Local Hydrology Research Articles

Compound Climate Extremes Under the Future Climate Change Scenarios: A Case Study of Chattogram City, Bangladesh

ABSTRACTWaterlogging during the monsoon and water shortness during the pre‐monsoon are increasingly affecting the socio‐economic condition of Chattogram City. It is suspected that, climate change will lead frequent occurrence of compound climate extremes in future, which may result in greater destructions compared to those caused by individual extremes alone. Hence, it is of particular interest to predict the future climate more precisely. In this study our effort was to improve the understanding the effects of climate change on future compound climate extremes, the trends, variabilities and seasonal patterns. Here, we have evaluated CMIP5 and CMIP6 models from the high resolution bias corrected CORDEX data, and the best performing data sets (CanESM2, CSIRO and GFDL) were selected for the future climate change analysis. Using both RCP 4.5 and RCP 8.5 scenarios for 2021–2060, and 2061–2099 period, significant upward trends were projected for the daily maximum and minimum temperatures. However, rainfall pattern showed more complex criteria for the future. The current study revealed that the warm and cold spell, as well as the wet and dry spell characteristics will be altered in the future. The joint analysis of future temperature and rainfall anomalies using copulas revealed two folds effects of climate change on the local hydrology. Projected decrease of rainfall while increase of temperature during the pre‐monsoon season will potentially cause water scarcity. On the other hand, increase of extreme rainfall during the monsoon will complicate the waterlogging problems in Chattogram region. In this study, we have identified the time and the extent of combined temperature and rainfall anomalies, that can amplify the adverse impact on the hydro‐climatology of Chattogram City. The insights gained from this study are crucial for effectively addressing and managing the complex future hydroclimatic challenges in this region.

Optimizing Visibility of Historical Structures Using mWDE: Insights from the Kromni Valley, Gümüşhane, Türkiye

It is very important for historical structures to see each other in order to reveal the historical and cultural identity of a region. Historical structures in the Kromni Valley of Gümüşhane, located near the Sümela Monastery, served as places of worship, communication, trade, and social activity centers during their period of active use. This study analyses the spatial relationships of 38 historic buildings, including churches, chapels and castles, whose 3D models are created by in-situ measurements and point clouds obtained by unmanned aerial vehicles, using a 3D viewshed analysis using geographic information systems and remote sensing data. The research introduces a modified weighted differential evolution-based viewshed analysis (mWDE-WS) to enhance the visibility of these structures. In order to assess the applicability of the proposed method, a statistical comparison was conducted between four different Differential Evolution (DE) algorithms (standard DE, LSHADE, CobiDE, JADE and WDE) and the mWDE. The Wilcoxon signed-rank test indicates that mWDE is a more effective solution than alternative methods for addressing the relevant real-world issues. The study also integrates drainage network analysis to assess flood risks and the relationship between cultural structures and water flow. Findings show that historical structures in the region were built not randomly but within a rational approach and 64% of the study area is visible from structures and 2% of the area is visible from ten or more structures. mWDE-WS analysis revealed that the visible area could increase by 20% to 84.37% if the historic structures were placed in optimal locations. In addition, the historical structures were built away from 3rd order streams to minimize flood risk and humidity, demonstrating the community's awareness of the local topography and hydrology

Decomposing the Tea Bag Index and finding slower organic matter loss rates at higher elevations and deeper soil horizons in a minerogenic salt marsh

