Search Results (13)

Ecosystem service flows are critical linkages between ecological supply and human demand. As a vital component of ecosystem services, water yield service is essential for human survival and development. Therefore, it is of great significance to explore the supply–demand relationship of water yield service and its spatial flow process. This study investigates the supply–demand dynamics and spatial flow of water yield service in the transnational area of Tumen River (2000–2020), utilizing the InVEST model and the miniature delivery-path-mechanism model. The results show the following: (1) From 2000 to 2020, the supply of water yield service in the Tumen River Basin exhibited a spatial distribution pattern of “low center, high surrounding”, with significant spatial heterogeneity in the distribution of supply and demand. (2) Despite the substantial surplus of water yield service in the study area, the ecosystem service supply–demand ratio (ESDR) shows an overall declining trend. The dominant spatial mismatch type is high-supply–low-demand (HL type) zones, primarily located in mountainous and hilly areas, accounting for over 40% of the total identified pixel types. (3) Driven by economic and social development, the spatial scope of water yield service flow has gradually expanded. Supply-side flows initially increased before declining, while demand-side flows followed the opposite trend. By mapping ecosystem service flows, this study provides a reference and basis for establishing the regional ecological compensation mechanism and promoting integrated water resource management, both of which are crucial for the long-term sustainable development of the basin. Full article

Evaluating environmental sustainability in the transnational basin of the Tumen River (TBTR) is of great significance for promoting sustainable development in Northeast Asia. However, past research has mostly concentrated on a particular environmental element, making it impossible to thoroughly and effectively show the environmental sustainability dynamics in this transnational area. In this study, we attempted to reveal environmental sustainability trends in the TBTR from 2000 to 2021 using the Environmental Degradation Index (EDI) and analyze the driving forces using a geographical detector. It was found that the TBTR’s environmental sustainability decreased significantly, with a degraded region (13,174.75 km²) accounting for 31.01% of the whole area from 2000 to 2021. The dynamics of environmental sustainability on the three sides of China, the Democratic People’s Republic of Korea (DPRK), and Russia have shown significant differences, with the most significantly improved in environmental sustainability being the subregion of China. On the Chinese side, the area that significantly improved in environmental sustainability accounted for 26.19% of the area on the Chinese side, which was 1.17 times higher than that of the DPRK’s side and 1.24 times higher than that of the Russian side. Land use intensity (LUI), land use and land cover (LULC), and population density (PD) were the most dominant driving forces for environmental sustainability dynamics on the three sides of China, the DPRK, and Russia. China, the DPRK, and Russia can improve international environmental cooperation to promote sustainable development in the TBTR and Northeast Asia. Full article

The Mekong River is one of the most biodiverse, productive rivers in the world, supporting more than 1000 fish species and the livelihoods of tens of millions of people. The spatial dynamics and population status of many Mekong fish species, especially megafishes, are poorly understood. Therefore, this information is rarely incorporated into environmental risk assessments for large infrastructure projects, such as mainstream hydropower developments, which have been accelerating rapidly in the Mekong Basin. In this study, we present initial findings from the ongoing, collaborative, transnational acoustic telemetry monitoring of nearly 300 tagged fishes representing 27 species, which yield important insights into the potential impacts that proposed hydropower dams would have on populations of ecologically and economically important fish species. Included in these data are more than ten months of hydrophone records tracking the location of a 300 kg giant freshwater stingray, Urogymnus polylepis (Bleeker, 1852), currently the world’s largest known freshwater fish, used to detect its migration behavior and distribution patterns. The telemetry data, combined with fisher surveys used to gather local ecological knowledge, provide evidence that the proposed dams would fragment the existing populations of this iconic species as well as those of other fish species that support river food web balance and local food systems. Furthermore, the existence of giant freshwater stringray populations and other unique megafauna reinforces the universal natural heritage value of the stretch of the Mekong River between the Lao People’s Democratic Republic/Cambodia border and the city of Kratie. This stretch of river is located between two proposed megadams, the 900 MW Stung Treng Dam and the 2300 MW Sambor Dam. However, the Cambodian Ministry of Environment has also proposed this area for designation as a UNESCO World Heritage Site (Biosphere Reserve). The documentation of the movement of migratory fishes through this reach of the river using acoustic telemetry, the surprising discovery of the world’s largest freshwater fish, the potential threat posed by dam construction, and the management ramifications of UNESCO World Heritage Site designation underscore the importance of scientific research and community involvement in landscape-scale development decisions. The decisions made today will affect the fate of this global biodiversity hotspot, the world’s most productive inland fisheries, and the livelihoods of millions of people throughout the Lower Mekong Basin. Full article

