Soil Hydrological Characteristics Research Articles

Effects of the conversion of natural tropical rainforest to monoculture rubber plantations on soil hydrological processes

Abstract Rubber plantations have increased significantly under unprecedented economic growth in tropical areas, which leads to soil degradation and thereby alters soil hydrological processes. However, our understanding of how forest conversion affects soil hydrological processes remains unclear. Here, we collected soil samples from secondary forests (SF) and rubber plantations (RP) to determine the soil hydrological characteristics. We found the topsoil (0–20 cm) water retention in SF was higher than that of RP but displayed the contrast pattern in a deeper soil layer (20–60 cm). Meanwhile, the soil infiltration rates among the two vegetation types decreased significantly with infiltration time, with higher stable soil infiltration rates in SF than those in RP. Moreover, soil properties were also impacted by the forest conversion, such as the topsoil capillary porosity (CP) and total porosity (TP) in SF were higher than those of RP but contrasted in a deep soil layer. In comparison, the topsoil bulk density (BD) in SF was lower than that of RP, but contrasted in the deep soil layer and reached a significant level in the 0–10 and 40–50 cm (P < 0.05). Overall, the soil water retention was mainly determined by the CP, which could explain 31.56% of the total variance in soil water retention, followed by TP (26.57%) and soil BD (26.47%), whereas soil texture exerts a weak effect on soil water retention. Therefore, we can conclude that the conversion of tropical rainforest into rubber plantations may accelerate soil erosion owing to its lower topsoil water retention and soil infiltration rates.

Enhancing Watershed Management through Seasonal Water Yield Modelling using InVEST (Case Study: Rawa Pening Catchment Area)

Located in the upstream of the Tuntang Watershed in Indonesia, Rawa Pening catchment is a significant watershed, recognized as one of the nation’s priority watersheds. Evaluating the catchment’s sustainability relies on its water yield, a crucial determinant in guaranteeing a steady water supply, thereby enhancing water security. This study aims to achieve the following objectives: 1.) To utilize the InVEST model for the estimation of temporal water yield potential within the Rawa Pening Catchment Area from 2018 to 2022, 2.) To assess the accuracy of the InVEST model in temporally estimating water yields within the Rawa Catchment Area, and 3.) To investigate the spatial distribution and characteristics of water yield in the Rawa Pening Catchment Area between 2018 and 2022.The results of the study demonstrate significant trends: The peak rate of flow was recorded in November 2022, reaching 645.87 mm/month, and the minimum rate was seen in July 2018, measuring only 0.82 mm/month. The model calibration shows a substantial correlation value of 0.95, a PMARE Index of 12.84%, and a determination coefficient of 0.9011. Despite minor variations, the InVEST model’s accuracy remains substantial due to the high interconnectivity of variables. Various elements, including rainfall patterns, land use practices, soil hydrological characteristics, and threshold flow accumulation, influence the spatial dynamics of quick flow.

Controlling enhanced surface runoff components as a result of a freezing-thawing cycle by inoculating soil bacteria and cyanobacteria

