publish our findings on the floor of the Rio San Girolamo riasseto sent to the Agency as well as river basin
del Rio S. Analysis of the physical Jerome - Masone Ollastu after the event of flooding of October 22, 2008.
Step 1.1 - Proposal for infrastructural base
RTI: DHI Italy - Hydrodata SPA - ART territory Environment Resources Ltd
COMMENTS drawn up by the October 22
Introduction Following the meeting held on December 4, 2009 the presence Hydrodata technicians in charge of the project and advise the Agency of the river basin, during which the Association on October 22 was invited by the City of Capoterra as representatives of the territory and subject matter experts, we send, as agreed occurred, our comments on the proposed infrastructural base and our alternative proposals.
In the pages that follow, the Association on October 22 shows the point of view, even technical, of residents in the basin of the Rio San Gerolamo who personally experienced the devastating effects of the flood of October 22, 2008 and for this they believe they can provide a specific contribution, which is considered particularly useful analysis for the identification of interventions for the safety of Rio San Girolamo.
This document contains a summary of comments received by the Association in a number of meetings, sponsored by the Association, held with the citizens of the town of Capoterra in 2009.
This contribution can in no way intended as a list of requests for assistance, for the making of which is still in need technical investigations and inspections to which the Association has neither formal assignments, or to provide technical support to public facilities, nor even of its own funds and volunteer resources to devote quite sufficient.
Although it may be unnecessary to point out, l'Associazione 22 ottobre sottolinea di non volere in alcun modo generare l'idea erronea che i possibili interventi di cui si discute nelle pagine seguenti possano essere eseguiti senza tutte le opportune ulteriori verifiche del caso.
Pertanto, resta inteso che tutte le ulteriori indagini necessarie alla verifica delle condizioni di realizzabilità e sicurezza dei possibili interventi di cui si tratta nel seguito sono, e restano, di piena competenza dell'ente pubblico.
SOMMARIO
1 Tronco SG01- Da confluenza riu S’Arriu de Sa Figu a località C. Musiu (da sez. SG062 a sez. SG058) - Pag 56 della Relazione 2
2 Tronco SG03 – Da località S. Girolamo al ponte della strada 52 per Capoterra (da sez. 051 a sez. 043) - Page 56 - Table 3 interventions SG03_01
Trunk SG04 3 - From the bridge the road to the bridge for 52 per Capoterra Poggio dei Pini (from sect. SG043 in sect. SG033) - Page 57 - Table 4 interventions SG04_01
4 Trunk SG05 - Poggio dei Pini from the deck to the earth dam of the reservoir of Poggio dei Pini (from sect. 033 in sect. 028) - Page 57 - Table 6
interventions SG05_01 5 Trunk SG06 - from the earth dam of the reservoir of the Poggio pines to cross the lake less (by sect. SG028 in sect. SG024) - Page 58 of Report 6 7
Trunk SG07 - From cross the lake to the residence of the minor Poggio (from sect. SG024 in sect. SG020) - to be corrected in : Trunk SG07 - by crossing the lake less than the Sport Zone Poggio dei Pini - Page 58 of the Report - Table interventions SG07_01 8
Trunk SG08-7 from the sports center in town of Poggio dei Pini Isca On loi (greenhouses) (from sect. SG020 to SG014) - Page 58 of the Report - No action table 8
SG09-8 Trunk From the village of Isca On loi (greenhouses) to the deck of the SS 195 (from sect. SG014 in sect. SG008) - Page 58 of the Report - Table measures 10 SG08_01
Trunk SG10 9 - From the deck of the SS 195 at the mouth to the sea (from sect. SG008 in sect. SG001) - Page 59 of the Report - Table measures 11 SG09_01
10 CONCLUSION S 12 11 13 PROPOSED OPERATING
1 Trunk SG01-From confluence riu S'Arriu de Sa Figu a località C. Musiu (da sez. SG062 a sez. SG058) - Pag 56 della Relazione
NELLO STUDIO SI LEGGE CHE:
”Durante l’evento alluvionale del 2008 l’azione erosiva delle acque ha asportato la vegetazione arbustiva e arborea esistente; la pendenza media del fondo alveo piuttosto elevata, ha fatto si che gran parte del materiale a pezzatura grossolana sia stato trasportato verso valle. Durante l’evento i numerosi canali tributari, sia in sx che in dx idrografica, per ruscellamento delle acque piovane, hanno portato verso valle una notevole quantità di materiale a pezzatura medio grossolana facendo riemergere lungo i versanti il substrato granitico e generando alla confluenza con il riu San Girolamo conoidi di detrito”.
These observations are concluded as follows:
"In the mountain section under study are not critical, given the substantial stability of the riverbed, the lack of housing and social infrastructure."
OUR COMMENTS AND SUGGESTIONS: We believe
its problems, however, there are and are due to the remarkable amount of materials that are mobilized because of the erosion of the slopes and the concentrated along the grooves of the gullies, the method of fast-moving mass of water mixed with debris (flash flood) , and at very high speeds (calculated in the study hydraulic) that pose a risk to the bed sovralluvionamento and at the risk of damage to all targets located further downstream (roads, bridges, private hospitals), as has already happened on October 22.
submit for evaluation of the experts the following proposals: the design and construction of dams in mountain areas (eg, dams and drainage mouth calibrated) to reduce the speed of the water already upstream blocking and stabilize the materials mobilized at the confluence between the mountain canyons el'alveo Main St. Jerome, the provision of hydraulic-forestry interventions by restoring the vegetation cover (where absent or burned by the fires) and resettlement of mountain trails destroyed (tracks with drywall work of charcoal dating from 1800).
2 Trunk SG03 - From S. Jerome bridge of the road for 52 Capoterra (from sect. 051 in sect. 043) - Page 56 - Coffee interventions SG03_01
STUDY SHOWS THAT
Immediately upstream of the bridge to the structure of the research center Capoterra Hydrocontrol "contracts in the left the scope river causing a significant barrier to the natural flow of water. "
Just downstream of the bridge road (not as mentioned in provincial report) has a clear opening inadequate compared to the morphology of the water body;
The project involves the construction of a defense rock quarry blocked, left bank, along the perimeter of the research center, tidal waves, a landmark event, which aims to protect the settlement from erosion. It is noted that the expenditure will amount to approximately € 800,000, or a little less than half the assessed value of the building before the flood.
