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

Abstract

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.

Assessing the Impacts of Extreme Precipitation Change on Vegetation Activity

“…The cumulative soil moisture from extreme precipitation events is beneficial to vegetation growth. The result is in accordance with soil moisture simulation [58].…”

Vegetation Greening and Climate Warming Increased the Propagation Risk From Meteorological Drought to Soil Drought at Subseasonal Timescales

“…The regions with significant influence of precipitation and AI are located in central Africa, where significant drying trend contributes to the decreased soil moisture (Figures S7c–S7f in Supporting Information ) and increased soil drought. The relatively minor contribution of precipitation identified over many regions may be associated with the fact that increased precipitation is not sufficiently large to compensate for drying caused by temperature increase (Flannigan et al., 2016) and the strong links between soil moisture and precipitation intermittence rather than precipitation intensity (Mimeau et al., 2021). Results for trigger threshold are similar (Figure S8 in Supporting Information ), with NDVI and temperature changes being the dominant drivers over most regions (>71%) with significant trends in drought propagation risk.…”

Assessment of the Impact of Climate Change on Soil Moisture Using Remote Sensing and Geographic Information Systems

“…(Taylor et al, 2012) studied the relationship between soil moisture and precipitation was highlighted, with the suggestion that afternoon rains are more frequent on drier soils. (Mimeau et al, 2021), The authors investigated the impact of climate change on soil moisture and extreme hydrological events in the Mediterranean region based on observations over a 10-year period and model simulations. Results showed that soil moisture is more sensitive to changes in precipitation intermittency than intensity and temperature.…”

“…The annual monitoring of soil moisture is important to assess the effect of changes in climatic parameters. By tracking soil moisture over time, it is possible to identify patterns and trends that may be related to changes in precipitation, temperature, or other climatic factors (Mimeau et al, 2021). This information can be used to better understand the impacts of climate change on soil moisture and to inform land management decisions (Nitu, 2021).…”