Mine reclamation and surface water balances : an ecohydrologic classification system for mine-affected watersheds

Understanding reclamation effects on surface water balances in mine-affected watersheds is critical to both prediction of, and design for, water movement through the post-closure landscape, and for development of appropriate reclamation and revegetation treatments for mine closure. Substantial effort has been invested in increasing knowledge of the effects of mine-waste cover systems on key water-balance terms such as net percolation, but tools to extend that knowledge to effects of cover systems on vegetation establishment and the subsequent effects of these vegetation-substrate interactions on water-balance terms are lacking. The concept of a “soil moisture regime” is used worldwide to understand edaphic conditions and plant communities. However, in most applications, soil moisture regime is a relative or unquantified parameter estimated from the presence of indicator plants or soil properties observed in natural ecosystems. Applications of these approaches to post-mining landscapes are challenging because soils/surficial materials are reconstructed and reference plant communities are often not fully re-established. Some quantitative approaches to estimation of properties that influence soil moisture regime (e.g. available water storage capacity) have been developed, but these are generally based on agricultural soil science, and have limited utility to many post-mining materials. The authors propose new methods for estimating soil moisture regime in post-closure landscapes, using concepts from existing biogeoclimatic ecosystem classification systems and analyses of effects of particle-size distribution on soil water retention. Key variables in the proposed estimation model include regional and local climate, material particle-size distributions (including distributions typical of mine-waste materials), organic-matter accumulation, and topography. This paper discusses methods development of this estimation approach, and presents suggestions for broader application of the approach for quantifying surface-water-balance components (e.g. net percolation) and for reclamation planning (e.g. revegetation species selection) in closure landscapes.Non UBCUnreviewedOthe