FullPaper Simpozion Rotaru Elena Daniela FINAL ENGLEZA 2003

7/29/2019 FullPaper Simpozion Rotaru Elena Daniela FINAL ENGLEZA 2003

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THE IMPROVEMENT OF REDIU RIVERBED, UPSTREAM OF THE

TARGU FRUMOS CITY, IASI COUNTY

Elena Daniela ROTARU

University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Mărăşti Blvd,

District 1, 011464, Bucharest, Romania, Phone: +4021.318.25.64, Fax: + 4021.318.25.67,

Email: [email protected],

Advisor Professor Augustina TRONAC

University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Mărăşti Blvd,

District 1, 011464, Bucharest, Romania, Phone: +4021.318.25.64, Fax: + 4021.318.25.67,Email: [email protected]

Corresponding author email: elenadaniela.rotaru@gmail.

Abstract

The estabilshment’s goal is to to provide flood defense and to protect the objectives from the south side of

Targu Frumos. In this article I approach the issues of the optimal choice for an ideal projection. This thing

was possible by interpreting two solutions, using multi-criteria analysis.

Also I analyse the aspect of the environmental impact during the execution of the work, as well as during

the exploatation.

After calculations, the second way of projection is considered to be the optimal, thus solving the flooding

problem from the south area of the city.

Key words: defence, flood, riverbed, environment.

THE ESTABILSHMENT’S GOAL

The estabilshment’s goal is to to provide flood

defense and to protect the objectives from the

south side of Targu Frumos. houses,greenhouses, land, rail, by increasing the

transport capacity of the river for transit Rediuflood flows.

NATURAL CONDITIONS,

CURRENT SITUATION AND

PROPOSED SOLUTION

2.1 The River flows from the hill Breazu,

flowing through the valley The, along the road

Rediu that connects Iasi city The Thecommune. The River is affluent of River

Bahluiet and is part of a complex scheme of arrangement river basin Bahlui (river basin

Prut), whose main purpose is the protectionagainstOfloodsOof OcityOIasi.

The river has a total length of 14 km and a river basin confluent zone of 42 km.

Current situation is as follows:

Fig. 1. Current situation

The current situation is as follows:Dam accumulation shows a gap of about 80 m

located between the bottom and left side drain.Also there is subsidence of fillings about 70

cm. Bottom emptying (monk + box) are

destroyedOinO proportionOof O90%.

The branch surface (overflow + channel + sink)are destroyed 50%



On the left bank is Pascani railroad - Podu

Iloaiei. Currently, the storage basin is anextensive in progress social project that

includes a stadium and a natural park with playgrounds for children.

As a result of the accumulation of non-

permanent shutdown in recent years have madeworks unsilting and calibration of bed

downstream of the dam, achieving a channel

width of approximately 10m based on providing sufficient transmission capacity for a

transit ensuring flow of 10%. Works werecarried out and unsilting downstream of the

confluence with the River Bahlueţ. (Consitrans,

2009 )

Fig.2 Current situation

Taking into account this accumulation is

considered rehabilitation works, includingunsilting basin involves high costs, low

efficiency.Therefore, the proposed work area fitting Rediu

riverbed in Tg. Frumos to defend against

flooding will be work-damming recalibration of

bed to make possible the safe transit of largewater Oflows.Considering the equipment assets, works to be

performed will be included in Class IV of

importance, according to STAS 4273/83, for the flow calculation is according to STAS

4068/88 Q5% = 49mc / sThe arrangement works Rediu stream

The situation of the stream Rediu aranjament

looksOasOfollows:- earth-dam upstream (L = 3000ml) is

uncalibratedO bed,Oundeveloped.- earth-dam downstream, to bridge DN28 (L =

350ml): bed was enlarged with a base width of

about 10 m, and the resulting material was

systematized on the left bank, in the form of dikes with slopes of 1: 1 ÷ 1: 1.5 and canopy

cover width of about 3 m, poorly compacted.-DN28-bridge downstream to the confluence

with the Bahlui river (L = 200ml), the bed has

reduced transport capacity. On the left side is adefense dyke a little high, beyond the waters.

Such an area is frequently flooded homes.

A.RecalibratingOtheO bedThe technical solution adopted for this work

takes into account the morphologicalcharacteristics of Rediu riverbed and

geotechnical characteristics of the materials

from the riverbed banks. It is proposedrecalibration bed, ensuring a riverbed width of

10m based on 1:2 slopes. Material extractedfrom the the bed will be used for filling in the

body of defense dykes.

Fig. no. 1 Dyke section

B.Dams defense. Are proposed defence dykes

and for the existing ones, to bring thecoresponding share for the class IV, plus a

guard importance of 0.3-0.5 m.

Defense dams are proposed and existing dams

bring appropriate share class IV, plus a guardimportance of 0.3-0.5 m This will ensure thetransit flow to the probability of exceeding the

5% according to class designed.

