喀斯特石林发育演化的地表水土过程作用机制

喀斯特环境中地表水土过程对表层喀斯特过程具有重要意义。在石林区域的地质环境变化条件下,石林形成是从剥蚀夷平期的厚层红土覆盖环境下的石芽溶蚀发育,至厚层覆土受侵蚀后出露深大石芽,再至现代石林的多重侵蚀改造的宏观演变过程。与地表水土过程有关的的风化壳覆盖溶蚀机制与揭露侵蚀机制是石林发育演变中的两个关键机制。

面向生态文明建设 面向重大国家战略 水利部黄土高原水土保持重点实验室推介

一、实验室简介“水利部黄土高原水土保持重点实验室”于2011年12月由水利部批准成立,依托单位为黄河水利委员会黄河水利科学研究院。实验室原名“水利部黄土高原水土流失过程与控制重点实验室”,2021年1月经水利部重点实验室改革重组后正式更名为“水利部黄土高原水土保持重点实验室”。实验室主任为肖培青正高级工程师(二级),实验室学术委员会主任为崔鹏院士。

黄河流域水循环规律与水土过程耦合效应

在气候变化和人类活动的共同影响下,黄河流域水循环和陆面过程正在发生深刻变化,其水资源和泥沙形成、分布和演变均呈现出显著的时空变异特征和高度的不确定性,并将影响流域未来的可持续发展。因此,揭示黄河流域水循环演变规律与水土过程耦合效应,对"黄河流域生态保护与高质量发展"国家重大战略实施具有重要意义。本文分析了黄河流域水循环与水土过程研究现状和面临的挑战,探讨了流域水循环和水土过程研究的发展趋势和关键科学问题,并针对黄河流域水循环规律与水土过程耦合效应研究提出了一些建议方向,为未来相关基础研究和应用基础研究提供参考。

西南岩溶区水土流失过程及防治对策

长期岩溶作用导致的双层岩溶水文地质结构,使岩溶区的水循环过程(含水的流失)和土壤侵蚀过程具有特殊性和复杂性,且受到岩溶地质条件的影响。基于岩溶环境空间分异大的特点,在分析水循环、土壤侵蚀过程的基础上,根据不同尺度区域水土流失的特点分别提出坡地、洼地(谷地)及流域水土流失的防治对策。

地理过程中人类活动定量分析的数学模型——以水土流失和沙漠化过程为例

一前言地理过程是指地表事物分布位置、模式及其成因的动态变化。应该指出的是,在过去关于地理过程的研究中,自然过程与人文过程的相互结合尚不够,人类与地理环境的关系曾被歪曲,过份地强调了地理环境对人类的影响,以致环境决定论占了统治地位。本世纪以来,随着世界人口的日益增长、科学技术的进步及后工业社会的发展,人类利用自然的范围不断扩大,人类活动强度不断提高,从而使许多自然过程(如土壤侵蚀过程、沙漠化过程等)大大加速,环境质量恶。如森林、草场破坏导致了生态平衡的破坏;土地利用不当致使大量的土地盐渍化;

河南大别山区水土流失的原因及治理意见

河南大别山区位于大别山北麓西段,北纬31°23＇～32°42＇,东经113°42＇～115°56＇之间。区内最南端近东西走向的中山,向北延伸出大量的支脉,地势由南到北依次是中山、低山、丘陵岗地,渐次降低,最后抵达淮河平原。南北方向的淮河支流十分发育,形成无数小流域,每个小流域内河沿两侧形成大小不等的冲积平地。区内修建了大、中、小各类水库840座,从而构成了该区群山起伏,沟谷和支脉相间排列,库塘、堰、坝星罗棋布的地貌格局。本文就河南大别山区水土流失的原因做一简要的分析,并提出治理浅见。

人类活动对自然环境演变的影响及其定量评估模型

本文从人地关系研究入手,探讨了自然环境演变过程中人类活动的特征及其与自然过程的关系,运用系统分析方法建立了人类活动对自然环境演变过程影响的数学模型,并结合有关实例,运用该模型对水土流失过程中人类活动的影响作了定量评估.