Abstract. Environmental gradients can affect organic matter decay within and across wetlands and contribute to spatial heterogeneity in soil carbon stocks. We tested the sensitivity of decay rates to tidal flooding and soil depth in a minerogenic salt marsh using the Tea Bag Index (TBI). Tea bags were buried at 10 and 50 cm depths across an elevation gradient in a subtropical Spartina alterniflora marsh in Georgia (USA). Plant and animal communities and soil properties were characterized once, while replicate tea bags and porewaters were collected several times over 1 year. TBI decay rates were faster than prior litterbag studies in the same marsh, largely due to rapid green tea loss. Rooibos tea decay rates were more comparable to natural marsh litter, potentially suggesting that is more useful as a standardized organic matter proxy than green tea. Decay was slowest at higher marsh elevations and not consistently related to other biotic (e.g., plants, crab burrows) or abiotic factors (e.g., porewater chemistry), indicating that local hydrology strongly affected organic matter loss rates. TBI rates were 32 %–118 % faster in the 10 cm horizon than at 50 cm. Rates were fastest in the first 3 months and slowed 54 %–60 % at both depths between 3 and 6 months. Rates slowed further between 6 and 12 months, but this was more muted at 10 cm (17 %) compared to 50 cm (50 %). Slower rates at depth and with time were unlikely due to the TBI stabilization factor, which was similar across depths and decreased from 6 to 12 months. Slower decay at 50 cm demonstrates that rates were constrained by environmental conditions in the deeper horizon rather than the composition of this highly standardized litter. Overall, these patterns suggest that hydrological setting, which affects oxidant introduction and reactant removal and is often overlooked in marsh decomposition studies, may be a particularly important control on organic matter loss in the short term (3–12 months).

The Influence of Seismic Lines on Local Hydrology and Snow Accumulation in the Boreal Region of Northern Alberta

ABSTRACTSeismic lines are 1.5 to 10 m wide linear corridors associated with petroleum exploration that fragment the landscape of northern Alberta. After clearing, seismic lines frequently exhibit low seedling recruitment and growth rates, due in part to the altered hydrologic conditions on the line. This research quantifies how seismic lines alter soil hydrophysical properties, hydrologic properties and snow accumulation patterns at two sites south of Fort McMurray, Alberta. During 2021 and 2022, water table levels were measured weekly during the summer months and were paired with measurements of soil properties (bulk density, saturated hydraulic conductivity, porosity and specific yield) on seismic lines and in the adjacent matrix. Bulk density increased on seismic lines by 19% and 113% in lowland and upland ecosystems, respectively. Saturated hydraulic conductivity decreased on seismic lines by one order of magnitude for both upland and lowland ecosystems. Water table variability was increased on seismic lines, but depth to water table was related to external factors such as topographic position. Snow measurements in March 2022 indicated that snow water equivalent was greater on seismic lines that were oriented in the East–West (EW) direction and on lines that were widest compared to SWE within the adjacent matrix. Our results provide information to researchers and industry on the alteration of important ecosystem factors on seismic lines that may limit line recovery trajectories. This information will help to guide restoration planning decisions through an enhanced knowledge of limiting factors for vegetation growth on seismic lines.

Long-term effects of underground mining on surface soil moisture and vegetation environment: evidence from the Xishan mining area.

This research aims to study the prolonged effects of underground mining on the ecological environment, particularly on surface soil moisture (SM) and fractional vegetation cover (FVC). Using 21years of data (2000-2020) from the Xishan mining area, a novel quantitative relational model was developed to disentangle the effects of mining activities from those of climate, soil type, and topography. The findings reveal that climatic factors, such as precipitation and air temperature, have significant effects on SM and FVC, while soil type and topographic features are important factors affecting SM and FVC. After years of data analysis, when controlling for factors such as climate, soil, and topography, there were no significant differences in the effects of different mining areas and types of mining activities on SM and FVC. This suggests that the disturbance of mining activities themselves on local hydrology and ecological environment did not exceed the impact range of climate change, surface characteristic changes, and their own restoration capacity. These research findings offer a comprehensive perspective for understanding the impacts of underground mining activities on ecological landscapes and provide a scientific basis for developing effective strategies for ecological conservation and rehabilitation.

Linking the Flow Regime of Papyrus‐Dominated Wetlands to Biologically Relevant Hydrologic Attributes

ABSTRACTThe dominant plant species in many African wetlands is Cyperus papyrus. Its adaptation to saturated and low‐oxygen conditions and its dense structure and height provide breeding and feeding grounds for unique flora and fauna. As a keystone species adapted to local hydrology, the flooding regime of papyrus offers the full range of hydrologic conditions and events essential to ecosystem health. However, no study has attempted to link papyrus wetlands' flow regimes to their biologically relevant hydrologic attributes. This study assesses hydrologic alterations of a papyrus wetland's flow regime due to rice irrigation. We develop a conceptual ecological model linking papyrus to hydrologic attributes to determine the consequences of changed environmental flow components (EFCs) on papyrus as a habitat. We find that agricultural water management considerably alters the magnitude, duration, timing and rate of change of EFCs, which could affect productivity (seed dispersal, germination and establishment; rhizome spreading; papyrus distribution across transects; and dispersal of floating mats) in papyrus wetlands. However, the effect on the papyrus wetlands' natural pulsed regime is negligible when the ratio of irrigated area to catchment area is no greater than 1:150. Overall, a better understanding of the threats of water diversion for agriculture is made by linking papyrus' flow regimes to biologically relevant hydrologic attributes. Knowledge of the roles of the various EFCs could provide opportunities for conserving and protecting papyrus wetlands, especially for systems at risk of altered flows.

