The long-term success of surface coal mining reclamation in the strippable coal belts of northwestern New Mexico is dependent on the relative stability of undisturbed and restored landscapes. Landscape stability is measured by the rate of modification of a landscape component of a given age. Field instrumentation in selected watersheds measures modern rates of modification. Areas of rapid modification, or relative instability, include headwaters of high-relief watersheds and areas of active base-level lowering. Studies of the Quaternary geomorphic history in the coal belts indicate a variety of landscape ages. Relict landscapes of the Pleistocene indicate long-term stability, and many of these landscapes have been preserved by upper Quaternary eolian deposits. These stabl landscapes are characterized by high infiltration rates, low sediment yields, low relief, and relatively dense root systems. Landscape classification schemes incorporating modern geomorphic processes and relative landscape ages serve as analogs for reclaimed landscapes.

Evaluating the success of postmining reclamation procedures requires that both internal (within reclaimed areas) and external (outside reclaimed areas) geomorphic variables be considered. Internal geomorphic variables include hillslope gradients and areal configurations, infiltration rates, degree of drainage integration, and surface roughness. External geomorphic variables include base-level changes, arroyo-headcutting rates, valley-fill geometry, and the ratio of bedrock to valley fill. Engineering designs are significant to internal variables, whereas the geomorphic history of a watershed influences the external variables. Research at the McKinley coal mine in northwestern New Mexico suggests that external variables pose the greatest threat to reclaimed landscapes.

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