OUR COMMENTS AND SUGGESTIONS:
This solution seems to disregard the statement in the analysis and geomorphological evidence reflected on the ground, namely that the building was built Hydrocontrol sull'alveo. In fact, the outer limit of the fence is currently less than 10 m dall'alveo lean (November 2009) and most of the fence on the left bank of the river was built on a river terrace visible dall'alveo recently, only a small portion north seems built on a hill made of granite arenizzato.
The report does not say clearly that the structure was placed in the historical and natural flooding of the river and that is exactly the confluence with the Rio Sa Scabitzada, which comes from the mountain basin of Mount St. Barbara on the right bank, with NNE-SSW direction.
It does not appear the slightest hint to what occurred upstream of the source of Scabitzada Sa - Santa Barbara. It seems at least strange that the study does not know that the Rio Sa Scabitzada has suffered a massive erosion process from the altitude of about 600 m above sea level, the excavation of a huge channel erosion (approximate size H = 2.3 m, width 3.4 m, length = 200 -300 m), which removed vegetation, soil and blocks, leaving a completely smooth surface of granite, to the very source. Immediately downstream of the source is present along the canyon and its grounds, a huge fan of debris, made up of boulders and blocks, which stretches for hundreds of meters and spilling into the bed of the Rio S. Jerome opposite all'Hydrocontrol. The presence of this channel erosion and examination of damage to small seventeenth-century chapel that housed the source, were under the eyes of all in the days immediately following the event (newspaper articles have appeared on), also said the channel is visible on clear days, even from Cagliari (Viale Buoncammino) and by the SS 195 towards Pula. The structure of the research center, therefore, received in full this huge mass of water and solid debris and has been the obstacle to their expansion nell'alveo. Given the morphology of the riverbed, with the right bank of granite that acts as a spur and diverts the current into the river just Hydrocontrol, the conditions of the influent and the morphology of the area of \u200b\u200bconvergence, it is clear that the Hydrocontrol is located directly above the alluvial fan of debris formed as a result of repeated injections of the Rio Sa Scabitzada solid. Of all this geomorphological and hydraulic there is the slightest hint in the report, indicating that the study is clearly partial and incomplete. In fact, the river morphology can not be studied without knowing the boundary conditions, let alone the main tributaries, and in this particular case, it is believed that they play a vital and decisive importance for the design choices.
In light of the above, it is not clear why the relocation is not expected dell'Hydrocontrol, considering that the defense does not guarantee the security of the building blocks and its appurtenances, even with capacity equal to those considered critical in the simulation (with T = 200 years back).
It is considered unlikely that, after what has happened, a conversion of the structure (should it ever be sold) will allow transfer of personnel, which could reasonably refuse to stay for business, because the site can not provide the necessary security guarantees hydrogeology.
It is suggested to provide an alternative to demolition "tout court", his relocation with the maintenance of the current space requirements, perhaps by transferring property to another site safer from the hydrogeological point of view (if compatible with the guidelines of the SAR), within the same municipality of Capoterra
In reference to the proposed viaduct, also, it is noted that the section called "access detected" in length 125 m, was positioned at the curved road (on the right bank of the river on which stretches in a granite rock outcrop), where there is a box for the passage of water. At that point is well evident, both from aerial photos of the November 2, both from the many photographs taken immediately after the flood, the presence of a slice of alluvial fans in large boulders and blocks deposited over river. The section of the viaduct seems inadequate and therefore it may be better stretch it a bit 'to the south at the corner.
Among the actions planned in this trunk is never spoken of sghiaiamento entire channel (or disalveo), that is, from a point upstream of the bridge to the church of S. Jerome until Hydrocontrol research center and even in the downstream section of the proposed rail bridges. This trunk river, instead appears sovralluvionato throughout its course, with a section of the riverbed is clearly insufficient.
It is also considered essential to provide the banks with the planting of suitable tree species (alder, willow, oleander) that would hold the banks with the roots and slow processes of erosion, contributing to their stabilization and strengthening.
Trunk SG04 3 - From the bridge the road to the bridge for 52 per Capoterra Poggio dei Pini (from sect. SG043 in sect. SG033) - Page 57 - Coffee interventions SG04_01
STUDY SHOWS THAT
settlements and infrastructure restricting the existing road digression planimetric natural watercourse in the middle part of the trunk terminal.
The majority of these are critical issues related to crossing the road (local road Santa Barbara - 26 of subdivision street) for Poggio dei Pini, inadequate transit compared to the reference event, and the presence of a sports area near focus of the riverbed.
Intervention proposto prevede la realizzazione di un nuovo manufatto di attraversamento sul Rio San Girolamo, circa 170 m a monte rispetto all’attuale con innesto in corrispondenza della strada 24 e una sostanziale modifica della strada 51 che corre parallela la fiume
L’area sportiva attrezzata (piscine) è ubicata in una posizione incompatibile con l’assetto di progetto: si propone la delocalizzazione. Nella relazione si legge che: “Il centro piscine, posizionato nell’area golenale destra ostruisce il regolare deflusso delle acque durante gli eventi di piena ed indirizza la corrente verso la sponda sx con potenziale coinvolgimento di alcuni edifici e delle strutture dell’attraversamento della strada comunale”.