Radiocarbon dating and isotopic paleoecology of Notiomastodon platensis (Mammalia: Proboscidea) from the late Pleistocene of Minas Gerais, Brazil

Proboscidea is a group of large mammals abundant in the fossil record and in Brazil it is represented by Notiomastodon platensis (Ameghino, 1888). To improve the understanding on its taxonomy, chronology, annual diet, and habitats paleoenvironmental aspects, we conducted a morphological description, absolute dating, and analysis of stable isotopes of carbon and oxygen (δ13C and δ18O) in Notiomastodon' remains from the northern (Norte de Minas) and western (Triângulo Mineiro) mesoregions of Minas Gerais State, Brazil. The material includes isolated teeth, mandibular portions, and postcranial bones at different levels of fragmentation, associated with at least eight adults and one juvenile. The only individual from Triângulo, found in Campina Verde municipality, was dated at 27,715–27,903 Cal yr BP. It presented a mixed diet based on C4 plants (piC4 = 90 %; δ13C = 0.5 ‰), which implies the occupation of an open environment, mostly pasture. The region was relatively humid (δ18O = 24.7 ‰), which is supported by the existence of humidity corridors in the Amazon region. A similar phytophysiognomy was inferred for the Norte de Minas region between at least 21,966–22,279 Cal yr BP and 18,944–19,157 Cal yr BP. However, one specimen showed a different δ13C value (piC3 = 0.87 %; δ13C = −10.2 ‰). This indicates it lived in a transitional environment between low-density forest and arboreal savannah. This likely occurred during a period that favored the expansion of trees and shrubs. The region underwent climate change, from relatively humid conditions (δ18O = 25.6 ± 0.2 ‰) to expressively dry (δ18O = 34.6 ‰) between the dated periods, a change corroborated by some palynological data. The multiannual paleoecological analysis, based on sequential sampling of three dentin layers of an incisor, indicated the relative stability of vegetation and climate despite fluctuations in hydrology. The perceived disassociation between vegetation dynamics and local hydrology corroborates the idea that factors other than precipitation may play a significant role in the environmental dynamics of the Cerrado biome.

Intensive short-term sampling with long-term consequences: characterizing pollutant transport with implications for developing monitoring.

Riverine sampling of pollutants is commonly used to understand pollutants' transport pathways, relationships with hydrology, and overall presence in a waterbody. However, temporal gaps between sample collection introduce errors to these efforts, and guidance prescribing sampling frequency remains sparse. The magnitude of error often depends on a contaminant's transport mechanisms and local hydrologic conditions, making the creation of comprehensive sampling guidance difficult. This study analyzed a unique dataset that measured 18 analytes, including pesticides, nutrients, and pathogens, in three Iowa rivers for 90 consecutive days (May 4-August 1, 2000). This dataset provided a novel opportunity to relate pollutants to local hydrology and quantify errors associated with recurring sampling. Pesticide concentrations followed the spring flush phenomenon, where values were greatest during high streamflow in May and June but often depleted by July. Fecal coliform and total phosphorus (TP) also coincided with high flow, but unlike pesticides, their concentrations never diminished. Nitrate exhibited more complex behavior; concentrations were diluted during high flows and then increased as streamflow receded. Autocorrelations were significant for nitrate and atrazine in larger rivers but negligible for fecal coliform and TP. Loads were calculated for four pollutants with minimal non-detects (atrazine, fecal coliform, nitrate, and TP). We simulated intermittent sampling by selecting evenly spaced subsets of measured values to estimate loads, which were compared to the loads calculated using every daily sample to quantify error. This method typically overestimated nitrate loads but underestimated other pollutants, and errors often decreased in larger watersheds. Nitrate generally had the lowest error, while fecal coliform had the highest. We used these results to approximate the sampling frequency needed to bind errors within a certain threshold.

