Risk assessment method of level-induced water scarcity in the city located along rivers: Application in Nanchang, China

Abstract

In the context of global environmental changes, the problem of low water levels (LWLs) is becoming increasingly prominent and posing a significant threat to urban water security. At the same time, there have been noticeable changes in basin hydrological conditions, leading to compromised consistency of water level data based on historical monitoring. Assessing the adaptability of urban water intake projects to water level changes has become a challenging problem currently. Firstly, we have designed a new indicator with good consistency - velocity of water level descending (VWD). Secondly, we have interpreted the connotation of the risk of urban level-induced water scarcity (LIWS) based on the perspective of the coupling system of “water source - water intake engineering - the subsystem of urban water demand” (CSWWU). Thirdly, we constructed a risk assessment model of urban LIWS to quantify the possibility and consequences of adverse scenarios, aiming to enhance the city’s ability to respond to extreme events. Taking Nanchang as an example, we generated 972 preset scenarios, calculated the probability of all scenarios, and drew the risk map of LIWS. The results showed that: (1) When the water level of Nanchang Station descends to 10.33, 10.14 and 10.04 m, the water supply deficit of the urban water plant can be balanced by the saved water volume, which is released by activating three types of emergency measures, respectively. (2) The city faces the greatest risk of LIWS in January and February of each year, which is the key period of risk management. (3) By drawing a risk map, we have comprehensively evaluated the important scenarios about urban LIWS in the future. The risk assessment method for urban LIWS is based on the new indicator, which can provide theoretical support for urban emergency water supply management and promote local governments to fully utilize the resilience of coupling systems to adapt to constantly changing society and environment.