Sewage network operational risks based on InfoWorks ICM with nodal flow diurnal patterns under NPIs for COVID-19.

Non-Pharmaceutical Interventions (NPIs) have been widely employed globally over the past three years to control the rapid spread of coronavirus disease 2019 (COVID-19). These measures have imposed restrictions on urban residents' activities and significantly influenced sewage discharge characteristics within sewage network, particularly in densely populated cities in China. This study focused on the nodal flow diurnal patterns and sewage network operational risks before and after epidemic lockdown in Beijing from March to May in 2022. Nodal flow diurnal patterns on weekdays and weekends before and after NPIs were analyzed using measured data through statistical and mathematical methods. A sewage network model was established to simulate and analyze the operational risks based on InfoWorks ICM before and after epidemic lockdown. The main conclusions were as follows: (1) In predominantly residential areas, the total wastewater volume increased by approximately 28.76 % to 33.52 % after the implementation of strict NPIs. The morning and midday "M" peaks on normalized weekdays transformed into "N" peaks, and the morning peak time was delayed by 0.5 to 1 hour after the lockdown; (2) Following NPIs, More than 90 % of manholes' average water levels rose to varying degrees, approximately 50 % of pipe lengths exhibited a full flow state; (3) When the lockdown was in place during a hot summer day, sewage overflow phenomena were observed in 4.6 % and 9.6 % of manholes, respectively, with per capita daily drainage equivalent reaching 40-50 %. These findings hold significant implications for the proactive planning and operational management of water industry infrastructure during major emergencies.

Site prioritization and performance assessment of groundwater monitoring network by using information-based methodology.

The arbitrary distribution of groundwater monitoring sites and the redundancy of observation data restrict the ability of monitoring network to provide reliable and effective data information. The purpose of this study is aimed at finding a quantitative method to screen ideal monitoring locations and evaluate the efficiency of the monitoring network. In terms of site selection, we use hydrogeological information, monitoring density and monitoring location to select the suitable site to monitor groundwater quality, understand the temporal trends and identify the abnormal signals of pollution sources. To evaluate the efficiency of monitoring network we used the groundwater quality data for consecutive years to evaluate the groundwater monitoring network based on information entropy and principal component analysis (PCA). The results show that the optimized groundwater monitoring network is comprised of 10 monitoring wells. The efficiency evaluation results of information entropy and PCA are basically consistent. The maximum mutual information (T) and comprehensive index of monitoring site (Laiguangying) were 1.29 and 3.25 respectively, while the minimum T and comprehensive index of monitoring site (Jinzhan) were 1.05 and -0.36 respectively, and the data efficiency was low. This study provides a good example for optimizing a groundwater pollution monitoring network.

Evaluation of Groundwater Using an Integrated Approach of Entropy Weight and Stochastic Simulation: A Case Study in East Region of Beijing.

Groundwater is an important source of water in Beijing. Hydrochemical composition and water quality are the key factors to determine the availability of groundwater. Therefore, an improved integrated weight water quality index approach (IWQI) combining the entropy weight method and the stochastic simulation method is proposed. Through systematic investigation of groundwater chemical composition in different periods, using a hydrogeochemical diagram, multivariate statistics and spatial interpolation analysis, the spatial evolution characteristics and genetic mechanism of groundwater chemistry are discussed. The results show that the groundwater in the study area is weakly alkaline and low mineralized water. The south part of the study area showed higher concentrations of total dissolved solids, total hardness and NO3--N in the dry season and wet season, and the main hydrochemical types are HCO3--Ca and HCO3--Ca-Mg. The natural source mechanism of the groundwater chemical components in Chaoyang District includes rock weathering, dissolution and cation exchange, while the human-made sources are mainly residents and industrial activities. Improved IWQI evaluation results indicate that water quality decreases from southwest to northeast along groundwater flow path. The water quality index (WQI) method cannot reflect the trend of groundwater. Sensitivity analysis indicated that the improved IWQI method could describe the overall water quality reliably, accurately and stably.

Mechanisms and Empirical Modeling of Evaporation from Hardened Surfaces in Urban Areas.

Urban evaporation, as an essential part of local water vapor resources in urban areas, has often been underestimated. One possible reason is that the evaporation of urban hardened surfaces is seldom considered and poorly understood in urban evaporation estimation. This study focused on the mechanisms and calculation of evaporation on hardened surfaces in urban areas. Experimental monitoring was used to monitor the processes and characteristics of evaporation on hardened surfaces. Mathematical models based on water quantity constraints were built to calculate evaporation of hardened surfaces. The results showed that: The interception abilities for rainwater and rainfall days of impervious hardened surfaces determine their evaporated water amount, which means no water, no evaporation for the impervious surfaces. The greater evaporation of artificial sprinkling on roads happened in fewer days of rainfall and frost. The evaporation of pervious hardened ground is continuous compared to the impervious surface. Its soil moisture in the sub-layer of permeable concrete decreases periodically with a period of one day. The evaporation of hardened surfaces occupies 16-29% of the total amount of evaporation in the built-up areas in cities. Therefore, the hardened surface evaporation has great significance on the urban hydrological cycle and urban water balance.