15 research outputs found
Procedures for the feasibility study for flood risk reduction
In this thesis we took under consideration the field of economic evaluation of flood damage in the case of village Pšata. In the beginning we present theoretical principles and methodology of the economic evaluation of public investments, which is legally required for all investments financed from public funds in Republic of Slovenia. Then we focus on a model for the evaluation of the expected annual damage on the basis of structure related individual flood\ud
damage assessment (HEC-FDA). Initially the operational principles of the model are introduced. Afterwards the expected annual flood damage for our settlement is calculated. The calculation is based upon the gathered input data. The result of flood damage analysis serves as\ud
an input for the cost-benefit (C/B) analysis. We determined marginal costs under condition of a positive net present value of the investment, which depends on the assumed discount rate and economic duration of the investment. Since the primary purpose of the thesis is to get acquainted with the basic approach of modeling of flood damage, we do not consider the eligibility of individual measures to protect the village from the floods, but we only compare the existing situation with the reference to "doing nothing" scenario. Nevertheless, the results of the analysis indicate that larger investments for the flood damage reduction in the analyzed area are not justified from an economic point of view. Therefore, we propose to concentrate on individual flood protection measures and preventive actions implemented by the individual property owners
A review of nature-based solutions for urban water management in European circular cities: a critical assessment based on case studies and literature
Abstract
Nature-based solutions (NBS) can protect, manage and restore natural or modified ecosystems. They are a multidisciplinary, integrated approach to address societal challenges and some natural hazards effectively and adaptively, simultaneously providing human well-being and biodiversity benefits. NBS applications can be easily noticed in circular cities, establishing an urban system that is regenerative and accessible. This paper aims to offer a review on NBS for urban water management from the literature and some relevant projects running within the COST Action 'Implementing nature-based solutions for creating a resourceful circular city'. The method used in the study is based on a detailed tracking of specific keywords in the literature using Google Scholar, ResearchGate, Academia.edu, ScienceDirect and Scopus. Based on this review, three main applications were identified: (i) flood and drought protection; (ii) the water-food-energy nexus; and (iii) water purification. The paper shows that NBS provide additional benefits, such as improving water quality, increasing biodiversity, obtaining social co-benefits, improving urban microclimate, and the reduction of energy consumption by improving indoor climate. The paper concludes that a systemic change to NBS should be given a higher priority and be preferred over conventional water infrastructure
Management of Urban Waters with Nature-Based Solutions in Circular Cities—Exemplified through Seven Urban Circularity Challenges
Nature-Based Solutions (NBS) have been proven to effectively mitigate and solve resource depletion and climate-related challenges in urban areas. The COST (Cooperation in Science and Technology) Action CA17133 entitled “Implementing nature-based solutions (NBS) for building a resourceful circular city” has established seven urban circularity challenges (UCC) that can be addressed effectively with NBS. This paper presents the outcomes of five elucidation workshops with more than 20 European experts from different backgrounds. These international workshops were used to examine the effectiveness of NBS to address UCC and foster NBS implementation towards circular urban water management. A major outcome was the identification of the two most relevant challenges for water resources in urban areas: ‘Restoring and maintaining the water cycle’ (UCC1) and ‘Water and waste treatment, recovery, and reuse’ (UCC2). s Moreover, significant synergies with ‘Nutrient recovery and reuse’, ‘Material recovery and reuse’, ‘Food and biomass production’, ‘Energy efficiency and recovery’, and ‘Building system recovery’ were identified. Additionally, the paper presents real-life case studies to demonstrate how different NBS and supporting units can contribute to the UCC. Finally, a case-based semi-quantitative assessment of the presented NBS was performed. Most notably, this paper identifies the most typically employed NBS that enable processes for UCC1 and UCC2. While current consensus is well established by experts in individual NBS, we presently highlight the potential to address UCC by combining different NBS and synergize enabling processes. This study presents a new paradigm and aims to enhance awareness on the ability of NBS to solve multiple urban circularity issues.publishedVersio