OUR COMMENTS AND SUGGESTIONS:
What about the pools and the need of their displacement is not clear what evidence supporting the above statements, of which there is no trace in the General Report but only to the Technical Summary and is not an effective response site. The examination of aerial photographs and the examination of the riverbed geomorphology in the study did show that the stream that passes to the pools (apart, the closest point, 22 m from the right bank of the riverbed carved by the flood) is almost always been straight and does not seem particularly influenced by the presence of the same. The pools were affected in part by water that overflows beyond argini scavati dalla piena e si sono espanse lateralmente nella piana, in parte dalle acque di dilavamento superficiale che arrivavano dal versante soprastante. Non è chiaro in particolare quali evidenze supportino l'affermazione che le infrastrutture delle piscine avrebbero spinto la corrente verso un'abitazione a valle e verso l'area del ponte. Le immagini satellitari successive all'alluvione mostrano, all'altezza delle piscine, l'incipiente formazione all'interno dell'alveo di piena di un meandro incassato (tratto di alveo di magra, curvilineo, che tocca le sponde rettilinee dell'alveo di piena nel quale è ospitato) deviato verso la sponda sinistra. Il meandro presenta però un rientro immediato verso il centro dell'alveo, trasformandosi in a path of lean anastomosed channels (twisted) already about 80 m upstream of the damaged house, where the slowdown of the water due to the presence of the bridge started to produce the deposition of solids transported in bulk. The road on the left side does not come out dall'alveo full (which is almost straight) and do not come to affect all the houses that are on the same side, let alone the bridge that is much further down). The house was reached by the gradual erosion developed in parallel with the straight edge of the riverbed to flood. In short: it is evident that the water would come to houses and the bridge anyway, with or without swimming pools. About the causes actual erosion that has affected the left side, it would be helpful to interview the member and owner of the property to be told what happened in the last 25 years along the left bank and how it has been exposed to the erosive action of water following the destruction of vegetation cover in this mountain of the house along the bank, because of cuts to the rich vegetation made in the past and especially the fire of August 2007.
The proposed new viaduct with the construction of the bridge over the Rio San Jerome about 170 m upstream from the current state is obviously drawn on the aerial photo without knowing the real existing roads in the subdivision. The intervention, infatti, che garantirà le più rispettose caratteristiche geometriche costruttive e normative previste, non trova assolutamente riscontro nella viabilità esistente. La sua realizzazione comporterebbe il transito di tutto il traffico in ingresso e in uscita per i quartieri Anello Bellavista, Residenza S. Barbara, Centro Commerciale, Residenza Lago, Residenza Parco, nonché tutto il traffico tra le lottizzazioni di Poggio dei Pini e di Residenza del Poggio e le case sparse in direzione Capoterra (strada 52), e viceversa in direzione Cagliari, attraverso un’unica stradina della lottizzazione. Quest’ultima costituisce viabilità interna alla lottizzazione (strada 24 che conduce alla scuola materna e media di Poggio) e non ha le caratteristiche size of the main road. For the morphological conditions of the land and for construction (slope and dimensions) is by no means able to withstand such a huge amount of traffic too heavy (trucks, buses, refuse collection, shuttle buses for middle school, etc..) besides the fact that along the way face the entrances of many existing homes. The most critical point occurs where the road narrows to pass between four houses that are within 5 to 10 meters from the road and where there is a slope in the granite rocks that would be necessary to kill in order to expand the section, not to mention that, Because of insufficient width, you should not change radically the geometric structure of the whole way, this possibility somewhat questionable. In addition, the road is regularly used by pupils to return home on foot or by bicycle, so the viaduct should include sidewalks and bike lanes.
This situation of unsustainability by the road 24, road traffic has already been cited widely and visibly noted during the period immediately following the flood, when all vehicles had to pass that way, as they were in work in progress drainage canal of the lake and the road was closed to traffic 26.
It highlights the possibility that studies the movement of more viaduct valley, shortly after the Telecom booth, close the section of the existing bridge (section 33.2-33.3 banks share from 67.80 to 67.95 m), where both banks of the river are completely free of artifacts and homes and seem to fit implementation of the shoulders of the viaduct. The area would be fully available for the construction of a bridge with a section such as to dispose of the full purpose (see section hydraulic), roads connecting the 26 and 51 without unnecessary complications without changing the route and adjacent roads.
It was agreed on the need to translate the little road that stretches between the 51 swimming pools and the new bridge (given above) up against the granite hill located on right bank.
The planned embankment on the left bank it would seem, at least in part, unnecessary. In fact, the bank should be almost entirely of granite, and apart from the three nearby houses all'alveo, downstream there are no other buildings in critical situations. The cabin Telecom, in fact, was not affected by the flood of October 22. The enlargement of the section of the river, until you reach the ridge on the left bank of granite stone, should ensure sufficient strength of the bank itself.
In the area there are also two rivers: the road 51 (Rio Santa Barbara) and running through the streets 62, 47, and broke through the bridge on the road 49 (Rio Is Tintionis). Currently the two rivers join just upstream of the viaduct provided, then the Rio S. Barbara - Is Tintionis flows into the lake road past the bridge section 51 with an inadequate, it is noted that both rivers, for now, are ignored in the study, it refers to a later stage of their examination and resolution related problems. This study is not non-trivial, as these two rivers have contributed significantly to the sediment transport downstream in the stretch in which they are parallel to the Rio S. Jerome and then to the damage of the embankment along the right side of the bridge 26 on the road, blocking a crucial section of the outflow.
In relation to the planned diversion del Rio S. Barbara - Is Tintionis, it is not clear from the card as it will be realized in practice, since it gives an indication of a detected (L = 400 m) but not the work of crossing (bridge, box, pipe?) And no is clear what the section, provided, of course not be calculated. In this regard it is suggested to go to first check what happened on that river upstream, in the streets 51 and 49.
Among the actions planned in this trunk is never spoken of sghiaiamento entire riverbed, from upstream to downstream (and this is clearly sovralluvionato throughout its course and not only in small areas in the plan, in correspondence with the bridges or near the lake), or we speak of the many tributaries of the Rio sghiaiamento S. Jerome, already mentioned above.
surprising, moreover, that no actions are planned schemes to cross the river and tributaries for the slow speed of the river and to keep debris upstream of the confluence zone and sedimentation.
Also tab is not about relocation of the pumping wastewater located in the tail of the lake. It seems to ignore the presence of this important artifact. Also no mention of the presence of water and sewage pipelines, in the trunk between the pools and the tail of the lake, crossing many times the bed is the S. Jerome is the Rio S. Barbara - Tintionis (including new water pipes to newly restored Abbanoa). It should be clarified whether the plan for reshaping and disalveo tail of the lake has been provided for their relocation and where they should locate safe these works, which, however, also lacks the economic assessment.
It is considered essential to provide the banks with the planting of suitable tree species (alder, willow trees, carob trees, oleander) those to be retained in the roots with the erosion of the banks themselves, contributing to their stabilization and strengthening.