Identifying soil structure along headwater hillslopes using ground penetrating radar based technique

Soil structure plays an important role in understanding soil attributes as well as hydrological processes. Effective method to obtain high quality soil map is therefore important for both soil science research and soil work ability improvement. However,traditional method such as digging soil pits is destructive and time-consuming. In this study, the structure of headwater hillslopes from Hemuqiao catchment(Taihu Basin, China) have been analyzed both by indirect(ground penetrating radar, GPR) and direct(excavation or soil auger) methods. Four transects at different locations of hillslopes in the catchment were selected for GPR survey. Three of them(#1, #2, and #3) were excavated to obtain fullscale soil information for interpreting radar images.We found that the most distinct boundary that can be detected by GPR is the boundary between soil and underlain bedrock. In some cases(e.g., 8-17 m in transect #2), in which the in situ soil was scarcely affected by colluvial process, different soil layers can be identified. This identification process utilized the sensitive of GPR to capture abrupt changes of soil characteristics in layer boundaries, e.g., surface organic layer(layer #1) and bamboo roots layer(layer#2, contain stone fragments), illuvial deposits layer(layer #3) and regolith layer(layer #4). However, in areas where stone fragments were irregularly distributed in the soil profile(highly affected bycolluvial and/or fluvial process), it was possible to distinguish which part contains more stone fragments in soil profile on the basis of reflection density(transect #3). Transect #4(unexcavated) was used to justify the GPR method for soil survey based on experiences from former transects. After that, O horizon thickness was compared by a hand auger.This work has demonstrated that GPR images can be of a potential data source for hydrological predictions.

Effects of Shrub on Runoff and Soil Loss at Loess Slopes Under Simulated Rainfall

Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation programs.Laboratory rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic characteristics.In these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/h.The average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub plots.Average soil loss rates varied from 44.19 to 114.61 g/(min·m^2) for bare soil plots and from 5.61 to 84.58 g/(min·m^2) for shrub plots.There was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/h.Runoff and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and rills.The unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion mechanisms.The soil loss rate increased linearly with the unit stream power on both shrub and bare soil plots.Critical unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots.

In-situ experiment investigations of hydrothermal process of highway in deep seasonal frozen soil regions of Inner Mongolia, China

To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years, based on which the freezing-thawing rules and water content changing characteristics were analyzed. The main results show the subgrade presents a frequent freezing-thawing alternation, and the water content of subgrade exhibits an obvious seasonal alternation. The subbase has the maximum water content, while the base has the minimum water content. The change of water flux is concentrated in the thawing period and consistent with the change of temperature gradient. The subbase layer has the most active water flux due to the heat absorption and impermeability of pavement that easily causes the water accumulation in this layer. Therefore, the prevention and treatment for the freezing-thawing disease should be started from heat insulation and water resistance.

Research on soil salt transfer under freeze-thawing condition

Soil salt transformation plays an important role in the freeze-thawing process,which is also one of basic problems of cryopedology. The very special law is made up of the two time salt-moisture transfer under freeze-thawing condition. Based on the latest research at home and abroad,through the investigation of soil moisture-salt change in the freeze-thawing process,the conclusion is made that the soil water potential gradient is the main driving force of soil salt movement and the factors are of quantities. The research shows that,when freezing,temperature drops,salt and moisture move towards frozen layer. All make the salinity content of the frozen layer increase significantly. In the thawing process,salinity and moisture in the soil move up again with evaporation and makes the salt second migration.

