Author(s)

F. A. Comín, J. M. Nicolau, M. Trabucchi, L. Miguel, S. Nyssen & S. Pérez

Abstract

River basins with surface coal mines require restoration but priorities must be established hierarchically to achieve efficient river basin management. The watershed of River Martin (1993 km2 in NE Spain, Mediterranean continental climate) is characterized by a mountainous upper half part with low water flow regulation and a flat lower half with high water flow regulation (three reservoirs). Land cover of the upper part is scrub and wood (37%) and dry agriculture (32%), with some large natural areas (8.5%) and open coal mine zones (1%). Extensive dry agriculture dominates the lower part of the basin. Soil loss by erosion takes places at higher rates (average 125 Mg ha-1 yr-1) in most of the upper part of the basin and at lower rates (average 27.5 Mg ha-1 yr-1) in most of the lower part of the basin. Based on a combination of water runoff and soil loss, priorities for management actions of River Martin watershed should be given to areas covered by abandoned agriculture fields which did not develop a dense plant cover and extensive agriculture land use which may contribute high amounts of soil loss and pollutants to the river. A combination of the amount of soil loss estimated using RUSLE 1.06, a Revised version of the USLE, and the degree of soil conservation, let identify three mine zones in the upper part of the watershed as the major sources of sediment impacting the river waters. These are old reclaimed coal mines which require further restoration to decrease their high rates of soil loss. Water flow regulation and decreased water quality below the reservoirs, indicated by a biotic community dominated by hydrobids oligochaetes and gammarids, show that re-establishment of a dynamic water

Keywords

river basin, ecology restoration, revised universal soil equation (RUSLE), surface coal mining reclamation, surface runoff generation, Spain, Mediterranean river, aquatic communities