With the economic development of many communities and the growing human population more food is needed. The livestock industry is one of the fastest growing industries in developing countries. The development of the l...With the economic development of many communities and the growing human population more food is needed. The livestock industry is one of the fastest growing industries in developing countries. The development of the livestock industry and the increase of livestock waste happens as a result of the growth in food production. The wastes are stored in a way that contamination of groundwater and surface water pollution in the environment has a significant impact on environment. This study analyses the environmental impact of livestock facilities and nitrate leaching in groundwater. After site sampling and libratory analysis, calibration of a simulation model with observed data was done to show nitrate contamination in “Rey” groundwater. The movement of nitrate into soil and groundwater was simulated by LEACHN. By defining various scenarios and performing sensitivity analysis, we examined precisely the factors affecting ground water contaminations. Along together with the analysis of different scenarios and comparing them with the measured values, seasonal rainfall conditions have greatest impact on the rate of recharge of nitrate to groundwater. Therefore soil with low rainfall shows 44% reduction of nitrate leakage at a depth of 30 cm of soil conditions. Finally, the modeling results and graphs from different scenarios for purpose of nitrate reduction in groundwater were presented. The good match between model results and observed data showed that the model is calibrated to this area and can be used for prediction purposes and further studies.展开更多
This study investigates the impacts of climate change on temperature and precipitation patterns across four governorates in southern Iraq—Basrah,Thi Qar,Al Muthanna,and Messan—using an inte-grated modeling framework...This study investigates the impacts of climate change on temperature and precipitation patterns across four governorates in southern Iraq—Basrah,Thi Qar,Al Muthanna,and Messan—using an inte-grated modeling framework that combines the Long Ashton Research Station Weather Generator(LARS-WG)with three CMIP5-based Global Climate Models(Hadley Centre Global Environmental Model version 2-Earth System(HadGEM2-ES)),European Community Earth-System Model(EC-Earth),and Model for Interdisciplinary Research on Climate version 5(MIROC5).Projections were generated for three future time periods(2021–2040,2041–2060,and 2061–2080)under two Representative Concentration Pathways(RCP4.5 and RCP8.5).By integrating high-resolution climate simulations with localized drought risk analy-sis,this study provides a detailed outlook on climate change trends in the region.The novelty of this research lies in its high-resolution,station-level analysis and its integration of localized statistical downscal-ing techniques to enhance the spatial applicability of coarse GCM outputs.Model calibration and validation 2 were performed using historical climate data(1990–2020),resulting in high accuracy across all stations(R=0.91–0.99;RMSE=0.19–2.78),thus reinforcing the robustness of the projections.Results indicate a significant rise in average annual maximum and minimum temperatures,with increases ranging from 0.88°C to 3.68°C by the end of the century,particularly under the RCP8.5 scenario.Precipitation patterns exhibit pronounced interannual variability,with the highest predicted increases reaching up to 19.26 mm per season,depending on the model and location.These shifts suggest heightened vulnerability to drought and water scarcity,particularly in already arid regions such as Muthanna and Thi Qar.The findings under-score the urgent need for adaptive strategies in water resource management and agricultural planning,providing decision-makers with region-specific climate insights critical for sustainable development under changing climate conditions.展开更多
An understanding of the long-term changes in the nitrate and microbial contamination pattern of the groundwater of Sidi Bouzid （Centre West of Tunisia） is critical to conservation of drinking water in rural areas su...An understanding of the long-term changes in the nitrate and microbial contamination pattern of the groundwater of Sidi Bouzid （Centre West of Tunisia） is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. The phreatic aquifer was revealed polluted by domestic disposals of the wastewaters in the urban zone. The average nitrate concentration in the groundwater of the east of the mioplioquaternary aquifer of Saddaguia （Sidi Bouzid） rose from 50 mg NO3- during 1996 to over 100 mg in 2003, which represents an increase of some 10 mg per year. Nitrate groundwater pollution during the period 1996-2003 was the result of the abusive use of fertilizers.In the cultivated zone, we must reduce the effects of the excessive use of the nitrogen fertilizers on the basis of monitoring soil once a year, managing water resources, rationalizing the use of the chemical substances. In urban zones, most of lost wells located in the perimeter reveal the gravity of the state of the aquifer. This last is organically polluted and requires an immediate action for the generalization of the purification network. We need to take into account the reality of under soil in all future planning＇s and arrangements. A scheme of sanitation seems necessary before all plans of arrangement. The extension of the sewer network must give the priority to the most vulnerable zones.展开更多