Variation characteristics of temperature and moisture content of seasonal frozen soil during freezing process in Changchun,China

In China, seasonal frozen soil is widely distributed. The freezing damage of subgrade soil in Jilin Province has been one of major engineering geological problems troubling the safety of road, in which some common damage phenomena, such as frost heave, subsidence deformation and frost boiling, are all caused by water translocation. Aiming at the phenomenon, the changes of moisture content of seasonal frozen soil in Changchun City are mainly studied by long-term field observation and indoor testing of physical properties under different conditions, and then the variation characteristics of moisture content in soil under different compactness and temperature conditions are realized. The results show that the increasing section of moisture content and negative temperature section all lie in O. 0 - 1.0 m of subgrade. Both lowest air and earth temperature occur in January to February, and the most negative temperature ranges from -7℃ to -10℃.

A Two-parameter Exponential Recession Model for Simulating Cropland Soil Moisture Dynamics

To simulate the soil moisture variation in cropland, a two-parameter exponential recession model was derived to depict the recession process of soil moisture in the root zone. The model is based on the assumption that the recession rate of soil water is proportional to the potential evapotranspiration rate and the difference of soil water content and steady soil water content. Two parameters in this model are soil texture-dependent recession constant and steady soil water content. The model was calibrated and validated with measured soil water data at two experiment sites in North China with different soil textures and cropping systems. Coefficients of determination between measured and model simulated soil water content were all greater than 0.7, indicating that both models gave satisfactory simulation results. Results showed that values of two parameters mentioned above are both larger for finer soil than those for coarser soil. At the same potential evapotranspiration rate and soil water content, the recession rate of finer soil is usually lower than that of coarser soil. The proposed model can be used in irrigation management to predict approximate date for irrigation, as well as be embedded into watershed hydrological models to estimate the antecedent precipitation index.

Subdaily to Seasonal Change of Surface Energy and Water Flux of the Haihe River Basin in China: Noah and Noah-MP Assessment

The land surface processes of the Noah-MP and Noah models are evaluated over four typical landscapes in the Haihe River Basin(HRB) using in-situ observations. The simulated soil temperature and moisture in the two land surface models(LSMs) is consistent with the observation, especially in the rainy season. The models reproduce the mean values and seasonality of the energy fluxes of the croplands, despite the obvious underestimated total evaporation. Noah shows the lower deep soil temperature. The net radiation is well simulated for the diurnal time scale. The daytime latent heat fluxes are always underestimated, while the sensible heat fluxes are overestimated to some degree. Compared with Noah, Noah-MP has improved daily average soil heat flux with diurnal variations. Generally, Noah-MP performs fairly well for different landscapes of the HRB. The simulated cold bias in soil temperature is possibly linked with the parameterized partition of the energy into surface fluxes. Thus, further improvement of these LSMs remains a major challenge.

Effects of Permafrost Degradation on Soil Hydrological Processes in Alpine Steppe on the Qinghai-Tibet Plateau

Permafrost degradation is prevalent on the Qinghai-Tibet Plateau.This may lead to changes in water and heat transition in soils and thus affect the structure and function of ecosystems.In this paper,using the measured data of alpine steppe in Wudaoliang assessed the model performance in simulating soil freezing and thawing processes.Comparison of the simulated results by simultaneous heat and water(SHAW) model to the measured data showed that SHAW model performed satisfactorily.Based on analyzing the simulated and predicted results,two points were obtained:(1) freezing and thawing of the active layer proceeded both from the soil surface downward.Compared with the freezing process,the thawing process was slower.The freezing period persisted in the surface layer(4 cm depth) for about 5 months;(2) in the next 50 years,frozen period would be shorten about 20 days in the top 100 cm depth while the thawing would start earlier 40 days than present.Soil water storage in the 0-60 cm would decrease by 22% averagely,especially from June to August when the vegetation is at the dominating water consumed stage.Therefore,this kind of permafrost degradation as active layer freezing and thawing processes changes will reduce soil water content and thus influence those ecosystems above it.