Local hydroclimate alters interpretation of speleothem δ18O records

Oxygen isotopes (δ18O) are the most commonly utilized speleothem proxy and have provided many foundational records of paleoclimate. Thus, understanding processes affecting speleothem δ18O is crucial. Yet, prior calcite precipitation (PCP), a process driven by local hydrology, is a widely ignored control of speleothem δ18O. Here we investigate the effects of PCP on a stalagmite δ18O record from central Vietnam, spanning 45 – 4 ka. We employ a geochemical model that utilizes speleothem Mg/Ca and cave monitoring data to correct the δ18O record for PCP effects. The resulting record exhibits improved agreement with regional speleothem δ18O records and climate model simulations, suggesting that the corrected record more accurately reflects precipitation δ18O (δ18Op). Without considering PCP, our interpretations of the δ18O record would have been misleading. To avoid misinterpretations of speleothem δ18O, our results emphasize the necessity of considering PCP as a significant driver of speleothem δ18O.

Environmental Impacts of Rock Quarrying at the Afikpo Quarry Sites, Ebonyi State, Southeastern Nigeria

The importance of the quarrying industry to livelihood and development cannot be overemphasized. However, its activities result in significant damage to the immediate environment. This study investigates the environmental effects of quarrying activities in Afikpo, focusing on environmental degradation, health, and socio-economic implications for local communities. Field surveys, environmental assessments, and interviews with local residents and quarry operators were conducted to gather data on the extent of environmental degradation and its effects on the surrounding ecosystem. A total of 100 copies of a questionnaire were administered in the study area. Findings indicate that quarrying activities have led to substantial deforestation, soil erosion, and disruption of local hydrology, which in turn affects agricultural productivity and water availability for local populations. Additionally, the dust and noise generated by blasting and heavy machinery, as well as water quality degradation resulting from quarrying activities, pose health risks, including the possible impact of water quality degradation on the emergence and spread of antibiotic-resistant genes among nearby residents. The study also highlights the socio-economic trade-offs faced by communities, where the immediate economic benefits from quarrying often overshadow the long-term environmental costs. The results of this investigation underscore the urgent need for sustainable quarrying practices and effective regulatory frameworks to mitigate environmental impacts while considering the socio-economic realities of local communities. Recommendations include the implementation of rehabilitation plans for degraded sites, community engagement in decision-making processes, and the promotion of alternative livelihoods to reduce dependency on quarrying activities.

Estimation of Freshwater Discharge from the Gulf of Alaska Drainage Basins

The freshwater discharge from catchments along the Gulf of Alaska, termed Alaska discharge, is characterized by significant quantity and variability. Owing to subarctic climate and mountainous topography, the Alaska discharge variations may deliver possible impacts beyond the local hydrology. While short-term and local discharge estimation has been frequently realized, a longer time span and a discussion on cascading impacts remain unexplored in this area. In this study, the Alaska discharge during 1982–2022 is estimated using the Soil and Water Assessment Tool (SWAT). The adequate balance between the model complexity and the functional efficiency of SWAT suits the objective well, and discharge simulation is successfully conducted after customization in melting calculations and careful calibrations. During 1982−2022, the Alaska discharge is estimated to be 14,396 ± 819 m3⋅s−1⋅yr−1, with meltwater contributing approximately 53%. Regarding variation in the Alaska discharge, the interannual change is found to be negatively correlated with sea surface salinity anomalies in the Alaska Stream, while the decadal change positively correlates with the North Pacific Gyre Oscillation, with reasonable time lags in both cases. These new findings provide insights into the relationship between local hydrology and regional climate in this area. More importantly, we provide rare evidence that variation in freshwater discharge may affect properties beyond the local hydrology.

