Soil Hydrological Response Research Articles

Combined impacts of climate and land use scenarios on sediment loads in small agricultural watershed in Tunisia

This study investigates the impact of conservation practices, specifically mulching and terracing, on soil erosion in the Kamech watershed (2.6 km²) situated in the Cap Bon region of northeastern Tunisia, under both current and future climate scenarios. Utilizing the Soil and Water Assessment Tool (SWAT) model, the research evaluates the effectiveness of these Best Management Practices (BMPs) in reducing soil loss, revealing significant reductions of 1.5 t ha⁻¹ yr⁻¹ for mulching and 2 t ha⁻¹ yr⁻¹ for terracing. The findings indicate that these practices play a crucial role in enhancing soil conservation amidst climate change challenges, including altered precipitation patterns and increased temperatures. Additionally, the study highlights a notable decline in average monthly rainfall projected for the period 2051 to 2100 under the RCP8.5 scenario, further emphasizing the importance of implementing effective soil management strategies. This paper indicates that both methods, mulching and terracing, significantly contribute to reducing soil erosion under future scenarios (2051-2100). Their implementation proves essential for effective soil conservation, helping to mitigate the impacts of climate change and maintain soil health in the Kamech watershed. The results contribute to a better understanding of BMP performance in addressing soil erosion, water quality, and hydrological responses in the face of evolving environmental conditions. By enhancing our understanding of these interactions, this research aims to provide valuable insights for sustainable watershed management, particularly in regions prone to water scarcity and land degradation.

Response time of soil moisture to rain in a vineyard with permanent cover

The time elapsed between the moments of maximum rainfall intensity and maximum soil moisture, known as peak to peak (P2P), is part of the hydrological response of the soil, but literature has missed this metric in any woody crop. In a vineyard with permanent vegetation cover (humid climatic conditions), the influence of two cultivars (Agudelo and Blanco Legítimo) and two zones (rows and inter-row areas) on the values of soil moisture response time, absolute change in moisture (ΔS) and P2P was evaluated for 118 rainfall events in three soil layers. 12 capacitance probes and a weather station were used, and data measured every 15 min. A positive response (ΔS > 0) was observed in 79 %, 73 % and 67 % of all events at soil depth of 5, 15 and 25 cm, decreasing ΔS with increasing soil depth. Differences of ΔS were significant among layers, but not among cultivars and zones. The maximum ΔS occurred at 15 cm, while the minimum was observed at 25 cm. No response was evident when specific thresholds were not reached: rainfall depth (0.60 mm event−1), maximum intensity (1.20 mm h−1) or duration (30 min). Topsoil conditions –high rainfall interception by the dense cover and high soil organic matter content– influenced the results at 5 cm. Rain parameters correlated well with ΔS, but weak with the response time and P2P. P2P occurred earlier in the rows than between the rows, especially at 15 cm. Shorter P2P appeared in Agudelo, with significant differences in the rows at 5 cm. P2P differed significantly among layers, increasing P2P with soil depth. Similar ΔS values appeared in Spring and Autumn, and were significantly different than those in Summer, but P2P did not differ significantly among seasons. Therefore, the magnitude and timing of the soil hydrological response were independent processes.

Conservation practices reverse soil degradation in Mediterranean fig orchards

Agriculture is an important driver of soil degradation, especially where intensive practices are applied. It is essential to reduce the impact of agriculture intensification and find different solutions to halt this. This work investigates the effect of different types of treatments: 1) tillage (Tilled), 2) Grass covered (Grass), 3) olive pomace (Pomace) and 4) Hay in different seasons (Spring, Summer, and Fall) using rainfall simulations (58 mm h−1 for 30 min). Tillage reduced bulk density (BD) compared to treatments with mulch cover. Grass-covered treatments increased soil organic matter (SOM) and water-stable aggregates (WSA). Additionally, they enhanced hydrological properties, thus mitigating sediment loss (SL) and element transport. The principal component analysis (PCA) showed strong relations between SL and element losses, as well as P soil and Cu soil with SOM. Thus, implementing soil conservation practices, such as hay used as a surface cover, is crucial for fig orchards and agricultural area management to reduce soil erosion, enhance soil quality, and mitigate element transport and SL. Further on, continuous monitoring of soil properties and hydrological responses throughout different seasons should be prioritized, along with exploring alternative methods to ensure sustainable soil management.

