Meneses, B. (2011) Erosão Hídrica do Solo - Caso de Estudo do Concelho de Tarouca. Dissertação de Mestrado apresentada à Faculdade de Ciências Sociais e Humanas da Universidade Nova de Lisboa.
KEY WORDS: Erosion by water, USLE, Remote Sensing, GIS, Tarouca County.
Determining susceptible areas to soil erosion by water is fundamental when taking decisions related to soil use, especially agricultural activities. These decisions can be taken based on preventive measures, with the intent of avoiding future soil loss, or on reactive ones, when real soil has already been lost and immediate intervention in the territory is needed to minimize the loss. This assessment should include all intervening factors in the process (e.g. soil properties, precipitation, use and ground cover).
Being Tarouca County (study area) a highly dependent area on farming, soil preservation is extremely important and thus recognizing areas which are most susceptible to soil erosion by water. With that goal in mind, the Universal Soil Loss Equation (USLE) was used to determine potential and real erosion by water in this area and Remote Sensing (RS) and Geographic Information Systems (GIS) were used to determine soil occupation through satellite images and to calculate all the equation factors. The satellite images provided essentially Normalized Difference Vegetation Indexes (NDVI), which were then used to complement the already available soil occupation cartography. Precipitation data of weather stations located inside and around the study area were analyzed taking into account time and space variations. Part of the data was included in the erosion assessment through the USLE. The results obtained allowed to point out areas more susceptible to soil erosion by water, being the most influential factors in the distribution variation of potential and real erosion the relief, precipitation, physic-chemical properties of the soil, groundcover and developed activities on it. Part of the results was compared to data regarding soil erosion by water, obtained through punctual monitoring in two watersheds with different expositions, types of use and occupation within the county. This last procedure was sustained by the observation of removed or accumulated sediment which were beside graduation sticks strategically inserted in the soil and also by drawn squares on the soil. In this area daily precipitation was measured through an installed rain gauge in order to understand the erosion results obtained during the monitoring period. The results led to the conclusion that soil erosion by water is higher in farming areas than in areas without human intervention, showing how important vegetation is in reducing this type of erosion.
Sem comentários:
Enviar um comentário