SSS11.11

EDI
New challenges in measuring geomorphological dynamics and estimating erosion rates in badland areas

Badlands are unique landscapes with intense past or present geomorphological dynamics and high erosion rates, being among the most outstanding and impressive erosion landforms on earth.
Given the problems that follow from the rapidity of geomorphological processes and the high magnitude of erosion of badland areas, there are important associated environmental and management implications (i.e. high sediment transport and water turbidity, loss of biodiversity). Many methods with different degrees of complexity can be used to measure these processes. However, there is not standard protocol for measuring erosion dynamics, and the selection of method mainly depends on several factors as the characteristics of the research group (e.g. number of members, training capacity), financial support (e.g. instrument availability), objectives, and size of the study area. These methods can be mainly considered dynamic or volumetric: (i) dynamic methods aim to measure fluxes from plots (e.g. rainfall simulation, Gerlach troughs), micro-catchments (e.g. collectors), or experimental catchments (e.g. turbidity sensors); while (ii) volumetric methods aim to measure sediment erosion rates through the analysis of topographic changes by sparse observations (e.g. erosion pins, microprofile methods) or by the use of high-resolution topographic survey methods (e.g. Structure from Motion photogrammetry, terrestrial laser scanning). Also, methods should include determining weathering rates of various lithologies in different climate conditions (including both field measurements and simulations in laboratory conditions).
In this session, we would like to gather studies focusing on badland dynamics, especially facing new challenges in measuring geomorphological dynamics and erosion rates: mapping badland evolution and geomorphological dynamics, measuring erosion rates using different methods, discussing new challenges in measuring erosion rates in badlands (including piping erosion), definition of mapping protocol and erosion estimation procedures.

Co-organized by GM8
Convener: Manel LlenaECSECS | Co-conveners: Milica Kasanin-Grubin, Alberto BosinoECSECS, Paolo Tarolli, Peiqing Xiao, Estela Nadal Romero
Presentations
| Wed, 25 May, 15:55–18:17 (CEST)
 
Room G1

Presentations: Wed, 25 May | Room G1

Chairpersons: Manel Llena, Anita Bernatek-Jakiel
15:55–16:00
New challenges in measuring geomorphological dynamics and estimating erosion rates in badland areas
16:00–16:07
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EGU22-577
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ECS
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Highlight
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Virtual presentation
Nevena Antic, Milica Stefanovic, Nevenka Mijatovic, Tomislav Tosti, Chunxia Xie, and Milica Kašanin-Grubin

Badlands, between researcher also known as natural field laboratories, present areas formed in a wide range of lithologies and different climate conditions. Complex mineralogical and physico-chemical sediment composition make them suitable for numerous laboratory experiments that can replicate changes that occur in the field.

As climate is one of the most significant factors in badlands forming and since climate changes are one of the biggest environmental concerns nowadays in this research badlands material was exposed to different conditions with the aim to monitor changes caused by extreme climate.

Three samples of badlands from China were organized in twelve sets and treated with rain, acid rain, ice (presenting snow) and acid ice (frozen acid rain). Six sets were treated with rain and acid rain of different intensity and under high and low temperatures during fifteen cycles, while the other six were treated with ice and acid ice during fifteen cycles, dried at 50°C for three cycles and then treated with ice and acid ice for additional five cycles. All of the samples were photographed after each cycle to follow physical change occurring on the sample surface Leachate was collected and volume, electrical conductivity, pH and ion concentration were measured.

Generally parameters did not oscillate much neither between samples, nor between treatments except electrical conductivity that was higher in the samples treated with ice and acid ice. Physical changes that occurred during the experiment present the main difference. In all of the samples high temperature caused the most noticeable decay, in samples treated with rain, sediment decay was minimal, while in samples treated with ice a noticeable decay occurred.

This experiment confirmed that high temperature/drought has great impact on land degradation, but interestingly pointed out that ice/snow and its thawing have greater impact on degradation then rain and its intensity. These kind of result opens up a new perspective on climate impact on forming and badlands evolution that should be further examined.

How to cite: Antic, N., Stefanovic, M., Mijatovic, N., Tosti, T., Xie, C., and Kašanin-Grubin, M.: Is snow more distructive agent than rain from the perspetive of land degradation?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-577, https://doi.org/10.5194/egusphere-egu22-577, 2022.