Extreme climatic features, such as the freezing-thawing cycles, impact soil erosion processes and make natural-human linked ecosystems more vulnerable to soil erosion and loss. In order to achieve sustainable development, more efficient and comprehensive efforts are necessary. This entails using several techniques to preserve natural resources and ecosystems, resulting in soil and water conservation and economic success. Recent research has focused on natural-based methods, such as developing soil biological crusts by bacteria and cyanobacteria inoculation for soil stability. Modification of soil hydrologic characteristics owing to the inoculation of indigenous microorganisms, on the other hand, has received little attention. The current study assessed the function of inoculation of native bacteria and cyanobacteria in preventing surface runoff during a physical simulation of a freezing-thawing cycle at the laboratory scale. The research soil was obtained mainly from dry terrain in the Badranlou Area of North Khorasan Province and transported to tiny erosion plots (0.5 × 0.5 m) with a constant slope of 20% in the Tarbiat Modares University's Rain and Erosion Simulation Laboratory. The dominant and non-pathogenic bacteria and cyanobacteria found in the study soil's micro-bank were identified, purified, and proliferated. The bacteria and cyanobacteria were inoculated into the study soil before undergoing a six-replication freezing-thawing cycle. The hydrologic outputs of the treated and control plots were compared after a simulated study rain with an intensity of around 70 mm.h-1 continued for 30 min. The surface runoff components improved significantly (p < 0.001) compared to the control and inoculated treatments following individual and combination inoculation of bacteria and cyanobacteria during a freezing and thawing cycle 60 days after inoculation. As a result, bacteria, cyanobacteria, and combined treatments increased the start time by 102%, 228%, and 266%, respectively, and the time to peak by 26%, 49%, and 56%, respectively, while decreasing the runoff peak by 22%, 48%, and 55%, and the runoff volume by 33%, 65%, and 73%. The findings showed that inoculating soil with bacteria and cyanobacteria is a practical, cost-effective, and environmentally friendly way to improve runoff components in locations prone to freezing and thawing.

A game theory-based prioritization of drought affected demo vineyards using soil main properties in the northern apennines, italy

The selection of appropriate strategies is required to mitigate drought effects in farmlands. Prioritizing the severity of the water deficit in vineyards is further essential to take early remedial action in the most endangered areas to provide a starting point and sketch out a plan for choosing “the most suitable water resilient management practices” for various research sites. We selected six pilot/ demo sites viz., Santa Maria della Versa (SMV), Canevino (CNV), Borgo Priolo (BPR), Creta (CRT), Vicobarone (VCB), and Genepreto (GNP) in the Northern Apennines, Italy. As a result, the input data on soil profiles, pedological variables, and soil hydrological characteristics were gathered. After calculating and preprocessing the soil properties, the study demo vineyards were ranked for each prioritization criterion. Therefore, we used the Condorcet Game Theory method to identify high-priority vineyards. The findings demonstrated that, for most of the research criteria, the physicochemical characteristics of the soil at two depths (i.e., 0–30 and 30–90 cm) reacted differently. In this regard, BPR 2 and CRT 1 sites were the worst sites encountering drought stress at depths of 0–30 and 30–90 cm, respectively. While at both depths, the SMV1 site was identified as the least important site. The results, on the other hand, revealed that the factors that had the most significant influence on drought stress at the depth of 0–30 cm were the dry density (36.37 %), unit weight (13.74 %), void index (11.11 %), and silt content (9.35 %). However, in soil depths between 30 and 90 cm, dry density (23.96 %) was the most critical component, followed by porosity (12.88 %) and saturation degree (11.48 %). The current study's findings provide a solid foundation for choosing a practical management approach to reduce, cope with, or mitigate the impact of droughts on the Mediterranean region's vineyards.

Hydrological characteristics and available water storage of typical karst soil in SW China under different soil–rock structures

Soil hydrological characteristics are influenced by factors such as parent rock weathering, human activities, and soil texture. However, the influence of the complex soil–rock structures and heterogeneous soil types on soil hydrological characteristics resulting from the weathering of carbonate rocks into soils on slopes in the karst region of SW China is not fully understood. The relationships between zonal and nonzonal soil hydrological characteristic differences, land uses, and soil–rock structures were analyzed using a typical watershed in the SW China karst region. In this study, (1) the difference between zonal and nonzonal soil hydrological characteristics is significant. For infiltration capacity (Ks), yellow soil (19.50 ∼ 1058.00 cm·d-1) < limestone soil (34.50 ∼ 2364.00 cm·d-1), while for soil available water storage, limestone soil on the dolomitic slope (43.26 mm) > yellow soil (20.16 ∼ 35.25 mm) > limestone soil on the limestone slope (17.73 ∼ 34.72 mm). (2) Land-use practices and soil–rock structures have long affected the hydrological characteristics of soil in karst. (3) The bare bedrock on carbonate slopes leads to a reduction in the total amount of soil per unit area on the slope, which compresses the space for vegetation growth and reduces the total amount of water provided by the soil for vegetation growth per unit area, which confirms one of the reasons for the low plant biomass in karst. These results suggest that the utilization of soil water in karst areas should consider the weights of soil type, lithology, and soil–rock structures.