Mulch and Grass Cover Unevenly Halt Runoff Initiation and Sediment Detachment during the Growing Season of Hazelnut (Corylus avellana L.) in Croatia

Hazelnut orchards are popular for cropping on sloped sites, which are often highly erodible. This study aimed to assess the impact of soil management and season in a hazelnut orchard on soil properties and hydrological response. Three treatments (Tilled, Straw, and Grass) were established in Munije (Croatia) on Stagnosol. In Spring, Summer, and Fall, a rainfall simulation was performed (intensity of 58 mm h−1 for 30 min). Results reveal higher water stable aggregate values were observed for the Straw treatment in all seasons. Higher soil organic matter (SOM) content was noticed for the Grass treatment in all seasons, while lower values were recorded for the Tilled treatment. Sediment loss in Summer was up to 650% and 1300% higher for the Tilled treatment compared with the Straw and Grass treatments. This study strengthens the comprehension of utilizing a permanent ground cover in hazelnut orchards as a sustainable practice, contributing to the mitigation of soil erosion processes and the improvement of soil properties. The Straw treatment is a viable option since it increases soil stability and SOM, consequently preventing high soil erosion.

Quantification of Root Systems and Soil Macropore Networks Association to Soil Saturated Hydraulic Conductivity in Forested Wetland Soils

Understanding the relationship between root systems, soil macropore networks, and soil hydraulic properties is important to better assess ecosystem health. In this study, treatments were performed in forested wetland soils with different vegetation densities, i.e., large (LWa) and small communities (LWb) of reed (Phragmites australis (Cav.) Trin. ex Steud.). At each plot, three undisturbed PVC cylinders (10 cm in diameter and 50 cm in height) were obtained, and X-ray microtomography (μCT) scanning was used to determine the root and macropore architectures. Results showed that the values of total root length and total root volume at LWa were significantly larger than those at LWb (p < 0.05). Imaged macroporosity, macropore volume, macropore length density, macropore node density, macropore branch density, mean macropore surface area, mean macropore diameter, and mean macropore volume at LWa were significantly larger than those at LWb (p < 0.05), whereas mean macropore length, mean macropore branch length, and mean macropore tortuosity at LWb were larger than those at LWa. Total root length and total root volume were positively correlated with soil saturated hydraulic conductivity. Imaged macroporosity, macropore volume, macropore length density, macropore node density, macropore branch density, mean macropore surface area, mean macropore diameter, and mean macropore volume were positively correlated with soil saturated hydraulic conductivity, whereas mean macropore length, mean macropore branch length, and mean macropore tortuosity were negatively correlated with soil saturated hydraulic conductivity. In conclusion, root systems and soil macropore networks constitute a complex synthesis inside soil environments, and together affect soil hydrological responses.

Effects of wildfire and post-fire salvage logging on rainsplash erosion in a semi-arid pine forest of Central Eastern Spain

Rainsplash erosion on forested hillslopes can be increased by both wildfires and post-fire salvage logging, especially under semi-arid Mediterranean conditions. However, few studies have compared rainsplash erosion among forest sites impacted by logging to other forest areas. To fill this gap, this study has evaluated surface runoff and soil erosion in a burnt and logged (manually or mechanically) pine forest of Central-Eastern Spain under simulated rainfall and compared it to unlogged and unburnt plots. Compared to the unburnt plots, surface runoff significantly increased (over 150%) in logged areas, with a peak of 220% on the areas directly subjected to logging machinery. Peak runoff was substantially increased by fire (+130%) and less by logging (+8. Soil loss due to rainsplash erosion was about 235% (manual logging) to 750% (mechanical logging) higher compared to the unburnt plots. Wildfire exerted a much higher soil disturbance compared to salvage logging, with a soil hydrological response that can be up to an order of magnitude higher. The increased runoff and erosion rates in response to wildfire and logging were ascribed to soil compaction, which increased on average 60% on logged plots as well as to the removal of vegetation cover (−80%), whereas soil roughness played a minor role. From these results, we suggest using lightweight machinery in burnt soils, to reduce surface runoff and erosion. The possibility of building contour felled log debris using the burnt wood may also be considered, in order to retain the eroded sediments.

