SSS11.11

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.