Design and Simulation of Stormwater Control Measures Using Automated Modeling
Stormwater control measures (SCMs) are decentralized technical elements, which can prevent the negative effects of uncontrolled stormwater flow while providing co-benefits. Optimal SCMs have to be selected and designed to achieve the desired hydrological response of an urban catchment. In this study, automated modeling and domain-specific knowledge in the fields of modeling rainfall-runoff (RR) and SCMs are applied to automate the process of optimal SCM design. A new knowledge library for modeling RR and SCMs, compliant with the equation discovery tool ProBMoT (Process-Based Modeling Tool), was developed. The proposed approach was used to (a) find the optimal RR model that best fits the available pipe flow measurements, and (b) to find the optimal SCMs design that best fits the target catchment outflow. The approach was applied to an urban catchment in the city of Ljubljana, Slovenia. First, nine RR models were created that generally had »very good« performance according to the Nash–Sutcliffe efficiency criteria. Second, six SCM scenarios (i.e., detention pond, storage tank, bio-retention cell, infiltration trench, rain garden, and green roof) were automatically designed and simulated, enabling the assessment of their ability to achieve the target outflow. The proposed approach enables the effective automation of two complex calibration tasks in the field of urban drainage
Modelling and evaluation of impacts of distributed retention and infiltration measures on urban runoff
Urbanizacija povzroči spremembe v naravnem hidrološkem krogu, ki se kažejo v manjši infiltraciji in evapotranspiraciji ter povečanem površinskem odtoku. Temu botruje spremenjena raba tal, saj so predhodno prepustne površine nadomeščene z neprepustnimi. Mešani kanalizacijski sistemi so dimenzionirani tako, da prevajajo sanitarno vodo in v omejenih količinah tudi padavinsko vodo do čistilne naprave. Med padavinskimi dogodki, ko je njihova prevodna sposobnost presežena, razbremenilniki odvajajo presežne količine vode v odvodnik.
Cilj te naloge je vzpostavitev modela, s katerim bodo ocenjeni ukrepi razpršenega zadrževanja in ponikanja meteornih voda (ang. SUDS), ki so alternativna oz. dopolnjujoča rešitev tradicionalnim rešitvam, kot so podzemni zadrževalniki in kanaliziranje, ki naj bi preprečile prelivanje iz mešanega kanalizacijskega sistema v reko Onyar prek razbremenilnika ob trgu Plaça dels Països Catalans v Gironi, Španija.
V skladu s pogoji v urbanem povodju, ki pokriva 2,7 km2, sem razvil pet scenarijev možnih ukrepov razpršenega zadrževanja, ki so zajemali infiltracijske kotanje, infiltracijske jarke, zelene strehe in njihove kombinacije. Najbolj učinkovit scenarij glede na kriterij zmanjšanja prelivanja na enoto implementiranega ukrepa je bila kombinacija infiltracijskih kotlin in jarkov. Po večkriterijski analizi, v kateri so bili scenariji ocenjeni tudi s kriteriji: stroški, dodane vrednosti, biotska raznovrstnost, se je scenarij, ki vključuje samo infiltracijske kotanje, izkazal kot najbolj ugoden. Ta scenarij v povprečju zmanjša razbremenjevanje za 45 %.
Ugotovili smo, da lahko SUDS-i znatno zmanjšajo količino razbremenjevanja iz mešanega kanalizacijskega sistema, medtem ko nudijo dodatne koristi. Zato bi morali biti vključeni v bodoče aktivnosti, povezane z upravljanjem voda na urbanih območjih, tj. v načrtovanje urbanega odvodnjavanja.Urbanization leads to disrupted natural hydrological circle resulting in lower infiltration and evapotranspiration and higher surface runoff of precipitation. This is caused by changed land use, where previously pervious surfaces are replaced by impervious surfaces. Combined sewer systems (CSS) are designed to convey sanitary flow and a limited amount of stormwater to the WWTP. Combined sewer overflows (CSO) are employed to discharge the excess water into the recipient during rain events when CSS capacity is exceeded.
