Soil Moisture Variations and Their Relationships with Different Vegetation Types In The Upper Blue Nile River Basin

In this study the spatiotemporal patterns of vegetation response to soil moisture changes were explored using time series of Normalized Difference Vegetation Index (NDVI) and soil moisture datasets from 1982 through 2015. Non-parametric trend and correlation analyses were conducted to quantify the changes over time and the degree of relationship between soil moisture and vegetation response. Vegetation along the Ethio-Sudan border and southern Ethiopian highlands show significant increasing trends. The land cover types in these areas are mostly shrublands. On the other hand, the sparse grassland of the southwestern lowlands shows a decreasing vegetation activity trend. Croplands, followed by shrublands and grasslands, show the highest correlation with soil moisture changes. Consequently, these vegetation types are highly vulnerable to climate variability and require more attention than others. The correlation between same month (lag0) NDVI and soil moisture is substantially higher than the subsequent previous month (lag1-lag5) soil moisture values. This quick response relates to croplands, shrublands and grasslands, confirming their sensitivity to short-term soil moisture changes. Forested areas of the basin didn't show an appreciable correlation with soil moisture fluctuations either in the same month (lag0) or subsequent previous month (lag1-lag5) soil moisture values. Keywords: Soil moisture; Vegetation; Correlation; Blue Nile River