An extreme drought occurred in the Yangtze River Basin in 2022,inflicting huge impacts nationwide.To provide a reference for drought prevention and mitigation,this paper presents a comprehensive analysis of the drough...An extreme drought occurred in the Yangtze River Basin in 2022,inflicting huge impacts nationwide.To provide a reference for drought prevention and mitigation,this paper presents a comprehensive analysis of the drought in the Yangtze River Basin in terms of its characteristics,causes,impacts,and response strategies.It concludes that this extreme drought stood out by its long duration,wide impact range,and severe intensity,as a combined result of abnormal hightemperature weather and massive social water consumption.Serious impacts are observed in various fields of the economy,including agricultural irrigation,urban and rural water supply,power generation,and navigation.Finally,drought mitigation measures and effects are examined,and future drought response and mitigation strategies are proposed.展开更多
We present a comparative analysis of electrical and gravity data on the Geographic Information System of the prerifaines ridges. At the Meso-Cenozo?c sequence, the geometry of the prerifaines ridges is fairly well kno...We present a comparative analysis of electrical and gravity data on the Geographic Information System of the prerifaines ridges. At the Meso-Cenozo?c sequence, the geometry of the prerifaines ridges is fairly well known. However, the post-Miocene series remain to be characterized. In this perspective, we use a database composed of gravity and vertical electrical sounding profiles and geo-electrical sections in order to characterize this structuration. These data are calibrated by many oil and hydrogeological boreholes. Preliminary results lead to better understanding of the organization of its underlying structures in this area. The Gravimetric filtering results show that the area may be dissected by tree major faults striking NW-SE, NE-SW and N-S. All these faults have contributed, since Hercynian to Alpines orogenies, to the structuring of this area, being proved to be the deepest and can reach 4500 m. The comparison of gravity maps, geological and structural maps under Geographic Information System allows the identification of major structural directions and trends of the study area. It confirms some structural elements gathered from outcrops and define new ones. Results from this work show the importance of using various filtering and interpretation techniques in the analysis of gravity data. They also provide news insights into the deep structure of the study area.展开更多
The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view...The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view, the protolith context and weathering conditions, u</span><span><span style="font-family:Verdana;">sing major element geochemistry and mineralogy of the sedimentary rocks. Microscopic observations of diagenetic phenomena (on and around detrital grains of the basin), and the study of precipitation of the cement show that these sediments have undergone phenomena of compaction, dissolution, recrystallization and cementation. Cementation of quartz by silica is controlled by the rate of precipitation of silica, which is closely related to temperature than pressure. Thus, the sediments of the basin could be influenced by hydrothermalism during diagenesis, which would have inhibited their reservoir quality by generalized cementation phenomena. Geochemical features of the sediments show high contents in SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (47.49 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">90.79 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (2.92 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">23.18 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (0.2 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">6.22 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">) and alkali and alkaline earth metals (>3</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">). The chemical alteration index varies between 30.92</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;"> and 95.08</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">. This variation in the CIA values reflects the variation in the proportion of feldspars and different clay minerals in these sediments. How</span></span><span style="font-family:""><span style="font-family:Verdana;">ever, the ICV calculation and the ICV versus CIA show compositional immature to mature sediments, with </span><span style="font-family:Verdana;">low to intense weathering character of these sediments. Petrographic and</span><span style="font-family:Verdana;"> geo</span><span style="font-family:Verdana;">chemical characteristics of sediments of the basin are compatible with the</span><span style="font-family:Verdana;"> composition of the granitic and gneissic surrounding bedrocks.</span></span>展开更多
Climate-related hazards like drought are associated with loss of life and lead to food insecurity in many parts of sub-Saharan Africa. Food insecurity, which affects more than 220 million sub-Saharan Africans, manifes...Climate-related hazards like drought are associated with loss of life and lead to food insecurity in many parts of sub-Saharan Africa. Food insecurity, which affects more than 220 million sub-Saharan Africans, manifests as starvation that leads to more than 50% of children under the age of 5-years presenting as underweight for age in many communities on the continent. This household survey reports the means by which rural fisher folk and farming communities in Uganda gained access to early warning meteorological information. The survey covered five districts across different climatic zones in Uganda and recruited a total of 405 respondents with an average age of 41 years (SD 16). Economic activity was used to categorize each of the five districts into farming (crops and livestock) and fishing areas. The results showed that most respondents were unaware of drought as one of the climate-related hazards. Compared to respondents from the fishing communities, the respondents from farming communities were more likely to be receiving weather-related information (<em>P</em>-value < 0.01). There were 204/405 (50.37%) female respondents who, compared to male respondents, were less likely to have access to weather information, less willing to pay for weather information, and less likely to have and/or own devices like a radio for receiving weather information. The survey demonstrated that: 1) there were gaps in the knowledge about climate-related hazards, 2) there is a need for additional interventions targeting fisher folk communities access timely weather information, and 3) introducing user paid access to weather information may increase climate-related gender-based disparities.展开更多