The aim of this thesis is to develop a model to assess the implementation of SUDS as an alternative and as a complementary solution to conventional solutions such as underground storage tanks and rechanneling to prevent overflows from CSS into the river Onyar through the CSO object located at Plaça dels Països Catalans in Girona, Spain.
In accordance with the conditions in the urban catchment which covers 2.7 km2, five scenarios were developed consisting of following measures: infiltration basins, infiltration trenches, green roofs and their combinations. The most efficient scenario in terms of overflow reduction per unit of implemented SUDS measure was the one including the combination of infiltration basins and infiltration trenches. According to the multi-criteria analysis (including evaluations for costs, amenity and biodiversity), the scenario including only infiltration basins was most favorable. This scenario reduces overflow in average by 45%.
In conclusion, SUDS can significantly reduce CSOs while offering additional benefits. Therefore, they should be included in the strategies of urban water management, i.e. in the design of the urban drainage systems
Avtomatizirano modeliranje in načrtovanje ukrepov za obvladovanje padavinskih voda v urbanih območjih
Stormwater control measures (SCMs) are technical elements designed to prevent and mitigate the negative effects of uncontrolled stormwater flow. To investigate the impact of SCMs at different spatial scales, SCM models need to be integrated into or coupled with catchments rainfall-runoff (RR) models. Moreover, approaches that include auto-calibration of the RR model and objective-driven automated SCM design can be of great assistance. This research focused on applying automated modelling by using the Process-Based Modelling Tool (ProBMoT) to (a) find the most suitable RR model combining the choices among multiple alternatives for describing hydrological processes, (b) to calibrate RR model parameters against measured data, and (c) to design SCMs based on a target catchment outflow. To this end, a new domain knowledge library that includes RR and SCMs models was encoded. Furthermore, a multi-criteria decision analysis was performed to rank SCMs according to additional criteria. The mark is derived from SCM design parameters and can range between 0 and 5.1, where 0 is the best score. Given the conceptual model of the case study area and the knowledge library, ProBMoT first explored 9 alternative structures of RR models. On average, the models achieved a value of the Nash-Sutcliffe coefficient of 0.82, confirming the efficiency of the proposed approach for calibration of model parameters. Given the target catchment outflow, six SCM scenarios (i.e., bio-retention cell, rain garden, green roof, infiltration trench, detention pond, and storage tank) were designed by using ProBMoT to reduce the peak and total volume of the catchment outflow. Finaly, the developed approach for multicriteria decision analysis was applied to evaluate the designed SCMs. The results showed that landscapeintegrated SCMs (i.e., detention pond, infiltration trench, rain garden, bio-retention cell) are better scored (1.44 - 2.24) than building-integrated SCMs (i.e., green roof, rainwater-harvesting storage tank) (2.57 – 2.73) and grey infrastructure (i.e., underground storage tank) (3.48). The results confirmed the effectiveness of applying automated modelling to the field of RR modelling and optimal SCM design. Furthermore, they underline the importance of multi-criteria SCM evaluation.Ukrepi za obvladovanja padavinskih voda (OPV) so inženirski objekti, ki so načrtovani z namenom preprečevanja in blažitve negativnih posledic nenadzorovanega odtoka padavinskih voda. Da bi bolje razumeli vpliv ukrepov za OPV na različnih prostorskih nivojih, je potrebno njihove modele povezati ali vključiti v modele površinskega odtoka (PO). Proces lahko izboljšamo z uporabo pristopov, ki vključujejo avtomatizirano kalibracijo