16:07–16:14
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EGU22-386
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ECS
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On-site presentation
Aydogan Avcioglu, Nevena Antić, Milica Kašanin-Grubin, Tolga Gorum, Tomislav Tosti, Biljana Dojčinović, and Omer Yetemen

The formation of badlands is commonly linked to the presence of dispersive deposits. Meanwhile, the sediments having more resistance to disintegration might also cause badlands formation given the time and adequate climate conditions. Although the notable influences of climate conditions have been highlighted on badlands morphologies so far, only a few attempts illustrated how materials weather in response to the diverse climate conditions. Supportingly, this research aims to learn about the primary weathering processes in various types of badland landforms (sharp-edged, rounded-edged, tower type, and calanchi mammellonari) in the Mediterranean arid, semi-arid, and humid climate of Turkey. For that purpose, we have used 11 badlands bedrock samples and determined climate conditions to simulate realistic weathering conditions in the laboratory condition. Bedrock samples were marl from the arid region, poorly sorted and packed sandstones from the Mediterranean region, highly consolidated sandstones from the humid region, pyroclastic sediments from the Cappadocia – semi-arid region. We have conducted four cycles representing each season during one water year to simulate precipitation and temperature variations. In this regard, we compiled the total amount and type of precipitation and insolation data for each season. Prior to the experiment, we have determined grain size, mineralogical composition, physico-chemical properties, the content of major elements of badland samples that enable us to discuss their morphological variety.

Regarding the temperature conditions, we simulated day spring/autumn (~20°C), mild winter (4-5°C), winter (-2°C), summer (~25 – 35°C) conditions considering fluctuation of temperature along the different seasons. After precipitation in each cycle, represented by either rain or snow, we collected leachates to quantify the variations between the seasons by measuring volume, pH, electrical conductivity (EC), concentrations of anion, and cations.

The laboratory experiments testing weathering processes under the different climate conditions and various types of badland materials show that the apparent differences in crust and desiccation crack emerged between the seasons. Although the obtained highest sediment flux in Mediterranean badlands having the deep crack systems, especially in autumn after high drying in summer, the ponds were formed relatively temporarily (a few hours) to long-lived (a few days) by filling the cracks with the sediments during spring seasons due to the scarcity in drying during the winter. The badland materials under arid climate conditions are highly likely to disintegrate because of their critical susceptibility to dispersivity; after one year of simulation (4th cycle), they became highly unstable due to their higher content of clay swelling capacity. However, the humid badland materials subjected to harsh climate conditions -snow and freezing conditions appeared to be the most durable samples reason for which is the strong cementation of coarse-grain sandstone. Seasonal trends in sample leachates' properties were also obtained. We can conclude that drying and wetting are more effective than the cooling and thawing processes in weathering of the bedrock from sampled badlands.

This study has been produced benefiting from the 2232 International Fellowship for Outstanding Researchers Program of the Scientific and Technological Research Council of Turkey (TUBITAK) through grant 118C329.

How to cite: Avcioglu, A., Antić, N., Kašanin-Grubin, M., Gorum, T., Tosti, T., Dojčinović, B., and Yetemen, O.: Seasonal influences on weathering processes in Turkish Badlands: Laboratory-based climate experiments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-386, https://doi.org/10.5194/egusphere-egu22-386, 2022.

16:14–16:21
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EGU22-3018
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Virtual presentation
Carlos Castillo, Miguel Vallejo-Orti, Rafael Pérez, Encarnación V. Taguas, Robert Wells, Ronald Bingner, and Helena Gómez-MacPherson

Gully filling practices are periodically carried out in commercial farms of annual crops in the Guadalquivir Campiña to reduce the extension of gully erosion after erosive events. Large quantities of fertile topsoil are scraped, transported and deposited by tractors and specialized machinery within eroded waterways. Thus, gullies are filled at the expense of soil quality in their vicinity leading to decreasing crop yields.

          The aim of this study is to evaluate the impact of recent filling practices in soil quality and crop production (wheat and sunflower) in four small gullied watersheds (< 5 ha) in a commercial farm near the town of Córdoba (Spain). Soil samples were taken at four transects defining 27 locations in each watershed (108 in total), including scraped, non-scraped and reference areas for analyzing  chemical and physical soil properties (cation exchange capacity CEC, texture, organic matter OM, carbonate content). In addition, at each sampling site, bulk density (BD, clod method), undrained shear strength (USS, vane test), soil colour (Munsell) and soil erodibility (jet test) were measured. At the same locations, yield surveys were conducted in 2 m2 plots at the end of May and July 2021 in watersheds on wheat and sunflower, respectively. Wheat grain and sunflower seeds were extracted, dried at 60ºC and weighted for the determination of crop yield.

          Significant differences were found between sampling sites in chemical and physical soil properties, with scraped areas showing light colours, lower CEC and OM and higher dry BD and USS. Soil colour was found to be a good proxy for soil quality. Topography along with soil quality explained ~ 60% of the crop yield variance, with showed large variations (between 3 and 6 t·ha-1 for wheat and 100 and 800 kg·ha-1 for sunflower). These results emphasize the need for quantitative analyses of gully erosion degradation to provide alternative and more efficient and sustainable management approaches for gully control.