An improved multi-criteria decision analysis approach for watershed soil erosion susceptibility assessment

Soil erosion within watersheds is a common phenomenon worldwide, and many scientific efforts have been made to address this problem. The Revised Universal Soil Loss Equation (RUSLE) model has been widely employed in soil erosion estimation. However, several studies have highlighted its limitations and the need to account for some key aspects of soil erosion which are not considered in the model. This study explores the potential of utilizing locally dominant soil erosion driving factors alongside the RUSLE model for soil erosion susceptibility assessment within the OIO watershed. Landsat 8 OLI image for the year 2020, DEM, soil data, Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) datasets coupled with field observed datasets were employed to derive these factors. They include soil loss, sediment yield, sediment transport index, and runoff. Numerical rankings that represent the level of contribution of each factor and their attributes to soil erosion within the watershed were generated using the Fuzzy Analytical Hierarchy Process (FAHP). Each factor was reclassified according to these rankings and overlaid using the GIS-based weighted overlay technique to model soil erosion within the OIO watershed. Finally, we employed a statistical combination of the modelled soil erosion map and Hydrological Response Unit (HRU) to assess erosion susceptibility within the watershed. Initial results from the study highlighted the variabilities in annual soil loss (min: < 6.0 t ha−1 yr−1, max: ≥ 58.0 t ha−1 yr−1, mean: 13.55 t ha−1 yr−1) and identified areas with high predispositions to soil loss within the OIO watershed. The annual sediment yield of the entire OIO watershed ranged between ≤ 14.04 to 715.10 t ha−1yr−1 with an annual average of 14.88 t ha−1yr−1. In addition, the sediment transport index and runoff volume for the OIO watershed range between 0.00–69.07 and 0.00–70.00 mm, respectively. Five erosion susceptibility levels were delineated: very slight, slight, moderate, severe, and severe. They occupied 65.00%, 24.43%, 7.69%, 2.63%, and 0.23% of the watershed, respectively. Accuracy assessment conducted using the Receiver Operating Curve (ROC) showed that the soil erosion susceptibility map has an AUC value of 0.86, indicating acceptable results. Our methodological approach improves the RUSLE model, especially regarding preliminary soil susceptibility assessment for watershed development under typical data-scarce conditions.

Physically-based distributed modelling of the hydrology and soil erosion under changes in landuse and climate of a humid tropical river basin

The effects of landuse/landcover (LULC) and climate change on hydrology and soil erosion processes are of major concern, especially in the humid tropics. In this study, an evaluation of these changes is performed in a humid tropical catchment (Vamanapuram river basin, India) using a physically based distributed model, SHETRAN. The past landuse maps and climate data from six fine resolution NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) are used to force the SHETRAN model. A comparison of the change in the rate of soil erosion and hydrological responses during the future climate scenarios (near: 2021–2050 and far: 2071–2100) with respect to the historical period (1980–2005) is conducted.The isolated effects of landuse, climate variability and the combined effect caused change in streamflow (1.1%, 7.9%, 9.0% respectively) and sediment load (−10.4%, 1.7%, −10.5% respectively) in the past. An ensemble mean of general circulation model (GCM) projections showed that mean temperature and average annual precipitation under representative concentration pathway RCP 4.5 (8.5) scenarios for near and far futures increased from the historic period by 0.51 °C (1.6 °C), 0.6 °C (3.2 °C) and by 9% (6%), 15% (22.8%), respectively. Under RCP4.5(8.5), the average annual streamflow increased gradually from the near to far future, by 3.2% (−1.8%) and 13.6 % (22.1%) whereas, the projected sediment load a showed change of −21.05% (−26.63%) in near future while far future indicated change by −11% (4%). The SHETRAN model has been found to be effective in evaluating climate change impacts on hydrology and sediment yield and is useful for future river basin management.