modelov PO ter ciljno in avtomatizirano načrtovanje ukrepov za OPV. V raziskavi smo se osredotočili na aplikacijo avtomatiziranega modeliranja z uporabo orodja »Process-Based Modelling Tool« (ProBMoT) z namenom (a) iskanja najbolj primernega modela PO, ki vključuje kombinacije alternativnih možnosti za opis posameznih hidroloških procesov, (b) kalibracije parametrov modelov PO na podatke meritev in (c) načrtovanja ukrepov za OPV glede na ciljni odtok iz prispevnega območja. S tem namenom je bila zapisana nova knjižnica domenskega znanja, ki vključuje modele PO in ukrepe za OPV. Poleg tega je bila opravljena večkriterijska odločitvena analiza, ki razvršča ukrepe za OPV, glede na dodatne kriterije. Dosežena ocena je določena na podlagi načrtovanih vrednosti parametrov ukrepov za OPV ter lahko zavzame vrednosti med 0 in 5,1, pri čemer 0 predstavlja najboljšo oceno. Ob zagotovljenem konceptualnem modelu študijskega območja in knjižnici znanja je ProBMoT najprej raziskal 9 alternativnih struktur modelov PO. Povprečna vrednost koeficienta Nash-Sutcliff, ki so jo dosegli modeli znaša 0,82, kar potrjuje učinkovitost predlaganega pristopa za kalibracijo modelskih parametrov. Šest scenarijev ukrepov za OPV (tj. bioretenzijske enote, deževni vrtovi, zelene strehe, infiltracijski jarki, suhi zadrževalniki in zadrževalni bazeni) je bilo načrtovanih z orodjem ProBMoT, da bi zmanjšali konico in skupni volumen odtoka iz prispevnega območja, glede na ciljni odtok. Razvit pristop k večkriterijski odločitveni analizi je bil uporabljen za oceno načrtovanih ukrepov za OPV. Rezultati so pokazali, da dosegajo v krajino vključeni ukrepi za OPV (tj. suhi zadrževalniki, infiltracijski jarki, deževni vrtovi, bioretenzijske enote) boljše ocene (1,44 – 2,24) od v objekte vključenih ukrepov za OPV (tj. zelene strehe in zbiralniki deževnice) (2,57 – 2,73) in sive infrastrukture (tj. podzemni zadrževalni bazeni) (3,48). Rezultati so potrdili učinkovitost uporabe avtomatiziranega modeliranja na področju modeliranja PO in optimalnega načrtovanja ukrepov za OPV. Poleg tega poudarjajo pomembnost večkriterijskega vrednotenja ukrepov za OPV
Vodarski pogled na uvajanje modro-zelene infrastrukture v mestih
Modro-zelena infrastruktura (MZI) so naravni in polnaravni (zato zelena) decentralizirani sistemi, namenjeni upravljanju padavinskih voda (zato modra) v mestih, ki hkrati opravljajo zelo raznovrstne ekosistemske storitve. Razen v nekaj tujih mestih, kjer so že sprejeli strategije za njihovo sistematično uvedbo, je uvajanje MZI omejeno na zgolj posamezne osamljene primere. To še posebej velja za Slovenijo, kjer uporaba MZI še ni postala pravilo. Zaradi utečenih prostorskonačrtovalskih praks imamo v slovenskih mestih zadosten delež razmeroma enakomerno razporejenih zelenih površin, ki pa niso načrtovane po načelih MZI, zato njihova večfunkcionalnost z vidika voda ni izkoriščena. Ker upravljanje mestnega prostora in pripadajočih prvin spada pod okrilje več strok, nas je zanimala predvsem povezava med prostorskim načrtovanjem in upravljanjem voda v mednarodnih strateških dokumentih in v slovenski zakonodaji. Na podlagi pregledane literature smo lahko sklenili, da je tovrstna povezava predvsem na mednarodni ravni, na nacionalni ravni pa je že šibkejša in je delovanje predvsem na izvedbeni ravni vezano na posamezne sektorje. V nadaljevanju so predstavljeni štirje primeri sistemskega uvajanja MZI v tujini: v Rotterdamu, Københavnu, v izbranih kitajskih mestih in v Filadelfiji, tem je skupno povezovanje med prostorskim načrtovanjem in upravljanjem voda pri načrtovanju MZI. Rezultati analize stanja so bili izhodišče za oblikovanje priporočil, s katerimi je mogoče preseči sektorsko upravljanje mestnega prostora in doseči celovitejše upravljanje voda v (slovenskih) mestih
Determination of Spatial and Temporal Variability of Soil Hydraulic Conductivity for Urban Runoff Modelling
