Water Balance to Recharge Calculation: Implications for Watershed Management Using Systems Dynamics Approach

Groundwater depletion in the face of growth is a well-known problem, particularly in those areas that have grown to become dependent on a declining resource. This research comprises a broad synthesis of existing water resources data, to understand the long-term implications of continued growth in water demand on groundwater dominant water resources, and to develop a tool for sustainable water management. The Palouse region of Washington and Idaho, USA. (approximately 60,000 people in a rural setting) is entirely dependent on groundwater from two basalt aquifers for potable water. Using the systems dynamics approach and a water balance that considered the entire hydrologic cycle, a hydrologic model of these aquifers was developed, tested and applied to simulate their behavior over a 150 year time period assuming the current infrastructure does not change. With 1% population growth and current water extraction rates, the results indicated the upper aquifer use may be sustainable, while the lower aquifer use is likely unsustainable in the long term. This study also shows that uncertainties in key aspects of the system create limitations to groundwater management.