate, and a and c are the coefficient and constant Furthermore, considering the nonlinear property of the interception-rainfall relation, a statistical form was proposed.After the daily transpiration has been confirmed to be almost proportional to net radiation or potential evaporation by using many observation data not only in Japan but also over the world, the proportional coefficient of the relation between transpiration and potential evaporation is formulated as a function of vapor pressure deficit and runoff depth that is related to soil moisture.The model parameters of interception evaporation and transpiration could be identified using several year data of daily rainfall, runoff discharge, air temperature and relative humidity for several watersheds of the Naka River , Hiji River, Sarukawa and Tatsunokuchi.The alleviation functions of forest soil layers for flood and drought can be evaluated by means of using a rainfall-runoff model capable for separating overland flow component from observed discharge and using the interception evaporation rate estimated on a rainy day and the daily transpiration rate estimated on a non-rainy day, and these property of interception, transpiration and forest soil layers are very important for evaluating the alleviation functions for flood and drought.