Erosion, flooding and channel management in Mediterranean environments of southern Europe

1997 ◽  
Vol 21 (2) ◽  
pp. 157-199 ◽  
Author(s):  
J.W.A. Poesen ◽  
J.M. Hooke

Soil erosion by water is one of the most important land degradation processes in Mediterranean environments. This process is strongly linked to problems of flooding and channel management. This article reviews existing knowledge on these topics and defines research gaps. In the framework of environmental change studies it is important to consider soil erosion at various spatial and temporal scales. Most field measurements and modelling efforts have hitherto concentrated on water erosion processes operating at the runoff plot scale. Soil erosion processes operating at other spatial scales have received much less attention in the literature. Yet, there are indications that gully and channel erosion are probably the dominant sediment sources in a variety of Mediterranean environments. Beside water erosion, other erosion processes operating within catchments, such as tillage erosion, land reshaping for land preparation (e.g., terracing) or soil quarrying can have significant impacts on soil profile truncation. Land use changes strongly affect the intensity of these processes. The conditions, position and connectivity of the runoff and sediment generating areas within catchments have a profound effect on flood characteristics within the main channels but the dynamics are not well understood. Some research has taken place into meteorological conditions producing catastrophic flooding and into development of hydrological models using catchment variables. Much less is known of the properties and effects of flood waves within channels, partly because of lack of records of these infrequent events. It is not only water but also sediment which causes destruction in floods, yet sediment is frequently ignored in channel management. The extreme conditions associated with floods in the region, the variability of flows and of flood zones, the mobility of the channels and the high sediment loads create particular challenges for channel management. Trends in land use and channel management are tending to exacerbate these problems. From this review it can be concluded that there is still an important need for process-based understanding and modelling of key soil erosion processes operating at a range of scales: i.e., from plots over hillslopes, catchments to regions. In particular, more research is needed on the linkages between upland areas which produce large volumes of runoff and sediment and channels on the other hand. Such linkages are through gullies and sedimentation zones. Monitoring and experi mental data on key soil erosion and channel processes operating within Mediterranean landscapes are crucial for the improvement of soil erosion and channel models for a range of scales. In particular, long-term monitoring of soil erosion processes and stream channel changes seems to be essential to observe the effects of infrequent torrential rain events on severe erosion, flooding and stream channel changes as well as on the transient response of Mediterranean landscapes to changes in land use and climate. Systematic collation of historical evidence of changes would be valuable. Implications of land and water use need to be examined in detail. A wide range of alternative strategies and techniques of channel and basin management must be explored and modelled. A holistic approach to management of the fluvial system is recommended.

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2786 ◽  
Author(s):  
Safwan Mohammed ◽  
Hazem G. Abdo ◽  
Szilard Szabo ◽  
Quoc Bao Pham ◽  
Imre J. Holb ◽  
...  

Soils in the coastal region of Syria (CRoS) are one of the most fragile components of natural ecosystems. However, they are adversely affected by water erosion processes after extreme land cover modifications such as wildfires or intensive agricultural activities. The main goal of this research was to clarify the dynamic interaction between erosion processes and different ecosystem components (inclination, land cover/land use, and rainy storms) along with the vulnerable territory of the CRoS. Experiments were carried out in five different locations using a total of 15 erosion plots. Soil loss and runoff were quantified in each experimental plot, considering different inclinations and land uses (agricultural land (AG), burnt forest (BF), forest/control plot (F)). Observed runoff and soil loss varied greatly according to both inclination and land cover after 750 mm of rainfall (26 events). In the cultivated areas, the average soil water erosion ranged between 0.14 ± 0.07 and 0.74 ± 0.33 kg/m2; in the BF plots, mean soil erosion ranged between 0.03 ± 0.01 and 0.24 ± 0.10 kg/m2. The lowest amount of erosion was recorded in the F plots where the erosion ranged between 0.1 ± 0.001 and 0.07 ± 0.03 kg/m2. Interestingly, the General Linear Model revealed that all factors (i.e., inclination, rainfall and land use) had a significant (p < 0.001) effect on the soil loss. We concluded that human activities greatly influenced soil erosion rates, being higher in the AG lands, followed by BF and F. Therefore, the current study could be very useful to policymakers and planners for proposing immediate conservation or restoration plans in a less studied area which has been shown to be vulnerable to soil erosion processes.


