Stochastic Network Design for River Networks

Stochastic network design techniques can be used effectively to solve a wide range of planning problems in ecological sustainability. We propose a novel approximate algorithm based on the sample average approximation (SAA) and mixed integer programming (MIP) to efficiently address the problem of using a limited budget to remove instream barriers, which prevent fish from accessing their natural habitat. In comparison with a dynamic programming (DP) benchmark algorithm, the advantage of our algorithm is the ability to produce a near optimal solution much faster, particularly when the budget is large and the DP based algorithm becomes intractable. Furthermore, while the DP based algorithm can only solve tree-structured stream networks, our algorithm is applicable to networks with a more general directed acyclic graph structure.