Climate change impact on groundwater recharge and suggested adaptation strategies for selected Asian citiesCurrently, 54% of the world's population live in urban areas, and this figure is expected to increase to 66% by 2050. Major cities and municipalities in the region rely either wholly or partially on groundwater. Four Asian cities, namely Bangkok, Bandung, Ho Chi Minh City, and Lahore, are selected for the study as their groundwater dependency is in the critical range of 45% to 100%. Therefore, this study aims to assess current and future climate, quantify changes in climatic drivers, analyse the vulnerability of groundwater recharge systems to such changes, and then formulate adaptation strategies to reduce the vulnerability to groundwater resources in these cities. The methodology includes model-backed analysis of groundwater recharge vulnerability, which is later discussed with stakeholders (policymakers, scientists, and local water users) to prescribe possible adaptation options. The results show that Ho Chi Minh City and Bandung will receive less rainfall and Lahore and Bangkok more rainfall in the future. Bangkok is the only city in which minor fluctuations in future temperature is observed, while the remainder have significant increases (up to 3.1 °C). In line with the rainfall projections, Ho Chi Minh City and Bandung are projected to experience decreased groundwater recharge while the other two cities, Bangkok and Lahore are expected to have higher groundwater recharge in future.Groundwater, Climate change, Bangkok,

Despite being a simple and inexpensive pretreatment technology, the cost-effectiveness of riverbank filtration (RBF) depends on complex hydrogeological and hydrogeochemical variables. One of the most important issues for decision makers regarding RBF is optimal site selection. Therefore, a methodology for multicriteria site evaluation for large-scale RBF schemes is offered. The methodology is primarily designed as a prescreening method, applied over a wide area, but can also serve as a guide for evaluating individual RBF sites. To facilitate further discussion about improvements on the methodology, the reasoning behind each relevant factor and its weight in the evaluation is presented. The methodology is divided into three sequential steps through which a site can be assessed. The first step is to establish the existence of connectivity between the river and aquifer. This is termed the essential criterion, and is a binary determination of site suitability. If the site is determined to be suitable, it is then assessed via a set of quantity criteria, which measure the aquifer capacity and amount of bank filtrate that can be effectively abstracted. Lastly, water quality criteria are assessed by means of surface-water and groundwater quality. The quantity and quality criteria form a result expressed as the site suitability index (SSI), which ranges from 0 to 1, where higher scores represent increased suitability. Finally, the methodology is applied to evaluate existing sites of large-scale RBF application as a demonstration of its applicability. The success of these existing sites is compared to the calculated SSI value and discussed.