2020 ◽  
Author(s):  
Leticia Gaspar ◽  
Lionel Mabit ◽  
Ivan Lizaga ◽  
Ana Navas

&lt;p&gt;The main route for the lateral movement of soil organic carbon (SOC) is water erosion. Awareness of the distribution and magnitude of land carbon mobilization is important both for improving models of the carbon cycle and for management practices aimed to preserve carbon stocks and enhance carbon sinks. There is a need to consider the global significance of soil erosion from soil organic carbon cycling schemes and for this reason, the movement of SOC during erosion processes should be elucidated.&lt;/p&gt;&lt;p&gt;Our study aims to estimate the SOC redistribution induced by water erosion during a 40 years period in an agroforestry mountain ecosystem located in northern Spain. To this purpose, topographically driven transects were selected with mixed land uses to i) assess what factors modify the runoff patterns with impact on soil and carbon redistribution and ii) evaluate the mobilization of topsoil organic carbon along the transects.&lt;/p&gt;&lt;p&gt;The lateral movement of SOC shows similar spatial patterns with that of soil erosion. To identify whether erosional or depositional processes have been predominant in the sampling sites we used &lt;sup&gt;137&lt;/sup&gt;Cs inventories and the characterization of terrain attributes of the study with a detailed analysis of the main runoff pathways. Results indicate that SOC losses were related to an increase in water flow accumulation, while the highest SOC gains were recorded at concave positions. Soil erosion processes and the content of SOC in soils are the two main factors controlling carbon budgets. The topographical and geomorphological characteristics of the transects, the spatial distribution of land uses and the presence of landscape linear elements such as terraces or paths, affect runoff and determine the sediment connectivity and carbon dynamics along the slopes.&lt;/p&gt;&lt;p&gt;The interactions between topography and land use produce significant positive or negative effects on SOC accumulation, particularly in areas with complex topography, as the results obtained in our study sustain. Even though the effect of topography and land use/land cover and their interactions on the horizontal distributions of carbon remains largely unknown, our approach contributes to better understand the pattern of gains and losses of soil organic and inorganic carbon induced by water erosion.&lt;/p&gt;


2014 ◽  
Vol 18 (9) ◽  
pp. 3763-3775 ◽  
Author(s):  
K. Meusburger ◽  
G. Leitinger ◽  
L. Mabit ◽  
M. H. Mueller ◽  
A. Walter ◽  
...  

Abstract. Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as a soil erosion agent for four different land use/land cover types in a subalpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide depositions, the fallout radionuclide 137Cs and modelling with the Revised Universal Soil Loss Equation (RUSLE). RUSLE permits the evaluation of soil loss by water erosion, the 137Cs method integrates soil loss due to all erosion agents involved, and the measurement of snow glide deposition sediment yield can be directly related to snow-glide-induced erosion. Further, cumulative snow glide distance was measured for the sites in the winter of 2009/2010 and modelled for the surrounding area and long-term average winter precipitation (1959–2010) with the spatial snow glide model (SSGM). Measured snow glide distance confirmed the presence of snow gliding and ranged from 2 to 189 cm, with lower values on the north-facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is an important information with respect to conservation planning and expected and ongoing land use changes in the Alps. Snow glide erosion estimated from the snow glide depositions was highly variable with values ranging from 0.03 to 22.9 t ha−1 yr−1 in the winter of 2012/2013. For sites affected by snow glide deposition, a mean erosion rate of 8.4 t ha−1 yr−1 was found. The difference in long-term erosion rates determined with RUSLE and 137Cs confirms the constant influence of snow-glide-induced erosion, since a large difference (lower proportion of water erosion compared to total net erosion) was observed for sites with high snow glide rates and vice versa. Moreover, the difference between RUSLE and 137Cs erosion rates was related to the measured snow glide distance (R2 = 0.64; p < 0.005) and to the snow deposition sediment yields (R2 = 0.39; p = 0.13). The SSGM reproduced the relative difference of the measured snow glide values under different land uses and land cover types. The resulting map highlighted the relevance of snow gliding for large parts of the investigated area. Based on these results, we conclude that snow gliding appears to be a crucial and non-negligible process impacting soil erosion patterns and magnitude in subalpine areas with similar topographic and climatic conditions.


