scholarly journals Modeling the response of soil moisture to climate variability in the Mediterranean region

2021 ◽  
Vol 25 (2) ◽  
pp. 653-669
Author(s):  
Louise Mimeau ◽  
Yves Tramblay ◽  
Luca Brocca ◽  
Christian Massari ◽  
Stefania Camici ◽  
...  

Abstract. Future climate scenarios for the Mediterranean region indicate a possible decrease in annual precipitation associated with an intensification of extreme rainfall events in the coming years. A major challenge in this region is to evaluate the impacts of changing precipitation patterns on extreme hydrological events such as droughts and floods. For this, it is important to understand the impact of climate change on soil moisture since it is a proxy for agricultural droughts, and the antecedent soil moisture condition plays a key role on runoff generation. This study focuses on 10 sites, located in southern France, with available soil moisture, temperature, and precipitation observations for a 10-year time period. Soil moisture is simulated at each site at the hourly time step using a model of soil water content. The sensitivity of the simulated soil moisture to different changes in precipitation and temperature is evaluated by simulating the soil moisture response to temperature and precipitation scenarios generated using a delta change method for temperature and a stochastic model (the Neyman–Scott rectangular pulse model) for precipitation. Results show that soil moisture is more impacted by changes in precipitation intermittence than precipitation intensity and temperature. Overall, increased temperature and precipitation intensity associated with more intermittent precipitation leads to decreased soil moisture and an increase in the annual number of days with dry soil moisture conditions. In particular, a temperature increase of +4 ∘C combined with a decrease of annual rainfall between 10 % and 20 %, corresponding to the current available climate scenarios for the Mediterranean, lead to a lengthening of the drought period from June to October with an average of +28 d of soil moisture drought per year.

2020 ◽  
Author(s):  
Louise Mimeau ◽  
Yves Tramblay ◽  
Luca Brocca ◽  
Christian Massari ◽  
Stefania Camici ◽  
...  

Abstract. Future climate scenarios for the Mediterranean region indicate a possible decrease in annual precipitation associated with an intensification of extreme rainfall events in the coming years. A major challenge in this region is to evaluate the impacts of changing precipitation patterns on extreme hydrological events such as droughts and floods. For this, it is important to understand the impact of climate change on soil moisture since it is a proxy for agricultural droughts and the antecedent soil moisture condition plays a key role on runoff generation. This study focuses on 10 sites, located in Southern France, with available soil moisture, temperature, and precipitation observations on a 10 year time period. Soil moisture is simulated at each site at the hourly time step using a model of soil water content. The sensitivity of the simulated soil moisture to different changes in precipitation and temperature is evaluated by simulating the soil moisture response to temperature and precipitation scenarios generated using a delta change method for temperature and a stochastic model (Neyman-Scott rectangular pulse model) for precipitation. Results show that soil moisture is more impacted by changes in precipitation intermittence than precipitation intensity and temperature. Overall, increased temperature and precipitation intensity associated with more intermittent precipitation leads to decreased soil moisture and an increase in the annual number of days with dry soil moisture conditions. In particular, a temperature increase of +4 °C combined with a decrease of annual rainfall between 10 and 20 %, corresponding to the current available climate scenarios for the Mediterranean, lead to a lengthening of the drought period from June to October 15 with in average +22 days of soil moisture drought per year.


2020 ◽  
Author(s):  
Louise Mimeau ◽  
Yves Tramblay ◽  
Luca Brocca ◽  
Christian Massari ◽  
Stefania Camici ◽  
...  

<p>Studies on future precipitation trends in the Mediterranean region show a possible decrease in annual precipitation amounts with an intensification of extreme events in the coming years. A major challenge in this region is to evaluate the impacts of changing precipitation patterns on extreme hydrological events such as droughts and floods. For this, it is important to understand the effects of changing temperature and precipitation on soil moisture since it is a good proxy for drought monitoring and it plays a key role on flood runoff generation. This study focuses on 11 sites located in the South of France, with soil moisture, temperature, and precipitation observations over a 10 year time period. Soil moisture is simulated at the hourly time step for each site using a soil moisture model based on the Green-Ampt infiltration scheme. The elasticity of the simulated soil moisture to different changes in precipitation and temperature is analyzed by simulating the soil moisture response to temperature and precipitation changes, generated using a delta change method for temperature and a stochastic model (Neyman-Scott rectangular pulse model) for precipitation. Results show that soil moisture is more impacted by changes in precipitation intermittence than precipitation intensity and temperature. Although there is variability in the soil moisture response to the considered forcing scenarios, increased temperature combined to increased precipitation intensity and intermittency leads to decreased median soil moisture and an increased number of dry days.</p>


