Spatio Temporal Soil Moisture Dynamics and Runoff under Different Soil Cover Conditions in a Semiarid Representative Basin in Brazil

摘要

Abstract. Hydrological studies in small basins are essential forinvestigating the role of distinct processes on water resources conservationand to assess the impact of the natural ecosystems on improving watersecurity especially in semiarid environments. In Brazil, the cooperativehydrological Network REHISA (“REde de HIdrologia do Semiárido”)comprises hydrologists from several universities of Brazil, focusing onfield measurements, monitoring and modeling activities in well instrumentedexperimental rural catchments located at different regions and biomes inSemiarid environment. Water scarcity is a common aspect among thecatchments, as well as risks of soil and water degradation. The objective ofthis work is to present assessments of near surface soil moisturespatial-temporal distribution, and to evaluate the impact of soilconservation techniques in reducing runoff, using small-scale experimentalplots in a representative catchment of the Pernambuco State, Brazil. Thestudy catchment is located in Alto Ipanema River Basin (AIRB) (with an areaof 150km ~(2) ), which is located at the semiarid region of the S?oFrancisco River (area of 641000km ~(2) ). Soil and water monitoring wasperformed in experimental plots with different soil cover conditions (Baresoil plots; Plots with natural cover – Caatinga Biome vegetation; Plots withcactus Palma barriers; and Plots with mulch cover – Dry grass mulch at 4tha ~(?1) ), where probes were installed for high resolution soil moistureassessment. In addition, regular soil moisture monitoring campaigns wereconducted at 7 different locations, using a capacitance probe, with arborealand shrub Caatinga vegetation, pasture and bare soil, predominantlyBrachiaria decumbens. Mulch cover runs close to the Caatinga cover, butstill with higher runoff generation, and presenting lower soil moisturetemporal mean values. Caatinga was highly effective in terms of soil andwater conservation at the small basin scale for both the dry and the wetseason, resulting in a positive nexus between vegetation and wateravailability at the region.