Five countries share the catchment of the Tisza River (Central Europe). In most households electricity and water are available, and by washing synthetic clothes they can produce a large number of microfibers. However, in many sub-catchments of the river, the wastewater treatment is insufficient; therefore, microplastics (MP), especially plastic microfiber emissions into rivers, represent a problem. Our goal was to analyze the suspended sediment and microfiber transport at the low stage, making repeated (2021 and 2022) measurements in the Tisza River (946 km) at 26 sites across three countries. Water sampling was performed by pumping 1 m³ of water through sieves (90–200 µm). The mean MP transport in 2021 was 19 ± 13.6 items/m³, but it increased by 17% in 2022 (22.4 ± 14.8 items/m³). The most polluted sections were the Upper Tisza (Ukraine, Hungary) and the Lower Tisza (Serbia), where wastewater treatment is not satisfactory, whereas the Middle Tisza (Hungary) was less polluted. The tributaries increased the sediment and MP budget of the main river. Microfibers dominate (84–97%) the suspended MP transport, and thus it can be determined that they originated from wastewater. The MP transport was influenced by the availability of wastewater treatment plants, dams, tributaries, and mobilization of bottom sediments. At the low stage, no connection was found between the suspended sediment and MP particle transport. Full article

LIFE FLUVIAL project (LIFE16 NAT/ES/000771) is a transnational project between Spain and Portugal, whose overall objective is the improvement in the conservation of Atlantic Natura 2000 river corridors and associated wetlands, mainly targeting the 91E0* priority habitat. IAS have become one of the main threats to these ecosystems, as they affect the composition and structure of riverine habitats, as well as the decrease in their area. In this conference, we present the results and learned lessons of IAS elimination in several river basins (Miño, Mandeo, Mero, Barcés) of Galicia (NW Spain) by LIFE FLUVIAL, including herb (Cortaderia selloana, Crocosmia x crocosmiiflora, Delairea odorata), scrub (Tamarix gallica,) and tree (Eucalyptus spp., Acacia dealbata, Robinia pseudoacacia, Populus x canadensis, Salix viminalis) alien species. An integral strategy has been developed, as they have been removed from the upper and middle basin, as well as from estuaries, so LIFE FLUVIAL has a highly demonstrative character as it can be applied on a larger scale to similar situations, or elsewhere in similar circumstances. The project has refused to use herbicides because of the high fragility of the aquatic environment, nor are they a 100% effective method. Removing plant IAS through manual or light mechanical means has revealed the best practices to improve the conservation status of priority habitat 91E0* and river corridors, carrying out active and continuous management, because many of them have a high resprouting potential. Following this methodology, plant IAS can be completely eliminated, or at least controlled, as they are confined in very specific places from where they cannot disperse. In some cases, the eliminated plants (both herbaceous and woody plants) reached large sizes, which has been a major challenge when it comes to eliminating, handling and removing them. When this happened, the plant material was stacked and dried in an isolated place from which it cannot spread, to finally be removed for treatment by an authorized waste manager. In this regard, the herbaceous IAS have been valued as raw material in the economic system, undergoing treatment to obtain agricultural fertilizers; thus, the project has also contributed to the circular economy. Full article