2016 ◽  
Vol 16 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Pramila Paudyal ◽  
Dinesh Raj Bhuju ◽  
Manoj Aryal

Understanding the problem increasingly posed by climatic change is one of the critical challenges of our time. A study was carried out in Salyantar village in Dhading district of central Nepal to understand and assess the extent of climate change impacts on agriculture. The impact assessment was performed through analysis of meteorological data, Landsat images, and people’s perception on changes relative to agriculture sector. Mann-Kendall statistical trend test was used to assign statistical significance to the trend whereas temperature vegetation dryness index (TVDI) was used to identify soil moisture condition as an assessment criterion. The perception of local people on climate change and its impacts was studied through generalized questionnaire survey and participatory rural appraisal. The results of the study portrayed rise in temperature in the study area in the recent years in comparison to the past. The maximum temperature increment was 0.03p C per year. As for precipitation, it showed decreasing trend by 1.855mm per year. The TVDI obtained from Landsat image, showed decreasing trend of soil moisture in different years, which indicate an increased longer dry spell. This has unswerving effect on agriculture as the entire Salyantar village is dependent upon rain-fed agriculture. The perceived impacts on agriculture were decreased crop yield, reduced soil moisture, and increased incidence of new pests and invasive plant species. Such impacts were fairly heterogeneous in distribution. The Salyantar village, a raised flat-land of river deposition already stuck in the grip of water stress, was found exacerbated by the effect of climate change.Nepal Journal of Science and Technology Vol. 16, No.1 (2015) pp.59-68


2012 ◽  
Author(s):  
Raheleh Malekian ◽  
Robert Gordon ◽  
Ali Madani ASABE Member ◽  
Seyyed Ebrahim Hashemi

1979 ◽  
Vol 27 (3) ◽  
pp. 191-198
Author(s):  
J.H. Smelt ◽  
A. Dekker ◽  
M. Leistra

The decomposition of oxamyl in four soils under moist conditions was measured in incubation experiments at 15 deg C. Half-lives of oxamyl in soils with moisture tensions of approx. -9.8 X 103 Pa were 13 days in a clay loam, 14 days in a loamy sand, 34 days in a peaty sand and 39 days in a humic loamy sand. The rate of oxamyl decomposition in the clay loam decreased with decreasing soil moisture content down to values for below wilting point. Oxamyl decomposition in the humic loamy sand decreased with decreasing soil moisture content, but increased sharply in the very dry range. (Abstract retrieved from CAB Abstracts by CABI’s permission)


Author(s):  
Tiago de M. Inocêncio ◽  
Alfredo Ribeiro Neto ◽  
Alzira G. S. S. Souza

ABSTRACT The sequence of drought events in the Northeast of Brazil in recent decades raises attention to the importance of studying this phenomenon. The objective of this study was to evaluate the duration and severity of drought events from 1988 to 2018 in hydrographic basins of the state of Pernambuco, Brazil, using two drought indexes: Standardized Soil Moisture Index and Soil Moisture Condition Index, calculated based on data of the Soil Moisture Project of the European Space Agency’s Climate Change Initiative. The duration of the droughts was determined considering the months between their beginning and end, and their severity was based on the area formed in the graph between the curve of the index and the x-axis. The soil moisture database showed to be a promising tool for the analysis and monitoring of drought events in the Northeast region of Brazil, mainly for analysis and monitoring of drought events. The indexes allowed the evaluation of the drought phenomenon over the 30-year period, showing increases from 2012, which were more pronounced in the Semiarid region. The hydrographic basins responded differently to a same event, depending on the climate characteristics of the region in which they are located. Consecutive years with rainfall below the historical mean increased the magnitude of the droughts, as found for the 2012-2017 period, in which the indexes presented delays to return to more favorable values, showing the effect that one drought year has on the following year.


2021 ◽  
Author(s):  
Sandra Pool ◽  
Félix Francés ◽  
Alberto Garcia-Prats ◽  
Manuel Pulido-Velazquez ◽  
Carles Sanichs-Ibor ◽  
...  