Soil hydraulic conductivity has a direct influence on infiltration rate, which is of great importance for modelling and design of surface runoff and stormwater control measures. In this study, three measuring techniques for determination of soil hydraulic conductivity were compared in an urban catchment in Ljubljana, Slovenia. Double ring (DRI) and dual head infiltrometer (DHI) were applied to measure saturated hydraulic conductivity (Ks) and mini disk infiltrometer (MDI) was applied to measure unsaturated hydraulic conductivity (K), which was recalculated in Ks in order to compare the results. Results showed significant differences between investigated techniques, namely DHI showed 6.8 times higher values of Ks in comparison to DRI. On the other hand, Ks values obtained by MDI and DRI exhibited the lowest difference. MDI measurements in 12 locations of the small plot pointed to the spatial variability of K ranging between 73%−89% as well as to temporal variability within a single location of 27%−99%. Additionally, a reduction of K caused by the effect of drought-induced water repellency was observed. Moreover, results indicate that hydrological models could be enhanced using different scenarios by employing a range of K values based on soil conditions
Determination of spatial and temporal variability of soil hydraulic conductivity for urban runoff modelling
Soil hydraulic conductivity has a direct influence on infiltration rate, which is of great importance for modelling and design of surface runoff and stormwater control measures. In this study, three measuring techniques for determination of soil hydraulic conductivity were compared in an urban catchment in Ljubljana, Slovenia. Double ring (DRI) and dual head infiltrometer (DHI) were applied to measure saturated hydraulic conductivity (K) and mini disk infiltrometer (MDI) was applied to measure unsaturated hydraulic conductivity (K), which was recalculated in K in order to compare the results. Results showed significant differences between investigated techniques, namely DHI showed 6.8 times higher values of K in comparison to DRI. On the other hand, K values obtained by MDI and DRI exhibited the lowest difference. MDI measurements in 12 locations of the small plot pointed to the spatial variability of K ranging between 73%-89% as well as to temporal variability within a single location of 27%-99%. Additionally, a reduction of K caused by the effect of drought-induced water repellency was observed. Moreover, results indicate that hydrological models could be enhanced using different scenarios by employing a range of K values based on soil conditions
Design and simulation of stormwater control measures using automated modeling
Stormwater control measures (SCMs) are decentralized technical elements, which can prevent the negative effects of uncontrolled stormwater flow while providing co-benefits. Optimal SCMs have to be selected and designed to achieve the desired hydrological response of an urban catchment. In this study, automated modeling and domain-specific knowledge in the fields of modeling rainfall-runoff (RR) and SCMs are applied to automate the process of optimal SCM design. A new knowledge library for modeling RR and SCMs, compliant with the equation discovery tool ProBMoT (Process-Based Modeling Tool), was developed. The proposed approach was used to (a) find the optimal RR model that best fits the available pipe flow measurements, and (b) to find the optimal SCMs design that best fits the target catchment outflow. The approach was applied to an urban catchment in the city of Ljubljana, Slovenia. First, nine RR models were created that generally had "very good" performance according to the Nash%Sutcliffe efficiency criteria. Second, six SCM scenarios (i.e., detention pond, storage tank, bio-retention cell, infiltration trench, rain garden, and green roof) were automatically designed and simulated, enabling the assessment of their ability to achieve the target outflow. The proposed approach enables the effective automation of two complex calibration tasks in the field of urban drainage