At a global level, different land use change processes (changes in use, presence of invasive alien species, public use activities, intensification in agricultural and livestock activities, loss of compatible and low-intensity traditional uses, climate change, etc.) and phytosanitary problems (black alder disease) are currently threatening factors that generate, with different degrees of intensity, the deterioration and fragmentation of the habitats of river corridors, both in the upper and middle basin, as well as in the estuarine sections. LIFE FLUVIAL (LIFE16 NAT/ES/000771) develops a transnational strategy of sustainable management of river corridor habitats in several Atlantic river basins of the Iberian Peninsula (Spain and Portugal), so the overall objective is the improvement in the conservation status of Atlantic Natura 2000 river corridors and associated wetlands, mainly targeting the 91E0* priority habitat (alluvial forests with Alnus glutinosa and Fraxinus excelsior). Another target habitat is considered in the project, the habitat type 9230 Galician-Portuguese oak woods with Quercus robur and Quercus pyrenaica, which represents continuity with the 91E0* habitat type. To achieve the overall objective, a series of specific objectives are considered, which are designed to combat threats that contribute to habitat degradation: (1) implementation of a transnational model for sustainable management of river corridors for the improvement in their conservation status, through the restoration of the composition, structure and functionality of their types of habitats, as well as improving the connectivity and reduction in fragmentation; (2) control of exotic invasive alien plants; (3) improvement in the plant health of river corridors by the partial removal of dead trees; (4) promoting the dissemination and awareness of the natural values, socio-economic benefits and ecosystem services of river corridors; (5) improvement in training and technical capacity for stakeholders in the management and conservation of river corridors. To achieve these objectives, the project proposes a set of specific conservation actions that constitute a compendium of best practices in relation to the design and execution of viable and effective action measures to improve the conservation status of river corridors and contribute to halting the loss of biodiversity. Full article

The main objective of the LIFE Fluvial project is the improvement of the conservation status of Atlantic river corridors in the Natura 2000 network, developing a transnational strategy for the sustainable management of river corridor habitats in several Atlantic river basins of the Iberian Peninsula. The project includes seven partners in Northwest Spain (Galicia, Asturias) and one partner in Portugal (Instituto Superior de Agronomia). In Portugal, the preparatory, conservation, monitoring and dissemination actions of the project are focused on the improvement of the state of conservation of habitat 91E0* in the Estorãos River (ZEC Lima River, PTCON0020), with a total intervention area of circa 21 ha, within the property of the Municipality of Ponte de Lima. Special effort has been devoted to the control and removal of invasive plants directly affecting the riparian habitats, and indirectly affecting the aquatic habitats. The major target species addressed in ZEC Lima River are the trees Acacia melanoxylon, A. dealbata, invading the riparian zone; Eucalyptus camaldulensis plantations in the floodplains of Estorãos river; and the herbaceous species Phytolacca americana and Tradescantia fluminensis. The restoration measures were designed according to the spatial and temporal scale of threats and applied species-specific methods. This included the tree cut and control of vegetative sprouts (Eucalyptus), debarking and cut (Acacia spp.), and the uprooting of seedlings of invasive exotic individuals; complete uprooting of the individuals and the destruction of fruits (Phytolacca americana); and exposition to sunlight (Tradescantia fluminensis). An additional key action included Public Awareness and Dissemination. Throughout the development of the project, knowledge transfer to different target audiences was promoted, and several didactic materials, including an online game for children, were produced. For the general public, the project created a website, in four languages, and different social media pages, TV programs, promotional videos and an annual bulletin, and celebrated several events used for awareness-raising (e.g., World Wetlands Day in 2018, or Natura 2000 day). Notably, for invasive species control and awareness, we promoted training and volunteer actions that engaged students, technicians, NGOs and other relevant stakeholders. The major lessons learned are to be followed up during the After Life period. Full article