4 Trunk SG05 - From the bridge to the Poggio dei Pini earth dam of the reservoir Poggio dei Pini (from sect. 033 in sect. 028) - Page 57 - Coffee SG05_01
Before considering interventions reported for this stretch, points out that in another part of the report can be read as follows:
"The mountain section ( Jerome of the RS, ed) is characterized by steep slopes with a transport capacity of especially large in the intermediate section, due to the channelization of the two works cross artificial (dams Poggio dei Pini, ed) and the decrease of the slope, have the predominant storage medium to coarse material. Downstream, the floodplain, the action is related to the material transport medium end and the average slope progressively diminishing (<1%).”
This statement therefore seems to confirm that the two lakes, however small, have had an effect of channelization upstream, which resulted in a decrease in the slope of that stretch of water, so they stopped and encouraged the settling of coarse material that If it were not for the bars, was also transported to the valley because of the speed of the current (between 2 and 7 m / s as shown on page. 45-46 Report). This action of the lakes we believe it is irrefutable and well findings with the examination of places.
STUDY SHOWS THAT
The section in question affects the reservoir of Poggio dei Pini in the intervention project involves the channeling waters of the Rio San Girolamo in existing spillway, the flow to ensure adequate resection of the full reference. The waters of the river will be concentrated on the left bank through the removal of large accumulations lithoid present and the building of a longitudinal channel which separates the river from the reservoir.
Section of outflow of the channel spillway is not adequate to pass the full reference (T200 years). The houses left in these roads and related infrastructure are not properly protected. The confluence of two smaller bodies of water along the right bank and its tombinature crossing represent another critical issue.
The report also states that the entrance of the lake there would be a narrowing.
OUR COMMENTS AND SUGGESTIONS:
It is not clear what you are referring to when it comes to narrowing of the tail section of the river in the lake. The only restriction was made upstream from the bridge (road 26) for which see the preceding paragraph, and all the sediment that the river had carried over the years and settled.
The proposed project on the Rio S Jerome on the left bank of the lake, almost relegates the bed of the river to a flume of rectangular section, completely altering the natural order, and the fact that in this modo invece di rallentarne la velocità si consente al fiume di arrivare a valle della diga con una velocità molto maggiore dell’attuale. Non si capisce quale sia la tipologia costruttiva della canalizzazione con rivestimento in massi, in quanto non è presente il disegno con i particolari costruttivi, non si conosce l’altezza di tale canale e delle sue sponde, nonché i rapporti del canale, in sponda destra, con il lago. Non viene chiarito se i massi saranno slegati e semplicemente incastrati tra loro o se verranno intasati da calcestruzzo, in caso contrario non si capisce come questa struttura possa restare in piedi, visto che il fiume ha abbondantemente dimostrato di essere in grado di trasportare massi anche superiori a 1 mc, come quelli di cui si parla nelle tavole. Non è chiaro inoltre se tale canale in derivazione sia stato dimensionato per una piena di riferimento di circa 94 mc/s o di 114 mc/s con T ritorno rispettivamente = 200 anni e = 500 anni (vedi Tab. 9 Valori delle portate al colmo e dei contributi unitari nelle sezioni idrologiche lungo l’asta del riu San Girolamo per il tempo di ritorno di 500 anni e per l’evento di piena del 22/10/2008 – pag. 14 della Relazione Hydrodata ), perché se fosse dimensionato per una piena di portata inferiore il canale non sarebbe in grado di escludere dalla circolazione attiva il lago, proprio quando ciò sarebbe auspicabile per evitare ulteriori danni alla diga. Inoltre non si capisce come mai il canale non sia stato dimensionato to the extent of 22 October.
From the table it is clear that interventions will be a cliff along the right bank of this channel artificial reef that will, in fact, an embankment with the final effect of preventing the filling of the lake, then questioned his very existence of which, however, the report does not provide comprehensive technical justification. Furthermore, it is not clear whether this threshold will have a cliff skimming towards the canal, and in the case will be sized as needed to ensure that the lake can be emptied in case of reaching the maximum amount of overrun.
understand that only tributaries of the lake would remain the Rio de Mustaddinu, proveniente dalla zona del centro Commerciale e un altro piccolo impluvio che attraversa la strada 54, ma questi due corsi d’acqua non sarebbero in grado, per l’esiguità delle loro portate, di riempire il lago che verrebbe così a perdere le sue funzioni di riserva antincendio oltre che di elemento con particolarità paesaggistiche, naturalistiche ed ecologiche (risulta attualmente l’unico sito di nidificazione dei cigni più meridionale d’Europa).
Si evidenzia la possibilità che per far sopravvivere il lago e consentire il suo utilizzo principalmente in funzione antincendio si realizzi, nella parte iniziale del canale artificiale (a monte), una tubazione di dimensioni adeguate che consenta the passage of flood flow in normal conditions, corresponding to about 4 cm / s (T = 2 years back see Table 4 Bring the Riu San Girolamo estimated in PSFF - pag. Hydrodata 7 of the Report) to ensure all years to fill the lake in the short rainy season: The capacity in excess (flood) will continue to flow into the canal, thus avoiding that the dam has to bear in new future similar events. We must then evaluate the desirability of a small sovralzo eyelash embankment in order to increase the franc and thus increase the capacity of the lake. In this case, the dam could be put into a different category than the current category (LR n.12/2007).
It is not clear why he does not refer to the report prepared by Eng. Rav about the possibility of retrofitting the dam on the basis of existing national and regional legislation and the size of the spillway. You can not make the slightest sign of stability tests on the body of the surveys carried out in the harshest conditions, always performed by prof. Rav, nor the alternative proposed by the same professional about the demolition of the existing building and the reconstruction of a concrete central blossom with a threshold that would eliminate the whole problem of the spillway side, too close to homes and the street. On such a solution is likely to take essere fatti i necessari approfondimenti, anche in termini di costi/benefici e dell’aumento della sicurezza a monte e a valle dell’opera idraulica. Infatti, molti dei lavori previsti nella Tavola interventi SG05_01 sarebbero inutili se si optasse per questa soluzione.
