SAR interferometry (InSAR) is a useful tool to detect vertical surface displacements. One of the main obstacles is the loss of coherence (or interferometric correlation) which is defined as the complex cross-correlation coefficient of the SAR image pair and reflects the presence or absence of changes of the radar backscatter properties of the surface. Such changes can be caused by snow cover, vegetation growth, rapid land movement like thaw slumps and landslides, or soil moisture changes. Image pairs with little correlation (correlation coefficient close to 0) cannot be used for a displacement analysis, but, if interpreted correctly, the weak correlation is evidence for surface changes. Using TerraSAR-X data at a spatial resolution of up to 3 m we created coherence maps of the central Lena River Delta. The high temporal resolution of the data allows to detect changes within the surface on short time scale (11 days). The spatial and temporal variability of coherence is investigated together with an existing area classification and meteorological data.