기후변화로 인한 극한 고온 현상은 상수도 배수시스템에서 수온 상승 문제를 심화시키고 있다. 본 연구는 여름철 수돗물 고온 민원이 반복 발생하는 J시의 A, B 배수지 계통을 대상으로 혹서기 수온 변화를 실측하고 구간별 상승 메커니즘을 규명하여 실용적 저감 방안을 제시하였다. 배수시스템을 배수지, 배수관로, 급수관로, 취약구간으로 분류하고 2025년 8월 혹서기에 연속 모니터링을 실시하였다. 배수지 구간에서 지상식 A 배수지는 18.5℃에서 23.2℃로 4.7℃ 상승한 반면, 지하식 B 배수지는 12.5℃에서 15.5℃로 안정적 수온을 유지하였다. 배수관로 구간의 체류시간-수온 관계를 회귀분석한 결과 로그함수 형태의 관계식이 도출되었으며, 초기 20시간까지 급속 상승, 20-65시간 완만 상승, 65시간 이후 30℃ 수렴의 3단계 패턴을 확인하였다. 취약구간인 노출관로의 표면온도는 최대 55℃를 기록하였으며, 25 mm 소구경 관로에서 8분 체류 시 16.1℃의 급격한 수온 상승이 발생하였다. 급수관로는 온도 상승에 취약하나 체류수량이 적어 선행 배수로 해결 가능한 것으로 분석되었다. 비용-효과를 고려한 대응 우선순위는 취약구간 개선, 급수관로 관리, 배수지 구조 개선, 배수관로 체류시간 단축으로 제시되었다. 본 연구는 기존 연구의 단편적 접근 방식을 탈피하여 배수시스템 전체를 통합적 관점에서 분석하고, 실제 운영 중인 시설의 실증 데이터를 기반으로 구간별 수온 거동 특성을 정량화하였다는 점에서 의의가 있다. 또한 제시된 체계적 분석 틀과 정량적 평가 방법론은 다른 지역 상수도 시설의 수온 관리에도 적용 가능하며, 기후변화 대응 상수도 정책 수립 및 시설 개선 우선순위 결정에 근거를 제공할 것으로 기대된다.

본 연구는 대수용가 공급체계 전환을 통한 상수관망 운영 에너지 절감방안을 검토하였다. 연구대상지역에 대한 대수용가 공급체계를 SD배수계통에서 JH배수계통으로 전환할 때의 물 공급 가능성과 전력비 절감효과를 분석하고, 능동형 관망관리 방안을 제시하였다. 수리해석 모델을 구축하여 2024년 7월 하절기 최악조건과 물축제 기간을 포함한 시나리오별 분석을 수행하였다. 분석결과, 하절기 최악조건에서는 물 공급 안정성 확보를 위해 SD배수계통 전량공급이 필요하며, 일반조건에서는 JH배수계통을 통한 제한적 공급이 가능한 것으로 나타났다. 전력비 절감효과는 물축제 미포함시 8.1%(SD가압장 57.1%), 물축제 포함시 13.9%(SD가압장 59.0%)로 분석되어 연간 최대 46.2백만원의 절감이 가능한 것으로 산정되었다. 능동형 관망관리 방안으로는 유량제어밸브 설치, 전동제수밸브를 이용한 교축운전, 경부하 시간대 펌프운영 등 3가지 방안을 제시하였다. 본 연구 결과는 대수용가가 포함된 상수관망의 효율적 운영과 에너지 절감을 위한 실무적 지침을 제공할 것으로 기대된다.

상수도 관망은 지하에 매설되어 있어 노후화로 인한 누수, 파손, 부식 등의 문제가 지속적으로 발생하고 있으며, 상수도 관망에서의 노후도 평가와 정비는 수돗물 안전성과 서비스 안정성을 확보하기 위한 중요한 과제 중 하나이다. 본 연구는 상수도 관망에서의 노후도를 효율적으로 평가하기 위해 모든 간접⋅직접평가 인자를 조사하지 않고도 최소한의 주요 평가 인자만으로 실제 직접평가 등급에 근접한 예측 결과를 효율적으로 도출할 수 있는 머신러닝 기반 상태평가 절차와 모델을 제안하였다. 상수관로 상태평가 모델은 랜덤 포레스트와 SHAP 해석기법을 결합한 머신러닝 기반 상태평가 절차를 제안하였으며, 28개 지자체의 강관과 주철관에 대한 간접⋅직접평가 데이터를 대상으로 SHAP-based feature importance 순위가 낮은 평가 인자부터 단계적으로 제거하여 주요 평가 인자를 도출하였다. 결과적으로 강관의 경우 내부 슬라임 분포면적 비율, 수질부식성, 매설연수, 최대 및 외면 부식깊이 비율, 내⋅외면 도장재 손상 비율, 외면 부식 면적 비율, 파손건수, 토양 산화환원전위 및 함수율로 11개의 평가 인자가 주요 인자로 선정되었고, F1 Score는 0.9273이었다. 주철관의 경우 CML 중성화도, 최대 부식깊이 비율, 내부압력, 외부 토압으로 4개의 평가 인자가 주요인자로 선정되었고, F1 Score는 0.6188이었다. 주요 평가 인자만으로도 직접평가 등급에 근접한 예측 결과를 도출할 수 있었으며, 이를 통해 효율적인 상수관로 상태평가를 위한 머신러닝 기법 적용 가능성을 확인할 수 있었다.