Local hydrology control of radiocarbon in stalagmites from the Kyusendo Cave, Kumamoto, Japan

Stalagmite is an important archive of paleoclimate especially in the region of the East Asian Monsoon. Despite the widespread use of radiocarbon (14C) dating to explore past environmental changes, the contribution of a14C-free carbon fraction leached from soil and/or host rocks during stalagmite formation, known as the dead carbon fraction (DCF), impedes its application to stalagmite chronology. Thus, uranium series dating is preferentially used to determine stalagmite ages. However, both U/Th and 14C dating can be applied to stalagmite samples, U/Th can be used to calibrate the radiocarbon ages by assuming a relatively constant DCF contribution over time. Studies exploring DCF changes from glacial to interglacial periods remain scarce, suggesting that temporal and speleothem-specific DCF studies are needed. Here, we present findings on DCF changes over the last 38 ka in speleothems obtained from southwestern Japan. Our analysis includes measurements of both 14C in drip water and speleothem calcite alongside U/Th dating of three stalagmites collected from Kyusendo Cave, located in southern Japan. The DCFs reconstructed from these stalagmites exhibited variations of 37.8%–73.9% between 4.2 and 38.3 ka, which exceeded the typical DCF values reported previously. Intra-test variations of the DCF values in Kyusendo Cave also revealed differences of up to 30%–40% among the three stalagmites. A higher drip water DCF and dripping rate showed a strong negative correlation, indicating that variations in DCF may reflect changes in local hydrology. The study findings suggest that speleothem-specific and temporally varied DCF should be considered in paleoclimate reconstructions using speleothems.

Control of landscape position on organic matter decomposition via soil moisture during a wet summer

Sustainable cropland management requires preservation of soil organic matter (SOM). In spite of in depth understanding gained from ample field and laboratory studies, we have a poor understanding of landscape scale spatial variation of fresh organic matter (OM) decomposition and its conversion into soil organic carbon (SOC). Particularly, local topographic position may be expected to co-control these processes via soil hydrology. In this study, we sought to identify if such control is significant by setting up a field experiment with two contrasting positions across 10 gently sloping cropland fields covering three different soil texture groups, i.e. loamy sand, (sandy) loam and silt loam. We wanted to link OM decomposition to within-field differences in soil moisture, whilst keeping variation in other soil and management factors minimal. Specifically, mesocosms with 13C enriched ryegrass (the OM source) were incorporated in the fields for ten weeks and afterwards, soil was separated into > 500 µm, 53 – 500 µm and < 53 µm sized fractions. Overall, we found that lower located positions were wetter than higher positions with average differences of 11 %, 20 % and 16 % in water-filled pore space for the loamy sand, (sandy) loam and silt loam soil, respectively. Mineralization of added OM was surprisingly independent of landscape position, even though moisture conditions appeared wetter than optimal at the low but not at the high landscape positions. Remaining ryegrass residues > 500 µm did follow local topography-driven gradients in soil moisture with higher amounts in low landscape positions. In other words, drier conditions at high landscape positions improved coarse OM decomposition, with consequently more ryegrass-carbon (C) ending up in finer soil fractions (< 500 µm). Additionally, soil texture affected decomposition of the smallest fraction (< 53 µm) with a stabilizing effect for finer-textured (silt loam) soils. We conclude that, despite significant contrasts in moisture conditions between landscape positions, within-field spatial variability of OM mineralization was overall limited during the observed wet summer period. Nevertheless, landscape position affected the quality of remnant unmineralized C, with relatively more conversion of freshly added OM into OM associated with silt and clay at the drier higher positions, potentially improving the long-term stability of SOM. Likewise observations under different weather conditions are needed to evaluate the necessity of precise modelling of local soil hydrology for predicting SOC stock evolution on the landscape scale.

Lake Water Ecological Simulation for a Typical Alpine Lake on the Tibetan Plateau

Lakes on the Tibetan Plateau (TP) serve as both indicators of and safeguards against climate change, playing a crucial role in the aquatic ecosystems of the TP. While considerable attention has been devoted to studying the thermal and dynamic processes of TP lakes, research focusing on their ecological variations has been limited. In this study, we selected Namco, a representative lake on the TP, to investigate its water ecological processes using the AQUATOX lake ecological model. Long-term ecological variations spanning from 1980 to 2020 were analyzed based on lake observations. Our results revealed a consistent increase in water nutrients, particularly total nitrogen (WTN), and total phosphorus (WTP), over the study period. Additionally, the concentrations of chlorophyll-a (Chl-a) and water gross and net primary production (WGPP and WNPP) exhibited a significant upward trend. Despite the persistent state of poor nutrition in the lake, the ecological conditions improved. Multiple linear regression analysis indicated that the concentrations of WGPP, WNPP, and Chl-a were more sensitive to the local climate and hydrology compared to WTN and WTP. A continuously warming climate would heat up the lake water body, further enhancing primary production and improving water quality in the future. This study provides insights for lake limnological and ecological research and can be used to inform water management strategies in high-altitude alpine regions.

