A Review of Soil-Improving Cropping Systems for Soil Salinization

A major challenge of the Sustainable Development Goals linked to Agriculture, Food Security, and Nutrition, under the current global crop production paradigm, is that increasing crop yields often have negative environmental impacts. It is therefore urgent to develop and adopt optimal soil-improving cropping systems (SICS) that can allow us to decouple these system parameters. Soil salinization is a major environmental hazard that limits agricultural potential and is closely linked to agricultural mismanagement and water resources overexploitation, especially in arid climates. Here we review literature seeking to ameliorate the negative effect of soil salinization on crop productivity and conduct a global meta-analysis of 128 paired soil quality and yield observations from 30 studies. In this regard, we compared the effectivity of different SICS that aim to cope with soil salinization across 11 countries, in order to reveal those that are the most promising. The analysis shows that besides case-specific optimization of irrigation and drainage management, combinations of soil amendments, conditioners, and residue management can contribute to significant reductions of soil salinity while significantly increasing crop yields. These results highlight that conservation agriculture can also achieve the higher yields required for upscaling and sustaining crop production

Climate change impact on the frequency of hydrometeorological extremes in the island of Crete

© 2019 by the authors. Frequency analysis on extreme hydrological and meteorological events under the effect of climate change is performed in the island of Crete. Data from Regional Climate Model simulations (RCMs) that follow three Representative Concentration Pathways (RCP2.6, RCP4.5, RCP8.5) are used in the analysis. The analysis was performed for the 1985-2100 time period, divided into three equal-duration time slices (1985-2010, 2025-2050, and 2075-2100). Comparison between the results from the three time slices for the different RCMs under different RCP scenarios indicate that drought events are expected to increase in the future. The meteorological and hydrological drought indices, relative Standardized Precipitation Index (SPI) and Standardized Runoff index (SRI), are used to identify the number of drought events for each RCM. Results from extreme precipitation, extreme flow, meteorological and hydrological drought frequency analysis over Crete show that the impact of climate change on the magnitude of 100 years return period extreme events will also increase, along with the magnitude of extreme precipitation and flow events

Integrated use of satellite remote sensing, artificial neural networks, field spectroscopy, and GIS in estimating crucial soil parameters in terms of soil erosion

© 2019 by the authors. Soil erosion is one of the main causes of soil degradation among others (salinization, compaction, reduction of organic matter, and non-point source pollution) and is a serious threat in the Mediterranean region. A number of soil properties, such as soil organic matter (SOM), soil structure, particle size, permeability, and Calcium Carbonate equivalent (CaCO3), can be the key properties for the evaluation of soil erosion. In this work, several innovative methods (satellite remote sensing, field spectroscopy, soil chemical analysis, and GIS) were investigated for their potential in monitoring SOM, CaCO3, and soil erodibility (K-factor) of the Akrotiri cape in Crete, Greece. Laboratory analysis and soil spectral reflectance in the VIS-NIR (using either Landsat 8, Sentinel-2, or field spectroscopy data) range combined with machine learning and geostatistics permitted the spatial mapping of SOM, CaCO3, and K-factor. Synergistic use of geospatial modeling based on the aforementioned soil properties and the Revised Universal Soil Loss Equation (RUSLE) erosion assessment model enabled the estimation of soil loss risk. Finally, ordinary least square regression (OLSR) and geographical weighted regression (GWR) methodologies were employed in order to assess the potential contribution of different approaches in estimating soil erosion rates. The derived maps captured successfully the SOM, the CaCO3, and the K-factor spatial distribution in the GIS environment. The results may contribute to the design of erosion best management measures and wise land use planning in the study region

Changes in climate extremes, fresh water availability and vulnerability to food insecurity projected at 1.5° C and 2° C global warming with a higher-resolution global climate model

