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United States Department of Agriculture

Agricultural Research Service

Title: Concentration-Discharge Regression Parameters in Watersheds of Varying Lithology Subjected to Surface Coal Mining and Reclamation

Author
item Bonta, James

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 4, 2003
Publication Date: March 1, 2004
Citation: Bonta, J.V. Concentration-discharge regression parameters in watersheds of varying lithology subjected to surface coal mining and reclamation. Journal of Soil And Water Conservation. 2004. v.59(2). p.86-101.

Interpretive Summary: Not much is known regarding the watershed-scale effects of mining and reclaiming originally undisturbed watersheds on relationships between surface water chemical concentrations and stream flow rates. Evaluations of the impacts of mining and reclamation, best-management practice development, and total maximum daily load (TMDL) development all require knowledge of changing watershed hydrologic conditions and of changing supplies of chemicals on a watershed that are found in stream waters. The impacts on relationships between chemical concentrations and stream flow rates were evaluated on three geologically dissimilar, small experimental watersheds subjected to surface mining for coal (C06, M09, and J11). Comparisons were made between phases of land disturbances: Phase 1 (natural/undisturbed), subphases of Phase 2 (mining and reclamation), and subphases of Phase 3 (incomplete reclamation, and final condition of the watersheds - 3F) using 5047 laboratory analyses of 36 chemical constituents. About 36% of all concentration-flow rate relationships showed definite relationships (were statistically significant). More statistically significant relationships were found during Phases 1 and 3F at the three sites - relatively stable watershed periods - than during times of active mining and reclamation. Stability in relationships is quickly achieved for some constituents, mostly for major ions. Constituents for which significant relationships were found and not found across all three watersheds during different phases of watershed disturbance were identified. A characteristic of an important equation parameter was similar across the three geologically dissimilar watersheds for different phases. At C06, surface diversions left during Phase 3F caused many large differences between Phase 1 and 3F relationships. At M09, the return of relationships to premine conditions is attributed to reclamation consisting of straw crimping and no diversions. The haul-back method of mining at J11 contributed to the observed relationship changes due to the diverse surface disturbances of ongoing mining and reclamation. This study contains tables for documenting expected relationships and changes in parameters due to mining and reclamation activities for 36 chemical constituents, three differing geologic settings and mined coal seams, two types of mining methods, and three reclamation practices. The tables also provide guidance for field sampling. The results are useful to scientists, regulators, and consultants interested in improving water quality in streams in which surface mining and reclamation has occurred or is planned. The results are also applicable to watershed TMDL development in general.

Technical Abstract: Not much is known regarding the watershed-scale effects of mining and reclaiming originally undisturbed watersheds on surface water chemical concentration vs. flow rate regression relationships. Evaluations of the impacts of mining and reclamation, best-management practice development, and total maximum daily load development require incorporation of knowledge of changing hydrologic conditions and of changing supplies and rates of release of chemicals into stream waters. These impacts were evaluated on three geologically dissimilar, small experimental watersheds subjected to surface mining for coal (C06, M09, and J11). Comparisons were made between phases of land disturbances: Phase 1 (natural/undisturbed), subphases of Phase 2 (mining and reclamation), and subphases of Phase 3 (incomplete reclamation, and final condition of the watersheds - 3F) using 5047 laboratory analyses of 36 constituents. Of 429 regressions, 153 (36%) were statistically significant. More statistically significant regressions were found during Phases 1 and 3F at the three sites - relatively stable watershed periods. Stability in log concentration vs log flow rate relationships is quickly achieved for some constituents, mostly for major ions. Constituents for which significant regression were found and not found across all three watersheds during different phases of watershed disturbance were identified. Sign of the slope parameter was similar across the three geologically dissimilar watersheds for different phases. At C06, surface diversions left during Phase 3F caused many significant differences between Phase 1 and 3F regressions. At M09, the return of regression relationships to premine conditions is attributed to reclamation consisting of straw crimping and no diversions. The haul-back method of mining at J11 contributed to the observed regression changes due to the diverse surface disturbances of ongoing mining and reclamation. This study contains tables for documenting expected C-Q relationships and changes in parameters due to mining and reclamation activities for 36 chemical constituents, three differing geologic settings and mined coal seams, two types of mining methods, and three reclamation practices. The tables also provide guidance for field sampling.

Last Modified: 10/20/2014
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