Quantification of enrichment processes in throughfall and stemflow in a mixed temperate forest

AbstractForest ecosystems depend on throughfall and stemflow fluxes for both water and nutrient input. Spatial and temporal variability of throughfall and stemflow fluxes are large and differ between tree species. The nutrient fluxes that accompany throughfall and stemflow are affected by climate, precipitation intensity, the seasonality of dry deposition, and canopy exchange processes. The interdependence of these factors makes it challenging to quantify changes in throughfall and stemflow amounts as well as their nutrient content. Here, we provide observation‐based evidence from 3.5 years of data collection with 222 rainfall events, of the seasonal variability of throughfall and stemflow magnitude and ion concentrations under a beech (Fagus silvatica) and spruce (Picea abies) tree. Interception and canopy cover were seasonally variable, average annual interception was 53% below beech, 61% below spruce and 68% below young spruce canopies. Further, we assess seasonality of ionic nutrients such as NH4 and NO3 as well as Mg, Ca and K and their dependence on both dry deposition and canopy exchange. Throughfall and stemflow were enriched compared to precipitation, with large differences between ions and different months. Antecedent precipitation was a main control on throughfall and stemflow enrichment. We developed a conceptual model of the potential drivers of throughfall and stemflow enrichment based on our observations. While NH4 and NO3 enrichment are likely dominated by dry deposition and dew and fog accumulation, Mg, Ca and K were additionally affected by canopy exchange. Observation based studies such as this one are needed to understand precipitation and nutrient partitioning across forests, which enables the prediction of how changes in climate and forest composition will affect local hydrology and nutrient inputs into forest ecosystems.

Modelling the impacts of future droughts and post-droughts on hydrology, crop yields, and their linkages through assessing virtual water trade in agricultural watersheds of high-latitude regions

This study elaborates on the effects of future drought and post-drought conditions on the reliability of global breadbaskets. The study simulates agro-hydrological processes in the Nelson River Basin, a large agricultural watershed in western Canada that supplies food for over 170 countries globally. In temperate zones of higher latitudes, future climate change scenarios suggest that global breadbaskets will likely experience increased precipitation and higher crop yields (Y). This could be perceived as an increased export potential of food from these regions. However, projected drought events in the future can affect agro-hydrological processes, Y, and, therefore, export potentials during and following the drought events. Using a process-based agro-hydrologic model, this research examines the potential impacts of future agricultural droughts and post-drought conditions on hydrological water yield (WYLD), Y, and their linkages through assessing the net virtual water export (NVWE), the water embodied in the production of crops that are destined for export. The results indicate that long-term average Y, NVWE, and WYLD are expected to improve in the future. However, droughts will become more extreme in the future, leading to considerable reductions in Y, NVWE, and WYLD. During the post-drought period, the recovery time for WYLD is considerably longer than Y and NVWE across regions. The slow recovery of WYLD, following an agricultural drought, is related to crop water uptake, which can be controlled by optimization of the cropping pattern. The continuous loss of WYLD during and after prolonged and more frequent droughts in the future can significantly affect not only the environment and several economic sectors but also the irrigated crop production and export potential from these regions. This finding highlights the connections between local hydrology and global trade systems in agricultural watersheds of higher-latitude regions. Future adaptation measures, such as changes in cropping patterns, can preserve WYLD during and after droughts, supporting water and food security.