Flood forecasting is an essential tool for mitigating flood risks and enhancing disaster preparedness,particularly in vulnerable urban and agricultural areas where timely and accurate predictions can significantly red...Flood forecasting is an essential tool for mitigating flood risks and enhancing disaster preparedness,particularly in vulnerable urban and agricultural areas where timely and accurate predictions can significantly reduce damage and ensure public safety.This paper presents a comprehensive approach to forecasting the water level of downstream network systems,including reservoirs and irrigation districts,during the flood season.The proposed methodology utilizes the Long Short-Term Memory(LSTM)deep learning technique to accurately predict flood water level patterns.Historical water level and rainfall data from a network comprising four rainfall gauging stations with long-term records and one water level gauging station within the case study area are processed and analyzed to improve prediction accuracy.The results demonstrate that the proposed LSTM model with SGDM technique effectively captures regime dynamics,providing valuable insights for decision-makers in flood risk management.The model achieves high accuracy in predicting flood peaks,both in magnitude and timing,with determination coefficient𝑅R^(2)values of 0.92 for 24-hour forecasts and 0.81 for 48-hour forecasts.The Root Mean Square Errors(RMSEs)for the entire flood season are 0.23 m for 24-hour forecasts and 0.35 m for 48-hour forecasts,within a water level range of approximately 2.0 m to 8.0 m during the intentional flood period at the control stations.The forecasted flow accuracy P are 84.85%and 87.60%for 24-hour and 48-hour forecasts,respectively.These findings highlight the potential of the LSTM model to enhance forecast performance,contributing to more efficient and sustainable water distribution systems while improving flood risk management practices.展开更多
The performance of the Revised Universal Soil Loss Equation(RUSLE)as the most widely used soil erosion model is a challenging issue.Accordingly,the objective of this study is investigating the estimated sediment deliv...The performance of the Revised Universal Soil Loss Equation(RUSLE)as the most widely used soil erosion model is a challenging issue.Accordingly,the objective of this study is investigating the estimated sediment delivery by the RUSLE method and Sediment Delivery Distributed(SEDD)model.To this end,the Talar watershed in Iran was selected as the study area.Further,700 paired sediment-discharge measurements at Valikbon and Shirgah-Talar hydrometric stations between the years 1991 and 2011 were collected and used in sediment rating curves.Nine procedures were investigated to produce the required RUSLE layers.The estimated soil erosion by RUSLE was evaluated using sediment rating curve data by two methods including least squares and quantile regression.The average annual suspended sediment load was calculated for each sub-watershed of the study area using the SEDD model.Afterwards,a sediment rating curve was estimated by least squares and quantile regression methods using paired discharge-sediment data.The average annual suspended sediment load values were calculated for two hydrometric stations and were further evaluated by the SEDD model.The results indicated that the first considered procedure,which utilized 15-min rainfall measurements for the rainfall factor(R),and the classification method of SENTINEL-2 MSI image for the cover management factor(C),offered the best results in producing RUSLE layers.Furthermore,the results revealed the advantages of utilizing satellite images in producing cover management layer,which is required in the RUSLE method.展开更多
Soil freeze-thaw(FT)cycles impact soil functions and atmosphere-land interaction,but accurate measurements are very limited.Since surface dielectric properties and microwave emissions are sensitive to the FT state,bri...Soil freeze-thaw(FT)cycles impact soil functions and atmosphere-land interaction,but accurate measurements are very limited.Since surface dielectric properties and microwave emissions are sensitive to the FT state,brightness temperature(TB)measurements at L-band allow retrieval of the FT state.We have demonstrated the potential of a soil FT retrieval algorithm from Soil Moisture Active Passive(SMAP)TB measurements.This retrieval algorithm is formulated regarding Diurnal Amplitude Variation(DAV),which is defined as the difference in TB observations of ascending and descending orbits.The DAV-FT algorithm uses globally fixed parameters.However,parameters should vary regionally considering factors like land cover type,terrain,and climate regions.We introduce Overall Classification Accuracy(OA)to characterize the extraction of DAV annual variation under different parameters.Then,the parameter optimization process,akin to maximum likelihood estimation,selects a combination of parameters to extract the annual variation of the DAV optimally.The DAV-FT algorithm uses optimized parameters,and the results show that compared to using fixed parameters,(a)the area with OA>0.7 increases from 54.43%to 89.36%;(b)consistency with ERA5-Land and SMAP data has improved in southwestern North America,the Qinghai-Tibet Plateau,and southwestern Eurasia,with regions showing over 0.7 consistency reaching 81.28%for ERA5-Land and 79.54%for SMAP-FT;and(c)in situ stations with higher accuracy outnumber those with lower accuracy(48.11%versus 22.97%for fixed parameters,35.14%versus 33.51%for SMAP FT).Furthermore,the algorithm achieves the highest median(0.92)and median accuracy(0.88),compared to fixed parameters and SMAP.展开更多
