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Title: IMPACT OF COAL-SURFACE MINING ON HYDROLOGY AND WATER QUALITY OF THREE OHIO WATERSHEDS - SURFACE-WATER HYDROLOGY

Author
item Bonta, James - Jim
item AMERMAN C RICHAR - 0501-00-00
item DICK WARREN A - OSU-OARDC
item HARLUKOWICZ THOM - PUBLIC SERVICE ELEC & GAS

Submitted to: Water Resources Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: A six-year study was conducted to determine the effects of mining and reclamation on surface-water hydrology on three small experimental undisturbed watersheds. The results showed that mining and reclamation activities cause a drastic increase in the watershed runoff potential compared to undisturbed conditions. The post-reclamation period showed a slightly higher runoff-volume potential compared to the period of time when mining and reclamation disturbances were occurring. Each watershed became more responsive to high rainfall rates, causing more frequent higher peak flow rates. This responsiveness to rainfall after reclamation tended to decrease, except at one site. At this site, diversions may have influenced the results. Mining and reclamation reduced seasonal variation of watershed flow volumes, but a tendency toward restoration of seasonal variations was apparent as vegetation became established. The results are useful to regulatory agencies and the mining industry because they document the effects of mining and reclaiming undisturbed watersheds. Also, measured Soil Conservation Service curve numbers in mined and reclaimed areas in which there was near complete watershed disturbance are documented. Measured values obtained under such conditions are rare, and are critically needed. The results of this study also show that the post-reclamation period should be used for the engineering design conditions for permanent hydraulic structures, such as sediment ponds, because of the higher runoff-volume potential under these conditions.

Technical Abstract: A study was conducted to determine the effects of mining and reclaiming originally undisturbed watersheds on surface-water hydrology in three small experimental watersheds in Ohio. Approximately 6 years of data were collected at each site, with differing lengths of premining (Phase 1), mining and reclamation (Phase 2), and post-reclamation (Phase 3) periods. Mining and reclamation activities impaired baseflow and caused more frequent higher daily flow volumes. Phase 2 and early Phase 3 periods caused noticeable reductions in seasonal variation in double mass curves compared with Phase 1. However, seasonal variations were restored to some extent. The response of the watersheds to rainfall intensities causing larger peak flow rates increased due to mining and reclamation, but did not necessarily tend to return to Phase 1 levels. Soil Conservation Service curve numbers increased due to mining and reclamation to values in the curve number range, 83 to 90. During Phase 3, curve numbers slightly increased to the range, 87 to 91.