How to cite: Castillo, C., Vallejo-Orti, M., Pérez, R., Taguas, E. V., Wells, R., Bingner, R., and Gómez-MacPherson, H.: Annual crops yield, soil quality and gully filling practices at the Campiña in Southern Spain , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3018, https://doi.org/10.5194/egusphere-egu22-3018, 2022.

16:21–16:28
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EGU22-9429
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Presentation form not yet defined
Milica Kasanin-Grubin, Nevena Antić, Milica Stefanović, and Aydoğan Avciouğlu

Badlands are landscapes in which, due to lithological properties and climate conditions, various geomorphological processes are active, resulting in high erosion rates. Comprehensive work has been done in badland areas both on the big and on the smaller scale in order to understand the subtle differences between sites. The development of weathering profile and surface crust have been recognized as crucial for hillslope processes in badlands. However, solely field work is not able to provide necessary detailed information regarding weathering processes. To better understand the development of the weathering profiles and surface crust, it is necessary to monitor badland materials exposed to different climate settings in controlled laboratory conditions. There are a number of issues that have to be considered when creating the experiment protocol. Those include defining the appropriate size and shape of the sample, reproducing the close as possible to natural wetting and drying conditions, determining the inclination of the sample, setting the duration of the experiment and choosing parameters that should be measured. A minimal error in the experiment protocol could endanger the whole experiment process and produce invalid results. In this study we will show different experiment setups and an array of parameters that should be measured. We will also show the most common obstacles and experiment shortcomings.

Nowadays there are a number of techniques available to ensure the precise following of changes in the chosen parameters during the experiment. For example, using image analyses for monitoring the surface changes has proven to be a very useful tool in monitoring both crack development or change in number, size and shape of fragments. Physico-chemical analyses of leachate characteristics provide information on infiltrations rates and mineral dissolution.  Analyses of mineralogical and physico-chemical properties of the material prior and after the experiment provides clear insight into changes in surface grain size, mineralogy, chemical composition, porosity etc. 

Mimicking nature conditions is not straightforward and one must bear in mind the limitations of the laboratory experiments. High on the shortcoming list is intentional excluding of certain parameters so that other parameters could be undisruptively monitored. This has to be done carefully and with a clear rational. Next limitation includes the sample size which has to be usable in the laboratory, but also large enough to produce valuable results. And finally setting the climate parameters is most challenging. Setting the drying temperature and the precipitation intensity, duration and its chemical composition will greatly influence the results. In conclusion, laboratory experiments can be very useful in close monitoring of weathering processes. However, there are certain limitations that the experimenter should take into consideration and make sure it is not an obstacle to correctly answer the research questions.

How to cite: Kasanin-Grubin, M., Antić, N., Stefanović, M., and Avciouğlu, A.: Weathering experiments on badland materials – advantages and obstacles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9429, https://doi.org/10.5194/egusphere-egu22-9429, 2022.

16:28–16:35
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EGU22-5080
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On-site presentation
Juan Martinez-Murillo and David Carruana-Herrera

Landscapes characterised with the existence of gullies and badlands are common in Mediterranean regions, but not so frequent in high mountains environments exceeding 1,500 m.a.s.l. This is the case of the study area: gullies and badlands located in the Sierra de las Nieves National Park. Both morphologies are not very extensive but has a remarkable impact in the landscape, geomorphology, and vegetation dynamic. In fact, their presence highly enriches the geodiversity of the national park. However, these morphologies have not been very much studied unless the geological characterization of the materials which let their development. Questions related to their origins and dynamic still remain unsolved.

This study aims to shed light on the age and origin of these gullied and badland morphologies located in the upper area from the Sierra de las Nieves National Park. Origin of gullies and badlands usually is related to either climate or human activity shifts, more common in cold regions the former whilst in semiarid regions the latter. In this case, Sierra de las Nieves, mainly of built on calcareous rocks, is characterised by Mediterranean mountain climate (exceeding 1,000 mm y-1 and humid and cold winter) and a long tradition of human activity in previous centuries. The experimental area is located in its upper part close to the highest peak (La Torrecilla, 1,919 m.a.s.l) forming plateu-like relief between 1,600 and 1,700 m.a.s.l where calcareous hills are separated by valleys of lower slopes filled with marls and quaternary sediments. Gullies and badlands are located in these materials. Vegetation corresponds to an opened-mixed vegetal formation of Quercus Faginea and Abies pinsapo Boiss. With typical high mountain shrubs and meadows. The current land use is a natural protected area, though goat and sheep grazing is permitted if the number of cattle is low. Before the declaration as protected area, the grazing pressure was major. In addition, the deforestation had a huge impact in last centuries.