5 Tronco SG06 – dalla diga in terra dell’invaso di Poggio dei Pini alla traversa del lago minore (da sez. SG028 a sez. SG024) - Pag 58 della Relazione
LO STUDIO RIPORTA CHE:
è prevista la demolizione completa del ponte crollato in seguito all’evento dell’ottobre 2008, per evitare che le opere ancora presenti possano recare ostacolo al deflusso delle acque;
è prevista la demolizione della traversa in muratura trough, which was also badly damaged during the same event, in order to avoid the highest levels of full may affect the surrounding road system. The operation is completed by the disalveo lithoid accumulated deposits upstream of the cross and the subsequent recalibration of the riverbed in the entire tract.
OUR COMMENTS AND SUGGESTIONS:
It should be noted that the bridge below the dam has not collapsed but was only detected in the resected left bank. Please note that the technical details are not quantified the costs for these two demolitions (bridge and dam in masonry).
It is not clearly explained as a barrier to create the bar in the valley walls, which accuracy is not seriously damaged but only partially damaged for a short stretch of a few meters (4-5), compared to its overall development.
It is said that one should avoid the highest levels of full, achieved with the maximum filling of dighetta, may affect the surrounding road system, but the only road currently consists of a short (about 10-20 m) of the road 3 damaged in the hanging valley of the earth dam and a short distance (about 10 m) of the road upstream of the cross 37, which gives on to any home. The problem could perhaps be solved by lowering the share of the crown of dighetta, which had a different sovralzo about 50 cm years ago, then returning the artifact to its original characteristics, and of course closing the hole opened in the right bank. This would create a settling tank sediment and slow the erosive power of the river downstream.
It is not clear whether a study was undertaken specifically to assess whether the maximum level of the lake, formed by dighetta, can get to lick the foot of the hanging valley of the great dam on the floor and then interferes with the structure of the dam, causing an erosion in the foot. This issue was raised in the report of Prof. Rav. Only in this case you might agree with the hypothesis of its demolition as an alternative to the restoration of damaged part.
It is said that some houses along the right side (on the road and then 37) would have been lapped by the wave of flood. It is not clear at what houses we refer, if those upstream or downstream of the ghetto. Please note that during the event the water leaking from the flooded dighetta only part of the road, because the houses in the first section of the road 37, to the junction with the road 35, are placed at a height greater than the level Street.
Trunk SG07 6 - From the street to the residence of the lake less Poggio (from sect. SG024 in sect. SG020) - to patch: Trunk SG07 - from minor to cross Lake Area Athletic Poggio dei Pini - Page 58 of the Report - Table interventions SG07_01
STUDY SHOWS THAT
In this course, the body develops tightly bound in a narrow gorge, there are no critical or provided assistance. SG020 section immediately downstream of the river widens in scope, involving the entire right wing to the riverside terrace unsinkable. In order to defend the settlements lateral erosion along the right side, still flood the transit of the full reference is provided for the construction of a shore defense in rock quarry blocked. Only once in front of the indoor gym.
OUR COMMENTS AND SUGGESTIONS:
The project called SG07_01 viene indicato in zona Residenza del Poggio, in realtà la denominazione è errata in quanto trattasi della zona sportiva di Poggio dei Pini. Pertanto la definizione del tronco deve essere modificata in: Tronco SG07 – Dalla traversa del lago minore alla Zona Sportiva di Poggio dei Pini. Anche questo denota una scarsa conoscenza dei luoghi. Curiosamente in questa parte della Relazione non si fa il minimo cenno alla presenza in questa zona di impianti sportivi, quasi ignorandone la presenza, si parla genericamente di “insediamenti in sponda destra che sarebbero inondabili al transito della piena”, senza specificare di quali insediamenti si tratti se case o altro.
Il piano prevede unicamente una piccola opera di protezione della No way 35 along the right bank in front of the gym, which is useful to support the street above, but not any full stop. Furthermore it is noted that the schema type of intervention "in defense rocks" showed that the cross-section scheduled for the cliff (about 6 to 7.5 m) would result in a significant reduction of the section of river runoff, in that area is particularly sovralluvionato (boulders, rocks and sand). It is advisable to study a type of bank protection by means of a retaining wall and large concrete blocks, which provides a horizontal section of the article quite low, but has a vertical development, in order to reduce clutter in bed, leaving the river as much space as possible.
Trunk SG08-7 from the sports center in town of Poggio dei Pini Isca On loi (greenhouses) (from sect. SG020 to SG014) - Page 58 of the Report - No board action
STUDY SHOWS THAT
In this section criticism is due to: the presence in the area of \u200b\u200bsport and road infrastructure (road No. 35 and related to ford the area in the left bank, as well as other smaller wading downstream), there are also various agricultural products (and a riding school its stables, on the right side). All of these buildings have the potential flood with flood events less than the reference (T = 200 years).
OUR COMMENTS AND PROPOSALS:
Although sports are always used (and therefore constitute targets to be defended), the plan does not consider it necessary to implement measures to protect the settlements. It is provided solely to moving the football locker rooms and the installation of sewage disposal (just restored from Abbanoa) without any indication of its rebuilding. Please note that along the way there are also some 35 wells owned by the Cooperative Poggio dei Pini.
With regard to the protection along the right bank is considered a minimal intervention would be useful and viable by providing an extension of the reef / retaining wall (Above) until you reach the entrance to the aqueduct of the Cooperative and from then on the retreat of 5-6 m of the road 35, which runs parallel to the river, so as to widen the section of runoff available River.
It is considered useful in order to protect the area from at least the sports events with T return lower than the reference value (T = 200 years), to study the possibility of eliminating a section of road 35 from a point roughly coincident with the entrance to the aqueduct and the demolition of the two dressing rooms rebuilt near the building of the clubhouse. In this way you could make a defense even better an embankment of rocks on earth, possibly higher than 2 - 3 m compared to the current PC, developed by the entrance of the aqueduct of Poggio dei Pini until the bridge in front of the indoor tennis courts. Would result in an enlargement of the river bed up to about 80 m wide, slightly reducing the area available to the sports area (which should be reconfigured into its structures, with the shift of the football field and soccer), but getting his protection at least in relation to flood events with return periods of less than or close to 200 years.
It would also be appropriate to make a total sghiaiamento of the riverbed from the section SG19 to the area of \u200b\u200bthe greenhouses, reproduced Hence the section of the river to a width of at least 80-100 m, with a suitable depth, as at present this area is clearly and practically sovralluvionata the section of flow is almost nonexistent. In fact, the resection performed immediately after the flood is entirely inappropriate in places you do not arrive at 1 m depth of the riverbed with a large section of perhaps ten meters.
