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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.

8An assessment of the impact of global climate change on the water resources status of the 9 island of Crete, for a range of 24 different scenarios of projected hydro-climatological regime 10 is presented. Three -state of the art‖ Global Climate Models (GCMs) and an ensemble of 11Regional Climate Models (RCMs) under emission scenarios B1, A2 and A1B provide future 12 precipitation (P) and temperature (T) estimates that are bias adjusted against observations. 13The ensemble of RCMs for the A1B scenario project a higher P reduction compared to GCMs 14 projections under A2 and B1 scenarios. Among GCMs model results, the ECHAM model 15 projects a higher P reduction compared to IPSL and CNCM. Water availability for the whole 16 island at basin scale until 2100 is estimated using the SAC-SMA rainfall-runoff model And a 17 set of demand and infrastructure scenarios are adopted to simulate potential water use. While 18 predicted reduction of water availability under the B1 emission scenario can be handled with 19 water demand stabilized at present values and full implementation of planned infrastructure, 20 other scenarios require additional measures and a robust signal of water insufficiency is 21 projected. Despite inherent uncertainties, the quantitative impact of the projected changes on 22 water availability indicates that climate change plays an important role to water use and 23 management in controlling future water status in a Mediterranean island like Crete. The 24 2 results of the study reinforce the necessity to improve and update local water management 25 planning and adaptation strategies in order to attain future water security. 26 27

Risk management has reduced vulnerability to floods and droughts globally1,2, yet their impacts are still increasing3. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change3.

A methodology for elaborating multi-temporal Sentinel-1 and Landsat 8 satellite images for estimating topsoil Soil Moisture Content (SMC) to support hydrological simulation studies is proposed. After pre-processing the remote sensing data, backscattering coefficient, Normalized Difference Vegetation Index (NDVI), thermal infrared temperature and incidence angle parameters are assessed for their potential to infer ground measurements of SMC, collected at the top 5 cm. A non-linear approach using Artificial Neural Networks (ANNs) is tested. The methodology is applied in Western Crete, Greece, where a SMC gauge network was deployed during 2015. The performance of the proposed algorithm is evaluated using leave-one-out cross validation and sensitivity analysis. ANNs prove to be the most efficient in SMC estimation yielding R2 values between 0.7 and 0.9. The proposed methodology is used to support a hydrological simulation with the HEC-HMS model, applied at the Keramianos basin which is ungauged for SMC. Results and model sensitivity highlight the contribution of combining Sentinel-1 SAR and Landsat 8 images for improving SMC estimates and supporting hydrological studies.

Climate change is expected to have a significant impact on the hydrologic cycle, creating changes in freshwater resources. The Intergovernmental Panel on Climate Change (IPCC) predicts that, as a result, floods and prolonged droughts will take place at increasingly frequent periods. The Mediterranean has been described as one of the main climate change "hot-spots", with recent simulations showing a collective picture of substantial drying and warming. This effect appears more pronounced during warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25-30%. Despite the decreasing annual rainfall trend, an increase in the amount and intensity of wintertime rainfall is evident. However, the scientific question on the quantitative impact of these signals to small scale coastal watersheds and Mediterranean islands has not been answered. The state-of-the-art Ensembles dataset was employed to assess the impact of the changing climate on the water availability of the island of Crete at basin scale. Here, the Ensembles precipitation and temperature data is used as input for a rainfall-runoff model previous calibrated for the whole island with the principle of regionalization. Data analysis for the period Ioannis K. Tsanis on leave from Department of Civil Engineer, McMaster University, Canada. Electronic supplementary materialThe online version of this article (