To carry out the study, one transect was defined in one selected gullied-area including 15-sampling points and ecogeomorphology described: vegetation, soil surface conditions, and geomorphic processes. In addition, soils were also sampled in depth at the same points and some properties analysed in laboratory: color, texture, organic carbon, organic matter, pH, electrical conductivity, aggregate stability, and water holding. The transect run along the maximum slope line from one hill to the valley bottom and continue towards the top of the opposite hill. In the valley bottom, there was a fluvial Quaternary deposit covering and fossilising the marls formation. When outcropped, these marls were affected by concentrate water erosion forming gullies. Also, its surface developed typical morphologies of Badlands: cracks and crusts in dry conditions, short and shallow mudflows in wet conditions, and popcorn in winter. In that deposit, samples were taking in depth until the marls was reached and dated by means C14 technique. Ecogeomorphology inventory, soil properties, and datations have been used to shed light on the age and origin of the formation of gullies and badlands.

How to cite: Martinez-Murillo, J. and Carruana-Herrera, D.: Deciphering age and origin of gullied-shaped landscapes in Sierra de las Nieves National Park (South of Spain), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5080, https://doi.org/10.5194/egusphere-egu22-5080, 2022.

Coffee break
Chairpersons: Paolo Tarolli, Aydoğan Avcıoğlu
17:00–17:07
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EGU22-6290
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ECS
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Virtual presentation
Milica Stefanović, Branimir Jovančićević, Tomislav Tosti, Biljana Dojčinović, Nevena Antić, Francesc Gallart, Mariano Moreno-de las Heras, and Milica Kašanin-Grubin

Badlands are areas with limited vegetation, reduced or no human activity, and a great variety of geomorphic processes present. Besides lithology, the climate has a crucial role in the initiation and development of badlands. Controlled conditions during laboratory experiments provide detailed insight into processes that occur in the nature. Many studies have shown that the type and content of clay minerals, specifically presence of smectite is important for predicting the behavior of sediments subjected to different weathering treatments like freezing, thawing, wetting, and drying.

This study is aimed at comparing changes in physico-chemical properties of sediments caused by simulations of climatic conditions. For these experiments, three unweathered samples with different mineralogical content were taken from the Vallcebre and Bagà badlands in Spain. Besides quartz and calcite as dominant minerals, one sample contained smectite and gypsum, the second smectite, and the third neither smectite nor gypsum. The experiment was set up in a way that each sample had three sub-samples from which one was subjected to rain, the second to snow, and the third was the control sample. The experiment had two parts. In the first  part, after simulation of rain (~140 ml) or snow (~150 g), samples together with a control sample were placed in a climate chamber at a temperature of -3 °C. After initial 15 cycles, in the second part of the experiment, all samples regardless of the previous treatment were subjected to rain (~140 ml), after which together with the control sample were placed in a climate chamber at a temperature of 50 °C. These treatments were repeated 8 times. 

Throughout the experiment, after each cycle, samples were photographed for monitoring surface changes, while the leached solution was collected and its volume, pH, electrical conductivity (EC), and ion concentrations were measured. Field Emission Scanning Electron Microscopy (FESEM) results showed that the changes in microstructure occurred after weathering experiments, while Brunauer-Emmett-Teller (BET) surface area analysis confirmed that the sample with only smectite had the highest specific surface. Also, it was corroborated that temperature without simulation of rain or snow does not affect the decomposition since the control samples remained intact during the whole experiment. Results have shown that snow is a more destructive agent, especially for the sample with smectite. Due to the content of gypsum, which increases the weathering resistance of the material, the sample with smectite and gypsum has shown a lower degree of degradation than the sample with only smectite, while sample without smectite and gypsum has shown the lowest degradation of the structure. Furthermore, the sample with smectite and gypsum has shown significantly different values of leachate pH, and EC. The concentration of sulphate was the highest in the sample with smectite and gypsum, which is a consequence of the dissolution of gypsum. The obtained results confirm that the response of sediment to different climatic factors depends on their mineral and physico-chemical properties and provide a basis for further research of prediction land degradation in conditions of climate change.

How to cite: Stefanović, M., Jovančićević, B., Tosti, T., Dojčinović, B., Antić, N., Gallart, F., Moreno-de las Heras, M., and Kašanin-Grubin, M.: The influence of mineralogical composition on degradation of badland materials under different climate conditions , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6290, https://doi.org/10.5194/egusphere-egu22-6290, 2022.

