Comparative effect of traditional and collaborative watershed management approaches on flood components

Identifying the critical areas of flood generation and determining the optimal measures for flood control and management (FCM) is one of the most important basics of watershed management. Therefore, the current study was carried out to prioritize sub-watersheds (SWs) based on flood generation using physical (Ph-MA), technical (Te-MA), comanagerial (Com-MA), and conjunct management approaches (Con-MA), as well as determining the quantitative effects of the proposed FCM measures in the Cheshmeh-Kileh Watershed, Iran. To prioritize SWs based on flood generation, geo-environmental criteria were used in Ph-MA, HEC-HMS software was used in Te-MA, and semi-structured interviews with local stakeholders were used in Com-MA. Finally, using the Condorcet algorithm based on game theory, SWs were prioritized in each approach. In the semi-structured interviews, stakeholders were asked to provide suggested measures for FCM. Finally, the effect of each measure on the flood components was quantified. Based on the results, the measure of 10% improvement of forest cover in the entire watershed from the category of Con-MA was selected as the optimal measure. In the return periods of 2, 5, 10, 20, 50, and 100 years, the effectiveness of this measure was 80.08%, 70.09%, 58.10%, 55.67%, 50.58%, and 43.62%, respectively. The influence of Con-MA based on non-structural and structural measures on reducing the components of peak flow and flood volume was more than other approaches. In general, it can be concluded that non-structural measures have more effect than structural measures in FCM in the study watershed. The methods and approaches used in this study can be directly used by local executive managers, decision-makers, and policymakers of watershed management and flood management activities.