Effects of Spatial Information of Soil Physical Properties on Hydrological Modeling Based on a Distributed Hydrological Model

The spatial distribution of soil physical properties is essential for modeling and understanding hydrological processes. In this study, the different spatial information (the conventional soil types map-based spatial information (STMB) versus refined spatial information map (RSIM)) of soil physical properties, including field capacity, soil porosity and saturated hydraulic conductivity are used respectively as input data for Water Flow Model for Lake Catchment (WATLAC) to determine their effectiveness in simulating hydrological processes and to expound the effects on model performance in terms of estimating groundwater recharge, soil evaporation, runoff generation as well as partitioning of surface and subsurface water flow. The results show that: 1) the simulated stream flow hydrographs based on the STMB and RSIM soil data reproduce the observed hydrographs well. There is no significant increase in model accuracy as more precise soil physical properties information being used, but WATLAC model using the RSIM soil data could predict more runoff volume and reduce the relative runoff depth errors; 2) the groundwater recharges have a consistent trend for both cases, while the STMB soil data tend to produce higher groundwater recharges than the RSIM soil data. In addition, the spatial distribution of annual groundwater recharge is significantly affected by the spatial distribution of soil physical properties; 3) the soil evaporation simulated using the STMB and RSIM soil data are similar to each other, and the spatial distribution patterns are also insensitive to the spatial information of soil physical properties; and 4) although the different spatial information of soil physical properties does not cause apparent difference in overall stream flow, the partitioning of surface and subsurface water flow is distinct. The implications of this study are that the refined spatial information of soil physical properties does not necessarily contribute to a more accurate prediction of stream flow, and the selection of appropriate soil physical property data needs to consider the scale of watersheds and the level of accuracy required.

Field-Scale Contaminant Transport Through Soils:Current Understanding and Open Questions

Agro-chemical transport processes at different scales are discussed and relevant opening questions areidentified by literature review to make some suggestions concerning the improvement of research methods forfield scale solute transport by aid of evaluation of existing models, and examining transport behaviors of solutein vadose zones on different scales. The results indicate that present research progress and understanding onfield scale solute transport have not yet been enough to guarantee the use of our models for the management offield solute movement. Much more research work needs to be done, particularly, in aspects of high resolutionof spatial structures relevant to the hydraulic and transport properties, explicit numerical simulation of actualstructure on field scale and field measurement corroborated with model development.

Impact of Changing Climate in the Kairouan Hydrological Basin （Central Tunisia）

The Merguellil catchment （central Tunisia） has undergone rapid hydrological changes over the last decades. The most visible signs are a marked decrease in surface runoff in the upstream catchment and a complete change in the recharge processes of the Kairouan aquifer downstream. Fluctuations in rainfall have had a real but limited hydrological impact. Much more important are the consequences of human activities such as soil and water conservation works, small and large dams, pumping for irrigation. Several independent approaches were implemented： hydrodynamics, thermal surveys, geochemistry including isotopes. They helped to identify the different terms of the regional water balance and to characterize their changes over time.

Risk Assessment and Management of Hazardous Hydrological and Geological Processes in Ukraine

Due to long and irrational land-utilization, Ukraine deals with one of the most strained ecological situations in Europe. This work is devoted to the study of land resources transformation that was caused by human activity. The subject of study is to assess and forecast physical land and soil degradation, associated with the technical intensification of hazardous exogenous processes. The research is based on the use of methods of ecologic-geomorphological analysis, mathematical-statistical modeling and forecasting. This project gives characteristics to the main anthropogenic factors of threats and risks to land and soil, which take place in the territory of Ukraine. The estimation was conducted relatively dangerous hydrological and geological processes that are key factors of physical degradation of resources. These processes include erosion, flooding, secondary waterlogging, landslides and other collapsed phenomena. Graphic models reflect specific factors and environmental consequences of the most dangerous exogenous processes. Predicted is the development of dangerous hydrological and geological processes, influenced by technogenic factors. Different scenarios of physical land degradation are developed by the example of a specific technonatural geosystem. A measurement system of the sustainable usage and management of soil condition in Ukraine is improved.