Satellite precipitation estimation provides crucial information for those places lacking rainfall observations from ground–based sensors, especially in terrestrial or marine areas with complex climatic or topographic conditions. This is the case over much of Western China, including Upper and Middle Lancang River Basin (UMLRB), an extremely important transnational river system in Asia (the Lancang–Mekong River Basin) with complex climate and topography that has limited long–term precipitation records and high–elevation data, and no operational weather radars. In this study, we evaluated three GPM IMERG satellite precipitation estimation (IMERG E, IMERG L and IMERG F) over UMLRB in terms of multi–year average precipitation distribution, amplitude consistency, occurrence consistency, and elevation–dependence in both dry and wet seasons. Results demonstrated that monsoon and solid precipitation mainly affected amplitude consistency of precipitation, aerosol affected occurrence consistency of precipitation, and topography and wind–induced errors affected elevation dependence. The amplitude and occurrence consistency of precipitation were best in wet seasons in the Climate Transition Zone and worst in dry seasons in the same zone. Regardless of the elevation–dependence of amplitude or occurrence in dry and wet seasons, the dry season in the Alpine Canyon Area was most positively dependent and most significant. More significant elevation–dependence was correlated with worse IMERG performance. The Local Weighted Regression (LOWERG) model showed a nonlinear relationship between precipitation and elevation in both seasons. The amplitude consistency and occurrence consistency of both seasons worsened with increasing precipitation intensity and was worst for extreme precipitation cases. IMERG F had great potential for application to hydroclimatic research and water resources assessment in the study area. Further research should assess how the dependence of IMERG’s spatial performance on climate and topography could guide improvements in global precipitation assessment algorithms and the study of mountain landslides, floods, and other natural disasters during the monsoon period. Full article

Seismically triggered landslides are a major hazard and have caused severe secondary losses. This problem is especially important in the seismic prone Mailuu-Suu catchment in Kyrgyzstan, as it hosts disproportionately sensitive active or legacy uranium sites with deposited radioactive extractive wastes. These sites show a quasi-continuous release of radioactive contamination into surface waters, and especially after natural hazards, a sudden and massive input of pollutants into the surface waters is expected. However, landslides of contaminated sediments into surface waters represent a substantial exposure pathway that has not been properly addressed in the existing river basin management to date. To fill this gap, satellite imagery was massively employed to extract topography and geometric information, and the seismic Scoops3D and the one-dimensional numerical model, Hydrologic Engineering Centre, River Analysis System (HEC-RAS), were chosen to simulate the landslide-induced mass transport of total suspended solids (TSS) and natural radionuclides (Pb-210 as a proxy for modeling purposes) within the Mailuu-Suu river networks under two earthquake and two hydrological scenarios. The results show that the seismically vulnerable areas dominated in the upstream areas, and the mass of landslides increased dramatically with the increase of earthquake levels. After the landslides, the concentrations of radionuclides increased suddenly and dramatically. The peak values decreased along the longitudinal gradient of river networks, with the concentration curves becoming flat and wide in the downstream sections, and the transport speed of radionuclides decreased along the river networks. The conclusions of this study are that landslides commonly release a significant amount of pollutants with a relatively fast transport along river networks. Improved quantitative understanding of waterborne pollution dispersion across national borders will contribute to better co-ordination between governments and regulatory authorities of riparian states and, consequently, to future prevention of transnational political conflicts that have flared up in the last two decades over alleged pollution of transboundary water bodies. Full article

The Brahmaputra is one of the largest river systems of South Asia, providing life-supporting services to about 70 million people. Massive flooding, land erosion, over-exploitation of water, excessive fishing, habitat degradation and fragmentation, exploitation of flood plains, climate change impacts, absence of integrated basin wide management, and transboundary cooperation are major challenges for the present and future sustainability and development in the basin. Although hydrological connectivity is intact in most of the main course of the river, the infrastructure development plans may convert the Brahmaputra to a predominantly managed river system. In this regard, this paper examines the physiographic, ecological, hydrological, and socioeconomic status of the Brahmaputra river, its transnational basin in South Asia, and the basin population in the cross-cutting context to explore its sustainable management options. For a durable future of the river and its communities, an integrated management mechanism among the basin countries with the objective of equitable benefit sharing, disaster risk management, and resilience building is needed. The suggested strategies will help in maintaining the ecohydrological health and utilitarian services of the river for the socioeconomic development of millions of poor and marginalized people living in the basin. Full article