We projected changes in weather extremes, hydrological impacts and vulnerability to food insecurity at global warming of 1.5°C and 2°C relative to pre-industrial, using a new global atmospheric general circulation model HadGEM3A-GA3.0 driven by patterns of sea-surface temperatures and sea ice from selected members of the 5th Coupled Model Intercomparison Project (CMIP5) ensemble, forced with the RCP8.5 concentration scenario. To provide more detailed representations of climate processes and impacts, the spatial resolution was N216 (approx. 60 km grid length in mid-latitudes), a higher resolution than the CMIP5 models. We used a set of impacts-relevant indices and a global land surface model to examine the projected changes in weather extremes and their implications for freshwater availability and vulnerability to food insecurity. Uncertainties in regional climate responses are assessed, examining ranges of outcomes in impacts to inform risk assessments. Despite some degree of inconsistency between components of the study due to the need to correct for systematic biases in some aspects, the outcomes from different ensemble members could be compared for several different indicators. The projections for weather extremes indices and biophysical impacts quantities support expectations that the magnitude of change is generally larger for 2°C global warming than 1.5°C. Hot extremes become even hotter, with increases being more intense than seen in CMIP5 projections. Precipitation-related extremes show more geographical variation with some increases and some decreases in both heavy precipitation and drought. There are substantial regional uncertainties in hydrological impacts at local scales due to different climate models producing different outcomes. Nevertheless, hydrological impacts generally point towards wetter conditions on average, with increased mean river flows, longer heavy rainfall events, particularly in South and East Asia with the most extreme projections suggesting more than a doubling of flows in the Ganges at 2°C global warming. Some areas are projected to experience shorter meteorological drought events and less severe low flows, although longer droughts and/or decreases in low flows are projected in many other areas, particularly southern Africa and South America. Flows in the Amazon are projected to decline by up to 25%. Increases in either heavy rainfall or drought events imply increased vulnerability to food insecurity, but if global warming is limited to 1.5°C, this vulnerability is projected to remain smaller than at 2°C global warming in approximately 76% of developing countries. At 2°C, four countries are projected to reach unprecedented levels of vulnerability to food insecurity. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels’

A Simplified Water Accounting Procedure to Assess Climate Change Impact on Water Resources for Agriculture across Different European River Basins

