Application of a physically based soil erosion model, GUEST, in the absence of data on runoff rates - I. Theory and methodology

When physically based erosion models such as GUEST are used to determine so il erodibility parameters or to predict the rate of soil loss, data on runo ff rates, as distinct from event runoff amount, are often needed. Data on r unoff rates, however, are not widely available. This paper describes method s that can be used to overcome this lack of data on runoff rates. These met hods require only rainfall rates and runoff amounts, which are usually avai lable for sites set up primarily to test and validate the USLE technology. In addition, the paper summarises the data requirements for the erosion mod el GUEST and application procedures. In the accompanying paper, these metho ds are applied to 4 experimental sites in the ASIALAND Network.