Prescribed fire and soil mulching with fern in Mediterranean forests: Effects on surface runoff and erosion

Prescribed burning is increasingly used to reduce the wildfire risk, and the need to limit runoff and erosion after the fire suggests treating burned soils with mulching. To this aim, fern residues may be more advisable compared to the commonly used straw, since fern is directly available in forests and has lower drawbacks. However, the post-fire hydrological effects of both prescribed fire and soil mulching are contrasting in literature, and fern has not previously experimented as mulching material in Mediterranean forests. To fill these gaps, this study has evaluated the soil hydrological response in small plots installed in three Mediterranean forests (pine, chestnut and oak) after a prescribed fire and mulching treatment with fern. Compared to the unburned soils, runoff and erosion significantly increased immediately after fire (by 150% to 375% for the runoff coefficients, and by 100% to 800% for the soil losses). However, these increases are much lower compared to the highest values reported by some studies. The negative impacts on the hydrological response in burned soils were limited to three-four months after burning. Subsequently, the pre-fire runoff and erosion rates of the burned soils were practically recovered, and the hydrological changes were not significant compared to the unburned soils. In the short term after the prescribed fire application, soil mulching with fern residues was effective to limit the increase in the hydrological response of the burned and not treated soils, since the runoff coefficients and erosion were reduced by 25–30% in oak soils and 70–80% in forests of chestnut and pine. The changes surveyed in soil hydrology were associated to variations in the infiltration rates and water repellency immediately after fire, previously detected in the same experimental site. The recovery of the water infiltration rates and the disappearance of the soil repellency gained importance over time, and the incorporation of mulch residues became beneficial in driving the short-term runoff and erosion response of the burned soils.

Evaluation of Seasonal Effects of Tillage and Drainage Management Practices on Soil Physical Properties and Infiltration Characteristics in a Silt-Loam Soil

The impacts of tillage and drainage managements on soil infiltration characteristics need to be scrutinized for a better understanding and prediction of soil hydrological processes, such as runoff, evapotranspration and soil water storage. The objectives of this study were i) to evaluate the effects of tillage and drainage practices on soil physical properties and water infiltration, and ii) to compare prediction accuracy of estimated and optimized infiltration model characteristics for the observed and predicted quantities of infiltration process in the soil. The research site contains the Crosby-Kokomo soil series (fine, mixed, mesic, Aeric Ochraqualf and fine, mixed, mesic Typic Argiaquoll, respectively). The experiment was a two factorial completely randomized block design with two levels of tillage (chisel plow (CH) and no-till (NT)) and two levels of drainage (drained (D) and undrained (UD)) with three replicates. Soil bulk density (ρb), saturated hydraulic conductivity (Ksat), soil moisture retention curves (SMRC), soil infiltration capacity and piezometric water head in each treatment were also measured. Soil drainage flows at each drain lateral and outlet discharges were measured. The results showed that The UD treatments were always higher for Ksat values than the D treatments regardless of the tillage practices for both depths and the CH treatments always had greater Ksat values than those in the NT at both the depths regardless of drainage practices. The D treatments reduced the soil bulk density by 4.2 and 0.8 % in the surface soil and 4.61 and 6.7% for the subsurface soil in respect to no-till-UD and chisel-UD treatments. The UD treatments had higher bulk density at both of the depths than those of the D treatments regardless of tillage practices except the CH-UD treatments. The NT had higher bulk density at both depths of the soil than those of the CH treatments regardless of drainage practices. Drainage increased pore size distribution significantly higher than the UD treatments (p<0.05). The D treatments had significantly higher storage pores and effective pores (9.37%) (pores retaining water at -10kPa pressure head) than the ones in the UD treatments (8.96%) (p<0.05). The NT treatments yielded higher infiltration rates than the CH and the D treatments produced higher apparent infiltration rates and cumulative infiltration values than the UDs. The changes in soil physical properties were found to be strongly and significantly dependent on season, soil depth, and rainfall (p<0.05). The optimized infiltration models predicted larger range of infiltration rate values for each treatment than the estimated infiltration models, indicating that the optimization produced higher accuracy and validity of the predicted models in the field. To conclude, soil dry bulk density, soil saturated hydraulic conductivity, and increased macropore volumes can significantly impact soil hydrological responses to soil water infiltration, soil water storage and drainage flow under conservation tillage and drainage management practices on a seasonal basis. This impact enhances greater potential to capture water in soil for future crop use in the study site.