[EN] European agriculture and water policies require accurate information on climate change impacts on available water resources. Water accounting, that is a standardized documentation of data on water resources, is a useful tool to provide this information. Pan-European data on climate impacts do not recognize local anthropogenic interventions in the water cycle. Most European river basins have a specific toolset that is understood and used by local experts and stakeholders. However, these local tools are not versatile. Thus, there is a need for a common approach that can be understood by multi-fold users to quantify impact indicators based on local data and that can be used to synthesize information at the European level. Then, policies can be designed with the confidence that underlying data are backed-up by local context and expert knowledge. This work presents a simplified water accounting framework that allows for a standardized examination of climate impacts on water resource availability and use across multiple basins. The framework is applied to five different river basins across Europe. Several indicators are extracted that explicitly describe green water fluxes versus blue water fluxes and impacts on agriculture. The examples show that a simplified water accounting framework can be used to synthesize basin-level information on climate change impacts which can support policymaking on climate adaptation, water resources and agriculture.This research was funded by Horizon 2020 IMPREX project, grant number 641811Hunink, J.; Simons, G.; Suárez-Almiñana, S.; Solera Solera, A.; Andreu Álvarez, J.; Giuliani, M.; Zamberletti, P.... (2019). A Simplified Water Accounting Procedure to Assess Climate Change Impact on Water Resources for Agriculture across Different European River Basins. Water. 11(10):1-29. https://doi.org/10.3390/w11101976S1291110Jacob, D., Kotova, L., Teichmann, C., Sobolowski, S. P., Vautard, R., Donnelly, C., … van Vliet, M. T. H. (2018). Climate Impacts in Europe Under +1.5°C Global Warming. Earth’s Future, 6(2), 264-285. doi:10.1002/2017ef000710Koutroulis, A. G., Grillakis, M. G., Daliakopoulos, I. N., Tsanis, I. K., & Jacob, D. (2016). Cross sectoral impacts on water availability at +2 °C and +3 °C for east Mediterranean island states: The case of Crete. Journal of Hydrology, 532, 16-28. doi:10.1016/j.jhydrol.2015.11.015Dezsi, Ş., Mîndrescu, M., Petrea, D., Rai, P. K., Hamann, A., & Nistor, M.-M. (2018). High-resolution projections of evapotranspiration and water availability for Europe under climate change. International Journal of Climatology, 38(10), 3832-3841. doi:10.1002/joc.5537Forzieri, G., Feyen, L., Russo, S., Vousdoukas, M., Alfieri, L., Outten, S., … Cid, A. (2016). Multi-hazard assessment in Europe under climate change. 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Climatic Change, 135(2), 341-355. doi:10.1007/s10584-015-1570-4Samaniego, L., Thober, S., Kumar, R., Wanders, N., Rakovec, O., Pan, M., … Marx, A. (2018). Anthropogenic warming exacerbates European soil moisture droughts. Nature Climate Change, 8(5), 421-426. doi:10.1038/s41558-018-0138-5Panagopoulos, Y., Stefanidis, K., Faneca Sanchez, M., Sperna Weiland, F., Van Beek, R., Venohr, M., … Birk, S. (2019). Pan-European Calculation of Hydrologic Stress Metrics in Rivers: A First Assessment with Potential Connections to Ecological Status. Water, 11(4), 703. doi:10.3390/w11040703Macknick, J., Newmark, R., Heath, G., & Hallett, K. C. (2012). Operational water consumption and withdrawal factors for electricity generating technologies: a review of existing literature. Environmental Research Letters, 7(4), 045802. doi:10.1088/1748-9326/7/4/045802Koutroulis, A. G., Papadimitriou, L. V., Grillakis, M. G., Tsanis, I. K., Wyser, K., & Betts, R. A. (2018). Freshwater vulnerability under high end climate change. A pan-European assessment. Science of The Total Environment, 613-614, 271-286. doi:10.1016/j.scitotenv.2017.09.074Lobanova, A., Liersch, S., Nunes, J. P., Didovets, I., Stagl, J., Huang, S., … Krysanova, V. (2018). Hydrological impacts of moderate and high-end climate change across European river basins. Journal of Hydrology: Regional Studies, 18, 15-30. doi:10.1016/j.ejrh.2018.05.003Beck, H. E., Vergopolan, N., Pan, M., Levizzani, V., van Dijk, A. I. J. M., Weedon, G. P., … Wood, E. F. (2017). Global-scale evaluation of 22 precipitation datasets using gauge observations and hydrological modeling. Hydrology and Earth System Sciences, 21(12), 6201-6217. doi:10.5194/hess-21-6201-2017Naz, B. S., Kurtz, W., Montzka, C., Sharples, W., Goergen, K., Keune, J., … Kollet, S. (2019). Improving soil moisture and runoff simulations at 3 km over Europe using land surface data assimilation. Hydrology and Earth System Sciences, 23(1), 