Bârlad River in the industrial area of Vaslui

The first method Ph.D Razvan Voicu

rzvnvoicu@yahoo.com, getiiliberi@gmail.com,

Bârlad River, in the industrial area of Vaslui, is heavily eroded. This erosion is

found on both sides of the bridge (fig.1) traversed by cars and trains connecting the cities

Bacău and Vaslui. Due to large dike (fig.2) built inside river, the water by-passes it and

heavily erodes the right bank of the river. The right bank is eroded about 10 meters

downstream from the dike (fig.3).

bridge

Bârlad River Figure 1 Bridge on the industrial area of Vaslui

right bank erosion

dike Figure 2 Dike built inside Bârlad River bed

left bank erosion

right bank erosion

Figure 3 Bârlad River, downstream from the bridge

Heavy erosion is threatening the stability of pillars (fig.4) upstream of bridge, which

support the gas pipeline.

gas pipe line

Bârlad River

Figura 4 Gas pipeline crossing the Bârlad River

For ecotehnical redevelopment of Bârlad River regarding 100 meters in the

immediate vicinity of the bridge, the following works are to be performed downstream

from the bridge:

- Complete redirectioning of Bârlad River waters through a channel built in the left

bank;

- Consolidation of river banks using wooden sheet-piling for the two heavily

eroded areas;

- Linearization of both river banks for approximately one hundred meters

downstream from the bridge;

- Backfilling of any spaces in the banks throughout the length of the study section;

- Developing inclined banks in order to support the root system of plants meant to

hold up the banks.

Complete redirectioning of Bârlad River waters through a channel built in the left

bank;

Stopping erosion, which may extend up to dikes jeopardizing the road and railway

line, also the two roads near the banks, should be considered. Any major construction

of watercourses ecological restoration is achieved by redirecting water from the

channel selected as study. Redirecting water will be immediately performed behind

the wastewater pipeline located across the water course (fig.5)

wastewater pipeline

Bârlad River Figure 5 Redirecting water system

Barlad River water will be redirected by the means of a metal sheet-pile equipped

with supporters and anchorage system fixed in the river bank. (fig.5).

The water redirecting channel (Fig. 5) is rectangular and should entirely capture

the Bârlad river waters. The rectangular channel will be located on the left bank, at

almost five meters from the edge of major erosion on the left bank and lead its waters

towards the Bârlad riverbed, at about 100 meters from the bridge.(fig. 6).

road channel arable land

dike

heavy

erosion

Bârlad River

Figure 6 Rectangular channel construction for taking the Bârlad River waters

road channel arable land

redirecting water system

dike

heavy

erosion

Figure 7 Redirecting water system, rectangular channel functionality for collecting the

Bârlad river water on the established sector

In Figure 7, by redirecting the watercourse, the riverbed sector is ready for the

ecotehnical method presented.

Consolidation of river banks using wooden sheet-piling for the two heavily eroded

areas

Before compacting with soil, heavily eroded areas from the study sector should be

reinforced with wood sheet-piling fig 8. The sheet-piling are fixed into the slopes by the

means of some wooden plates. Both the plates and sheet-piling are fixed into the slopes

by the means of some plastic dowels provided with stoppers.

sheet-piling

plates supporting the sheet-piling dowels

Figure 8 Banks consolidation using wood sheet-piling

After setting all sheet-piling in the eroded areas, the water flow sector is smoothed

so as to form a rectangular channel able to support the riparian vegetation to be planted.

Banks will be arranged on inclined plane; various fast-growing woody species

(alder, willow) and herbaceous species with fasciculated roots (sedge, fescue, etc.) will be

planted in line or diamond along the banks). For example, figures (Fig. 9) and (Fig. 10)

show the success of ecotehnical methods applied to various river banks.

a) during ecotehnical works b) after completion of ecotehnical works,

Figures (9 şi 10) Ecotehnical arrangement of a river – UK

(Source: http://www.salixrw.com)

By the time the development of vegetation is completed, the area will have been

surrounded by a protective fence. These bioengineering methods are often used in

developed countries, successfully replacing the old classic engineering methods which

altered the ecological watercourses.

road channel arable land

redirecting water system

Figure 11 Ecotehnical measures completed for Bârlad River

After completion the ecotehnical works of banks consolidation, including

destruction of deck, the rectangular channel drawing all water off from the Bârlad River

can be destroyed, or can be used as side channel connectivity for the Bârlad River

waters. After the ecotehnical arrangement, the water redirecting system will be designed

to redirect up to 25% of Bârlad waters through the rectangular channel. If the channel

through which Bârlad River waters were redirected remains functional, then this channel

will be less deep and provided with other link channels in order to ensure an effective

connectivity.

The second method

There is some erosion on the other side of the bridge and it endangers a pillar

supporting the gas pipeline fig. 12.

gabion gas pipeline

Bârlad River

Figura 12 Erosion of the right bank of the Bârlad River, upstream of the bridge

Bank erosion can be stopped using wooden gabions filled with pressed rolls made

of coconut fibers or layers of fascines. The gabion will be bent and fixed in some beams

of wood which, in turn, are deeply attached to the ground. At the middle, the pillar must

be fitted with two cables, also attached to the ground fig.13.

gas pipeline

pillar supporting the pipe

supporting cable

Bârlad

River

wattle wooden elastic gabion

Figure 13 Stabilizing the bank of the Bârlad River

The arched gabion is a powerful system made to support the soil, both by its

structure but also by its pushing force. Also, a wattle fence for sustaining the river banks

is built. All these ideas can be implemented with greater chance of success.

All rights reserved Bucharest

2011