Rainfall simulation and Structure-from-Motion photogrammetry for the analysis of soil water erosion in Mediterranean vineyards

Soilwater erosion is a serious problem, especially in agricultural lands. Among these, vineyards deserve attention, because they constitute for the Mediterranean areas a type of land use affected by high soil losses. A significant problem related to the study of soil water erosion in these areas consists in the lack of a standardized procedure of collecting data and reporting results, mainly due to a variability among the measurement methods applied. Given this issue and the seriousness of soilwater erosion inMediterranean vineyards, this works aims to quantify the soil losses caused by simulated rainstorms, and compare them with each other depending on two different methodologies: (i) rainfall simulation and (ii) surface elevation change-based, relying on high-resolution Digital Elevation Models (DEMs) derived from a photogrammetric technique (Structure-from-Motion or SfM). The experiments were carried out in a typical Mediterranean vineyard, located in eastern Spain, at very fine scales. SfMdatawere obtained fromone reflex camera and a smartphone built-in camera. An index of sediment connectivity was also applied to evaluate the potential effect of connectivity within the plots. DEMs derived from the smartphone and the reflex camera were comparable with each other in terms of accuracy and capability of estimating soil loss. Furthermore, soil loss estimatedwith the surface elevation change-basedmethod resulted to be of the same order ofmagnitude of that one obtained with rainfall simulation, as long as the sediment connectivity within the plotwas considered.High-resolution topography derived fromSfMrevealed to be essential in the sediment connectivity analysis and, therefore, in the estimation of eroded materials, when comparing themto those derived from the rainfall simulation methodology. The fact that smartphones built-in cameras could produce as much satisfying results as those derived from reflex cameras is a high value added for using SfM

Pinpointing areas of increased soil erosion risk following land cover change in the Lake Manyara catchment, Tanzania

publisher: Elsevier articletitle: Pinpointing areas of increased soil erosion risk following land cover change in the Lake Manyara catchment, Tanzania journaltitle: International Journal of Applied Earth Observation and Geoinformation articlelink: https://doi.org/10.1016/j.jag.2018.05.008 content_type: article copyright: © 2018 Elsevier B.V. All rights reserved

UTJECAJ DJELOMIČNE DEFOLIJACIJE NA KOMPONENTE PRINOSA, VEGETATIVAN PORAST I SASTAV GROŽĐA SORTE MALVAZIJA ISTARSKA

Tema ovog završnog rada je utjecaj defolijacije na komponente prinosa, vegetativan porast i sastav grožđa sorte Malvazija istarska u uvjetima vinogorja Zapadna Istra. Istraživanje je provedeno tijekom 2009 godine. Defolijacijom se ručno skidalo tri do četiri lista po mladici u tri različita termina: neposredno prije cvatnje, neposredno poslije cvatnje i u fazi zatvaranja grozdova. U istraživanju je bio uključen i kontrolni tretman kod kojeg nije provedena defolijacija. Djelomična defolijacija nije značajno utjecala na komponente prinosa sorte Malvazija istarska. Kao odgovor na djelomičnu defolijaciju uslijedio je nešto izraženiji porast zaperaka, posebice kod tretmana defolijacije prije cvatnje. Najveći omjer lisne površine i mase grožđa, kao bitnog čimbenika za postizanje visoke kakvoće grožđa, imao je tretman defolijacije prije cvatnje. Provedbom defolijacije prije cvatnje postignut je veći udio šećera u moštu u odnosu na tretman defolijacije u fazi zatvaranja grozdova i kontrolni tretman, dok je provedbom defolijacije neposredno prije ili neposredno poslije cvatnje postignuta niža ukupna kiselost mošta u odnosu na ostala dva tretmana. Može se zaključiti da uklanjanje listova pri bazalnom dijelu mladica u intenzitetu od tri do četiri lista po mladici ne utječe značajno na komponente prinosa, ali ipak u određenoj mjeri utječe na osnovne pokazatelje kvalitete mošta Malvazije istarske

Social perception of soil conservation benefits in Kondoa eroded area of Tanzania

A soil conservation project was implemented in Tanzania for over 30 years. This study applied a socio-economic approach to examine and analyse the benefits of soil conservation in the Kondoa eroded area of Tanzania by conducting a household survey of 240 households. The study findings show that 89% and 70% of respondents consider soil conservation activities have increased vegetation and soil fertility, respectively. Decreased soil erosion was perceived by 68% of respondents, increased firewood by 98%, increased fodder by 50%, high crop yields by 56%, and food sufficiency by 68%. These are the outcomes of conservation tillage, integrated farming and use of organic fertilizers, controlled stall feeding, agroforestry, construction of cut off drains, contour bunds and contour ridges cultivation, which are the main land use practices in the area. Access to extension services, household sizes, long term land ownership, crop incomes and awareness of soil conservation project were found to determine the level of participation in soil conservation. Major challenges are the lack of sustainability of those activities because of a recent policy decision to withdraw conservation investment. Despite the challenge, this study concluded that past government efforts on soil conservation activities initiated since the early 1970s through decentralization, institutional collaboration, socioeconomic support to farmers and continuous local community participation in restoring the degraded ecosystem of Kondoa have contributed to ensure environmental and socio-economic sustainability in the area

Comparing theoretically supported rainfall‐runoff erosivity factors at the Sparacia (South Italy) experimental site

Interpreting rainfall‐runoff erosivity by a process‐oriented scheme allows to conjugate the physical approach to soil loss estimate with the empirical one. Including the effect of runoff in the model permits to distinguish between detachment and transport in the soil erosion process. In this paper, at first, a general definition of the rainfall‐runoff erosivity factor REFe including the power of both event runoff coefficient QR and event rainfall erosivity index EI30 of the Universal Soil Loss Equation (USLE) is proposed. The REFe factor is applicable to all USLE‐based models (USLE, Modified USLE [USLE‐M] and Modified USLE‐M [USLE‐MM]) and it allows to distinguish between purely empirical models (e.g., Modified USLE‐M [USLE‐MM]) and those supported by applying theoretical dimensional analysis and self‐similarity to Wischmeier and Smith scheme. This last model category includes USLE, USLE‐M, and a new model, named USLE‐M based (USLE‐MB), that uses a rainfall‐runoff erosivity factor in which a power of runoff coefficient multiplies EI30. Using the database of Sparacia experimental site, the USLE‐MB is parameterized and a comparison with soil loss data is carried out. The developed analysis shows that USLE‐MB (characterized by a Nash–Sutcliffe Efficiency Index NSEI equal to 0.73 and a root mean square error RMSE = 11.7 Mg ha−1) has very similar soil loss estimate performances as compared with the USLE‐M (NSEI = 0.72 and RMSE = 12.0 Mg ha−1). However, the USLE‐MB yields a maximum discrepancy factor between predicted and measured soil loss values (176) that is much lower than that of USLE‐M (291). In conclusion, the USLE‐MB should be preferred in the context of theoretically supported USLE type models