Implementation of Soil and Water Conservation in Indonesia and Its Impacts on Biodiversity, Hydrology, Soil Erosion and Microclimate

Soil and water are natural resources that support the life of various creatures on Earth, including humans. The main problem, so far, is that both resources can be easily damaged or degraded by human-induced drivers. The threat of damage or degradation is increasing due to rapid human population growth and humans’ insatiable daily necessities. Indonesia has had various experiences in soil and water conservation (SWC) programmes for a long time, which can be a good lesson learned for future strategy development. This article aims to provide an overview of the benefits of implementing SWC in Indonesia for biodiversity, hydrology, soil erosion, and microclimate to support sustainable ecological landscape management. Various vegetative and mechanical techniques that have been known and implemented can be utilized to improve future SWC strategies. It is expected that proper strategy development in the future for SWC in Indonesia will support the sustainability of ecological landscape management. Forthcoming SWC programmes are also expected to incorporate local knowledge into their implementation. The programmes also require coordination between stakeholders, i.e., local communities, management authorities, policymakers, and scientists, and seamless integration between varying fields and levels of governance. The main findings of this study are that SWC increased the adaptation of native plants to local rainfall and soil conditions; SWC increased infiltration and improved soil hydrological characteristics; and SWC, through vegetation techniques, played a role in lowering temperatures, increasing humidity, and reducing intensity levels.

Soil Nutrient Distribution and Preferential Flow Transport Patterns in Robinia Pseudoacacia Communities of Degraded Wetlands

The Yellow River Delta wetlands in the Yellow River Delta National Nature Reserve are facing serious degradation due to water scarcity and soil salinization. This study aims to investigate the mechanism of wetland degradation by analyzing the small-scale distribution of soil nutrients and preferential flow transport patterns in the Robinia Pseudoacacia community, which is a typical vegetation community in degraded wetlands. Soil physical and chemical properties based on field staining experiments were analyzed, and indoor solute penetration experiments were conducted to investigate the distribution of soil nutrients and hydrological characteristics. The results showed that the contents of soil organic carbon, organic matter, total nitrogen, and available phosphorus decreased with increasing soil depth, with higher contents in the preferential flow area than in the matrix flow area. Soil organic carbon, organic matter, total nitrogen, total phosphorus, and available phosphorus showed positive correlations with each other, while soil pH and conductivity exhibited negative correlations with the above nutrients. The efflux rate of the Acacia community exhibited a gradual decline as soil depth increased, and the relative concentration of the solution exhibited a non-monotonic pattern of decrease, increase, and subsequent decrease with increasing soil depth. The findings could provide valuable guidance for the restoration and management of degraded wetlands in the Yellow River Delta.

The Shadow Values of Soil Hydrological Properties in the Production Potential of Climatic Regionalization of the Czech Republic

The Czech Republic uses a dual system of agricultural land prices, namely the formal/official price—for tax purposes—and the market price in the case of a standard sale or purchase of farmland. This paper focuses on the construction of an econometric model to quantify the influence of soil hydrological characteristics on the production potential in a given climatic region. It also focuses on the use of this model for the determination of the official price of agricultural land, which is expressed on the basis of the code of the evaluated soil-ecological unit (ESEU) and based on defined soil characteristics. The pricing itself is based on the production potential of the land, which in practice is very important for spatial planning, as it determines the classes of agricultural land protection with regard to the possibility of setting aside agricultural land for non-productive purposes or for drawing subsidies for less favourable areas. In this context, the non-productive functions of agricultural land are also frequently discussed, especially its retention, which plays a very important role in the currently changing climatic conditions. There are a number of studies on soil retention, and numerous approaches to measuring it, but none of them address its impact on production potential and thus on the price of land. For this reason, this paper focuses on defining the influence of the retention of the main soil units (defined for the conditions of the Czech Republic) on production potential. For this definition, SUR models are used, where the endogenous variable is expressed as production potential and the exogenous variables include the basic soil characteristics such as grain size, porosity, hydrological component of the soil, and retention. The obtained outputs show both the high explanatory power of the model and the adequate parametric significance of most variables, which provides sufficient support for the use of the results in practice. In addition, the estimated models across all climatic regions are consistent with substantively logical assumptions about the link between production potential and soil hydrological properties, which secondarily demonstrates their applicability in practice, especially for state administration, but also for local government in the sense of municipalities, cities, and other organizational units.