Short-term hydrological response of soil after wildfire in a semi-arid landscape covered by Macrochloa tenacissima (L.) Kunth

A proper monitoring and management of semi-arid landscapes affected by wildfire is needed to reduce its effects on the soil hydrological response in the wet season. Despite ample literature on the post-fire hydrology in forest soils, it is not well documented how the hydrologic processes respond to changes in vegetation cover and soil properties of semi-arid lands (such as the forest and areas with sparse forests) after wildfire. To fill this gap, this study evaluates soil hydrology in a semi-arid soil of Central Eastern Spain dominated by Macrochloa tenacissima (a widely-spread species in Northern Africa and Iberian Peninsula) after a wildfire. Rainfall simulations were carried out under three soil conditions (bare soil, burned and soils with unburned vegetation) and low-to-high slopes, and infiltration, surface runoff and erosion were measured. Infiltration rates did not noticeably vary among the three soil conditions (maximum variability equal to 20%). Compared to the bare soil, the burned area (previously vegetated with M. tenacissima) produced a runoff volume lowered by 27%. In contrast, in the area covered by the same species but unburned, runoff was lowered by 58%. The burned areas with M. tenacissima produced soil losses that were similar as those measured in bare soils, and, in steeper slopes, even higher. Erosion was instead much lower (−83%) in the sites with unburned vegetation. Overall, the control of erosion in these semi-arid lands is beneficial to reduce the possible hydrological effects downstream of these fire-prone areas. In this direction, the establishment of vegetation strips of M. tenacissima in large and steep drylands of bare soil left by fire may be suggested to land managers.

Timing and duration of access mat use impacts their mitigation of compaction effects from industrial traffic

Grasslands are declining worldwide and are often impacted by industrial activities, including infrastructure development. Current best management practices for low-disturbance development on grasslands include the use of wooden access mats as temporary work platforms and roadways to mitigate soil compaction and rutting due to heavy traffic. We assessed the impacts of heavy traffic (TON), and the impacts of the same heavy equipment driven over top of access mats (AM), on soil physical, hydrological, and nutrient responses in sandy and loamy soils in the Dry Mixedgrass prairies over a 2-year period. We also assessed how the timing (early vs. late in the growing season) and duration (6 vs. 12 vs. 24 weeks) of AM and TON affected the same metrics. Compared to undisturbed soils, TON increased soil penetration resistance (15 cm depth) up to 93% in loamy and up to 101% in sandy soils, and decreased water infiltration rates from 53 to 71%, respectively. Notably, the negative impacts of TON on soil physical characteristics and hydrology were larger in sandy vs. loamy soils, and when moist soils were exposed to traffic early in the growing season. AMs were effective at mitigating soil compaction from industrial traffic when used on sandy soils. However, AM use increased the supply of total nitrogen and other plant macro- and micro-nutrients, particularly in soils subject to longer (12–24 wk) mat placement. Results indicate TON may have long-lasting effects on grassland (particularly sandy) soils, and that AM use represents an effective tool to mitigate traffic impacts. Further, early-season traffic should be avoided when soils are moist (whether with AM or not), and AMs should be placed on soils for limited durations (≤6 wk) to minimize potential nutrient losses.

Observation and simulation of water movement and runoff in a coarse texture water repellent soil

Water repellent or non-wetting soils show poor water infiltration, which leads to an increased runoff in both natural and agricultural setting. Some forest areas of northern Iran are characterized by extreme water repellency, which makes their soil hydrological response highly complex. A field experiment was carried out to study the effect of water repellency on water movement and runoff in coarse-textured soil covered in Pinus teada in northwestern Iran. An adapted version of the popular agrohydrological model SWAP (Soil, Water, Atmosphere and Plant) has been used to evaluate the modelling of soil water flow and runoff generation. Water repellency was accounted for by multiplying the soil water content and the unsaturated hydraulic conductivity of soil with the F factor. This factor is equal to the volumetric fraction of soil occupied by preferential flow paths. Twenty-seven rainfall experiments were carried out under artificial rainfall using soils with various wettability levels and various rainfall intensities (14 mm/h, 27 mm/h and 34 mm/h). The result show that during the summer and early autumn (May to October) the soil became extreme repellent and runoff was formed when the soils were dry (θ<2%) and the rain intensity was more than 27 mm/h. Also, we investigated the role of the repellent layer on evaporation losses. The results of laboratory and simulation data confirm that water repellency reduces evaporation from the soil surface. Comparing modelling results with field data shows that an assumption of uniform flow in water repellent soil leads to an overestimation of soil water content and an underestimation of runoff. After incorporating water repellency in SWAP with the mobile–immobile concept, the agreement between measured and model simulation data considerably improved.

