Leak detection and location in water distribution systems (WDSs) is of utmost importance for reducing water loss, which is, however, a major challenge for water utility companies. To this end, researchers have proposed a multitude of methods to detect such leaks in WDSs. Model-based and data-driven approaches, in particular, have found widespread uses in this area. In this paper, we reviewed both these approaches and classified the techniques used by them according to their leak detection methods. It is seen that model-based approaches require highly calibrated hydraulic models, and their accuracies are sensitive to modeling and measurement uncertainties. On the contrary, data-driven approaches do not require an in-depth understanding of the WDS. However, they tend to result in high false positive rates. Furthermore, neither of these approaches can handle anomalous variations caused by unexpected water demands.

The area covered by the four lakes in the Zhuonai Lake–Salt Lake Basin in Hoh Xil (Zhuonai Lake, Kusai Lake, Heidinor Lake, and Salt Lake) has changed significantly over the past 30 years. In this study, remote sensing image data gathered via the Landsat thematic mapper, enhanced thematic mapper plus, and operational land imager from 1989 to 2018 were used to extract the areal parameters of four lakes. The total area of the four lakes had increased by 18% in the past 30 years due to climate change. Interpolated results based on the meteorological data from 28 meteorological stations in the basin were used for trend analysis. A single-layer lake evaporation model was utilized to study the changes in the annual lake evaporation in the basin. The annual lake evaporation slightly increased from 1989 to 1995, followed by a sharp decrease from 1995 to 2018. From 1989 to 2018, the annual evaporation in the basin ranged between 615.37 and 921.66 mm, with a mean of 769.73 mm. A mass balance model was developed to estimate the changes in the lake volumes due to precipitation and evaporation. The increase in precipitation and the decrease in the annual lake evaporation promote the expansion of the four lakes. Lake evaporation is the main factor inducing changes in the lake areas.

The evaluation of building damage is of great significance for flood management. Chinese floodplains usually contain small- and medium-sized towns with many other scattered buildings. Detailed building information is usually scarce, making it difficult to evaluate flood damage. We developed an evaluation method for building damage by using airborne LiDAR data to obtain large-area, high-precision building information and digital elevation models (DEMs) for potentially affected areas. These data were then used to develop a two-dimensional (2-D) flood routing model. Next, flood loss rate curves were generated by fitting historical damage data to allow rapid evaluation of single-building losses. Finally, we conducted an empirical study based on the Gongshuangcha detention basin in China’s Dongting Lake region. The results showed that the use of airborne LiDAR data for flood-related building damage evaluation can improve the assessment accuracy and efficiency; this approach is especially suitable for rural areas where building information is scarce.