Spatial variability of surface soil water content and its influencing factors on shady and sunny slopes of an alpine meadow on the Qinghai–Tibetan Plateau

Soil moisture is a vital factor that influences soil characteristics and vegetation distributions in alpine meadow regions. Previous studies have mainly focused on the effects of alpine gradient change, climate change, and human activities on soil hydrological characteristics and vegetation distributions worldwide. However, the spatial variability of the surface soil water content and its influencing factors between shady and sunny slopes in alpine regions are seldom conducted, especially on the alpine meadow regions of the Qinghai–Tibetan Plateau. Based on soil sample collection, combined with statistical, geostatistical, stepwise regression, and geographical detector analysis, this study explores the spatial variability of the surface soil water content and its influencing factors on the shady and sunny slopes of the Mila Mountain pass area on the Qinghai–Tibetan Plateau. Results show that the average soil water content of various depths ranges from 23.14% to 35.52%. The soil moisture content of different soil layers on the shady and sunny slopes shows moderate variability. On the sunny slope, the spatial distribution of the soil water content in different soil layers is mostly patched and banded, while the soil water content on the shady slope shows patchy distribution. The correlation analysis shows that the soil water content of each soil layer has a very significant correlation (P < 0.01). Stepwise regression analysis shows that the main influencing factors of water content of different soil layers on the shady and sunny slopes are soil physical property indexes. Meanwhile, the vegetation coverage factor has a higher explanatory power except the physical indexes on the shady and sunny slopes. The index interaction detection shows interaction among all the evaluation indexes. On the shady slope, all the interactive combinations of the evaluation indexes in each soil layer shows a double-factor enhanced relationship. On the sunny slope, 60% of the interactive combinations of the evaluation indexes show a double-factor enhancement relationship, but 40% of the interactive combinations show a nonlinear enhancement relationship. This study contributes to knowledge on the variability of surface soil water content and its influencing factors on the shady and sunny slopes in the alpine meadow of the Tibetan Plateau, and provides guidance on artificial vegetation restoration and soil structure analysis in the alpine regions.

Understory biomass measurement in a dense plantation forest based on drone-SfM data by a manual low-flying drone under the canopy

Forest is an important part of the environmental system, which has a significant impact on soil hydrological characteristics and forest landscapes, because these processes are influenced by forest management and understory vegetation. Quantitative understory vegetation biomass (UVB) measurement and estimation are vital processes in forest ecology and environmental management. However, these estimations are difficult to make on a large scale especially dense planted forest. Here, we applied catchment-scale Structure from Motion and a manually operated ultralow-flying drone under the canopy of a dense planted (2000 stems/ha) Japanese cedar/cypress plantation forest to reconstruct the understory. An understory drone survey was performed over a 1.1-ha sub-catchment to generate a canopy height model based on dense point cloud data. A biomass survey of three 16-m2 harvesting plots was conducted to compute understory vegetation volume data based on point clouds. Combined with harvested biomass data in the field, quantitative models were developed between the understory vegetation volume and biomass. Subsequently, the models were used to map spatial understory vegetation biomass distribution in the sub-catchments. Aerial photos taken by the ultralow-flying drones under the canopy yielded a high-resolution catchment-scale understory with point cloud density >10/cm2. Strong cubic model coefficients of determination (R2 = 0.75) predicted the understory vegetation biomass based on the canopy height model. The mean understory vegetation biomass was 0.82 kg/m2 and dominated by low ferns. In the present study, we successfully reconstructed the multilayered forest structure and generated understory vegetation biomass distribution models. This results also will be essential to evaluate the erosion and evapotranspiration in dense plantation forests and future environmental management.

