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Expressing the sediment yield of the watershed as a factor of watershed characteristics is
important to avoid the continual measurement of sediments in the watershed. The study
investigates the effects of watershed characteristics on Sediment Yield by using GIS and
Principal Component Analysis (PCA) in the case of four sub watersheds in Tana sub
basin, Northern Ethiopia. The objective of the study is to identify the most principal
factors which affect Sediment Yield for the four selected sub watershed by correlation
and multiple linear regression. The Sediment Yield of each watershed was estimated in
the study area and the relationship of the watershed characteristics and Sediment Yield
was developed. This thesis used about 28 factors that affect the watershed property and
then determining which factors that may affect the Sediment Yield as dependent variable
in the study using principal component analysis. Factors that affect the watershed
characteristics included in the thesis were Area(A), Perimeter(P), Circular ratio(Cr),
Form factor(Ff), Max Discharge(MQ), Average Discharge(AQ), Longest flow path(Lfp),
Drainage density(Dd), Total Stream Length(TSL), Max. Daily Rainfall(MDRF), Total
Seasonal Rainfall(TSRF), Slope(S), Hypsometric Integral(HI), Relief ratio(Rr), Basin
relief(Br), Ruggedness number(Rn), Elongation ratio(Er), Stream frequency(Sf), Average
Elevation(Ave.E), Luvisols(Luv), Cambisols(Cam), Vertisols(Ver), Nitosols(Nit),
Lithosols(Lit), Average Suspended Sediment Concentration(ASSC), Forest(FC), Non-Cultivated Land(NCL) and Cultivated Land (CL). The Suspended Sediment Yield of the
watersheds was 31.5, 20.2, 34.9 and 36.2 tone/hac/season for the study area Tikur-Wuha,
Guale, Enkulal and Tomma watersheds respectively. The most principal factor which
determine Sediment Yield includes, NVC, TSRF, TLS, HI, Br, Rr, Rn, Dd, MDRF, VC,
P, ASSC, A, Nit, Lit, FC and Ave.E using SPSS. While using multiple linear regressions
the Forest Coverage of watershed, Stream Frequency and Hypsometric Integral are the
factors that affect Suspended Sediment Yield. To minimize the sediment loss of the
watershed the communities should have to practice reforestation and buffering the land
surface from cattle’s and grassing. While for the other two factors conservation structures
like stone / earth terracing and gully control structures.
Key words: Sediment Yield; Principal Component Analysis; Geographical Information
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