Topsoil structures and inhomogeneous distribution of moisture in the soil volume will induce dielectric discontinuities from air to bulk soil,which in turn may induce multiple and volume scattering and affect the micr...Topsoil structures and inhomogeneous distribution of moisture in the soil volume will induce dielectric discontinuities from air to bulk soil,which in turn may induce multiple and volume scattering and affect the microwave surface emission.In situ ELBARA-Ⅲ L-band radiometer observations of brightness temperature T_(B)^(p) (p=H or V polarization)at the Maqu site on the Eastern Tibetan Plateau are exploited to understand the effect of surface roughness on coherent and incoherent emission processes.Assisted with in situ soil moisture(SM)and temperature profile measurements,this study develops an air-to-soil transition(ATS)model that incorporates the dielectric roughness(i.e.,resulted from fine-scale topsoil structures and the soil volume)characterized by SM and geometric roughness effects,and demonstrates the necessity of the ATS model for modelling L-band T_(B)^(p).The Wilheit(1978)coherent and Lv et al.(2014)incoherent models are compared for determining the dielectric constant of bulk soil in the ATS zone and for calculating soil effective temperature T_(eff).The Tor Vergata discrete scattering model(TVG)integrated with the advanced integral equation model(AIEM)is used as the baseline model configuration for simulating L-band T_(B)^(p).Whereafter,the ATS model is integrated with the foregoing model for assessing its performance.Results show the ATS-based models reduce the underestimation of T_(B)^(p)(≈20-50 K)by the baseline simulations.Being dynamic in nature,the proposed dielectric roughness parameterization in the ATS model significantly improves the ability in interpreting T_(B)^(p) dynamics,which is important for improving SM retrieval at the global scale.展开更多
One-third of the Earth’s land surface experiences seasonal freezing and thawing.Freezing-thawing transitions strongly impact land-atmosphere interactions and,thus,also the lower atmosphere above such areas.Observatio...One-third of the Earth’s land surface experiences seasonal freezing and thawing.Freezing-thawing transitions strongly impact land-atmosphere interactions and,thus,also the lower atmosphere above such areas.Observations of two L-band satellites,the Soil Moisture Active Passive(SMAP)and Soil Moisture and Ocean Salinity(SMOS)missions,provide flags that characterize surfaces as either frozen or not frozen.However,both state transitions—freezing and thawing(FT)—are continuous and complex processes in space and time.Especially in the L-band,which has penetration depths of up to tens of centimeters,the brightness temperature(T_(B))may be generated by a vertically-mixed profile of different FT states,which cannot be described by the current version of the Community Microwave Emission Model(CMEM).To model such complex state transitions,we extended CMEM in Fresnel mode with an FT component by allowing for(1)a varying fraction of an open water surface on top of the soil,and(2)by implementing a temporal FT phase transition delay based on the difference between the soil surface temperature and the soil temperature at 2.5 cm depth.The extended CMEM(CMEM-FT)can capture the T_(B)progression from a completely frozen to a thawed state of the contributing layer as observed by the L-band microwave radiometer ELBARA-III installed at the Maqu station at the northeastern margin of the Tibetan Plateau.The extended model improves the correlation between the observations and CMEM simulations from 0.53/0.45 to 0.85/0.85 and its root-mean-square-error from 32/25 K to 20/15 K for H/V-polarization during thawing conditions.Yet,CMEM-FT does still not simulate the freezing transition sufficiently.展开更多
文摘With the economic development of many communities and the growing human population more food is needed. The livestock industry is one of the fastest growing industries in developing countries. The development of the livestock industry and the increase of livestock waste happens as a result of the growth in food production. The wastes are stored in a way that contamination of groundwater and surface water pollution in the environment has a significant impact on environment. This study analyses the environmental impact of livestock facilities and nitrate leaching in groundwater. After site sampling and libratory analysis, calibration of a simulation model with observed data was done to show nitrate contamination in “Rey” groundwater. The movement of nitrate into soil and groundwater was simulated by LEACHN. By defining various scenarios and performing sensitivity analysis, we examined precisely the factors affecting ground water contaminations. Along together with the analysis of different scenarios and comparing them with the measured values, seasonal rainfall conditions have greatest impact on the rate of recharge of nitrate to groundwater. Therefore soil with low rainfall shows 44% reduction of nitrate leakage at a depth of 30 cm of soil conditions. Finally, the modeling results and graphs from different scenarios for purpose of nitrate reduction in groundwater were presented. The good match between model results and observed data showed that the model is calibrated to this area and can be used for prediction purposes and further studies.