Optimization of stand structure in Robinia pseudoacacia Linn. based on soil and water conservation improvement function

The analysis of complex relationship between stand structure and soil and water conservation function (SWCF) of forests and the precise adjustment of stand structure based on an improvement in function are the key technical problems of forestry ecological engineering construction in the Loess Plateau. This study was conducted in the Caijiachuan watershed of the Loess Plateau in western Shanxi, China. Sixty standard plots (20 × 20 m2), including 20 stand densities (900 ∼ 2,800 plants·hm−2), of Robinia pseudoacacia L. were established in the watershed. The 10 factors of stand structure and four functional indices of the SWCF, including 29 sub-functional indices, were investigated and monitored each year from June to September in 2016 to 2019. The results indicated that there are differences in the SWCF under different stand structures, and the differences are concentrated in the water conservation function (FWC) and soil conservation function (FSC) of functional indices of the SWCF. In particular, they are reflected in the soil moisture and hydrological characteristics of the litter of sub-functional indices. Stand structure factors could effectively explain the differences of functional indices of the SWCF of a R. pseudoacacia forest, and a rate of 81.4% of functional indices could be explained by stand structure factors. Based on the configuration of the optimal stand structure (included a stand density of 1,800 plants·hm−2, mean diameter at breast height of 15.19 cm, mean tree height of 10.49 m, leaf area index of 2.86, canopy density of 0.85, uniform angle index of 0.50, story differentiation of 0.59, diameter dominance of 0.45, and biomass dominance of 0.46), the density of existing stands was concentrated in the range of 1,500 ∼ 1,900 plants·hm−2 and was more effective at optimizing the SWCF. The optimization strategy of the stand structure of the R. pseudoacacia forest in the study area should focus on increasing the differentiation of forest layer, enrich the vertical structure of the stand and maintain a random distribution pattern of trees. The overall growth of the stand remained uniform, avoiding the excessive dominance of individual trees and unreasonable stand density. These results will provide a more scientific and complete reference to optimize the stand structure of the R. pseudoacacia forest in the Loess Plateau.

Soil mechanical and hydrological characteristics as influenced by tillage and residue management practices

Soil mechanical and hydrological characteristics as influenced by tillage and residue management practices

The role of peat on permafrost thaw based on field observations

Rising temperatures result in permafrost degradation in cold regions, but with considerable spatial heterogeneity due to local factors including peat. Peat plays an important role in the permafrost carbon cycle by impacting the soil thermal and hydrologic characteristics. Here we use field observations to describe the role of peat on permafrost thaw based on comparisons at two sites: EBoTA characterized by primarily peat, and PT5 with more mineral soils. Compared to PT5, soil temperature at the EBoTA site was lower in the warm season, but higher in the cold season. Freezing onset was generally 0–19 days later at the PT5 site compared to EBoTA throughout the soil column, except at the 0.1 m depth where it occurred 11 days earlier. The average thawing onset at PT5 was 18–96 days earlier. There were 20–119 more freezing days and 19–118 fewer thawing days at EBoTA than at PT5, and the zero annual amplitude and active layer thickness were lower at EBoTA. Finally, the mean annual ground temperature was greater at PT5, and was even above 0 °C in three recent years. These results illustrate peat’s thermal insulation effect on permafrost due to its low thermal conductivity and high moisture content. Snow depth increases also amplify the insulation effect. These field observations therefore not only verify, but also quantify the protective role of peatlands on permafrost.

