Capability of LISEM to estimate flood hydrographs in a watershed with predominance of long-duration rainfall events

Process-based hydrological models are of great importance to understand hydrological processes and support decision making. The LImburg Soil Erosion Model (LISEM) requires information on soil and land-use-related attributes to represent the transformation of rainfall into runoff for isolated rainfall events. This study aimed at evaluating LISEM for estimation of direct surface runoff (DSR) hydrographs in a watershed in Southern Brazil under the predominance of long-duration rainfall events, dominated by Argisols and with availability of a high-density rain gauge network. In addition, this study sought to: (i) suggest and evaluate a procedure for definition of initial soil moisture from antecedent 5-day rainfall depth; (ii) reduce the degree of subjectivity involved in the determination of some vegetation-related parameters by using remote sensing; and (iii) recommend a validation procedure. The saturated soil hydraulic conductivity and the Manning’s surface roughness coefficient were calibrated considering 11 rainfall–runoff events, whereas the validation was performed for 4 events from the average calibrated parameters. The Nash–Sutcliffe coefficient was used to assess both calibration and validation, resulting in average values of 0.64 and 0.58, respectively. It can be inferred from the results that the use of remote sensing to derive some LISEM parameters, along with the suggested schemes for definition of initial soil moisture and validation, was effective and provided sound results even for long-duration rainfall events. The results of this study and its methodological procedures can serve as a basis for other professionals who intend to use LISEM for both conducting detailed analyses of DSR hydrographs and supporting water resources management.