A fin de caracterizar los patrones espaciales de los diferentes tipos de cobertura del suelo (TCS), se analizo por metodos geoestadisticos un mapa de TCS, derivado de la clasificacion de una imagen satelital de un sector de la provincia de Buenos Aires, que incluia 7 tipos de coberturas: Pastizales Alta Cobertura (PAC), Pastizales Baja Cobertura (PBC), Cultivo (CUL) Vegetacion Palustre y/o Agua (VPA), Montes (MON), Pradera Humeda (PRH) y Urbano (URB). Se evaluaron los componentes espaciales de cada TCS a partir de variogramas omnidireccionales experimentales, ajustandolos a modelos de referencia. La heterogeneidad de cada TCS exigio utilizar una estrategia que implico el muestreo de la imagen tematica con diferentes grado de resolucion y dimension del area de analisis. La distribucion espacial de los TCS en la imagen es irregular sin ser aleatoria; mientras que la dimension de cada uno es relativamente estable, aunque diferentes entre si. Los modelos que mejor ajustan los variogramas experimentales son distintos segun el TCS, siendo exponencial para PBC, PAC, PRH y CUL; esferico para URB, aleatorio para VPA y exponencial o aleatorio para MON. Los parametros geoestadisticos de los modelos de ajuste calculados para cada TCS, indican diferencias estructurales en su distribucion espacial a escala de parche (proporcion no explicada por el modelo), paisaje (modelo) o region (diferencias entre sectores), que pueden relacionarse con el uso. La aplicacion de tecnicas geoestadisticas a informacion derivada de imagenes satelitales permite identificar y diferenciar los patrones espaciales de los TCS existentes en la misma, por lo que puede servir de base para definir estrategias de analisis y monitoreo del uso del suelo.

Through a systematic modelling analysis for focus catchments in Costa Rica (131 km(2)), Ecuador (10 km(2)), Chile (0.35 km(2)) and Argentina (12.9 km(2)), the hypothesis is tested that, as the size of the hydrological event increases, the effect of forest cover on the peak discharge becomes less important. For each focus catchment, a 1000-year synthetic rainfall time series was generated, representative of the current climate. This time series was used to run SHETRAN hydrological models for each catchment with two contrasting land use scenarios (generally with and without a forest cover). The corresponding maximum daily discharges for the contrasting scenarios were then compared to show the extent to which the two responses converged as the size of the peak discharge increased. For a given forest catchment discharge there could be a range of larger non-forest catchment discharges, depending on antecedent soil moisture content. The simulations show consistently for the rainfall dominated sites that the width of this range either remains constant or narrows as discharge increases, indicating either relative or absolute convergence of the responses. The pattern is more difficult to distinguish for a snowmelt regime but a relative convergence of response still appears possible. The results therefore support the test hypothesis. However, the pattern is complicated by factors such as catchment scale, soil depth, antecedent moisture content and land management. Forests may also still offer significant flood mitigation benefits for moderate (and more frequent) rainfall events and they protect against soil erosion and sediment transport for a wide range of events. (C) 2011 Elsevier B.V. All rights reserved.

The major point for Lacar Demosite (LDS) is the sustainable management of a representative basin of Andean Patagonian region where the main problem is the impact of land transformation on water quality and environmental services. The aim of the LDS is the reduction of soil erosion, the mitigation of floods in urban areas and the improvement of ecosystem services, based on Ecohydrological ideas and principles, and using phytotechnologies. Advances are presented for LDS showing that regulation of surface hydrology (water runoff; nutrients and sediments loads) at the watershed scale, through land use, vegetation cover and phytotechnologies, improve the aquatic ecological processes and the ecosystems services (water quality, landscape aesthetic values).

Through a systematic modelling analysis for focus b a ins in Costa Rica (131 km ), Ecuador (10 km), Chile (0.35 km) and Argentina (12.9 km ), the hypothesis is tested that, as the size of the flood peak increases, the effect of land use on the peak becomes less important. For each focus basin, a 1000-year s ynthetic rainfall time series was generated, representative of the current climate. T his time series was used to run SHETRAN hydrological models for each basin with two c ntrasting land use scenarios (generally with and without a forest cove r). The corresponding maximum daily discharges for the contrasting scenarios were then compared to show the extent to which the two responses converged as the size of the peak discharge increased. For a given forest basin discharge there could be a ran ge of larger non-forest basin discharges, depending on antecedent soil moisture c ontent. The simulations show consistently for the rainfall dominated sites that the width of this range either remains constant or narrows as discharge increases, indicat ing either relative or absolute convergence of the responses. The pattern is more d ifficult to distinguish for a snowmelt regime but a relative convergence of respo n e still appears possible. The results therefore support the test hypothesis. Howe ver, the pattern is complicated by factors such as basin scale, soil depth, antecedent moisture content and land management. Forests may also still offer significan t flood mitigation benefits for moderate (and more frequent) rainfall events and th ey protect against soil erosion and sediment transport for a wide range of events.