Several impacts over ecosystem services have been produced by land use/cover changes, placing it as one of the main factors driving global environmental change. In the present study, the SWAT model was used to assess the effect of land use/cover changes on the hydrology response in the Andalien river basin from the south-central zone of Chile. Three land use/cover scenarios (LU_1986, LU_2001, and LU_2011) were compared over a period of 30 years (1984–2013) to remove the effect of climate variability on hydrology. The results show a significant decrease in total annual flows among the three LU scenarios. The greater differences in the annual flows of 25.05 m³/s were observed between LU_1986 and LU_2011 scenarios. The hydrological cycle dynamics in the basin show an increasing trend of evapotranspiration and surface flows with a significant decrease in percolation and lateral flow on a monthly and seasonal scale. This behavior can be explained by the increasing percentage of the basin area covered by exotic plantations, from 35.22% to 63.93% during the period. The evidence of these changes and the evaluation of their effects are particularly relevant for the long-term sustainable management of water resources.

A multidisciplinary approach is followed for analysis of the effect of changes in land use patterns on the hydrologic response of the Vergara watershed (4340 km²) located in central Chile. Probable future land use scenarios were generated using heuristic rules and logistic regression models, in order to identify and represent the main pressure on the watershed, namely forestation of extensive areas used for agriculture with rapid growing exotic species. The hydrologic response of the watershed was computed with a physically based distributed precipitation-runoff model, which was calibrated and validated for the current period. Results show that mean annual discharge increase with agricultural land use and diminish with introduced forest coverage. Thus, forestation of areas with introduced species like Pinus radiata and Eucalyptus globulus might be regulated in order to protect the water resources of the watershed.

The focus is on the application of the SWAT model for the Lonquimay River basin (Central Chilean Andes), a small sub-basin of the Biobío, in which snow accumulation and snowmelt dynamics play an important role. In the absence of local measurements of snow coverage, remotely-sensed snow cover information (MODIS) was combined with discharge time series in order to validate the model representation of stream hydrology and spatial snow cover extent. The results showed satisfactory to good general model performance in terms of representation of long-term or annual mean discharge at the basin outlet, as well as a reasonably good description of snow cover extent under most circumstances. The case study also provides an example quantitative indication of how well a model may perform under limited availability of input meteorological data. In the current work, the MODIS snow products were used for validation purposes only. The future inclusion of MODIS information directly into the model calibration proce... Résumé Cet article porte sur l'application du modèle SWAT au bassin versant de la Rivière Lonquimay (Andes Chiliennes Centrales), petit sous-bassin de celui du Biobío, au sein duquel la dynamique d'accumulation et de fonte nivales jouent un rôle important. En l'absence de mesures locales de la couverture neigeuse, des informations relatives au manteau neigeux obtenues par télédétection (MODIS) ont été combinées avec des séries temporelles de débit afin de valider la modélisation de l'hydrologie liquide et de la distribution spatiale du manteau neigeux. Les résultats montrent des performances générales de modélisation satisfaisantes à bonnes en termes de représentation du débit à long terme ou moyen annuel à l'exutoire du bassin, ainsi qu'une description raisonnablement bonne du manteau neigeux dans la plupart des circonstances. L'étude de cas fournit également un exemple d'estimation quantitative des performances qu'un modèle peut avoir en cas de données météorologiques peu disponibles. Dans cette étude, ...