文摘This study investigates the impacts of climate change on temperature and precipitation patterns across four governorates in southern Iraq—Basrah,Thi Qar,Al Muthanna,and Messan—using an inte-grated modeling framework that combines the Long Ashton Research Station Weather Generator(LARS-WG)with three CMIP5-based Global Climate Models(Hadley Centre Global Environmental Model version 2-Earth System(HadGEM2-ES)),European Community Earth-System Model(EC-Earth),and Model for Interdisciplinary Research on Climate version 5(MIROC5).Projections were generated for three future time periods(2021–2040,2041–2060,and 2061–2080)under two Representative Concentration Pathways(RCP4.5 and RCP8.5).By integrating high-resolution climate simulations with localized drought risk analy-sis,this study provides a detailed outlook on climate change trends in the region.The novelty of this research lies in its high-resolution,station-level analysis and its integration of localized statistical downscal-ing techniques to enhance the spatial applicability of coarse GCM outputs.Model calibration and validation 2 were performed using historical climate data(1990–2020),resulting in high accuracy across all stations(R=0.91–0.99;RMSE=0.19–2.78),thus reinforcing the robustness of the projections.Results indicate a significant rise in average annual maximum and minimum temperatures,with increases ranging from 0.88°C to 3.68°C by the end of the century,particularly under the RCP8.5 scenario.Precipitation patterns exhibit pronounced interannual variability,with the highest predicted increases reaching up to 19.26 mm per season,depending on the model and location.These shifts suggest heightened vulnerability to drought and water scarcity,particularly in already arid regions such as Muthanna and Thi Qar.The findings under-score the urgent need for adaptive strategies in water resource management and agricultural planning,providing decision-makers with region-specific climate insights critical for sustainable development under changing climate conditions.
文摘An understanding of the long-term changes in the nitrate and microbial contamination pattern of the groundwater of Sidi Bouzid （Centre West of Tunisia） is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. The phreatic aquifer was revealed polluted by domestic disposals of the wastewaters in the urban zone. The average nitrate concentration in the groundwater of the east of the mioplioquaternary aquifer of Saddaguia （Sidi Bouzid） rose from 50 mg NO3- during 1996 to over 100 mg in 2003, which represents an increase of some 10 mg per year. Nitrate groundwater pollution during the period 1996-2003 was the result of the abusive use of fertilizers.In the cultivated zone, we must reduce the effects of the excessive use of the nitrogen fertilizers on the basis of monitoring soil once a year, managing water resources, rationalizing the use of the chemical substances. In urban zones, most of lost wells located in the perimeter reveal the gravity of the state of the aquifer. This last is organically polluted and requires an immediate action for the generalization of the purification network. We need to take into account the reality of under soil in all future planning＇s and arrangements. A scheme of sanitation seems necessary before all plans of arrangement. The extension of the sewer network must give the priority to the most vulnerable zones.
基金funded by the National Key R&D Program of China(2018YFE0206400,2021YFC3000202)the National Natural Science Foundation of China(National Natural Science Foundation of China Grant No.42001039)the China Institute of Water Resources and Hydropower Research,Research and Development Support Program(JZ110145B0052021,F0203982012).