Management and seasonal impacts on vineyard soil properties and the hydrological response in continental Croatia

Soil degradation in vineyards is a global problem, indicating the need for the adoption of sustainable practices. Studies on the seasonal and long-term management impacts on soil properties and hydrological responses in vineyards are needed. Rainfall simulation experiments (60 mm h−1 for 30 min) and soil sampling were conducted on Cambisols in eastern Croatia during the dry and wet seasons in long-term grass-covered and tilled vineyards. The results show that bulk density (BD), soil organic matter (SOM), available phosphorous (P2O5), soil water content (SWC), mean weight diameter (MWD), and water-stable aggregates (WSA) were significantly higher in grass-covered plots than in tilled plots. WSA was significantly lower in the wet period, whereas the opposite trend was observed for SWC and MWD. The time to ponding (PT) and time to runoff (RT) were high (p < 0.05) in the tilled plot in the dry season and low in the wet season. The sediment concentration (SC), soil loss (SL), carbon loss (C loss), and P2O5 loss were significantly higher in the tilled plot than in the grass-covered plot. Runoff, SC, SL, C loss, and P2O5 loss were significantly lower in the dry period. Although the grass-covered plots exhibited high compaction, the stable structure reduced SL by 91% and 94% in the dry and wet seasons, respectively. The tilled plots increased disaggregation and the availability of sediments for transport, enhancing C loss (4.5 times higher) and P2O5 loss (6.4 times higher) compared with the values in the grass-covered plots. Tillage as an unsustainable practice was more pronounced in the wet season with 16.4, 10.1, and 11.1 times higher sediment, P2O5, and C losses, respectively, than those in the grass-covered plots. More sustainable practices are needed to decrease soil degradation and reverse these processes.

Impacts of Land Use and Land Cover Change on Soil Erosion and Hydrological Responses in Ethiopia

Land use and land cover (LULC) dynamics, in general, and the conversion of the natural vegetation cover into cultivated land, in particular, are major human-induced problems in Ethiopia, which have played a significant role in increasing the rate of soil erosion and altering the hydrological balance in the country. The main aim of this review was to view previous studies in Ethiopia that quantify the change in the rate of soil erosion and hydrological responses as a result of the change in land use and land cover in the country. From the past researches reviewed in this paper, the expansion of cultivated land at the expense of forest land, shrubland, and grassland in Ethiopia has increased the mean rate of soil erosion, sediment yield, surface runoff, mean wet monthly flow, and mean annual stream flow in the last four decades. On the other hand, the change has reduced the dry average monthly flow, groundwater recharge and groundwater flow, and evapotranspiration (ET) in the country. Future research works should pay more attention to the investigation of the impacts of land use and land cover change on groundwater hydrology and the prediction of future soil loss and hydrological imbalance under the changing land use and land cover in the country since little information is available from past researches on these issues. Research works are also required in lowland arid and semiarid areas in Ethiopia to effectively manage soil and water resources in all parts of the country.

Soil Management and Slope Impacts on Soil Properties, Hydrological Response, and Erosion in Hazelnut Orchard

Proper soil management is crucial to mitigate soil degradation. Hazelnut orchards are often raised on slopes and intensively managed, which makes them similar to the already defined highly erodible land uses like vineyards. This research aims to assess the impacts of soil management and the slope on the soil properties, hydrological response, and erosion in the hazelnut orchard. At eastern Croatia on Cambisols, four treatments were chosen, representing two soil managements in the study area (herbicide and mulched) on two different slope inclinations (high ~9° and low ~4.5°), for rainfall simulation experiments and soil sampling. The herbicide treatments on both slopes removed soil cover and reduced (p &lt; 0.05) soil organic matter, mean weight diameter, and water-stable aggregates. Mulched treatments recorded a lower (p &lt; 0.05) bulk density. These soil properties affected soil hydrological response, as the reduction of infiltration in herbicide plots lead to higher water and sediment losses. The higher slope increased erosion in herbicide soil to over 2.2 t ha−1. Mulching was shown as a superior practice as it enhances soil properties and reduces soil erosion, even reducing the effect of the higher slope on erosional processes.