277-301. doi:10.5194/hess-23-277-2019Haro, D., Solera, A., Paredes, J., & Andreu, J. (2014). Methodology for Drought Risk Assessment in Within-year Regulated Reservoir Systems. Application to the Orbigo River System (Spain). Water Resources Management, 28(11), 3801-3814. doi:10.1007/s11269-014-0710-3Zaniolo, M., Giuliani, M., Castelletti, A. F., & Pulido-Velazquez, M. (2018). Automatic design of basin-specific drought indexes for highly regulated water systems. Hydrology and Earth System Sciences, 22(4), 2409-2424. doi:10.5194/hess-22-2409-2018Koutroulis, A. G., Tsanis, I. K., Daliakopoulos, I. N., & Jacob, D. (2013). Impact of climate change on water resources status: A case study for Crete Island, Greece. Journal of Hydrology, 479, 146-158. doi:10.1016/j.jhydrol.2012.11.055Vargas-Amelin, E., & Pindado, P. (2014). The challenge of climate change in Spain: Water resources, agriculture and land. Journal of Hydrology, 518, 243-249. doi:10.1016/j.jhydrol.2013.11.035Giuliani, M., Li, Y., Castelletti, A., & Gandolfi, C. (2016). A coupled human-natural systems analysis of irrigated agriculture under changing climate. Water Resources Research, 52(9), 6928-6947. doi:10.1002/2016wr019363Giuliani, M., & Castelletti, A. (2016). Is robustness really robust? How different definitions of robustness impact decision-making under climate change. Climatic Change, 135(3-4), 409-424. doi:10.1007/s10584-015-1586-9Grindlay, A. L., Zamorano, M., Rodríguez, M. I., Molero, E., & Urrea, M. A. (2011). Implementation of the European Water Framework Directive: Integration of hydrological and regional planning at the Segura River Basin, southeast Spain. Land Use Policy, 28(1), 242-256. doi:10.1016/j.landusepol.2010.06.005Quevauviller, P., Barceló, D., Beniston, M., Djordjevic, S., Harding, R. J., Iglesias, A., … Werner, M. (2012). Integration of research advances in modelling and monitoring in support of WFD river basin management planning in the context of climate change. Science of The Total Environment, 440, 167-177. doi:10.1016/j.scitotenv.2012.07.055Edens, B., & Graveland, C. (2014). Experimental valuation of Dutch water resources according to SNA and SEEA. Water Resources and Economics, 7, 66-81. doi:10.1016/j.wre.2014.10.003Pedro-Monzonís, M., Jiménez-Fernández, P., Solera, A., & Jiménez-Gavilán, P. (2016). The use of AQUATOOL DSS applied to the System of Environmental-Economic Accounting for Water (SEEAW). Journal of Hydrology, 533, 1-14. doi:10.1016/j.jhydrol.2015.11.034Gouveia, C. M., Trigo, R. M., Beguería, S., & Vicente-Serrano, S. M. (2017). Drought impacts on vegetation activity in the Mediterranean region: An assessment using remote sensing data and multi-scale drought indicators. 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Water Accounting Plus (WA+) – a water accounting procedure for complex river basins based on satellite measurements. doi:10.5194/hessd-9-12879-2012Karimi, P., Bastiaanssen, W. G. M., Molden, D., & Cheema, M. J. M. (2013). Basin-wide water accounting based on remote sensing data: an application for the Indus Basin. Hydrology and Earth System Sciences, 17(7), 2473-2486. doi:10.5194/hess-17-2473-2013Orth, R., & Destouni, G. (2018). Drought reduces blue-water fluxes more strongly than green-water fluxes in Europe. Nature Communications, 9(1). doi:10.1038/s41467-018-06013-7Van den Hurk, B., Hirschi, M., Schär, C., Lenderink, G., van Meijgaard, E., van Ulden, A., … Jones, R. (2005). Soil Control on Runoff Response to Climate Change in Regional Climate Model Simulations. Journal of Climate, 18(17), 3536-3551. doi:10.1175/jcli3471.1Bergström, S., Carlsson, B., Gardelin, M., Lindström, G., Pettersson, A., & Rummukainen, M. (2001). 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Does investment in irrigation technology necessarily generate rebound effects? A simulation analysis based on an agro-economic model. Agricultural Systems, 128, 25-34. doi:10.1016/j.agsy.2014.04.002Pedro-Monzonís, M., Ferrer, J., Solera, A., Estrela, T., & Paredes-Arquiola, J. (2014). Water Accounts and Water Stress Indexes in the European Context of Water Planning: The Jucar River Basin. Procedia Engineering, 89, 1470-1477. doi:10.1016/j.proeng.2014.11.431Vanham, D., Hoekstra, A. Y., Wada, Y., Bouraoui, F., de Roo, A., Mekonnen, M. M., … Bidoglio, G. (2018). Physical water scarcity metrics for monitoring progress towards SDG target 6.4: An evaluation of indicator 6.4.2 «Level of water stress». Science of The Total Environment, 613-614, 218-232. doi:10.1016/j.scitotenv.2017.09.056Liu, J., Yang, H., Gosling, S. N., Kummu, M., Flörke, M., Pfister, S., … Oki, T. (2017). Water scarcity assessments in the past, present, and future. 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A SIFT-Based DEM Extraction Approach Using GEOEYE-1 Satellite Stereo Pairs