It should be noted also that the section of the riverbed downstream of the sewage disposal occupied by an orchard, a few months after the flood event was re-enclosed with a net perpendicular all'alveo, for which are asked to check the possible compatibilità con le condizioni generali dell’area (rischio di ostruzione per intasamento della rete ad opera di rami e tronchi, come già accaduto).
Anche in questa zona comunque si deve rimarcare il fatto che lo studio continua ad ignorare la presenza di affluenti provenienti dalla sponda destra. Infatti subito a valle della palestra coperta passa un ruscello che presenta un bacino di alimentazione di una certa rilevanza (pendici del Monte Pauliara). Questo corso d’acqua, nel suo ultimo tratto, risulta praticamente insabbiato e privo di un alveo definito, per tale motivo durante l’alluvione ha allagato la strada 33, soprastante la zona sportiva. Questo corso d’acqua ha riversato dentro l’area sportiva una massa enorme di detriti e sabbia contribuendo al sovralluvionamento della stessa area. Inoltre si è aperto una nuova via di scorrimento attraverso un canale di gronda parallelo alla strada n. 33 fino a confluire nel ponticello immediatamente sottostante i campi da tennis.
Nella zona delle serre di Isca Su Loi, la presenza di condotte interrate per scopi idropotabili e la presenza del ponte tubo ad arco e dei due blocchi di ancoraggio, appaiono incompatibili con la situazione idraulica tanto che un lungo tratto di condotta sulla sponda sx di fronte al laghetto di cava è stata totalmente asportata (100 m) e poi ripristinata nell’estate 2009. Altre tubazioni in polietilene sono venute a giorno sotto l’alveo. Anche per queste il Piano non prevede alcuna soluzione, mentre si ritiene importante segnalare la necessità del loro spostamento o quanto meno riposizionamento ad una quota compatibile con il futuro profilo longitudinale e trasversale del fiume.
8 Tronco SG09 –Dalla località Isca Su loi (serre) al ponte della strada statale SS 195 (da sez. SG014 a sez. SG008) - Pag. 58 della Relazione - Tavola interventi SG08_01
LO STUDIO RIPORTA CHE:
In questo tratto le criticità sono dovute agli insediamenti posti in dx e sx idrografica che causano un significativo restringimento della sezione di deflusso.
L’intervento prevede la realizzazione di difese spondali con massi intasati e gabbioni, di muri arginali e di arginature in terra, modest expansion of the light of the bridge on the way Europe and the demolition of the bridge-aqueduct pipe and left the road bridge of the SS 195. The aim would be to the waterway system for the safety of hydraulic subdivisions
present our observations and suggestions:
It is estimated that, based on examination of the pelvis performed up to this point, the amplitude of ' channel provided for this section is totally inadequate. In fact, while up to a few tens of meters upstream from the river bed was a bed of 80-100 m, continuing downstream section tends to decrease gradually and at the nursery would have a size of about 40 m.
I sistemi di argini previsti creerebbero delle sacche chiuse che, nel caso in cui l’acqua riuscisse ad aggirarli o sormontarli, potrebbero intrappolarla impedendone il deflusso ed allagando completamente tali sacche con gli edifici.
La lunghezza degli argini a protezione della frazione di Rio S. Gerolamo costituirà uno sbarramento continuo sul percorso del flusso di piena, capace di impedire alle acque di defluire su un lungo fronte. Presumibilmente, le acque tenderanno ad accumularsi su questa linea con un consistente rallentamento del deflusso, visto che la devono aggirare.
Lo spazio disponibile al deflusso delle acque tra i due argini in sinistra e in destra idrografica è di circa 60 m e darebbe luogo ad un effetto "Funnel", with consequent increases in the level and current velocity. On 22 October 2008, the waters on this site have expanded to a total of approximately 500 m on either side of the river bed, reaching levels of 1.50 to 1.80 m.
The water level reached by October 22, 2008 has been such that most, if not invade the lower floors of the houses in case of a new flooding, due to the accumulation of water in the presence of levees so extensive that level likely to be higher, much to overcome with predictable ease the embankments of 2 m. This results in an increase in the risk due to possibility of failure of the levees and flood waves formation of localized and effect, already documented in the course of the flood in New Orleans, where the presence of large embankments, bypassed by the water, caused the flooding of areas where water is trapped with no exit routes.
It highlights the need to consider a solution which involves a drastic expansion of the riverbed, with a weighted identification of both houses to relocate the right bank (about 60 buildings) is in the left bank (about 30 buildings), which belong to subdivision of S. Jerome, in the area that was invaded by the waters. The embankments, retaining an elevation of 2 feet and made in favor of current and in opposition to it at this point could be moved to the margins of the areas that were flooded by removing the root causes of injury to public safety.
The additional cost of relocation might be estimated as a hypothesis in an average of about 200,000 to 250,000 euros for building owners to repay, so could amount to about 20-25 MEuro, which should be added the cost of demolition of houses and infrastructure works for the reconstruction of housing development elsewhere. In this regard, of note that there is already a rather extensive and partially urbanized within walking distance, the highest and oldest terrace (Houses of the Sun - Rio San Girolamo 2) posta quindi ad una quota di piena sicurezza sull’alveo del fiume.
Alcune delle opere previste a protezione degli edifici da delocalizzare (gabbioni, muri arginali, difese con scogliere) potrebbero non rendersi più necessarie, consentendo un certo risparmio di risorse che potrebbero contribuire al finanziamento della delocalizzazione.
A fronte di questa spesa però gli argini verrebbero semplificati e ridotti in lunghezza ed elevazione, e non sarebbero necessarie opere di protezione spondali e platee in alveo ordinario.
Occorrerebbe predisporre una nuova strada di accesso dalla 195 alla parte di lottizzazione del Rio S. Gerolamo non delocalizzata in sponda destra, con un accesso direttamente dal futuro viaduct and to the non-relocated from the roundabout on the left bank of golden fruit.
The relocation of the school should be, of course, confirmed.
It should be realized only viaduct on 195, while the bridge at the nursery school may not be rebuilt if it opts for an alternative access roads to subdivisions on the right bank, however, some existing (Via dei Genovesi).