The study of forest land use on land characteristics and soil hydrological characteristics in the Wanggu Watershed, Southeast Sulawesi

The preservation of natural resources such as forest, land, water and air is needed to ensure their ecosystem availability. The existence of forests as a water regulator is the main element of human life and other living organisms. The research objectives were to examine and determine the role of forest land use on forest land characteristics and soil hydrological characteristics in the Wanggu watershed. This study used a survey method and then conducted intensive observations. Forest soil observations were carried out by making a soil profile. Soil infiltration and permeability parameters were carried out through an infiltrometer and a permeameter, erosion and ETol using erosion prediction. The data used were primary data and secondary data. The results showed that: 1) the use of protection forest, production forest and agroforestry improves forest land characteristics, soil fauna and soil hydrological characteristics and soil erosion, 2) protection forest produces field capacitance, soil infiltration capacity and soil permeability higher than production forest and agroforestry with runoff, runoff coefficient and erosion < tolerable soil erosion, followed by production forest and agroforestry and 3) protection forest, production forest and agroforestry.

Effects of tillage depth on soil hydrological characteristics and potato yield on northwest Loess Plateau

<p indent=0mm>The subsoiling can break the plough pan and optimize soil hydrological characteristics. However, the study on the effects of tillage depths on soil water characteristics, potato water consumption and yield, is insufficient. The field experiment was conducted with three tillage depths of <sc>15 cm</sc> (TT), <sc>40 cm</sc> (VRT), and <sc>60 cm</sc> (VRT6), to investigate the effect of tillage depths on the yield and water utilization of potato in semiarid rain-fed area in 2016 and 2017 on northwest Loess Plateau. The parameters of soil bulk density, soil hydrological properties, potato SPAD (soil and plant analyzer development) value, leaf area index (LAI), and tuber yield were measured. The soil bulk density, and increased saturation moisture, capillary moisture and field water capacity of VRT6 treatment compared with VRT and TT were decreased in <sc>40–60 cm</sc> and <sc>0–60 cm</sc> profile, respectively. Water consumption of VRT6 treatment was significantly increased in pre-squaring stage, resulting in the decrement of soil water storage in <sc>0–100 cm</sc> profile by <sc>22.3 mm</sc> and <sc>49.0 mm</sc> in 2016, and <sc>43.9 mm</sc> and <sc>56.6 mm</sc> in 2017. Water consumption in pre-squaring stage of VRT6 was significantly increased by <sc>42.2 mm</sc> and <sc>38.3 mm</sc> compared with VRT and TT treatment in 2017, respectively. Based on the excessive water consumption in pre-flowering period, the LAI of VRT6 was significantly higher than TT in whole growth period, than VRT in post-squaring period, and the SPAD value was higher than VRT in expanding stage in 2017, which indicated that the vigorous growth was subsistent in VRT6 treatment. The tuber yield of VRT6 were significantly higher than TT, but it significantly decreased in 2017 compared to VRT, and the water use efficiency (WUE) of VRT6 were significantly decreased by 61.2%–67.5% and 41.0%–53.5%, as compared with VRT and TT. Consequently, the suitable tillage depth for potato cultivation was <sc>40 cm</sc> in semiarid area, which could optimize the soil hydrological properties and potato water consuming process, and relieved the drought stress efficiently, resulting in significantly higher tuber yield and WUE.

Temporal and spatial variability of shallow soil moisture across four planar hillslopes on a tropical ocean island, San Cristóbal, Galápagos

Study regionThis paper provides a summary of findings from temporal and spatial studies of soil water content on planar hillslopes across the equatorial island of San Cristóbal, Galápagos (Ecuador). Study focusSoil water content (SWC) was measured to generate temporal and spatial records to determine seasonal variation and to investigate how the behavior of surface and near-surface root-zone soil water may support island-wide hydrogeology models. SWC probes were installed at four weather stations in a climosequence to generate a temporal record, and spatial surveys of shallow SWC across the selected sites were completed during wet and dry seasons. Temporal differences in SWC were driven by seasonal variations in rainfall and evapotranspiration, while spatial variability remained high during both wet and dry seasons. Unsaturated hydraulic conductivity determined by mini-disk infiltrometers was highly variable across the slopes, as were other hydrologic variables. New hydrological insights for the regionThe high heterogeneity of soil water and hydrologic characteristics provides a means to explain why little runoff is observed at the study sites: soils do not saturate uniformly across hillslopes, allowing for runoff generated in one part of the hillslope to be conducted into the soil in adjacent parts of the hillslope. The lack of connected surface runoff helps explain how water enters the groundwater system of the island.

