Watershed Conservation and Groundwater Management: An Integrated Perspective

US natural resource policy has explicitly acknowledged the hydrological connection between forest resources and water resources from the inception of the USDA Forest Service for the dual purpose of timber and watershed management,, but it is often overlooked in short run policy decisions. In Hawaii, these closely interconnected resources led to the establishment of the Ko`olau Mountains Conservation District in the early 1900s in order to improve water supplies. This early action on the part of the state has enabled today a healthy watershed. The health of the watershed, however, is now under threat from incremental ecosystem change, particularly in the form of invasive species (e.g. pigs (Sus scrofa) and weedy shrubs (Miconia calvescens)) that change the hydrological properties of the watershed to increase runoff and reduce aquifer recharge. Economic costs of reduced recharge in the face of rising water demand from a growing population are potentially large, with preliminary estimates suggesting the losses from reduced groundwater recharge in the Pearl Harbor aquifer have a present value of 1.4 to 2.6 billion dollars (Kaiser and Roumasset, 2002). To refine and improve these preliminary estimates we use spatial analysis of the water balance in the Ko`olaus to relate land use and land cover to recharge and we simultaneously explore the risk of degradation of the forest quality for recharge purposes through a survey of watershed experts. Using this information together with a dynamic model of water pricing as a function of aquifer recharge and use, we examine how much of an economic return (in present value) forest conservation expenditures may produce in the form of protecting aquifer recharge. In conjunction, we begin to examine additional integrated benefits of reducing runoff to near-shore resources by relating upland conservation to reef quality using monitoring data from the Hawaii Coral Reef Assessment and Monitoring Program. Kaiser and Roumasset (2002). "Valuation of Nature's Intermediate products: The Ko`olau Forest's Contribution to the Pearl Harbor Aquifer," Environment and Development Economics 7(4): 701-714.