A module for Very High Resolution (VHR) satellite stereo-pair imagery processing and Digital Elevation Model (DEM) extraction is presented. A large file size of VHR satellite imagery is handled using the parallel processing of cascading image tiles. The Scale-Invariant Feature Transform (SIFT) algorithm detects potentially tentative feature matches, and the resulting feature pairs are filtered using a variable distance threshold RANdom SAmple Consensus (RANSAC) algorithm. Finally, point cloud ground coordinates for DEM generation are extracted from the homologous pairs. The criteria of average point spacing irregularity is introduced to assess the effective resolution of the produced DEMs. The module is tested with a 0.5 m × 0.5 m Geoeye-1 stereo pair over the island of Crete, Greece. Sensitivity analysis determines the optimum module parameterization. The resulting 1.5-m DEM has superior detail over reference DEMs, and results in a Root Mean Square Error (RMSE) of about 1 m compared to ground truth measurements

Analysis of a Flash Flood in a Small Basin in Crete

Climate change will have a greater impact on the severity of flash floods, since precipitation intensity is expected to increase, even in areas where a reduction of precipitation is possible. This change in climate is expected to increase flood wave speed and its flood wave area extent. A case study of a small basin in the island of Crete was conducted to examine this effect, following the calibration and validation of the flow hydrograph of a flash flood event, in order to achieve model verification with the post-flood data. It was found that the most important parameters that affect the timing and magnitude of the peak discharge are the storage coefficient, the impervious rate and the curve number, as well as the time of concentration. Rainfall distribution was examined in different time intervals in order to study the effect of the intensity of precipitation on the peak hydrograph. From the precipitation records and according to the size of the watershed, the time step of the precipitation in the simulation model is recommended to be less than an hour. In other areas around the basin of interest, severe storms known as Medicanes that pass over Crete can produce higher precipitation in shorter time intervals. The impact of climate change scenarios results in an increase on the peak discharge by creating precipitation of higher intensity. Furthermore, the intensification of precipitation due to climate change results in higher flood depths and flooded area extent, as well as wave velocities

Evaluation of soil salinity amelioration technologies in Timpaki, Crete

Salinization is a soil threat that adversely affects ecosystem services and diminishes soil functions in many arid and semi-arid regions. Soil salinity management depends on a range of factors, and can be complex expensive and time demanding. Besides taking no action, possible management strategies include amelioration and adaptation measures. The WOCAT Technologies Questionnaire is a standardized methodology for monitoring, evaluating and documenting sustainable land management practices through interaction with the stakeholders. Here we use WOCAT for the systematic analysis and evaluation of soil salinization amelioration measures, for the RECARE project Case Study in Greece, the Timpaki basin, a semi-arid region in south-central Crete where the main land use is horticulture in greenhouses irrigated by groundwater. Excessive groundwater abstractions have resulted in a drop of the groundwater level in the coastal part of the aquifer, thus leading to seawater intrusion and in turn to soil salinization due to irrigation with brackish water. Amelioration technologies that have already been applied in the case study by the stakeholders are examined and classified depending on the function they promote and/or improve. The documented technologies are evaluated for their impacts on ecosystem services, cost and input requirements. Preliminary results show that technologies which promote maintaining existing crop types while enhancing productivity and decreasing soil salinity such as composting, mulching, rain water harvesting and seed biopriming are preferred by the stakeholders. Further work will include result validation using qualitative approaches