Rapid Ice‐Wedge Collapse and Permafrost Carbon Loss Triggered by Increased Snow Depth and Surface Runoff

AbstractThicker snow cover in permafrost areas causes deeper active layers and thaw subsidence, which alter local hydrology and may amplify the loss of soil carbon. However, the potential for changes in snow cover and surface runoff to mobilize permafrost carbon remains poorly quantified. In this study, we show that a snow fence experiment on High‐Arctic Svalbard inadvertently led to surface subsidence through warming, and extensive downstream erosion due to increased surface runoff. Within a decade of artificially raised snow depths, several ice wedges collapsed, forming a 50 m long and 1.5 m deep thermo‐erosion gully in the landscape. We estimate that 1.1–3.3 tons C may have eroded, and that the gully is a hotspot for processing of mobilized aquatic carbon. Our results show that interactions among snow, runoff and permafrost thaw form an important driver of soil carbon loss, highlighting the need for improved model representation.

The impact of Ethiopian Green Legacy Initiative (GLI) on landscape functionality and plant species diversity in Lake Hawassa watershed, Ethiopia

AbstractAs one of the responses to the global commitments against climate change, the Ethiopian Government launched a nationwide Green Legacy Initiative (GLI) in 2019, which largely focused on forest tree plantations with some inclusion of fruit trees. Despite its tremendous efforts and investments, its effectiveness and impacts have not been studied. This paper attempted to address this necessity by conducting a cross‐sectional quasi‐experiment in three randomly selected woredas/districts of Lake Hawassa Watershed from August 20 to September 2, 2023. The research hypothesized the likely impacts of GLI on four dependent variables (hydrological regulation, soil stability, nutrient cycling and plant species diversity). To achieve this, the research considered the two variants of GLI practices (plantation with and without soil and water conservation measures) and the corresponding control sites. Having three sites and three treatments with five replications, the study involved a total of forty‐five quadrats of the same size (20 m × 20 m). The first three parameters were analysed using the landscape functionality analysis method, while the fourth employed Shannon's diversity index. Results of ANOVA showed that, on average 87% of randomly selected quadrats were found to significantly improve the local hydrology (runoff potential) (≈ 83.3% with Av. p = 0.012), soil stability (≈100% with Av. p = 0.002), nutrient cycling (≈83.3% with Av. p = 0.017) and plant species diversity (≈83.3% with Av. p = 0.012). The research revealed positive results from the Ethiopian Green Legacy Initiative. The small number of samples is acknowledged as a limitation of the research.

Subalpine peatland development since the Last Glacial Maximum in subtropical China: Predominantly controlled by monsoonal climate and local topography

Peatlands interact significantly with the global carbon cycle and climate changes. A comprehensive understanding of the development of peatlands is extremely important to help address future climate challenges. Here, we combine three total organic carbon content records with seven published records from subalpine peatlands in the monsoonal region of subtropical China, aiming to reveal the general pattern of peatland development since the Last Glacial Maximum (LGM) in this region. The synthesis showed that organic carbon contents significantly increased at approximately 16 cal kyr B.P. These ten records clearly display two distinct patterns since that time: pattern one showed three intervals of high carbon contents at ca. 16−12 cal kyr B.P., 9.5−7.5 cal kyr B.P. and 6−4 (or 4−1) cal kyr B.P., whereas pattern two reached the maximum in the early Holocene and remained high and relatively stable during the Holocene. Through comparison with pollen indicators and climate reconstructions, we demonstrated that local hydrology linked to monsoonal climates (especially precipitation) was the dominant factor controlling carbon accumulation and the development of subalpine peatlands since the LGM in subtropical China. However, two dynamic patterns that occurred under the same climatic conditions were attributed to the significant modulation of local topography, i.e., intermontane basin (pattern one) or montane (pattern two) settings. The hydrology and development of peatlands are functions of the changes in monsoonal climate and local site-specific topography. These findings provide a comprehensive understanding of past long-term development of peatlands under monsoonal climates.

Taphonomy of human burials on beacon Island: archaeological observations informing forensic interpretations

ABSTRACT This paper demonstrates how the complex interaction of a number of intrinsic and extrinsic taphonomic factors have differentially affected the relative preservation of the skeletal remains recovered from Beacon Island. These include: local geology and hydrology; flora and fauna; human interactions; and burial type (e.g. body position and number). The latter function to demonstrate that contemporary burials dating to 1629 can present markedly divergent taphonomic ‘alterations’, even those buried within close proximity to one-another. It is evident that alterations can arise in a very short-time frame (months to a few years) and their recognition in a modern context is thus of forensic relevance. These are accordingly illustrated and described relative to their potential to inform forensic interpretations in a modern case-work context.