This dissertation presents an integrated modelingsystem for multi-objective management oflife-supporting ecosystem services, which arefrequently impaired by a wide variety of natural andanthropogenic activities in watersheds. The researchwork specifically focuses on maintaining waterquality in streams and rivers through evolution ofagricultural landscapes. The development of thisintegrated modeling system involves coupling ofmulti-objective evolutionary algorithms withphysically-based, distributed hydrologic model. Aspart of this research effort, automatic calibrationtools for the distributed hydrologic model aredeveloped, and sensitivity and uncertainty associatedwith the hydrologic modeling are investigated. Inaddition, the use of artificial intelligencetechniques is explored to reduce the computationaldemand of the integrated modeling system.