Distributed hydropower plants, characterized by fast start-stop capability and flexible operation, can effectively smooth the output fluctuations of wind and solar power, thereby enhancing the local consumption of renewable energy. However, the spatial mismatch between water-wind-solar resources and local loads necessitates coordinated optimization among multiple microgrids in different regions to further improve renewable energy utilization. This paper proposes a day-ahead and intra-day coordinative optimization strategy for multi-microgrids, considering the spatiotemporal correlation of distributed water-wind-solar generation. First, the spatiotemporal correlation of hydro, wind, and solar outputs is quantitatively evaluated based on hourly fluctuations, and a complementarity index is introduced to measure the degree of output complementarity. Second, a day-ahead coordinated optimization model is established, incorporating constraints on hydro-wind-solar complementarity, and the day-ahead power exchange plan among microgrids is determined using a decentralized coordinated optimization method. Third, an intra-day rolling correction model is formulated to complementarily accommodate renewables in real time and mitigate the impact of day-ahead forecasting errors. Finally, case studies validate the effectiveness of the proposed model, providing important technical support for the efficient utilization of renewable energy.