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University of Jyväskylä (2009)

Assessing the land cover and land use change and its impact on watershed services in a tropical Andean watershed of Peru

Gonzales Inca, Carlos A

Titre : Assessing the land cover and land use change and its impact on watershed services in a tropical Andean watershed of Peru

Auteur : Gonzales Inca, Carlos A

Université de soutenance : University of Jyväskylä

Grade : Master of Science 2009

Résumé
Understanding of land cover and land use change process and its implication for environmental condition and ecosystem functioning, it is essential to identify and recognize the services provided by the ecosystem. Remotely sensed data together with GIS increase the capability to analyze the human impact on the environment in quantitative, qualitative and spatial form. The main goal of this study was to generate the land cover and land use (LCLU) multi-temporal information, to quantify and to analyze the LCLU change and its impact on watershed soil erosion and sediment yield regulation services, and to identify the upstream and downstream relationship on sediment control in Huatanay watershed of Cusco region in the tropical Andes of Peru. Land cover and land use maps for 1988, 1997 and 2007 were generated and compared statistically through a cross-tabulation obtaining an overall kappa index of : 0.41 for 1988-1997, and 0.40 for 19972007, meaning significant changes between the LCLU classes in the studied periods. The LCLU change assessment evaluating area gains and losses and net change in each LCLU class revealed a high dynamic state of the Huatanay watershed landscape, where most of the classes represented changes more than 50% in the studied periods. Most of the LCLU changes were caused by the human action. The estimated annual average of soil losses in the Huatanay watershed were 319.5, 299.4 and 306.0 ton/ha/year in 1988, 1997 and 2007, which means a slight soil loss declining due to LCLU change (P=0.009). However, more than 50% of the watershed area had soil loss from moderate to extreme, which means that the erosion problem is very relevant in the watershed. The estimated sediment yields in the watershed were 1260.37, 1201.48 and 1227.61 ton/km2/yr in 1988, 1997 and 2007. The areas of the highest sediment yield values in downstream represent the areas of very active sedimentation process. This is a problem which is getting worse by urban growth in the floodplains, which are important areas for soil deposition. Finally, there was a clear quantitative sediment production and accumulation relationship between the upper and lower parts of the watershed, high sediment production by soil erosion occurring in the middle and upper part and high sediment accumulation occurring in the lower part of the watershed.

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