17:07–17:14
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EGU22-5141
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Virtual presentation
Francesca Vergari, Antonella Marsico, Domenico Capolongo, and Maurizio Del Monte

This study aims to assess erosion dynamics in two Italian biancane badland sites, by means of  Terrestrial Laser Scanner (TLS), with high spatial resolution multitemporal surveys. The study sites are located in Tuscany and in Basilicata regions and are representative of the Mediterranean badland landscape. The former is a biancana subhumid badland hillslope of the Upper Orcia Valley, while the latter is a semiarid biancana landscape located in the tectonically active area of Aliano. The multitemporal survey and the morphometric analysis of the derived high resolution digital elevation models allowed to quantify the short- to medium-term erosion rates (5-10 years) affecting these landforms and to identify the main denudation processes responsible of the morphoevolution.

The results showed a very high erosion rate at both biancane sites, where it reaches, on average, 1.4 cm y-1 in Basilicata and 2.7 cm y-1 in Tuscany. The differences could be attributed to the dissimilar climatic conditions of the two sites:  Radicofani is affected by higher annual average rainfall, mainly due to a second peak (in addition to the autumn one) that occurs in spring, that is also reflected in enhanced mass movement events that model the subhumid biancane together with water erosion;  Aliano site is characterized by lower annual rainfall, mainly concentrated in late autumn-early winter, followed by long dry periods that also affect the erosion processes.

TLS is the ideal method to quantify denudation and erosion dynamics in biancane badlands since it allows very precise and detailed morphology detection. Furthermore the obstacles due to time-consuming and labor-intensive surveys, together with the shadowing effects, can be easily overcome because biancane generally origin in gentle dipping slopes, thus effortlessly accessible areas, where vegetation is often sparse as a result of ancient anthropic deforestation practices or climatic conditions in more arid badlands.

How to cite: Vergari, F., Marsico, A., Capolongo, D., and Del Monte, M.: Erosion monitoring with terrestrial laser scanning in representative biancane badlands of Central and Southern Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5141, https://doi.org/10.5194/egusphere-egu22-5141, 2022.

Development of new technologies in soil conservation and eco-sustainability
17:14–17:21
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EGU22-2104
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ECS
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Virtual presentation
Wei Du, Liang Hu, Feinan Hu, and Jialong Lv

Soil water erosion and the resulting nutrient loss (such as phosphorus loss) and other ecological and environmental issues are still important obstacles that challenge the quality and efficiency of agricultural production and sustainable development in the Loess Plateau of China. Soil water erosion is affected by external environmental factors such as rainfall intensity and slope. Measures such as increasing vegetation coverage and reducing slope can play an external role in preventing and controlling soil and nutrient loss. At present, based on the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE), Chinese scholars have established regional soil loss models such as the erosion prediction model for small watersheds in loess hilly and gully regions, which play a very important role in soil erosion prediction and prevention. However, all the above models are empirical and lack consideration of the mechanism of soil erosion. In this study, using a self-designed needle drop micro-rainfall model device combined with the basic principles of soil electrochemistry, the effect of the interaction between soil particles on the loss of soil and its nutrients during long-term fertilization was studied on a mesoscopic scale. We found that: (1) the total phosphorus content of loess soil under long-term phosphate fertilizer treatment was 2.46 times that of non-phosphorus treatment, but its surface potential, surface charge density, surface electric field intensity, specific surface area, and number of surface charges were all lower than those of non-phosphorus treatment; (2) loess soils with varying levels of phosphorus exhibit a trend in which the loss of soil particles and phosphorus increases as the surface potential of the soil particles, and there is a linear positive correlation between the cumulative loss of particulate phosphorus and the cumulative loss of soil particles; (3) the net force (the combined force of van der Waals force, hydration repulsion force, and electrostatic repulsion force) between soil particles with different phosphorus levels at a given electrolyte concentration is all expressed as repulsive force and changes with the decrease of electrolyte concentration; (4) due to the relatively high surface potential of low-phosphorus loess soil, the electrostatic repulsion between soil particles is greater, resulting in poor stability of soil aggregates and more cumulative loss of soil particles and attached phosphorus. This study clarified the relationship between soil surface properties, soil internal forces, soil particles and nutrient element loss characteristics under long-term fertilization treatment, and provided new ideas for soil loss prevention and control and environmental risk assessment during long-term fertilization.

How to cite: Du, W., Hu, L., Hu, F., and Lv, J.: Using a tiny rainfall simulator to investigate the impact of soil internal forces on long-term location fertilization Loess soil loss, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2104, https://doi.org/10.5194/egusphere-egu22-2104, 2022.