<p>Irrigated agriculture is the major water consumer in the Mediterranean region. Improved irrigation techniques have been widely promoted to reduce water withdrawals and increase resilience to climate change impacts. In this study, we assess the impact of the ongoing transition from flood to drip irrigation on future hydroclimatic regimes in the agricultural areas of Valencia (Spain). The impact assessment is conducted for a control period (1971-2000), a near-term future (2020-2049) and a mid-term future (2045-2074) using a chain of models that includes five GCM-RCM combinations, two emission scenarios (RCP 4.5 and RCP 8.5), two irrigation scenarios (flood and drip irrigation), and twelve parameterizations of the hydrological model Tetis. Results of this modelling chain suggest considerable uncertainties regarding the magnitude and sign of future hydroclimatic changes. Yet, climate change could lead to a statistically significant decrease in future groundwater recharge of up -6.6% in flood irrigation and -9.3% in drip irrigation. Projected changes in actual evapotranspiration are as well statistically significant, but in the order of +1% in flood irrigation and -2.1% in drip irrigation under the assumption of business as usual irrigation schedules. The projected changes and the related uncertainties will pose a challenging context for future water management. However, our findings further indicate that the effect of the choice of irrigation technique may have a greater impact on hydroclimate than climate change alone. Explicitly considering irrigation techniques in climate change impact assessment might therefore be a way towards better informed decision-making.</p><p>This study has been supported by the IRRIWAM research project funded by the Coop Research Program of the ETH Zurich World Food System Center and the ETH Zurich Foundation, and by the ADAPTAMED (RTI2018-101483-B-I00) and TETISCHANGE (RTI2018-093717-B-I00) research projects funded by the Ministerio de Economia y Competitividad (MINECO) of Spain including EU FEDER funds.</p>


2011 ◽  
Vol 11 (9) ◽  
pp. 2469-2481 ◽  
Author(s):  
M. Gaetani ◽  
M. Baldi ◽  
G. A. Dalu ◽  
G. Maracchi

Abstract. This is a study on the impact of the jetstream in the Euro-Atlantic region on the rainfall distribution in the Mediterranean region; the study, based on data analysis, is restricted to the Mediterranean rainy season, which lasts from September to May. During this season, most of the weather systems originate over the Atlantic, and are carried towards the Mediterranean region by the westerly flow. In the upper troposphere of the Euro-Atlantic region this flow is characterized by two jets: the Atlantic jet, which crosses the ocean with a northeasterly tilt, and the African jet, which flows above the coast of North Africa. This study shows that the cross-jet circulation of the Atlantic jet favors storm activity in its exit region, while the cross-jet circulation of the African jet suppresses this kind of activity in its entrance region, with the 1st jet-stormtrack covariance mode explaining nearly 50% of the variability. It follows that the rainfall distribution downstream to these cross-jet circulations is strongly influenced by their relative positions. Specifically, in fall, rainfall is abundant in the western Mediterranean basin (WM), when the Atlantic jet is relatively strong but its northeasterly tilt is small, and the African jet is in its easternmost position. In winter, rainfall is abundant in the eastern Mediterranean basin (EM); this is when the Atlantic jet reaches the Scandinavian peninsula and the African jet is in its westernmost position. In spring, when the two jets weaken, the Atlantic jet retreats over the ocean, but the African jet stays in its winter position, rainfall is abundant in the Alpine region and in the Balkans. In addition, the covariance between precipitation and the jetstream has been evaluated. In fall, the latitudinal displacement of the Atlantic jet and the longitudinal displacement of the African jet modulate rainfall anomalies in the WM, with 38% explained covariance. In winter, the latitudinal displacement of the Atlantic jet produces rainfall anomalies in the western and central Mediterranean, with 45% explained covariance. In spring, the latitudinal displacement of the African jet produces rainfall anomalies, with 38% explained covariance.


2010 ◽  
Vol 7 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Kyung Won Seo ◽  
Su Jin Heo ◽  
Yowhan Son ◽  
Nam Jin Noh ◽  
Sue Kyoung Lee ◽  
...  

2020 ◽  
Author(s):  
Elcin Tan

<p>A debate on the probable Istanbul Isthmus Project that may have catastrophic impacts on our ecosystem has been recently accelerated in public, due to the fact that the approved environmental impact assessment (EIA) report of the hypothetical Istanbul Isthmus (HII) Project has recently been announced. The EIA report indicates that the assessment covers only the current conditions and the conditions that may arise during the construction of the HII. Unfortunately, The EIA report did not evaluate the climate change impact on either the Istanbul Area or Mediterranean Region after the inclusion of the HII, only the current conditions were evaluated. Therefore, the aim of this study is to investigate the impact of HII on the climate of the Mediterranean Region. The climate version of the WRF Model is utilized with 9 km resolution for the Region 12: Mediterranean (CORDEX) for the historical conditions and RCP8.5 scenarios of available climate model results from CMIP5 and CMIP6 projects. Land surface and land use maps are prepared by following the EIA report if the necessary information is included, otherwise, the current conditions are applied. The atmospheric conditions were not coupled to an Ocean Model, only the Sea Surface Temperature (SST) values of the Ocean Models are coupled to the WRF model during both historical and future simulations. The model results are evaluated in terms of temperature, precipitation, and sea-level changes. Consequently, the results indicate that the HII may decrease the resilience of the Mediterranean Region to Climate Change.</p>


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