Data/hora: 21/09/2024 18:12:21

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	06/06/1995	
Data da última atualização: 	18/03/2009	
Autoria: 	LIMA, W. de P.	
Título: 	Hydrologic behavior of two small watersheds in West Virginia undergoing natural reforestation.	
Ano de publicação: 	1971	
Fonte/Imprenta: 	1971.	
Páginas: 	144 f.	
Idioma: 	Inglês	
Notas: 	Thesis (Master of Science) - The Ohio State University.	
Conteúdo: 	Thirteen years of precipitacion and stream flow data from two water sheds from timber and Watershed Laboratory, in Parsons, West Virginia, were analyzed to determine the effectos of natural reforestation of former pastured and cultivated lands on streamflow.The watersheds were incorporated into the Monongahela National Forest about the year of 1940, and since then approximately 70 percent of their areas have reverted naturally to mexed hardwood forest cover.Streamflow measurement, hower, did not start until the year of 1957, and, therefore, the analyses in the present study do not encompass the entire period of forest development. Results of the analyses show an indication of reduction in the annual and dormant season streamflow from both watersheds between the period, 1957-1971, and all of the indicated annual reduction ocurred primarily in the dormant season period. This pattern of streamflow reduction would be explained in terms of an increase in soil water utilization by the increased forest cover, with would them require more of the dormant season precipitation to replenish the soil moisture deficit created during growing season before any surplus water was available for streamflow. None of indicated trends of streamflow with time, however, were statistically significant. Based on the findings of similar, earlier studies, and also on the results of the survey of the vegetation development in the study watersheds, it was believed that the major part of the change in streamflow had already occurred before 1957, that is, during the periods of initial and more rapid change in the cover conditions of the area. This assumption, coupled with the relatively short period of streamflow meassurement considered in the analysis, would it very difficult to significantly detect a possible change in streamflow. The Thornth waite water balance computed for the study watersheds showed that during the period of study, from an average annual precipitation of 58.4 inches, the mean annual evapotranspiration accounted for 24.3 inches, giving an annual water of 34.1 inches, which represents the water available for streamflow. From the total, annual streamflow yielded by study watersheds, 75 percent accurred in dormant season period, and 25 percent in the growing season period. During the interval, 1957-1971, therefore low flow regime of the study watersheds was practically unaffected, and high flow regime showed a slight, non-significant, downward trend.	
Palavras-Chave: 	Comportamento hidrológico; Riparian vegetation.	
Thesagro: 	Mata Ciliar; Regeneração Natural.	
Thesaurus Nal: 	natural regeneration; watersheds.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Florestas (CNPF)	
Exemplares: 	CNPF - (29577-1) - ADC - TS - -- - TS0060 -  - TS0060 - DIS