ALBERT

Description: As one of the hotspots for natural disaster studies on Earth, Qinghai-Tibet Plateau (QTP) is highly vulnerable to destructive rainstorm hazard and related natural disasters, which seriously threaten people’s lives and properties, environment, ecosystems and its downstream regions. Short-duration heavy precipitation at sub-daily scales is an important trigger for flash flood, landslide, debris flows and other disasters in QTP. However, it is a typical ungauged high mountain region, observed data for sub-daily precipitation is extremely limited. Although there have been several satellite products for sub-daily precipitation in QTP, their quality has large bias, leaving a large data gap for supporting rainstorm-related natural disaster studies in the region.The objective of this study is two-fold. We develop a new strategy to quantify the “temporal structure” of precipitation at sub-daily scales, as a basis of temporal downscaling. Then we use the new strategy to fill the data gap of sub-daily precipitation in QTP based on daily precipitation and geographical information. Findings show that the temporal structure of precipitation at sub-daily scales can be well described by a logarithmic function, and its uncertainty can be quantified by coefficient of variance and coefficient of skewness, whose values are estimated by a logarithmic and a linear function, respectively. The six parameters in the above three functions are found to be closely related to geographical conditions, which allows a 1-km parameters dataset to be created. The parameters dataset has the potential for wide applications in estimating sub-daily precipitation and supporting natural disasters studies in QTP.

Description: Rainwater harvesting systems (RHS) are implemented to deal with regional water scarcity and stormwater control problems for sustainable urban development. However, there have been limited studies on the regionalization of water saving, stormwater control and financial performances of RHS. In this study, a hydro-economic model is adopted to investigate regional water saving, stormwater control and economic performances of RHS by proposing a regionalization approach. We use the daily observed rainfall data from 77 stations across the Beijing region in China to develop and test the proposed regionalization approach. The multi-storey residential building with a roof area of 1000 m2 and the lawn area of 2000 m2 for 100 residents is considered. Three water demands (lawn irrigation, toilet flushing, and their combined demand) are evaluated. The economic analysis demonstrates that 10 m3 tank size of RHS provides the highest benefit-cost ratio values compared to other tank sizes across the Beijing region. The results of water saving performance indicators (water saving efficiency (WSE) and reliability(R)) display substantial regional differences, with the threshold values ranging from 5% to 53% for 10 m3 tank size of RHS. Locations in mountain area have smaller threshold values of WSE and R, whereas locations in northeast suburban and urban areas have larger threshold values. RHS with 10 m3 tank size show regional variations in stormwater capture efficiency (SCE), with the threshold values varying from 31% to 72%, respectively. Higher SCE is achieved in mountain area, while lower SCE is obtained in the northeast suburban and urban areas.

Description: On 6 February 2023, an M〈sub〉W〈/sub〉 7.8 earthquake occurred on the southwestern part of the East Anatolian Fault zone (EAF), followed by an M〈sub〉W〈/sub〉 7.5 at ~100 km away on the East-West striking Sürgü fault 9 hours later. The W-Phase inversions indicate major strike-slip with dip angles of 60° for both events. A notable difference in seismic waveforms between two major earthquakes suggests different rupture characteristics. High-frequency back projection images for the M〈sub〉W〈/sub〉 7.8 event from the dense broadband ChinArray shows a NE unilateral rupture from the onset for 40 sec with the expansion to the EAF trace since ~20 s and stopping at the junction of EAF and Sürgü fault, along with some late radiation at ~40-60 s to SW at the Amanos segment of EAF. The back projection image for the M〈sub〉W〈/sub〉 7.5 event shows a main high-frequency coherent energy release for the first 10 sec over ~40 km and late weak radiations to the west near the curved Cardak fault and to the east near the Malatya fault. Preliminary slip models inverted from teleseismic data indicate a complex rupture for the M〈sub〉W〈/sub〉 7.8 event predominantly on the EAF and a localized slip for the M〈sub〉W〈/sub〉 7.5 event. The difference also exhibits in body-wave magnitude with m〈sub〉B〈/sub〉=7.5 for the M〈sub〉W〈/sub〉 7.5 and m〈sub〉B〈/sub〉=7.2 for the M〈sub〉W〈/sub〉 7.8 events. We are exploring InSAR images, hr-GNSS, and strong-motion data to constrain details in the rupture process of both events.

Description: Variability of water balance in closed lakes in the Tibetan Plateau (TP) can be a useful indicator of climate change. Located in the Southern TP, the lake of the Yamzho Yumco (YY) is one of the “three holy lakes” of Tibet, and its water level drastically declined by more than 5.00 m over the last four decades, differing from the stable variations or weak decreasing trends in other lakes in the surrounding region. The decline in water storage of YY has disastrous influence on the fragile ecological systems, as well as the agriculture and livestock development in the basin. The abnormal phenomenon has been attracting extensive concerns. Previous studies mainly attributed the water decline of YY to the climatic variability, that is, due to precipitation decrease and evaporation increase. However, the results may not be reliable due to the limited observed data. Moreover, these studies have neglected the impacts of human activities (especially the operation of the pumped‐storage hydropower station) on the lake, without which the change of water level of YY may not be completely explained. Therefore, by collecting more observed hydroclimatic data including lake surface evaporation data over the last four decades, this study focuses on re-attributing the water level declines to various factors with the help of a physically based and a statistical model for the water balance of the lake. The key question to be clarified is: Are the lake level changes caused by climatic variability or human activity, or both in different periods?