Numerous ephemeral rivers and thousands of natural pans characterize the transboundary Iishana-System of the Cuvelai Basin between Namibia and Angola. After the rainy season, surface water stored in pans is often the only affordable water source for many people in rural areas. High inter- and intra-annual rainfall variations in this semiarid environment provoke years of extreme flood events and long periods of droughts. Thus, the issue of water availability is playing an increasingly important role in one of the most densely populated and fastest growing regions in southwestern Africa. Currently, there is no transnational approach to quantifying the potential storage and supply functions of the Iishana-System. To bridge these knowledge gaps and to increase the resilience of the local people’s livelihood, suitable pans for expansion as intermediate storage were identified and their metrics determined. Therefore, a modified Blue Spot Analysis was performed, based on the high-resolution TanDEM-X digital elevation model. Further, surface area–volume ratio calculations were accomplished for finding suitable augmentation sites in a first step. The potential water storage volume of more than 190,000 pans was calculated at 1.9 km³. Over 2200 pans were identified for potential expansion to facilitate increased water supply and flood protection in the future. Full article

Interactions among nitrogen (N) management and water resources quality are complex and enhanced in transboundary river basins. This is the case of Tagus River, which is an important river flowing from Spain to Portugal in the Iberian Peninsula. The aim was to provide a N assessment review along the Tagus River Basin regarding mostly agriculture, livestock, and urban activities. To estimate reactive nitrogen (N_r) load into surface waters, emission factor approaches were applied. N_r pressures are much higher in Spain than in Portugal (~13 times), which is mostly because of livestock intensification. Some policy and technical measures have been defined aiming at solving this problem. Main policy responses were the designation of Nitrate Vulnerable and Sensitive Zones, according to European Union (EU) directives. Nitrate Vulnerable Zone comprise approximately one third of both territories. On the contrary, Sensitive Zones are more extended in Spain, attaining 60% of the watershed, against only 30% in Portugal. Technical measures comprised advanced urban and industrial wastewater treatment that was designed to remove N compounds before discharge in the water bodies. Given this assessment, Tagus River Basin sustainability can only be guaranteed through load inputs reductions and effective transnational management processes of water flows. Full article

Southwest China’s Yunnan province is evolving into one of the world’s largest hydro-power-producing regions. It already rivals the world’s largest hydro-producing nations. However, five of Yunnan’s six basins are international and therefore its hydropower development is of great academic and geopolitical interest. While the implementation of large projects on Yunnan’s three large rivers (Jinsha, Mekong and Nu) is relatively well studied, hydropower development outside these three main streams is hardly known. Here, we identified 128 large hydropower projects (≥50 MW) having a capacity of 16.5 GW, along with another 16.4 GW of other types of power generation, neither of which has been discussed in the academic literature yet. The paper utilizes a powershed approach to study the rapid hydropower development underway in Yunnan, both in its implication and challenges (at basin and administrative level) as well as in its trade-offs within the broader electricity context. Yunnan’s power generation and consumption patterns are characterized by diverging interests of local/provincial usage and export utilization. Within the province, the largest (hydro-) power users are energy/electricity intensive industries, which themselves have strong impacts on land use changes. Yunnan is also evolving as a major power exporter, already in 2013 exporting about one-third of its generated electricity mainly to Guangdong’s Pearl River Delta. We see a need for a critical revision of those existing generation and consumption paradigms, which includes a rethinking of major development modes, both in terms of future hydropower generation and utilization projects as well as export obligations. Full article