본 연구에서는 2009년부터 2024년까지 발생한 수도관 파손 사례 29건(DCIP 16건, SP 13건)을 직접 조사하여 파손의 원인을 규명하였다. DCIP의 파손 유형은 주로 종방향 균열 또는 파손(62.5%, 10건)이었고, 그외 파손 유형으로는 홀(Hole) 발생(18.8%), 원주방향 균열 (12.5%), 접합부 부식으로 인한 누수(6.3%)이었다. SP는 5건의 홀 발생(38.5%), 그외 종방향 균열과 원주방향 균열은 각각 30.8%로 나타났다. 이러한 파손의 원인으로 DCIP는 제조상(관두께 부족, 편차, 몸통 기공, 표면 결함 등)이나 재질 결함(화학적 성분, 금속 구조, 인장강도 등)이 DCIP의 파손에 가장 큰 영향을 미쳤으며, 부식과 관련된 매설 환경과 관 하부 기초 시공(자갈, 보 등)과 관련된 사항이 영향을 주었던 것으로 나타났다. SP는 부식, 관의 처짐을 유발하는 매설 환경이나 시공 관련 요인이 SP에 가장 큰 영향을 미쳤고, 일부 롤벤딩으로 제작된 SP는 종방향 용접 결함(부분 용접 등)으로 인한 반복적인 파손 사고를 유발하는 것으로 나타났다. 마지막으로, DCIP와 SP의 파손 사고는 단일 원인이라기보다는 상기의 다양한 요인들이 복합적으로 작용하여 발생한 것으로 판단된다. 그러나 관의 파손에는 관 제조상, 재료 결함, 시공 요인들이 큰 영향을 주고 있어 상수도 관 진단 시 더욱 집중적으로 조사해야 할 영역으로 판단된다.

상수도 시스템에서의 사고 발생은 사용자들의 물 이용 불편으로 인해 막대한 사회경제적 피해를 초래할 수 있는 위협 요인이며, 따라서 수도사업자들은 수도정비기본계획 등을 통해 상수도 사고를 빠르게 복구하고, 피해 규모를 최소화하기 위한 다양한 노력을 기울이고 있다. 본 연구는 상수도 시스템에서 발생하는 관로사고 상황에 대하여 회복탄력성을 정량적으로 평가하고, 비상급수 방안을 포함한 사고 대응 전략의 효과를 분석하기 위한 평가 모형을 개발하였다. 개발 모형은 시스템의 회복탄력성에 기여하는 다양한 특성들을 반영할 수 있는 시간단위 공급 부족량과 충족률 지표를 통해 회복탄력성을 평가하며, 국내 지방상수도 시스템의 특정 구역을 대상으로 관로사고 시나리오를 모의하여 개발 모형의 적용 효과를 검증하였다. 결과적으로 개발 모형을 통해 비상연계관로, 배수지 충수, 병물 공급 등 비상대응 방안의 효과를 정량적으로 평가하였으며, 이를 통해 시스템의 회복탄력성 향상을 위한 설계 및 운영 전략 수립의 가능성을 확인하였다.

In this study, we developed a technology that can measure key evaluation items in the field for various rehabilitation methods and evaluated its performance. The results are as follows. First, when the spray-on lining adhesion strength is measured after drying at high temperature (60℃) for 4 hours and cooling for 2 hours, the results are equivalent to or higher than the adhesion strength measured at room temperature after 48 hours. Therefore, the time required for measuring the adhesion strength in the field can be shortened to 1/8, and it is expected to be helpful in evaluating the condition of the spray-on lining. Second, depending on close or adhesive to existing pipe of the liner of the close-fit lining or CIPP lining, and the grouting condition of the slip lining, the sound frequency generation pattern, the vibration magnitude, and duration using the impact echo showed different characteristics. Therefore, it is thought that it is possible to evaluate liner lifting or grouting failure through analysis of the acoustic frequency, vibration magnitude, and duration. Third, when water penetrates the back of the liner of the close-fit lining or CIPP lining, it was found that the water penetrated between the liner and the existing pipe acts as a couplant, and a signal is repeatedly generated in which ultrasonic energy is transmitted and reflected to the steel pipe after the liner. Therefore, it is judged that it is possible to check whether water has penetrated the back of the liner using ultrasonic waves. Fourth, the liner tensile strength of the close-fit, CIPP lining was compared with the tensile test and the instrumented indentation test, and it was found that the tensile strength was similar. So it was judged that it will be helpful in evaluating the mechanical strength change without the liner specimen in the future.