In the event that the public agency decides a case of opting for a partial relocation of residential buildings on the two sides, stressing the possibility that the river bed can be reshaped as from the pond near the greenhouses (site at 16) thereby eliminating the double bend near the subdivision San Girolamo. Thus the enlargement of the riverbed could be done essentially in the left bank and relocate from their homes could possibly be reduced. In any case, a possible option of this type must be supported by the deployment of simulation models, including several detailed scenarios, adjusted to represent realistically the effects of future flooding events, with maximum adherence to the morphology of existing sites and those of the proposed interventions and evaluation of courses for different return periods for extreme events experienced and potential.
Trunk SG10 9 - From the deck of the SS 195 at the mouth to the sea (from sect. SG008 in sect. SG001) - Page 59 of the Report - Table interventions SG09_01
STUDY SHOWS THAT
The section of drainage is inadequate , the neighborhood of golden fruit in hydrographic has left many buildings at risk of flooding. The final stretch focivo is at risk of erosion on the right bank at risk sports facilities (soccer field).
The project involves the construction of bank protection walls and embankments in riverside land.
OUR COMMENTS AND SUGGESTIONS:
It is estimated that, based on examination of the pelvis performed up to this point, l’ampiezza dell’alveo prevista per questo tratto sia totalmente inadeguata. Anche qui, infatti, l’alveo dovrebbe essere allargato fino ad una ampiezza di almeno 80-100 m e la stessa ampiezza dovrebbe essere mantenuta fino alla foce.
Ciò comporterebbe la delocalizzazione per almeno 40 edifici situati presso la foce. Il costo aggiuntivo delle delocalizzazioni potrebbe essere stimato in circa 8 MEuro (200.000-250.000 Euro ad edificio) a cui si aggiungono le spese di demolizione ed eventuali spese di urbanizzazione per la ricostruzione della lottizzazione altrove.
L’arginatura, qualora si evidenziasse che fosse ancora necessaria, potrebbe essere collocata in margine all’area delocalizzata. L’altezza of the bank should be carefully considered in relation to the volume of water that actually affected the area overflows during the event of 22 October (about 500 m extension of the left bank for an average height of 1.50 m ).
It is proposed to carefully estimated using the opportunity to enter a second bank in the right bank, to protect the subdivision of Torre degli Ulivi, considering the level of increase would be achieved by preventing water from expanding laterally.
Lastly, it should be studied to better the area of \u200b\u200bthe confluence with the Rio Ollastu Masone, of which, however, the report says very little. This area it is rather delicate and should be taken into account the following issues in addition to those of the sports (football field): the presence of the bar "Leeward" immediately downstream of the bridge over the Rio Ollastu Masone, the presence of elementary school immediately upon Loi downstream from the church of S. Efisio Submitted in the aqueduct Torrino very close to the right bank of Rio S Jerome, the presence of various sewage disposal plants near the church. In the case of an enlargement in the right side should be carefully assessed the need for adequate protection of these targets in the various hypotheses of flow rate according to different return periods. The
Masone Ollastu on the deck of the SS195, which has been topped by flood waters in the course, it is highly underpowered and being located on an artery with high traffic density, is a significant risk. We agree on the need for an appropriate size for this bridge.
In the event that the public agency decides a case of opting for a partial relocation of residential buildings at risk, it shows the possibility of enlargement on the right bank of the riverbed to the sports field. In any case, this option must be supported by the implementation of realistic simulation models, adequately detailed, updated the morphology attuale e comprendenti diversi scenari per portate su vari tempi di ritorno e per eventi estremi sperimentati e potenziali.
10 CONCLUSIONI
Si ritiene che Il Piano esaminato:
Non abbia perseguito compiutamente gli obiettivi previsti nella convenzione ossia “il conseguimento di un assetto del corso d’acqua compatibile con la sicurezza idraulica dei territorio e la salvaguardia delle componenti naturali e ambientali”. Il primo obiettivo non appare conseguito in quanto viene totalmente disattesa l’esigenza di agire sul fiume e sulla sua sezione idraulica, attualmente manifestamente insufficiente in più punti, su cui non si interviene con alcuna opera di adeguamento della sezione stessa. Il secondo obiettivo non viene achieved since they ignore the landscape and the lake of fire-protection, as well as its fundamental action of upstream sediment retention as a result of channelization and wildlife aspects.
suffers from a lack of knowledge and depth of the problem of "sediment transport", as it believes that the only hydraulic calculation on the liquid flow is not sufficient to analyze the flood as a whole. It is believed that, based on what has been observed during and after the flood event, the magnitude of sediment transport is a decisive factor in future decisions sull'assetto total of the river and its tributaries, and thus has a weight fundamental choices of structural (bridges, dams) and the definition of the hydraulic sections from upstream end to the mouth.
suffers from a lack of knowledge of the geomorphological and hydrogeological "boundary conditions", as a result of the failure study of the tributaries of the right bank of the Rio S. Jerome, who played a crucial role in determining the event and flood damage to public and private infrastructure present at the edge of them.
Whether suffering from a "lack of local knowledge" of intervention, as evidenced in the questionable choices on the road, especially in the area of \u200b\u200bPoggio dei Pini. Need for
study on alternative proposals for the dam and lake area in loose material, including through detailed examination of the report prepared by Prof. Rav.
require further study and a clear definition of the possibility of relocation of individual buildings or entire settlements most at risk, as well as their economic cost.
has improved and perfected through a planning interventions based on more accurate knowledge and a constant dialogue with the residents.
It should be noted, moreover, as general consideration, that the study has some shortcomings Hydrodata quite important, even if partly motivated by the need to restrict the execution time to give answers to the people waiting for action.
It is noted that the Civil Protection Plan, recently issued by the municipality of Capoterra was made, however briefly, a lucid analysis of the causes can be considered the root of the serious consequences of the flood of October 22, 2008. It was not so clearly detected in the analysis made by the preliminary study Hydrodata, although this has the specific purpose of civil protection, but not the provision of interventions for homeland security by new events.
is therefore requested that the developments after the study Hydrodata focalizzino better the structural causes of the disasters produced by the flood, to better target interventions in it and, hopefully, to have as well as indications of good practice in the administration of the territory, making it possible to take shelter from the devastating effects of future flooding.
