Field Trip 1:  Pierre Bénite Side-Channel on the Rhône
Our entire week will be spent in the basin of the Rhône, one of the most important rivers in Europe, and indeed, in the world. From its source in the Swiss Alps, the snowmelt-dominated Rhône flows westward to Lyon, where it joins with rainfall-runoff-dominated Saône. From Lyon, the enlarged Rhône flows southward through the geologically-controlled Rhône Valley picking up rainfall-generated runoff from western tributaries (draining the volcanic Massif Central) and eastern tributaries (draining calcareous terrain, such as we have seen in the Eygues and Ouvèze). The Rhône flows into the Mediterranean just west of Marseilles, in the Bouches du Rhône (literally the mouths of the Rhône), where it supports the distinctive wetlands, salt ponds, and cowboy culture of the Camargue. The Romans (no fools) centered their colonization along the Rhône axis, and made Lyon their capital. In the 20th century, the Rhône was heavily regulated by impoundments: in the steeper reach descending from the Alps, mostly to generate electrical power, and in the lower gradient reach along the Rhône valley, to facilitate navigation and generate power. The dams and hydroelectric canals along the Rhône have impacted the main channel and side channels. We will visit the Pierre Bénite section which has been recently restored : the minimum flow has been increased from 10 to 100 m3/s in the main channel and a few side channels, which had been hydrologically isolated and silted in, before their restoration, have been excavated and rewatered.

Field Trips 2 and 6: The Lez River
The Lez River drains a small basin dominated by limestone and marl, immediately north of the Eygues River basin in the PreAlps of southestern France, flowing southwesterly across the Rhône Valley to join the Rhône at Bollène. In the fall of 1993, intense rains produced a flood that killed two people and caused extensive damage, especially within the urban area of Bollène. The severity of the flooding was related to disconnection of the floodplain upstream, as levees confined flood flows to the channel, eliminating former overbank flows onto agricultural lands. To manage floodwaters, the river basin authority is now weighing options for diverting flood flows back onto the floodplain, limitations on land use on the flooded lands, and limited in-channel work for flood conveyance and to improve fish passage and instream habitat. We review maps, aerial photographs, and hydrologic data, then visit the river at several key points, discuss issues with residents and managers, then work in small groups to develop approaches to flood management and ecological restoration of the river and floodplain. We then meet with river basin managers and elected officials to discuss potential strategies. If you speak French, more details are available from the Syndicat Mixte du Bassin Versant du Lez.

 Field Trip 3: The Toulourenc River
 We will conduct facies mapping, long profile and cross-section surveys, and learn subsurface  sampling techniques in two contrasting tributaries of the Toulourenc River. Afterwards, you will have the option to swim or return directly to the Institut.

 
Field Trip 4: The Ouvèze River
The Ouvèze River drains the Baronnies region and the north slope of the Mont Ventoux in the preAlps of southeastern France. At Vaison-la-Romaine it has a drainage area of 1800 km2, and transitions from mountains to alluvial plain, which is traverses for about 40 km to its confluence with the Rhône River at Orange. The drainage basin of the Ouvèze has a Mediterranean climate, with the highest peak flows generated by infrequent but intense convective rainstorms (typically Sept-Nov), characterized by very rapid rise in stage and little warning of impending high floods. Such an extreme event occurred on the Ouvèze in September 1992, resulting in 28 deaths in a campground along the river and extensive damage. Some of the bridges along the river washed out, with the exception of the Roman-era bridge at Vaison-la-Romaine, which was built at a bedrock narrows.

We will review aerial photographs and maps depicting changes in the catchment and river channel, visit the Roman bridge and floodplain lands affected by the 1992 flood, examine the post-19th century riparian forest along the river, and examine areas of recent vineyard expansion. We will use the visit to the Ouvèze to demonstrate field techniques including mapping channel forms and habitats, facies maps/pebble counts, and vegetation surveys. Near Gigondas, we will visit a family property that has been producing wine since 110 AD (when it was settled by a retired Roman general), and examine wine cuves carved by the Romans and still in use today. We’ll consider implications of the long history of settlement in setting restoration goals for rivers, and as it is expressed in the fruits of this extraordinary terroir.

 
Optional Saturday Field Trips:  The Yzeron and Ain Rivers
 

The Yzeron
The Yzeron drains part of the urban area south-west of the center of Lyon. It has been heavily used by humans for centuries, with large public lavoires (fountains for washing clothes) and mills located along its banks. Its upper reaches are still undergoing a cycle of incision and sediment generation in response to construction disturbance and flashier runoff from increased area of impervious surface. The higher stormwater runoff peaks have created flooding problems downstream. To increase channel capacity in the densely urbanized downstream reach, and to provide opportunities for ecological enhancement, the river’s corridor will be expanded. Additional width for the channel will come from a combination of narrowing an adjacent road and selective removal of structures. The Yzeron illustrates many problems common to urban rivers: increased runoff from impervious surfaces, channel incision and simplification, canalization, and loss of ecological function. The flood management-restoration solution planned here differs from that on the Lez, reflecting different basin context, physiography, and urban density. The approach illustrated by the Yzeron project provides a potential model for other areas, and stimulates discussion about urban rivers and their restoration potential ‘on-the-back-of’ flood control.

The Ain
The Ain River (3640 km2 catchment) drains the Jura Mountains, flowing south and thence southwest to join the Rhône just upstream of Lyon. The Ain is the site of an unusual set of complementary restoration projects. The Ain was a dynamic, wandering, gravel-bed river with multiple channels, bars, and islands, and numerous former channels providing a diverse assemblage of floodplain habitats. As a result of dam construction in the 1960s, the channel became sediment starved, and it incised. As the mainstem incised, the river abandoned some formerly connected secondary channels, which by virtue of their weaker flows were subject to deposition and filling. To reverse the loss of the secondary channel habitat, two of these filled former channels near Varambon have been excavated so that they are hydrologically re-connected with the mainstem. 

The gravel produced by the excavation has been placed in the mainstem to partially offset the sediment deficit, and the mobility of the placed gravels has been carefully monitored using high resolution imagery from a low-elevation platform. The field trip concludes with an evening in Lyon, a visit to the quais of the Rhône and Saône, and dinner in Vieux Lyon.