17:21–17:28
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EGU22-12791
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ECS
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Virtual presentation
Ran Guang, Xu xiangzhou, and Liu mingyang

Check dams helps to improve the arable-land quality, agricultural productivity, and ecological environment, and the check dams can also have obvious effects on food production and land use in nearby urban areas. In this study, the statistical yearbook data and remote sensing data from 2000 to 2020 were used to explore the effects of check-dam construction on the food production and land use in local and nearby area in Shaanxi Province. The results show that the construction of check dams has significantly improved the food production per unit of arable land in Yulin from 2000-2020, increasing the rate of the annual food production in Yulin to the total amount of Shanxi Province was increased from 6% to 19%. Hence, Yulin became the main region in Shaanxi province of food production due to the construction of check dams, which had greatly relieved the pressure of food production in Xian, resulting in a reduction of the annual rate of Xi’an to the total amount of Shanxi Province from 18% to 11% during the period of 2000 and 2020. In this period, the dam area of Yulin increases, and Xi’an has the largest net gain in urban construction land among all cities, with 98% of the increase in urban construction land coming from arable land. We found that Yulin is the richest city in the province for land resource reserves due to the construction of check dams, and the new arable land is mainly used to make up for the loss of arable land due to urban expansion in more developed cities such as Xi’an and Xianyang, and to a certain extent promotes the increase of urban construction land. Hence, the construction of soil and water conservation measures, such as check dams, can promote the balance between soil erosion control and urbanization in order to achieve a sustainable development of resources, environment, and economy.

How to cite: Guang, R., xiangzhou, X., and mingyang, L.: Effects of check dam construction on nearby urban areas: a case study of Shaanxi Province, China , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12791, https://doi.org/10.5194/egusphere-egu22-12791, 2022.

17:28–17:35
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EGU22-2216
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ECS
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Virtual presentation
Hongguang Liu

The intensive management of orchards is posing substantial pressure to the surrounding environments, threatening the fruit quality and sustainable development of fruit industry. Arbuscular mycorrhiza (AM) is ubiquitous in soil established with arbuscular mycorrhizal fungi colonizing roots of host plants. AM connects the roots, bacteria and soil, enhancing the interactions between plants and soil microbiome, augmenting the nutrient uptake of plants, improving fitness in facing abiotic and biotic stresses, and strengthening the soil structure and function. Thus, AM is considered as an important grasp to improve the clean production, and an alternative for the shift from intensive to organic management in orchards. Our study showed that the disappearance or reduction of AM fungi community, in accordance with strong soil erosion and the losses of phosphorus. The practices, such as sod culture in orchards or inoculating with AM fungi, is beneficial to the recovery of AM fungi community. More suitable measures aiming at optimize the AM fungi community are being developed and extended in subtropical orchards. Collectively, the regulation of AM fungi community can be a significant way to improve the degree of clean productions of subtropical orchards.

How to cite: Liu, H.: Arbuscular mycorrhiza promotes the clean production of subtropical orchards, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2216, https://doi.org/10.5194/egusphere-egu22-2216, 2022.

17:35–17:42
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EGU22-5171
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Virtual presentation
Giulia Sofia, Claudio Zaccone, and Paolo Tarolli

Drought and surface water ponding (DSP) are one of the major natural hazards affecting crop production, especially in low-land irrigated areas.

This work focus on an irrigated area in north-eastern Italy, a territory of about 400k ha, part of the central Veneto, where water demands is met through a mechanical and well-regulated widespread distribution of water resources. For this complex landscape, reliance on weather data alone is not sufficient to monitor areas of DSP, particularly when these data can be i) untimely, sparse, and incomplete, and ii) water inflows are mechanically controlled, with varying flow exchanges, not necessarily reflecting climatic fluctuations.

Augmenting climatic data with satellite images to identify the location and severity of DSP phenomena, therefore, is a must for complete, up-to-date, and comprehensive coverage of current crop conditions.

The objective of this research is to apply and standardize open source data to augment DSP-monitoring techniques. The study was conducted with 5 years (2015-2021) of Sentinel2-10m satellite images. Z-scores of the NDVI distribution are used to estimate the probability of occurrence of the present vegetation condition at a given location relative to the possible range of vegetative vigor, historically. This information is coupled with soil data, topographic information, and accurate information on the system water fluxes, to identify and target locations more susceptible to DSP. Findings indicate that the framework, along with other monitoring tools, is useful for assessing the extent and severity of DSP at a spatial resolution of 10m. The framework is capable of providing a near-real-time indicator of vegetation conditions within irrigated regions, and, more specifically, areas of varying water management conditions.

The present study is founded by the Consorzio LEB, Cologna Veneta, Italy

How to cite: Sofia, G., Zaccone, C., and Tarolli, P.: Drought and surface water ponding monitoring in irrigated landscapes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5171, https://doi.org/10.5194/egusphere-egu22-5171, 2022.