文摘An extreme drought occurred in the Yangtze River Basin in 2022,inflicting huge impacts nationwide.To provide a reference for drought prevention and mitigation,this paper presents a comprehensive analysis of the drought in the Yangtze River Basin in terms of its characteristics,causes,impacts,and response strategies.It concludes that this extreme drought stood out by its long duration,wide impact range,and severe intensity,as a combined result of abnormal hightemperature weather and massive social water consumption.Serious impacts are observed in various fields of the economy,including agricultural irrigation,urban and rural water supply,power generation,and navigation.Finally,drought mitigation measures and effects are examined,and future drought response and mitigation strategies are proposed.
文摘We present a comparative analysis of electrical and gravity data on the Geographic Information System of the prerifaines ridges. At the Meso-Cenozo?c sequence, the geometry of the prerifaines ridges is fairly well known. However, the post-Miocene series remain to be characterized. In this perspective, we use a database composed of gravity and vertical electrical sounding profiles and geo-electrical sections in order to characterize this structuration. These data are calibrated by many oil and hydrogeological boreholes. Preliminary results lead to better understanding of the organization of its underlying structures in this area. The Gravimetric filtering results show that the area may be dissected by tree major faults striking NW-SE, NE-SW and N-S. All these faults have contributed, since Hercynian to Alpines orogenies, to the structuring of this area, being proved to be the deepest and can reach 4500 m. The comparison of gravity maps, geological and structural maps under Geographic Information System allows the identification of major structural directions and trends of the study area. It confirms some structural elements gathered from outcrops and define new ones. Results from this work show the importance of using various filtering and interpretation techniques in the analysis of gravity data. They also provide news insights into the deep structure of the study area.
文摘The purpose of this work is to characterize the sediments of the Babouri-Figuil<span style="font-family:""><span style="font-family:Verdana;"> Basin from a diagenetic point of view, the protolith context and weathering conditions, u</span><span><span style="font-family:Verdana;">sing major element geochemistry and mineralogy of the sedimentary rocks. Microscopic observations of diagenetic phenomena (on and around detrital grains of the basin), and the study of precipitation of the cement show that these sediments have undergone phenomena of compaction, dissolution, recrystallization and cementation. Cementation of quartz by silica is controlled by the rate of precipitation of silica, which is closely related to temperature than pressure. Thus, the sediments of the basin could be influenced by hydrothermalism during diagenesis, which would have inhibited their reservoir quality by generalized cementation phenomena. Geochemical features of the sediments show high contents in SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> (47.49 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">90.79 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Al</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (2.92 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">23.18 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">), Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;"> (0.2 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">6.22 wt</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">) and alkali and alkaline earth metals (>3</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;">). The chemical alteration index varies between 30.92</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;"> and 95.08</span><span style="color:#4F4F4F;font-family:Verdana;">%</span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">. This variation in the CIA values reflects the variation in the proportion of feldspars and different clay minerals in these sediments. How</span></span><span style="font-family:""><span style="font-family:Verdana;">ever, the ICV calculation and the ICV versus CIA show compositional immature to mature sediments, with </span><span style="font-family:Verdana;">low to intense weathering character of these sediments. Petrographic and</span><span style="font-family:Verdana;"> geo</span><span style="font-family:Verdana;">chemical characteristics of sediments of the basin are compatible with the</span><span style="font-family:Verdana;"> composition of the granitic and gneissic surrounding bedrocks.</span></span>
文摘Climate-related hazards like drought are associated with loss of life and lead to food insecurity in many parts of sub-Saharan Africa. Food insecurity, which affects more than 220 million sub-Saharan Africans, manifests as starvation that leads to more than 50% of children under the age of 5-years presenting as underweight for age in many communities on the continent. This household survey reports the means by which rural fisher folk and farming communities in Uganda gained access to early warning meteorological information. The survey covered five districts across different climatic zones in Uganda and recruited a total of 405 respondents with an average age of 41 years (SD 16). Economic activity was used to categorize each of the five districts into farming (crops and livestock) and fishing areas. The results showed that most respondents were unaware of drought as one of the climate-related hazards. Compared to respondents from the fishing communities, the respondents from farming communities were more likely to be receiving weather-related information (<em>P</em>-value < 0.01). There were 204/405 (50.37%) female respondents who, compared to male respondents, were less likely to have access to weather information, less willing to pay for weather information, and less likely to have and/or own devices like a radio for receiving weather information. The survey demonstrated that: 1) there were gaps in the knowledge about climate-related hazards, 2) there is a need for additional interventions targeting fisher folk communities access timely weather information, and 3) introducing user paid access to weather information may increase climate-related gender-based disparities.
