
159Understanding Sea Level Rise and CoastalHazards
of O(10
−2
−100 s). In contrast, the length and the evolutionary timescales
for the barrier beach are O(10
4
−10
6
m) and O(10
7
−10
10
s), respectively. Such
a space–time hierarchical classication helps us recognize that we must
be able to model the role of sand grains in the development of large land-
forms from a basic knowledge of grain motion together with iterative inter-
actions between landforms at all intermediate scales and the respective
forces. Morphodynamic modeling attempts to achieve this aim by meansof
co-adjustments between forces, processes, and forms as they evolve over
different ...