17:42–17:49
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EGU22-8997
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Presentation form not yet defined
Zhihui Wang and Yonglei Shi

Sparse mixed forest with trees, shrubs, and green herbaceous vegetation is a typical landscape in the afforestation areas in northwestern China. It is a great challenge to accurately estimate the woody aboveground biomass (AGB) of a sparse mixed forest with heterogeneous woody vegetation types and background types. In this study, a novel woody AGB estimation methodology (VI-AGB model stratified based on herbaceous vegetation coverage) using a combination of Landsat-8, GaoFen-2, and unmanned aerial vehicle (UAV) images was developed. The results show the following: 1) The woody and herbaceous canopy can be accurately identified using the object-based support vector machine (SVM) classification method based on UAV red-green-blue (RGB) images, with an average overall accuracy and kappa coefficient of 93.44% and 0.91, respectively. 2) Compared with the estimation uncertainties of the woody coverage-AGB models without considering the woody vegetation types (RMSE=14.98 t∙ha-1 and rRMSE=96.31%), the woody coverage-AGB models stratified based on five woody species (RMSE=5.82 t∙ha-1 and rRMSE=37.46%) were 61.1% lower. 3) Of the six VIs used in this study, the near-infrared reflectance of pure vegetation (NIRv)-AGB model performed best (RMSE=7.91 t∙ha-1 and rRMSE=50.89%), but its performance was still seriously affected by the heterogeneity of the green herbaceous coverage. The normalized difference moisture index (NDMI)-AGB model was the least sensitive to the background. The stratification-based VI-AGB models considering the herbaceous vegetation coverage derived from GaoFen-2 and UAV images can significantly improve the accuracy of the woody AGB estimated using only Landsat VIs, with the RMSE and rRMSE of 6.6 t∙ha-1 and 42.43% for the stratification-based NIRv-AGB models. High spatial–resolution information derived from UAV and satellite images has a great potential for improving the woody AGB estimated using only Landsat images in sparsely vegetated areas. This study presents a practical method of estimating woody AGB in sparse mixed forest in dryland areas.

How to cite: Wang, Z. and Shi, Y.: Estimating Aboveground Biomass for Sparse Tree-shrub Mixed Forest Using Muti-scale Optical Remote Sensing data in the Dryland Ecosystem, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8997, https://doi.org/10.5194/egusphere-egu22-8997, 2022.

17:49–17:56
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EGU22-1461
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ECS
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Virtual presentation
Annan Yang, Chunmei Wang, Guowei Pang, Yongqing Long, Lei Wang, Richard M. Cruse, and Qinke Yang

Gully erosion is the most severe type of water erosion and is a major land degradation process. Predicting gully erosion susceptibility (GES) map efficiently and interpretably remains a challenge, especially in complex terrain areas. In this study, a new method called WoE-MLC model was used to solve the above problem, which combined machine learning classification algorithms and the weight of evidence (WoE) model in the Loess Plateau. The three machine learning algorithms taken into account included random forest (RF), gradient boosted decision trees (GBDT), and extreme gradient boosting (XGBoost). And the performance of the models was evaluated by the receiver operating characteristic (ROC) curve. The results showed that: (1) GES maps were well predicted by machine learning regression and WoE-MLC models, with the area under the curve (AUC) values both greater than 0.92, and the latter was more computationally efficient and interpretable; (2) The XGBoost algorithm was more efficient in GES map than the other two algorithms, with the stronger generalization ability and best performance in avoiding overfitting (averaged AUC = 0.947), followed by the RF (averaged AUC = 0.944), and GBDT algorithm (averaged AUC = 0.938); (3) Slope gradient, land use, and altitude were the main factors for GES mapping. This study may provide a possible method for gully erosion susceptibility mapping at large scale.

How to cite: Yang, A., Wang, C., Pang, G., Long, Y., Wang, L., M. Cruse, R., and Yang, Q.: An ensemble model for gully erosion susceptibility mapping in highly complex terrain area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1461, https://doi.org/10.5194/egusphere-egu22-1461, 2022.

17:56–18:03
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EGU22-4977
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ECS
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On-site presentation
Ci-Jian Yang, Pei-Hao Chen, Jr-Chuang Huang, and Tse-Yang Teng

Erosion-induced weathering is significant control of Earth’s surface process, however, the impacts of extreme weather on chemical weathering dynamics are poorly understood. Badland landscapes formed with highly erodible, homogeneous substrates have the potential to respond measurably to the individual event on scales that are open to direct observation. Here, using the high temporal resolution of suspended sediment and riverine chemistry records in the badland basin in southwestern Taiwan, we assess the mineralogical, geochemical and grain-size composition features that can be used to quantify landscape response to erosion drivers. During the typhoon period, sodium adsorption ratio is covariant with suspended sediment concentration, which can be assigned to sodium-induced dissolution. Further, sodium and calcium of suspended sediment account for about 10 % of the mass loss in this event, and the current-induced dissipation may be responsible for it. Plus, water chemistry is dominated by silicate weathering at 18 ton/km2/day. We expect that the observation of physico-chemical reactions in badlands provides a deeper explanation of coupling of hillslope-channel landscape within erosional cycle.

