An assessment of uncontrolled human interventions on the contemporary sediment budget and morphological alterations of the Vu Gia Thu Bon River basin, central Vietnam.

The Vu Gia Thu Bon (VGTB) River basin is critical for regional development and prosperity in water resources. However, human interventions (e.g., dam construction and sand mining) have significantly affected this basin's sediment budget and morphological alterations over recent decades. Such humane actions drive an imbalance in water resources in the basin from upstream to downstream. Therefore, this study investigated spatiotemporal changes in sediment budget and morphology alterations using long-term data and bathymetric surveys; from these data, dams and sand mining contributions were quantified and differentiated. Based on field survey data and interviews, we estimated the sand-mining volume by incorporating reported and a newly proposed empirical formula. The results show that the total riverbed incision volume from 2010 to 2021 was 63.30 Mm3, with an incision rate of 0.14 m/yr. The officially reported sand-mining rate was 1.12 Mm3/yr, while the newly proposed empirical formula estimated 4.4 Mm3/yr. According to the developed empirical formula, the percentage reductions in the sediment budget due to sand mining and upstream dams were 69.7 % and 30.3 %, respectively, according to reports, and 17.8 % and 82.2 %. The statistical method was thus likely too conservative compared to the developed empirical formula. We found that the natural sediment supplies sourced from upstream were insufficient to compensate for the mined bed material. Therefore, our combination of different datasets permitted the assessment of future geomorphological developments within the VGTB River basin under the ongoing sediment deficits. The results of this study provide valuable insights into the impacts of human interventions, specifically sand mining, on the sediment budget, morphological alterations, and riverbed incision. The developed assessment forms the foundation for developing and expanding the region's water/sediment resource management strategies.

Quantifying the consequences of unsustainable sand mining and cascade dams on aspects in a tropical river basin.

Human interventions at the river basin scale, such as sand mining and hydropower dam construction, have profoundly affected hydrological and hydraulic alteration regimes, sediment budgets, and morphological changes worldwide. Quantifying the consequences of unsustainable ongoing sand mining and hydropower is crucial for obtaining sediment load data and managing hydrogeomorphology. In this study, comprehensive long-term consecutive four-field monitoring, statistical methods, and hydrological models (SWAT) were applied to quantify the spatiotemporal changes in long-term discharge and sediment load from 1996 to 2020 for the tropical river of the Vu Gia Thu Bon (VGTB) in the central region of Vietnam. The SWAT model was calibrated from 1996 to 2010, validated from 2011 to 2020 and showed good performance for daily discharge and monthly sediment. The evolution of river bathymetric data (2010, 2015, 2018, and 2021) was analysed to clarify the upstream sediment supply trapped in the riverbed and how the sand mining volume was removed. The results showed that the mean annual sediment in the Vu Gia and Thu Bon Rivers decreased by 57.3% and 23.8%, respectively, in the postdam period compared with the predam period. The thalweg elevation decreased at the Ai Nghia and Giao Thuy stations from 2010 to 2021 by 1.8 m and 3.9 m, respectively. The water level decreased by 21.1% at Ai Nghia and 44.3% at Giao Thuy. Dam development, sand mining, and changes in land use are the main factors responsible for flow discharge and sediment morphodynamic alterations. Morphological change have increased the water transfer rate from the Vu Gia River to the Thu Bon River through the Quang Hue channel. Downstream of the Vu Gia River, water transfer and riverbed incision have decreased flow discharge and water level and increased saltwater intrusion in recent years. As a result, water shortages induced by saltwater intrusion during drought periods have emerged as a significant constraint in hindering the domestic water supply and agricultural production.

Does tourism reduce the shadow economy? An international evidence.

This paper investigates one of the positive contributions of tourism to the economy through the lens of its influences on the shadow economy. Specifically, our study analyzes the effects of five indicators of tourism consumption (including domestic tourism spending, international travel and tourism consumption, business tourism spending, leisure tourism spending, and outbound tourism spending on the percentage of shadow economy to GDP) in 129 economies between 1996 and 2015. We find interesting results that contribute to the existing literature about tourism economics. Firstly, the development of the inbound tourism industry reduces the shadow economy significantly, while outbound tourism causes higher underground economic activities. Secondly, the influence of tourism on the shadow economy is significant in both the short-run and long run with a stronger effect in the long run. Thirdly, the effect of tourism on the shadow economy is more significant in the 42 High-Income Economies and 54 Low and Lower-middle Income Economies, while it is less obvious in the 33 Upper-Middle Income Economies. These findings have been checked by a battery of robustness checks ensuring their statistical consistency.

Financial development and energy poverty: global evidence.

This study aims to shed light on the determinants of energy poverty by examining the role of financial development. Notably, the study analyses the multidimensional effects of financial development (including two subsectors and three dimensions on five indicators of energy poverty). Various estimates are applied with a global sample of 65 economies, consisting of 36 low- and lower-middle-income economies and 29 upper-middle-income economies for 2002-2015. First, financial development can alleviate energy poverty. Second, the results are properly consistent across the two subsectors and three dimensions. Third, the two subsectors and three dimensions of financial development are found to reduce energy poverty in low- and lower-middle-income economies but have heteroscedastic effects in upper-middle-income economies.