Contenu du sommaire

The author records the différents impacts related with the creation of a large-barge canal and studies the various ways of stopping them. In the case of the Rhone-Rhine canal, the acquisitions reach 4 200 ha, but 1 600 ha will be protected from flood damages. An agricultural agreement will supply the loss 3 100 ha arable land by help to intensification. The water consumption will be reduced by using water saving basins. Among the remaining problems are those of landscape valuation and of water fauna.

The authors have participated at the ecological part of the impact study (one the first of kind in France), concerning this big project of river's саnаlisation ; they bring summarily the contents of their study and some teachings on this new and legal procedure, and its insertion in the process of administrative decision.

Amongst the six french « agences de bassin » created in 1964 to solve French water problems (as volumes and pollutions) the « agence Rhône- Méditerranée-Corse » has succed during these last twelve years to reduce from a third — and perhaps to a half in 1985 — this real scourge ; for the Rhône-Alpes region, the agency has realised 679 operations since 1969, giving subventions to collectivities (20 % ) and manufacturers (30 % ) . Work amount (mainly : sewage works and physical-biological treatments) costed 839 112 002 F (collectivities: 55 %, manufacturers: 45 %). Yet, delays in works, gap in the geographical distribution of these works, a too less constrained structure regarding to polluters, nuisances linked to the nuclear programme, moderate this satisfying description.

The backbone of equipments against pollution. Are successively examined : The physical constraints of the activities of pollution treatment. Size effects and the nature of the equipments. The economies of scale. Some aspects in connection with problems of organization.

The rains which fall during the colder half of the year on the area of Saint-Etienne are particularly interesting because the town is located in the East of the Massif Central and this accounts for all sorts of falls. The dry winter is essentially due to lack of mediterranean rainfalls from the S-E which grow heavier from April on. In december and January the amount of rainfall is accounted for by the numerous though inefficient oceanic rainfalls from the N-W, whose disapearance explains the February minimum. The snow is an irregular and whimsical phenomenom which may as well last for 6 months asbe inexistent. Snowfalls stay within the usual limits of winter at low altitude with a december maximum due to N-W falls; on the other hand they last longer into spring higher up with a maximum in february due to S-E falls.