Short-Term Impact of Tillage on Soil and the Hydrological Response within a Fig (Ficus Carica) Orchard in Croatia

Tillage is well known to have impacts on soil properties and hydrological responses. This work aims to study the short-term impacts of tillage (0–3 months) on soil and hydrological responses in fig orchards located in Croatia. Understanding the soil hydrological response in the study area is crucial for soil management due to frequent autumn floods. The hydrological response was investigated using rainfall simulation experiments (58 mm h−1, for 30 min, over 0.785 m2 plots). The results show that the bulk density was significantly higher 3 months after tillage than at 0 and 1 months. The water holding capacity and amount of soil organic matter decreased with time. The water runoff and phosphorous loss (P loss) increased over time. The sediment concentration (SC) was significantly higher 3 months after tillage than in the previous monitoring periods, while sediment loss (SL) and carbon loss (C loss) were significantly lower 0 months after tillage than 3 months after tillage. Overall, there was an increase in soil erodibility with time (high SC, SL, C loss, and P loss), attributed to the precipitation patterns that increase the soil water content and therefore the hydrological response. Therefore, sustainable agricultural practices are needed to avoid sediment translocation and to mitigate floods and land degradation.

Effects of Slope Movements on Soil Structure and Hydrological Response

Active slope movements can lead to continuous changes in soil macro-fabric, micro-structure and properties. In fact, depending on landslide mechanisms, the internal deformations which are induced by movement can deeply remould the mass, favouring formation of cracks and fissures; in addition, sliding leads to formation of an anisotropic shear zone just at the interface with the underlying stable formation. The result of movements and associated deformation phenomena is then a continuous change of soil properties thus of the hydrological and mechanical slope response. This is the focus of the paper, which discusses the key role of the shear zone on the groundwater regime, based on data collected during long-lasting investigations on some slow active earthflows in the Basento valley, Southern Italy. The results of simple calculations highlight some significant effects, which are generally neglected in conventional analyses of rainwater infiltration.

Efficiency of SWAT model for determining hydrological responses of marl formation

The change in the amount of erosion, sedimentation and permeability is directly related to the change in the physical and chemical properties of soil, especially for marl formation (MF). Any hydrological modeling should be verified with land use (LU) and surface parameters of MF. For this purpose, soil hydrological response (HR) and soil loss were estimated for different LU units in Iran’s Sorkhab MF using ArcSWAT model. The output of the model was compared with the real data obtained from Kamphorst rainfall simulator (RS). The results showed that modeling well separated the changes through HR in different LUs of MF. Moreover, there was no statistically significant difference (R2 = 0.72 and ENS = 0.68) between results of RS and SWAT modeling (p < 0.05). The estimated sediment and the runoff rate were 4.62 t ha−1 and 6.54 m3 ha−1, respectively, for the large simulated unchanged units, and the amounts of sediment and runoff were 87.8 t ha−1 and 8.28 m3 ha−1, respectively, for units under land-use change (LUC). Generally, SWAT model has the ability to show the soil HR under LUCs in MFs.

Agriculture Management Impacts on Soil Properties and Hydrological Response in Istria (Croatia)

The objective of this work is to study the effects of traditional land uses (vineyard, cropland, and olive orchard) on soil properties, overland flow, and sediment loss in the Istria region (Croatia), by using simulated rainfall. The results showed that soil bulk density (BD) was significantly higher in cropland plots compared to the vineyard and olive orchard. No differences were observed in soil water content (SWC) and mean weight diameter (MWD). Water stable aggregates (WSA), soil organic matter (SOM), and total nitrogen (TN) were significantly higher in the olive orchard compared to the other land uses. In cropland, during the experiment, we did not identify runoff or soil losses. Runoff (Run) and sediment loss (SL) were significantly higher in the olive orchard compared to the other plots. This was very likely a consequence of tillage practices in vertic soils, the use of herbicides, low vegetation cover, as well as the incorporation of hydrophobic organic matter in the soil matrix. The principal component analysis results showed that factor 1 explained the majority of the runoff and erosion variables. Erosion rates and nutrient losses were substantially different between olive orchard plots, and vineyard and cropland. Factor 2 showed that WSA was inversely related to the available phosphorus, water holding capacity, and sediment concentration. Management practices in the studied area should use minimum tilling frequency to have plant cover and avoid erosion.