Abstract
Environmental flow requirement is estimated in global scale. The estimation is based on 0.5 degree grid river network dataset and river runoff calculation result provided by IIS, University of Tokyo. The whole world is divided into 4 groups by river runoff seasonality. For wet and seasonal dry region, flood pulses are also taken into account. Base flow is supposed to be 10% of mean monthly flow, except for wet months (>10 mm/month) which 30% of mean monthly flow is applied. Flushes are supposed to account for 1/3 of base flow. In extremely dry months (<1 mm/month), no environmental flow is required.
As a result, global averaged value turned out to be 88.17mm or 26% of total runoff.