He wonders that the study be completed as soon as possible with the analysis of the tributaries in the right bank of the Rio San Gerolamo, omission probably due to reasons of timing, but it can not reasonably be ignored without any errors that may affect assessment heavily on the choices of action.
It is requested that an evaluation is made also on the many bridges intersecting the above-mentioned tributaries, which were overcome by the flood in the whole basin, a problem which until now has not been adequately highlighted. These bridges, on the occasion of critical rainfall events may represent risk factors for the people who ride them every day on foot or in vehicles. He points out that many of them were covered with piles of debris more meters high, including large blocks, presumably deposited by dynamic "flash flood". These accumulations, removed in the next few days to allow full movement of population, are no longer visible and detectable by professionals, with possible consequent underestimation of the phenomenon. "The assessment should include an indication of the operations to be performed and a preliminary cost estimate. It is suggested in each case, immediately, that all road crossings at risk are identified by appropriate signs and road hazards.
It also needs to be analyzed and evaluated the possibility that the same figure for the October 22, 2008 may not have been the most experienced and eventual identification of potential extreme scenarios.
It is believed, finally, that in critical areas should be available in models simulation of flow in case of flood, made with a high level of accuracy and detail in the representation of risk scenarios relating to all the design options being evaluated.
appears however essential that you take all the relief of detail required to keep current reality and the model of the circulation of water surface on which to base the simulation scenarios, representing all the work properly reset, public and private, existing or provided on site, capable of influencing the runoff.
11 PROPOSED OPERATING
To meet the demands of reaching a "framework of the stream compatible with the flood safety of the territory" is proposed to initiate an action similar to that already implemented in various Italian regions (eg Province of Turin Strategic Project "Maintenance of the territory", reclamation Dese Sile) to determine how planning, implementation and management of routine maintenance of the territory that provides for the implementation of the necessary and important structural works (bridges, viaducts, embankments, walls and cliffs), and at the same time constant cycle of interventions, harmonious with the landscape, completely integrated in the ecosystem, combined with periodic monitoring. In this way we can ensure the progressive improvement of security conditions and environmental quality of the area, trying to maintain full functionality in all the works of defense, essential to water safety and hydro.
Among the interventions that we feel we are proposing the following are innovative and relevant to the topic of risk reduction, both areal and linear type:
1) Speech structural anti-erosion along the river courses areal and punctual in the mountain basin of the auction and its main tributaries Rio Scabitzada Sa, Rio Is Tintionis, Rio S. Barbara, Rio de Mustaddinu, Rio de Malamorti, Rio Sa Menta, etc., including.:
- 1.1) implementation of a streamlined and structured for slowing the river current and slowed down the drag of sediments from upstream to downstream, by a series of dams in sequence (harness and reins in his mouth draining calibrated), allowing the normal flow water, but are able to capture coarse debris (source of damage is greater) and at the same time allow to pass the finer sediments downstream and then to the sea,
- 1.1) implementation of a system of small and medium-sized banks to expand various points along the river;
- 1.3) intervention to stabilize the cones of debris in gullies, with gabions transverse
- 1.4) restoration of the historic mountain trails, damaged by erosion and channeled range.
2) Posts areal hydraulic-forestry in the mountain basin of the auction and its main tributaries include:
- 2.1) the ordinary and extraordinary management of the vegetation cover, trees and shrubs, which act as protection against erosion, when they show signs of distress;
- 2.2) in the replanted areas by fires (reforestation with native species resistant to fire);
- 2.3) the controlled management of the forest.
3) Operations of redefinition and extension of the drainage section, to include:
- 3.1) the environmental rehabilitation of the watercourse and its main tributaries (especially the right bank) without corrections and stiffening of the sections cut off unnaturally, trapezoidal, or worse confined by gabions;
- 3.2) to allow the river to create loops and meanders, pools, vegetated areas and expansion areas unbuilt upstream dell'Hydrocontrol inter Hydrocontrol and swimming pools and in agricultural area downstream of the sport;
- 3.3) the removal of cemented features (downstream toward the mouth);
- 3.4) by renaturation with plantings along the river banks in order to strengthen and protect it from erosion;
- 3.5) increased progressively from upstream to downstream section of the flow without creating bottlenecks, particularly in the area between the greenhouses and SS 195 and from there to the mouth.
4) localized removal of dead plant material including:
- 4.1) unstable eventual thinning of the plants found exclusively inside of the riverbed, and only in the immediate vicinity of crossings that have a critical situation to the orderly runoff or which might cause damage to goods on display.
- 4.2) to prevent the removal of natural vegetation from the banks, on the contrary, will be revegetation with native species able to withstand the erosive force of the current.
5) Removal of lithoids: limited and localized hot spots, which can also be relocated in other sections (most valleys) so that the river could carry them towards the sea, contributing to the nourishment of sandy coastline.
6) Assessment of costs and benefits of relocation: To evaluate the alternative of giving more space to the river (especially in the mouth) and its tributaries on the right bank, through the relocation of buildings at risk in areas of relevance river. Not only in the section closest to the mouth, but also within the subdivision Poggio dei Pini, there are some critical cases, in addition to those referred to the house to the valley of the pools, so should carefully consider the situations of some lots already built and in phase edification. In the event that the public body intends to confine itself to a partial relocation of buildings at risk in subdivisions Rio S. Jerome and golden fruit, it is considered that there should be a careful evaluation of all the risk factors associated with this choice, including any additional risks introduced by the implementation of protective and that this should be done not only for the return periods considered in the study Hydrodata for the data of October 22, 2008.
7) Assessment of costs / benefits of the intervention on the dam structure in bulk materials: It is proposed to evaluate the alternative proposed by prof. Rav about the demolition of the existing building and the renovation of a concrete gravity dam, with a threshold skimming station, which can perform the following tasks: slowing of the energy of the river, holding lithoid material, fire-fighting duties, functions taken for irrigation purposes, and possibly drinking functions for ecological niche and migratory birds, landscape features.
Consistent with the principles of its Statute, the Association on October 22, hopes that all future operations on the Rio S. Jerome, considered as the main stem river, tributaries and the catchment area, allowing the construction work and defense structures, consistent with achieving the "River Park Saint Jerome" in the promotion and provision, the Association is committed to actively contribute.