Analytical Solution of the Richards Equation under Gravity-Driven Infiltration and Constant Rainfall Intensity

In the field of soil hydrology, the Richards equation is commonly used to model water flow in unsaturated soils. The high nonlinearity of the Richards equation makes it very challenging to solve analytically for situations that are meaningful in practical applications. In this paper, an exact and simple analytical solution of the Richards equation under gravity-driven infiltration and constant rainfall intensity is derived. First, the solution is presented under Torricelli’s law, which mimics the soil hydraulic conductivity function and describes the emptying or filling process of a nonlinear water reservoir. Then, following a similar approach, the solution is extended to the Brooks and Corey soil hydraulic conductivity function, which is generally considered to well describe soil hydrological characteristics. The approach followed in this study is a simple hydraulic approach; therefore, the derived solutions are not affected by uncertainty as long as the hypothesis of the gravity-driven infiltration is satisfied for the selected soils. A comparison with the solution numerically derived by the Richards equation for which the gravity-driven assumption is relaxed is performed and discussed. Interestingly, the comparison indicated that the suggested solution delimits the solutions domain of the Richards equation.

Study on Soil Hydrological Characteristics of Highway Spoil Disposal Site in Loess Region

Due to complex climates, geological conditions and landform types, the ecological environment in the western region of China is very fragile. Thanks to the continuous large-scale construction of highway transportation infrastructure over the years, the social transport services are satisfactorily offered in the western region, but also some negative impacts on the ecological environment in the western region are accompanied, especially a large impact on the land resources in extreme scarce in the western and weak soil & water conservation in loess region. The western loess region faces low land bearing capacity, fragile ecological environment and severe soil & water erosion. Restricted by its own conditions of the spoil disposal site, in the case of lack of rainfall and loose soil, it is very important for later restoration to accurately learn the hydrological characteristics of the spoil disposal site.

Determining of soil resistivity by electrical resistivity tomography in agroforestry land system

The study of soil hydrological characteristics is expensive and time-consuming due to its exercises drilling, test pit, and even trenching. The electrical resistivity tomography (ERT) technique is known as one of the viable methods for determining soil resistivity as a proxy for soil water content. The research has been done in three resistivity lines at the sloping agroforestry land system in West Java province-Indonesia. Soil resistivity value in the Pangalengan line transect ranges from 4.3-2500 Ω, Mandalahaji line transect ranges from 23-288 Ω, and Kiara Payung line transect ranges from 24-500 Ω. Soil resistivity under the agroforestry land system was higher than non-agroforestry land. Soil resistivity is firmly related to the soil water content with an inverse pattern. The use of woody tree species as a water absorber in the agroforestry farming system was the potential to prevents rapid soil saturation and maintain the stability of the steep area. In the steep area, the saturated condition decreases soil shear strength and increases the load on the upper slope so that it triggers soil mass movement.

Study of the relation between soil erodibility and hydrological characteristics

Hydrological characteristics such as soil water retention curve and hydraulic conductivity, for which, however, there are no standardized measurement methods for the entire range of soil moisture, are most important for assessing the erodibility of soil. In the article, based on the energy approach to soil erodibility analysis, a relation was proposed linking the characteristic of soil erodibility, – the specific power spent on the destruction and removal of soil in the places of its natural occurrence, with soil hydrological characteristics. Modeling erosion processes based on the proposed ratio may allow both describing the erosion properties depending on the initial soil moisture and obtaining numerical information on the soil hydrological characteristics using measured values of soil erodibility characteristics at any time during the vegetation period.