Societies alter their territory to adapt it to their needs, thus interfering physical
process. In Brittany, within bocage landscape the question comes out among others in
terms of runoffs insidious vehicle for agricultural inputs of cultivated plot of land
towards rivers and as a consequence for the damage of water quality. In order to
reduce the runoff transfers, the organisations in charge of catchment basin have
settled landscape or hydraulic devices. Nevertheless, if on the one hand according to
the plot scale, the efficiency of a talus on the streaming is easily conceivable, on
the other hand, according to a catchment basin scale, it seems hard to measure the
impact of these devices without the proper tools. At this scale, phenomena are
discontinuous in space and time. To evaluate the impact of this, a prototype model
has been developed at the RESO laboratory in cooperation to Jaudy-Guindy-Bizien
watershed office (Bretagne, France). This model, named TAnaTo, propose a new approach
to integrate constraint in water pathway based on a Triangular Irregular Network
(TIN). First, from TIN, a network graph is produced. It represents topographic and
anthropic flow directions. Then, the drainage network enables to calculate spatial
and statistical indicators. Results are exploited by the country planner
Jaudy-Guindy-Bizien to evaluate impact on landscape transformation and to measure the
effectiveness of its territorials actions. The purpose here is to present the model
that was entirely developped with open source technology (OpenJUMP, GTS, PostGIS) and
a case of study in operationnal works.