基金funding from the Vietnam Ministry of Natural Resources and Environment entitled“To Study and Develop Hydrological Forecasting and Flood Warning Technologies for Small River Basins,Applying the Tests to Some Small River Basins in the North-West Region”,Code number:TNMT.2023.06.14.
文摘Flood forecasting is an essential tool for mitigating flood risks and enhancing disaster preparedness,particularly in vulnerable urban and agricultural areas where timely and accurate predictions can significantly reduce damage and ensure public safety.This paper presents a comprehensive approach to forecasting the water level of downstream network systems,including reservoirs and irrigation districts,during the flood season.The proposed methodology utilizes the Long Short-Term Memory(LSTM)deep learning technique to accurately predict flood water level patterns.Historical water level and rainfall data from a network comprising four rainfall gauging stations with long-term records and one water level gauging station within the case study area are processed and analyzed to improve prediction accuracy.The results demonstrate that the proposed LSTM model with SGDM technique effectively captures regime dynamics,providing valuable insights for decision-makers in flood risk management.The model achieves high accuracy in predicting flood peaks,both in magnitude and timing,with determination coefficient𝑅R^(2)values of 0.92 for 24-hour forecasts and 0.81 for 48-hour forecasts.The Root Mean Square Errors(RMSEs)for the entire flood season are 0.23 m for 24-hour forecasts and 0.35 m for 48-hour forecasts,within a water level range of approximately 2.0 m to 8.0 m during the intentional flood period at the control stations.The forecasted flow accuracy P are 84.85%and 87.60%for 24-hour and 48-hour forecasts,respectively.These findings highlight the potential of the LSTM model to enhance forecast performance,contributing to more efficient and sustainable water distribution systems while improving flood risk management practices.
文摘The performance of the Revised Universal Soil Loss Equation(RUSLE)as the most widely used soil erosion model is a challenging issue.Accordingly,the objective of this study is investigating the estimated sediment delivery by the RUSLE method and Sediment Delivery Distributed(SEDD)model.To this end,the Talar watershed in Iran was selected as the study area.Further,700 paired sediment-discharge measurements at Valikbon and Shirgah-Talar hydrometric stations between the years 1991 and 2011 were collected and used in sediment rating curves.Nine procedures were investigated to produce the required RUSLE layers.The estimated soil erosion by RUSLE was evaluated using sediment rating curve data by two methods including least squares and quantile regression.The average annual suspended sediment load was calculated for each sub-watershed of the study area using the SEDD model.Afterwards,a sediment rating curve was estimated by least squares and quantile regression methods using paired discharge-sediment data.The average annual suspended sediment load values were calculated for two hydrometric stations and were further evaluated by the SEDD model.The results indicated that the first considered procedure,which utilized 15-min rainfall measurements for the rainfall factor(R),and the classification method of SENTINEL-2 MSI image for the cover management factor(C),offered the best results in producing RUSLE layers.Furthermore,the results revealed the advantages of utilizing satellite images in producing cover management layer,which is required in the RUSLE method.
基金funded by the National Key R&D Program of China(grant no.2022YFF0801404)the Key Research and Development and Achievement Transformation Program of Inner Mongolia Autonomous Region,China(grant no.2025YFDZ0007)+1 种基金the Yan Liyuan-ENSKY Foundation Project of Zhuhai Fudan Innovation Research Institute(grant no.JX240002)the National Natural Science Foundation of China(grant no.42075150).
文摘Soil freeze-thaw(FT)cycles impact soil functions and atmosphere-land interaction,but accurate measurements are very limited.Since surface dielectric properties and microwave emissions are sensitive to the FT state,brightness temperature(TB)measurements at L-band allow retrieval of the FT state.We have demonstrated the potential of a soil FT retrieval algorithm from Soil Moisture Active Passive(SMAP)TB measurements.This retrieval algorithm is formulated regarding Diurnal Amplitude Variation(DAV),which is defined as the difference in TB observations of ascending and descending orbits.The DAV-FT algorithm uses globally fixed parameters.However,parameters should vary regionally considering factors like land cover type,terrain,and climate regions.We introduce Overall Classification Accuracy(OA)to characterize the extraction of DAV annual variation under different parameters.Then,the parameter optimization process,akin to maximum likelihood estimation,selects a combination of parameters to extract the annual variation of the DAV optimally.The DAV-FT algorithm uses optimized parameters,and the results show that compared to using fixed parameters,(a)the area with OA>0.7 increases from 54.43%to 89.36%;(b)consistency with ERA5-Land and SMAP data has improved in southwestern North America,the Qinghai-Tibet Plateau,and southwestern Eurasia,with regions showing over 0.7 consistency reaching 81.28%for ERA5-Land and 79.54%for SMAP-FT;and(c)in situ stations with higher accuracy outnumber those with lower accuracy(48.11%versus 22.97%for fixed parameters,35.14%versus 33.51%for SMAP FT).Furthermore,the algorithm achieves the highest median(0.92)and median accuracy(0.88),compared to fixed parameters and SMAP.