Author(s):  
Valeriy Demidov ◽  
Oleg Makarov

The monograph summarizes the information over the past 20 years on the currently widely used. The textbook is intended for students of higher educational institutions, studying in the specialty of soil science, as well as specializing in erosion and soil protection. The textbook describes the physical basis and mechanism of erosion processes, based on some sections of hydraulics, hydrology, hydro-and aeromechanics, knowledge of which is necessary to understand the mechanism of water, wind and irrigation soil erosion. The main mathematical models and principles of forecasting the values of soil losses as a result of erosion processes are considered. The textbook will be useful not only for students and postgraduates studying in the specialty of soil science, but also for geographers, ecologists and a wide range of specialists interested in the problems of soil cover conservation and environmental protection.


2021 ◽  
Author(s):  
Ivan Dugan ◽  
Leon Josip Telak ◽  
Iva Hrelja ◽  
Ivica Kisić ◽  
Igor Bogunović

&lt;p&gt;&lt;strong&gt;Straw mulch impact on soil properties and initial soil erosion processes in the maize field&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Ivan Dugan*, Leon Josip Telak, Iva Hrelja, Ivica Kisic, Igor Bogunovic&lt;/p&gt;&lt;p&gt;University of Zagreb, Faculty of Agriculture, Department of General Agronomy, Zagreb, Croatia&lt;/p&gt;&lt;p&gt;(*correspondence to Ivan Dugan: [email protected])&lt;/p&gt;&lt;p&gt;Soil erosion by water is the most important cause of land degradation. Previous studies reveal high soil loss in conventionally managed croplands, with recorded soil losses high as 30 t ha&lt;sup&gt;-1&lt;/sup&gt; under wide row cover crop like maize (Kisic et al., 2017; Bogunovic et al., 2018). Therefore, it is necessary to test environmentally-friendly soil conservation practices to mitigate soil erosion. This research aims to define the impacts of mulch and bare soil on soil water erosion in the maize (Zea mays&amp;#160;L.) field in Blagorodovac, Croatia (45&amp;#176;33&amp;#8217;N; 17&amp;#176;01&amp;#8217;E; 132 m a.s.l.). For this research, two treatments on conventionally tilled silty clay loam Stagnosols were established, one was straw mulch (2 t ha&lt;sup&gt;-1&lt;/sup&gt;), while other was bare soil. For purpose of research, ten rainfall simulations and ten sampling points were conducted per each treatment. Simulations were carried out with a rainfall simulator, simulating a rainfall at an intensity of 58 mm h&lt;sup&gt;-1&lt;/sup&gt;, for 30 min, over 0.785 m&lt;sup&gt;2&lt;/sup&gt; plots, to determine runoff and sediment loss. Soil core samples and undisturbed samples were taken in the close vicinity of each plot. The results showed that straw mulch mitigated water runoff (by 192%), sediment loss (by 288%), and sediment concentration (by 560%) in addition to bare treatment. The bare treatment showed a 55% lower infiltration rate. Ponding time was higher (p &lt; 0.05) on mulched plots (102 sec), compared to bare (35 sec), despite the fact that bulk density, water-stable aggregates, water holding capacity, and mean weight diameter did not show any difference (p &gt; 0.05) between treatments. The study results indicate that straw mulch mitigates soil water erosion, because it immediately reduces runoff, and enhances infiltration. On the other side, soil water erosion on bare soil under simulated rainstorms could be high as 5.07 t ha&lt;sup&gt;-1&lt;/sup&gt;, when extrapolated, reached as high as 5.07 t ha&lt;sup&gt;-1 &lt;/sup&gt;in this study. The conventional tillage, without residue cover, was proven as unsustainable agro-technical practice in the study area.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Key words: straw mulch, &lt;/strong&gt;rainfall simulation, soil water erosion&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgment&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;This work was supported by Croatian Science Foundation through the project &quot;Soil erosion and degradation in Croatia&quot; (UIP-2017-05-7834) (SEDCRO).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Literature&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Bogunovic, I., Pereira, P., Kisic, I., Sajko, K., Sraka, M. (2018). Tillage management impacts on soil compaction, erosion and crop yield in Stagnosols (Croatia). Catena, 160, 376-384.&lt;/p&gt;&lt;p&gt;Kisic, I., Bogunovic, I., Birk&amp;#225;s, M., Jurisic, A., Spalevic, V. (2017). The role of tillage and crops on a soil loss of an arable Stagnic Luvisol. Archives of Agronomy and Soil Science, 63(3), 403-413.&lt;/p&gt;


Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2221
Author(s):  
Qihua Ran ◽  
Feng Wang ◽  
Jihui Gao

Rainfall patterns and landform characteristics are controlling factors in runoff and soil erosion processes. At a hillslope scale, there is still a lack of understanding of how rainfall temporal patterns affect these processes, especially on slopes with a wide range of gradients and length scales. Using a physically-based distributed hydrological model (InHM), these processes under different rainfall temporal patterns were simulated to illustrate this issue. Five rainfall patterns (constant, increasing, decreasing, rising-falling and falling-rising) were applied to slopes, whose gradients range from 5° to 40° and projective slope lengths range from 25 m to 200 m. The rising-falling rainfall generally had the largest total runoff and soil erosion amount; while the constant rainfall had the lowest ones when the projective slope length was less than 100 m. The critical slope of total runoff was 15°, which was independent of rainfall pattern and slope length. However, the critical slope of soil erosion amount decreased from 35° to 25° with increasing projective slope length. The increasing rainfall had the highest peak discharge and erosion rate just at the end of the peak rainfall intensity. The peak value discharges and erosion rates of decreasing and rising-falling rainfalls were several minutes later than the peak rainfall intensity.


Geosciences ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 478 ◽  
Author(s):  
Miriam Marzen ◽  
Thomas Iserloh ◽  
Wolfgang Fister ◽  
Manuel Seeger ◽  
Jesus Rodrigo-Comino ◽  
...  

The relative impact of water and wind on total erosion was investigated by means of an experimental-empirical study. Wind erosion and water erosion were measured at five different sites: (1) Mediterranean fallow, (2) Mediterranean orchard, (3) wheat field, (4) vineyard and (5) sand substrate. Mean erosion rates ranged from 1.55 to 618 g·m−2·h−1 for wind and from 0.09 to 133.90 g·m−2·h−1 for rain eroded material over all tested sites. Percentages (%) of eroded sediment for wind and rain, respectively, were found to be 2:98 on Mediterranean fallow, 11:89 on Mediterranean orchard, 3:97 on wheat field, 98:2 on vineyard and 99:1 on sand substrate. For the special case of soil surface crust destroyed by goat trampling, the measured values emphasize a strong potential impact of herding on total soil erosion. All sites produced erosion by wind and rain, and relations show that both erosive forces may have an impact on total soil erosion depending on site characteristics. The results indicate a strong need to focus on both wind and water erosion particularly concerning soils and substrates in vulnerable environments. Measured rates show a general potential erosion depending on recent developments of land use and climate change and may raise awareness of scientist, farmers and decision makers about potential impact of both erosive forces. Knowledge about exact relationship is key for an adapted land use management, which has great potential to mitigate degradation processes related to climate change.


Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 5
Author(s):  
Marx L. N. Silva ◽  
Bernardo M. Cândido ◽  
John N. Quinton ◽  
Michael R. James

