Renewable Resource Management with Stock Externalities: Coastal Aquifers and Submarine Groundwater Discharge

This paper develops a hydrologic-ecologic-economic model of groundwater use. Particularly, we model coastal groundwater management and its effects on submarine groundwater discharge, nearshore marine water quality, and marine biota. We show that incorporating the external effects on nearshore resources increases the optimal sustainable steady-state head level. Numerical simulations are illustrated using data from the Kuki’o region on the island of Hawaii. Two different approaches for incorporating the nearshore resource are examined. Including algae’s market value in the objective function results in only slightly lower rates of extraction. When a minimum constraint is placed on the stock of the keystone species, however, greater conservation may be indicated. The constraint also results in non-monotonic paths of water extraction, head level, and water price in the optimal solution.