Water utilities are making various efforts to reduce water losses from water networks, and an essential part of them is to recognize the moment when a pipe burst occurs during operation quickly. Several physics-based methods and data-driven analysis are applied using real-time flow and pressure data measured through a SCADA system or smart meters, and methodologies based on machining learning are currently widely studied. Water utilities should apply various approaches together to increase pipe burst detection. The most intuitive and explainable water balance method and its procedure were presented in this study, and the applicability and detection performance were evaluated by applying this approach to water supply pipelines. Based on these results, water utilities can establish a mass balance-based pipe burst detection system, give a guideline for installing new flow meters, and set the detection parameters with expected performance. The performance of the water balance analysis method is affected by the water network operation conditions, the characteristics of the installed flow meter, and event data, so there is a limit to the general use of the results in all sites. Therefore, water utilities should accumulate experience by applying the water balance method in more fields.

As an advanced study on the method of calculating the target revenue water ratio of local waterworks through the leakage component analysis method proposed by Kim et al. (2022), this study developed a model to calculate the achievable revenue water ratio within the specified project cost, the required project cost to achieve the specified target revenue water ratio, and the economically appropriate target revenue water ratio level by considering the leakage reduction cost and leakage reduction benefit for each revenue water ratio improvement strategy, and conducted an applicability evaluation of the developed model using actual field data. The procedure for calculating the target revenue water ratio of local waterworks considering economics proposed in this study consists of three stages: physical data linkage model construction, leakage component analysis, and economic analysis, and the applicability was evaluated for Zone H with branch type and the Zone M network type. As a result of the application, it was calculated that approximately 32.5 billion won would be required to achieve the target revenue water ratio of 70% in the Zone H, and approximately KRW 10.5 billion would be required to achieve the target revenue water ratio of 75% in the Zone M. If the business scale of Zones H and M was corrected to 10,000 ㎥/day of water usage, the required project cost for a 1% improvement in the revenue water ratio of Zone H was calculated to be 0.7642 billion won and 0.4715 billion won for Zone M.

This study set up the revenue water ratio that could be achieved within the range of the expenses of the water distribution network maintenance project, developed an analysis methodology that could estimate the additional project quantity to achieve the target revenue water ratio of 85% and applied and verified that to S. City. This methodology allowed the distribution of the leakage quantity for each leakage component by the pipeline through the total revenue water account balance analysis and BABE approach and the redistribution into the calculated leakage quantity more accurately through a step test. In addition, the level of reduction in leakage and the quantity of the project were estimated before and after the application of four strategies for the promotion of the revenue water ratio presented by IWA, according to the leakage components by the pipeline. As a result of the application of this analysis method to S. City, it would be possible to achieve up to the revenue water ratio of 81.0%, which was 74.7% in the beginning, if the water distribution network maintenance project was promoted within the range of the project expenses, and to achieve the revenue water ratio of 85.0%, the goal of the project, it would be necessary to replace the pipeline of 22.2% of the entire pipelines in the target area. As a result of the re-estimation of the revenue water ratio achievable, applying the actual water distribution network maintenance quantity in the scope of the business with the results of this analysis, the revenue water ratio was 81.7% while the actually measured revenue water ratio was 82.3%. Thus, the reliability of this analysis method could be secured to some extent.

In this study, we collect water control valves that have had accidents due to existing cracks, etc. are collected, and propose investigation items for strengthening the valve structural safety evaluation through a series of analyzes from valve specifications to physicochemical properties are proposed. The results of this study are as follows. First, there was a large variation in the thickness of the body or flange of the valves to be investigated, which is considered to be very important factor, because it may affect the safety of the valve body against internal pressure and the flange connected with the bolt nut. Second, 60% of the valves under investigation had many voids in the valve body and flange, etc. and the decrease in thickness due to corrosion was relatively large on the inner surface in contact with water rather than the outer surface. It is judged that the investigation of depth included voids is very important factor. Third, all valves to be investigated are made of gray cast iron foam, and therefore it is judged that there is no major problem in chemical composition. It is judged that the chemical composition should be investigated. Fourth, as a physical investigation item, the analysis of metal morphology structure seems to be a very important factor for nodular cast iron from rather than a gray cast iron foam water valve with a flake structure. As it was found to be 46.7~68.8% of the standard recommended by KS, it could have a direct effect on damage such as cracks, and therefore it is judged that the evaluation of tensile strength is very important in evaluating the safety of the valve.