Considering that: right slope is steep andtherefore extends and expands the area on the

left bank; There is an ongoing project to bypass belt town on the right bank of the stream;

During periods of high water, by overcoming

the right bank, floods cause damageon aunproductive land; Considered justified

realization a defence dam on the left bank .The dam will be done in extending bank will



take the canopy cover width of 3.5 m, and

slopes of 1:2 slopes.

To protect the dyke from the bank erosion,

preventing gullyng, the wet parament will be protected with a erosion mat set at the foot of

slope in a spur plainconcrete with dimension

0.4x0.8m.The parameter from the dam site will be

covered with a layer 20 cm thick topsoil to begrassed.

For the filling of the dam body will use

material from the riverbed and in additionrecalibration of the old dam front.

Fig. no. 2 Cross section of the recalibrated bed

UndercrossingFor pluvial water discharges inside dammed,

the project includes execution of 3

undercrossing by dyke defence body They willtake over the channel waters collected from the

dyke upstream slope protection and river willdownload in Rediu river. Undercrossings will

be placed into sections with low allowances to

ensure gravity flow gutters.Undercrossings will be equip with planar gates

upstream and downstream with inverted flapwhich is closed under the effect of water

pressure increase in the river.

PROPOSED WORKS ARE:Variant 1

Lenght dyke = 1040 ml. The defence dyke is

closed downstream (near confluence) in therailway ambankement and upstream in higher

terrance on a left bank, defending just thestadium and the park area ( project in

execution)Recalibration work will be done on a bed

lengthOof O850Oml.

Effect is thus removed from the flood an areaof approximately 9ha.

VARIANT 2Lenght dyke = 1650 ml. The defence dyke is

closed downstream (near confluence) in the

railway ambankement and upstream in existingdischarge channel defending the the stadium

and the park area ( project in execution) and an

additional area with an area of approximately11ha.

In this area it is possible to develop the city incomplete safety in terms of flooding.

Work will be done on a recalibration of bed

length 1600ml. Effect is thus removed from theflood a total area of approx. 20ha.

(Consitrans, 2009)

BACKGROUND BY CALCULATION

A.HydraulicOcalculations

For the rest of the Rediu riverbed whith for we propose recalibration I realized curve

remuneration calculation used 20 sectors (P1 -

P17 and intersections with to DN 280 DN 28)

for flows with insurance 5%, 2% and 1% twovariants: natural and regime arrangedcorresponding the current situation and the

situation that will occur after the execution of

the work.Has been developed calculation of study river

sector to determine control flow and todetermine appropriate levels of water flow

calculation and spectrum free surface velocity

curve. Hydraulic calculations are suportedsurveyings in this proiect.

Hydraulic calculations were performed withHEC-RAS computer program. This program

determines the water level applying uniform

motion energy equation by iterative procedurecalled the standard step method from a cross

sectionOtoOanother.Hydraulic calculation was performed assuming

both natural regime, thus establishing flood

flow curve by providing 5%, as well asarranged under unsilting considering the

riverbed and dikes designed. Given the currentconfiguration of the riverbed and valley and

earthworks required compensation of fitting

was accepted hypothesis that in some sections,water flooding the lands bordering the right

bank than on a small area, but without reachingthe road and houses. (Rotaru E.D., 2011)

B.StabilityOcalculations

For the cross section defence dike on the Rediuriver , I realized stability calculations with the

GeoSlope Studio program analysing methods:

Spencer, Fellenius, Jambu, Morgenstern-Priceand I chose values resulting Morgenstern-Price

method are the lowest. (GeoStudio, 2007)





microclimate, vegetation, wildlife, and

landscape.In principle the regularization works and flood

defense have a positive impact ontheenvironment.

Regarding the negative impact on the

environment, the most influence occurs duringexecutionOof Oworks.

During exploitation the negative environmentalimpact of work decreases and tends to a normal

situation that increases positive weight to

negative influences. The proposed works do notgenerate waste and require no materials leading

to environmental pollution.The project analyzes constructive solutions

which harmoniously frames with the landscape,

being used mostly natural materials.

Defense embankments slopes unprotected bydefensive works will be grassed. Uponcompletion of the work, the contractor will

dismantle buildings and facilities for the

organization of their site.On this occasion the arrangements will be

needed to playback the previous use of the landon which objects were site organization.

It will remove all their effects and potential

sources of pollution of land (production bases,repair shops and maintenance equipment, fuel

depots).On the occasion of the dissolution of the site,

the Contractor shall also ensure site cleaning

from the land requirement site organization.(Consitrans, 2009)

MULTICRITERIA ANALYSIS

Multicriteria analysis method allows comparingmultiple versions of a project solutions, based

on criteria relevant and representative to that project.