Water erosion affects all types of soils around the world at different intensities. However, in the tropics, water-based processes are the most important of the erosion processes and have received much attention in the last decades. Understanding and quantifying the processes involved in each type of water erosion (sheet, rill and gully erosion) is key to developing and managing soil conservation and erosion mitigation strategies. This study aims to investigate the efficiency of unmanned aerial vehicle (UAV) structure-from-motion (SfM) photogrammetry for soil erosion assessment, as well as to address some gaps in our understanding of the evolution of erosive processes. For the first time, we used a UAV-SfM technique to evaluate the relative contribution of different types of erosion (sheet, rill and gully sidewall) in gully development. This was possible due to the millimetric level of precision of the point clouds produced, which allowed us to evaluate the contribution of laminar erosion as a new component to gullies studies. As a result, it was possible to quantify sediment volumes stored in the channels and lost from the gully system, as well as to determine the main sediment sources. The UAV-SfM proved to be effective for detailed gully monitoring, with the results suggesting that the main source of sediments in the gully was mass movement, followed by rills and sheet erosion. Our findings support the use of UAV-based photogrammetry as a sufficiently precise tool for detecting soil surface change, which can be used to assess water erosion in its various forms. In addition, UAV-SfM has proven to be a very useful technique for monitoring soil erosion over time, especially in hard-to-reach areas.


2020 ◽  
Vol 12 (24) ◽  
pp. 4149
Author(s):  
Maxim Samarin ◽  
Lauren Zweifel ◽  
Volker Roth ◽  
Christine Alewell

Erosion in alpine grasslands is a major threat to ecosystem services of alpine soils. Natural causes for the occurrence of soil erosion are steep topography and prevailing climate conditions in combination with soil fragility. To increase our understanding of ongoing erosion processes and support sustainable land-use management, there is a need to acquire detailed information on spatial occurrence and temporal trends. Existing approaches to identify these trends are typically laborious, have lack of transferability to other regions, and are consequently only applicable to smaller regions. In order to overcome these limitations and create a sophisticated erosion monitoring tool capable of large-scale analysis, we developed a model based on U-Net, a fully convolutional neural network, to map different erosion processes on high-resolution aerial images (RGB, 0.25–0.5 m). U-Net was trained on a high-quality data set consisting of labeled erosion sites mapped with object-based image analysis (OBIA) for the Urseren Valley (Central Swiss Alps) for five aerial images (16 year period). We used the U-Net model to map the same study area and conduct quality assessments based on a held-out test region and a temporal transferability test on new images. Erosion classes are assigned according to their type (shallow landslide and sites with reduced vegetation affected by sheet erosion) or land-use impacts (livestock trails and larger management affected areas). We show that results obtained by OBIA and U-Net follow similar linear trends for the 16 year study period, exhibiting increases in total degraded area of 167% and 201%, respectively. Segmentations of eroded sites are generally in good agreement, but also display method-specific differences, which lead to an overall precision of 73%, a recall of 84%, and a F1-score of 78%. Our results show that U-Net is transferable to spatially (within our study area) and temporally unseen data (data from new years) and is therefore a method suitable to efficiently and successfully capture the temporal trends and spatial heterogeneity of degradation in alpine grasslands. Additionally, U-Net is a powerful and robust tool to map erosion sites in a predictive manner utilising large amounts of new aerial imagery.


Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1234
Author(s):  
Viera Petlušová ◽  
Peter Petluš ◽  
Michal Ševčík ◽  
Juraj Hreško

The water erosion research was carried out in the lowland type of hilly landscape. The aim was to monitor and evaluate the importance of environmental factors (steepness of slope, relief shapes, aspect, slope length, combination slope length (L) and slope (S)—LS factor, types of land use changes) for the development of water erosion. We focused on the identification of areas threatened by erosion by interpreting aerial photographs from several time periods. This was followed by verification of erosion using soil probes. We identified 408.44 ha of areas affected by erosion, and measured the depth of soil and “A” horizons thickness. The environmental factors were modeled in geographical information systems by tools for spatially oriented data. Subsequently, the influence and significance of individual environmental factors were compared, and the probability of erosion was statistically estimated. The decisive factors in the formation of erosive surfaces are the LS factor and the slope. We also consider the factor of the relief shape to be important. The shape did not appear to be very significant as a separately evaluated factor, but all convex parts correlate with the identified erosion surfaces. The susceptibility of erosion related to the aspect of the slopes to the cardinal directions has not been confirmed. Types of land use changes with the most significant relation of erosion were confirmed in areas of strong intensification. We confirmed the importance of factors and land use for the development of erosion processes.


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