This study set up the estimates of leakage management efficiency evaluation and leakage management goal that could be used in local water distribution networks efficiency business and modernization business. The data were analyzed using data envelopment analysis and multiple regression analysis. To this end, with leakage management input indices concerning leakage reduction activities (e.g., aged pipe replacement, water meter replacement, leakage restoration, and leakage detection) and leakage management calculation indices (e.g., the increase of revenue water ratio and the reduction of leakage ratio), the data on 22 K-water consignment local water supply systems were analyzed for the years from 2004 through 2018. Using the results of efficiency analysis by data envelopment analysis, the other DMUs (Decision Making Unit) benchmarked the DMU with the highest efficiency to maximize the leakage management efficiency for all DMUs. Through this, leakage management goal estimates were drawn with the input indices of four leakage reduction activities and calculation indices of the increase of revenue water ratio and the reduction of leakage ratio by multiple regression analysis for each group based on the revenue water ratio and leakage ratio. The correlation coefficients of the leakage management goal estimate for the criteria for the revenue water ratio amounted to 0.553 and 0.771. The correlation coefficients of the leakage management goal estimate for the criteria for leakage ratio were 0.397 and 0.865. Accordingly, we estimated the quantity and priority of four leakage reduction activities for the target leakage ratio and revenue water ratio.

The purpose of this study was to evaluate the corrosion damage of large diameter metallic pipes buried in reclaimed land due to the corrosion effect by soil, and to propose a method of installing metal pipes in the reclaimed land. The results are as follow. First, the soil of the reclaimed land was gray clay, the soil specific resistance indicating soil corrosiveness was at least 120 Ω-cm, the pH was weakly acidic(5.04 to 5.60), the redox potential was at least 62 mV, the moisture content was at most 48.8%, and chlorine ions and sulfate ions were up to 4,706.1 mg/kg and 420 mg/kg. Therefore, the overall soil corrosivity score was up to 19, and the external corrosion effect seems to be very large. Second, the condition of straight part of pipes was in good condition, but most of KP joints were affected by corrosion at a severe level. The reason for this seems to be that KP joints accelerated corrosion due to stress and crevice corrosion in addition to galvanic corrosion in the same environment. Third, as a result of evaluating correlations of each item that affects the corrosion on the external part, the lower the soil resistivity and redox potential, the greater the effect on the KP joints corrosion, and the moisture content, chloride ion, and sulfate ion, the higher the value, the greater the effect on the corrosion of KP joints. In addition, among soil corrosion items, the coefficient of determination of soil resistivity with corrosion of KP joints was the highest with 0.6439~0.7672. Fourth, when installing metal pipes or other accessories because the soil of the reclaimed land is highly corrosive, it is necessary to apply a corrosion preventive method to extend the life of pipes and prevent leakage accidents caused by corrosion damage to the joint.

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

In this study, air scouring cleaning was selected and applied among 5 small blocks (S1~S5) in domestic S cities to analyze the cleaning effect of particles causing discoloration. In order to identify the cleaning effect, 10 locations were selected as water quality investigation point, such as the stagnant or water mains ends. Removal of solids, variation of particle components, weight and concentration were analyzed. And the level of the cleanness of the surface inside water mains using endoscope was investigated. As a result of analysis, the solids discharged after cleaning were mainly sand and gravel, pieces related to pipe materials, and corrosion products. As a result of analyzing the concentrated particles of the filter before and after cleaning, it was found that the change in discoloration on the filter was large. In addition, as a result of comparing the weight and the concentration of the particles, it was found that the particles causing discoloration were significantly removed after cleaning. From the results of the endoscopy, it was confirmed that most of the precipitated and accumulated dark yellow discoloration matters inside water mains were removed through cleaning. Therefore, it seems that the particles causing discoloration in water decreased after cleaning. Therefore, it is expected that, if properly cleaning was applied, matters that cause discoloration can be removed from the water mains, and customer's complaints can also be reduced through water quality improvement.

This study would present a risk analysis method to evaluate stable tap water supply in a multi-regional water supply system and propose a measure for the evaluation of the effect of the conjunctive operation of the multi-regional water supply system using this. Judging from the vulnerability for the crisis response of the entire N. multi-regional water supply system, as compared to the result of Scenario 1 in which no conjunctive pipes were operated, it was found that in Scenario 2, in which conjunctive pipes were partially operated, the vulnerability of crisis response decreased by about 30.6%, and as compared to Scenario 3, the vulnerability of crisis response decreased by 86.2%. In setting a plan for stable tap water supply in N multi-regional water supply system, using the estimated value and the method for the evaluation of the vulnerability of crisis response by pipe, by interval and by line, it is judged that this can be utilized as a basis for the judgment of the evaluation of the operation or the additional installation of conjunctive pipes.

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.