How to cite: Yang, C.-J., Chen, P.-H., Huang, J.-C., and Teng, T.-Y.: Mobile Evaporite Enhances Cycle of Physico-chemical Erosion in Badlands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4977, https://doi.org/10.5194/egusphere-egu22-4977, 2022.

18:03–18:10
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EGU22-8208
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ECS
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Virtual presentation
Yue Yu, Keli Zhang, and Liang Liu

Soil erosion is a major worldwide threat to agriculture, food security, and ecosystems. Northeast Black Soil Region is an important food base in China and has an important strategic position for ensuring food security. Black Soil Region suffered severe water erosion due to long-term unreasonable utilization. The loss of topsoil in farmland decreases the amount of indispensable fertile soil for plants and reduces land productivity. The magnetic susceptibility (MS) technique has been successfully applied in describing farmland soil redistribution pattern as a reliable, economical, and rapid method, but it still need further study in soil loss quantification. In this study, four typical black soil farmland slopes (cultivated in 110a, 60a, 30a, and 20a) and a reference forest slope were selected, while undisturbed soil samples were collected at a 5 cm interval from the surface to 50 cm depth. The objective is to (1) utilize soil MS values (including χlf and χfd%) and other soil property indexes to represent soil loss on farmland slope; (2) recommend Δχ (the ratio of the difference between MS of the slopes cultivated in two certain periods) as an indicative index of soil loss rate to convert current soil erosion pattern in spatial scale to the certain historical period soil loss in temporal scale; (3) verify the feasibility of MS value in estimating farmland soil loss in multi-temporal scale by cultivation period. The results indicated that: (1) The MS approximately followed the trend of “110 a < 60 a < 20 a <30 a < Forest” at plow layer, that is, the slopes in longer cultivation periods expressed greater MS differences than reference slope; (2) Δχ values were greater at lowerslopes than those at upperslopes and middleslopes, and Δχ at all positions became nearly stable after 50a cultivation; (3) Δχ values were remarkably correlated exponentially with cultivation periods not only on the whole slope but three separated slope positions, with r2 from 0.50 to 0.86. Soil MS reflects soil redistribution and erosion patterns on farmland hillslope. MS values on farmland vary with cultivation periods which denotes soil redistribution. The MS variation caused by tillage was greater at lowerslope than middleslope and upperslope. Soil loss has exponent relation to the cultivation periods. Farmland in longer cultivation periods was associated with greater soil loss, but soil erosion and deposition tend to be stable for slopes in longer cultivation periods. This study demonstrates the feasibility to quantify soil loss in continuous tillage within centennial periods using the MS technique.

How to cite: Yu, Y., Zhang, K., and Liu, L.: Simulating soil loss on farmland hillslope cultivated in centennial periods using magnetic susceptibility in Northeast China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8208, https://doi.org/10.5194/egusphere-egu22-8208, 2022.

18:10–18:17
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EGU22-12214
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Presentation form not yet defined
Ruipeng Zhou and Qi Yang

Abstract: The Conservation Reserve Program (CRP) in the United States has been implemented for 35 years. The analysis and evaluation of its soil and water conservation benefits can provide experience and reference for the construction of China's the Grain for Green Project. Changes in CRP area and soil and water conservation benefits were analyzed based on CRP-related data obtained from the USDA Farm Service website and erosion rate data from the 2017 National Inventory Summary Report. From 1986 to 2020, the land area participating in CRP showed a bimodal change, with the largest area in 2007 reaching 1.498 million km2. The largest area of land types involved is Cropland, accounting for about 93%, and the largest area after the transfer of CRP is also Cropland, which is about 59%. During 2006-2017, soil, nitrogen and phosphorus reduction losses were 2318.28 million tons, 3.20 million tons and 0.64 million tons, respectively. When the CRP area reached 12 thousand km2, the soil, nitrogen and phosphorus sequestration no longer increased with the increase of the abandoned Cropland. There is a positive linear relationship between carbon dioxide absorption and CRP participation area, and the cumulative fixed CO2 amount from 2006 to 2017 is about 504 million tons. The U.S. land fallow protection project has significant soil and water conservation benefits, reducing soil erosion, nitrogen and phosphorus loss, and playing an important role in improving the ecological environment.

Key word: Conservation Reserve Program; soil loss; nitrogen; phosphorus; Carbon dioxide

How to cite: Zhou, R. and Yang, Q.: Analysis of Soil and Water Conservation Benefit of Conservation Reserve Program, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12214, https://doi.org/10.5194/egusphere-egu22-12214, 2022.