基金supported by the Chinese Scholar-ship Councilsupported by the National Natural Science Foundation of China(grant no.41971033)+1 种基金the Fundamental Research Funds for the Central Universi-ties,CHD(grant no.300102298307)the CEOP-AEGIS(Coordinated Asia-European long-term Observing system of Qinghai-Tibet Plateau hydro-meteorological processes and the Asian-monsoon systEm with Ground satellite Image data and numerical Simulations)project(https://www.futurewater.eu/projects/ceop-aegis-2/).
文摘Topsoil structures and inhomogeneous distribution of moisture in the soil volume will induce dielectric discontinuities from air to bulk soil,which in turn may induce multiple and volume scattering and affect the microwave surface emission.In situ ELBARA-Ⅲ L-band radiometer observations of brightness temperature T_(B)^(p) (p=H or V polarization)at the Maqu site on the Eastern Tibetan Plateau are exploited to understand the effect of surface roughness on coherent and incoherent emission processes.Assisted with in situ soil moisture(SM)and temperature profile measurements,this study develops an air-to-soil transition(ATS)model that incorporates the dielectric roughness(i.e.,resulted from fine-scale topsoil structures and the soil volume)characterized by SM and geometric roughness effects,and demonstrates the necessity of the ATS model for modelling L-band T_(B)^(p).The Wilheit(1978)coherent and Lv et al.(2014)incoherent models are compared for determining the dielectric constant of bulk soil in the ATS zone and for calculating soil effective temperature T_(eff).The Tor Vergata discrete scattering model(TVG)integrated with the advanced integral equation model(AIEM)is used as the baseline model configuration for simulating L-band T_(B)^(p).Whereafter,the ATS model is integrated with the foregoing model for assessing its performance.Results show the ATS-based models reduce the underestimation of T_(B)^(p)(≈20-50 K)by the baseline simulations.Being dynamic in nature,the proposed dielectric roughness parameterization in the ATS model significantly improves the ability in interpreting T_(B)^(p) dynamics,which is important for improving SM retrieval at the global scale.
基金funded by the Deutsche Forschungsgemeinschaft(DFG)via the research group FOR2131 on“Data Assimilation for Improved Characterization of Fluxes across Compartmental Interfaces”,subproject P2,the National Natural Science Foundation of China(Grant 42075150)the Natural Science Foundation of Shanghai(No.21ZR1405500).
文摘One-third of the Earth’s land surface experiences seasonal freezing and thawing.Freezing-thawing transitions strongly impact land-atmosphere interactions and,thus,also the lower atmosphere above such areas.Observations of two L-band satellites,the Soil Moisture Active Passive(SMAP)and Soil Moisture and Ocean Salinity(SMOS)missions,provide flags that characterize surfaces as either frozen or not frozen.However,both state transitions—freezing and thawing(FT)—are continuous and complex processes in space and time.Especially in the L-band,which has penetration depths of up to tens of centimeters,the brightness temperature(T_(B))may be generated by a vertically-mixed profile of different FT states,which cannot be described by the current version of the Community Microwave Emission Model(CMEM).To model such complex state transitions,we extended CMEM in Fresnel mode with an FT component by allowing for(1)a varying fraction of an open water surface on top of the soil,and(2)by implementing a temporal FT phase transition delay based on the difference between the soil surface temperature and the soil temperature at 2.5 cm depth.The extended CMEM(CMEM-FT)can capture the T_(B)progression from a completely frozen to a thawed state of the contributing layer as observed by the L-band microwave radiometer ELBARA-III installed at the Maqu station at the northeastern margin of the Tibetan Plateau.The extended model improves the correlation between the observations and CMEM simulations from 0.53/0.45 to 0.85/0.85 and its root-mean-square-error from 32/25 K to 20/15 K for H/V-polarization during thawing conditions.Yet,CMEM-FT does still not simulate the freezing transition sufficiently.