The purpose of the method consists in selecting

and recommending alternative which compliesas possible rigorous and complete

requirements.For multi-criteria analysis for the optimal

choice of regularization workscan be consider

the following criteria and sub-criteria:a) C1 - economic criteria:

- C1.1 - cost of investment and operation and

maintenance costs updated for a period of 20years;

- C1.2 - the cost of damage caused by erosion,

collapse of banks, flooding (affecting

households, land, crops etc.).- C1.3 - related costs: lower revenues from

tourism, sport, recreation b) C2 - Social criteria:

- C2.1 - aesthetic landscape;

- C2.2 - Protection of riparian waters;- C2.3 - recreation, tourism, sport,

- C2.4-impaired population in the area(restricted, circulation, stress, including the

execution of works);

- C2.4 - quality of water used by riparianc) C3 - ecological criteria:

- C3.1 - overall impact index due to spatialsolutions, IGSA;

- C3.2 - index overall impact due to

constructive solutions, IGSC;

- C3.3 - degree of impairment of ecosystems,namely preservation, conservation,transformation, destruction;

d) C4 - compliance criteria restrictions:

- C4.1 - compliance with urban river basin andriver basin management plan;

- C4.2 - approved areas "accepted" as the floodwaters;

- C4.3 - affecting protected areas

- C4.4 - public services affecting water supply,sewage, landfills.

Criteria and sub-criteria chosen are those for which the expected spatial differences between

variants considered.

For multi-criteria analysis of the optimal choicefor the regularization of Rediu stream, it

considers the following criteria and sub-criteria:

a) C1 - economic criteria:

- C1.1 - cost of investment and operation andmaintenance costs updated for a period of 20

years;- C1.2 - the cost of damage caused by erosion,

collapse of banks, flooding (affecting

households, land, crops etc.) For a period of 20years;

b) C2 - Social criteria:- C2.1 - aesthetic landscape;

- C2.2 - areas removed from the effect of

flooding;c) C3 - ecological criteria:

- C3.3 - degree of impairment of ecosystems,

namely preservation, conservation,transformation, destruction;

d) C4 - compliance criteria restrictions:



- C4.1 - compliance with urban river basin and

river basin management plan. Taking into account three types of calculation:

VARIANT 1Long dam defense = 1040ml.

unsilting and reshaping riverbed wors L = 850

ml. Effect is thus removed from the flood anarea about 9ha.

VARIANT 2Long dam defense = 1650ml. unsilting and

reshaping riverbed wors L = 1600ml. Effect is

thus removed from the flood a total area of approx. 20ha.

VARIANT 3 = option 0 - no work.The results of the 3 different scores obtained

are presented in the following table:

According to the above table, suitable for

multi-criteria analysis (by weight criteria) thevariant that has obtained the highest weighted

scoreOisOversionO2.

Variant 3 (variant "zero" - no investment) cannot be taken into account because, although

ecologically is the most advantageouseconomic and social factors are severely

affected. So by floods that occur, if they do not

perform anyplanning work on the streamRediu, a number of households are directly

affected.



The damages justifies realization of regularization works and flood protection.

Option 2 is the most advantageous socially andenvironmentally.

From the economic perspective, the investmentneeded to carry out the works in version 2 is

higher than in option 1, but the increase is not

directly proportional to the surface removedfrom the flood effect. (At a 30% increase of the

investment, the protected area is increased with100%). This means that from a social

perspective, the city will have secured an area

of land (owned by municipality) that canexpand public building objectives.

Variant 2, although ecologically, has somedisadvantages, especially in the execution of

works riverbed, thus directly affecting the

ecosystem of the area, is recommended for implementation.

Analysis method multicriteria decision clearlyshows that exclusive consideration of the

investment cost criterion is disadvantageous to

all general and local requirements and interests.It follows from the above that the project in

Variant 2 most responsive requirements

imposed by multi-criteria analysis and has theleast impact on the environment.

(Rotaru E.D., 2011)

CONCLUSIONS

Fitting Rediu riverbed upstream of Tg.

Beautiful, Iasi county for defense against floodsin the south of the objectives of Tg. Beautiful

by increasing the transport capacity of the river for transit Rediu flood flows, after studying

design alternatives, we chose as the best option

variant 2 involving defense breakwater length =1650ml.

The defense dam closes, downstream, and

upstream of the railway embankment in theexisting discharge channel, defending the park

and stadium but also an additional area with asurface of approx. 11 hectares. In this area it is

possible to develop the city in complete safety

from the point of view of the defense against

flooding. Work will be done on a recalibrationof bed length 1600ml. Effect is removed fromthe flood a total area of approx. 20 ha.

The proposed works will be carried out with

minimum employment of private land. Riparianresidents on whose property is to run defense

works are directly interested in their achievement, being the first to suffer when

floods.

REFERENCES

Consitrans , 2009. Feasibility Study – The improvementof Rediu riverbed, upstream of the , Targu frumos city,

Iasi County, p 3-28.

Daniela Elena Rotaru, Project license - The improvementof Rediu riverbed, upstream of the , Targu frumos city,

Iasi County, p 46-70.

Chen G.K, Zhu D.Y. , Fee C.F., Qian O.H., 2007. Conciscalculation algorithm safety factor using the method

Morgenstern price - Canadian Geotechnical JournalGeoStudio, 2007. Product details Slope / W software for

calculating the safety factor for soil and rocks.

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FullPaper Simpozion Rotaru Elena Daniela FINAL ENGLEZA 2003