Rainfall Threshold for Shallow Landslides Initiation and Analysis of Long-Term Rainfall Trends in a Mediterranean Area

The effects of climate change on landslide activity may have important environmental, socio-economic, and political consequences. In the last decades, several short-term extreme rainfall events affected Mediterranean regions, resulted in damaging geo-hydrological processes and casualties. It is unequivocal that the impact of landslides in several Mediterranean countries is increasing with time, but until now, there has been little or no quantitative data to support these increases. In this paper, both rainfall conditions for the occurrence of shallow landslides and rainfall trends were investigated in the Portofino promontory, which extends in the Ligurian Sea, where heavy rainfall and related ground effects often occur. Adopting a frequentist approach, the empirical intensity-duration threshold was estimated. Our findings highlight that the rainfall intensity required to trigger landslides is lower for the same duration than those expected in other similar environments, suggesting a high susceptibility to rainfall-induced landslides in the Portofino territory. Further, the Mann-Kendall test and Hurst exponent were used for detecting potential trends. Analysis of long-term rainfall time series showed statistically significant increasing trends in short duration precipitation occurrence and rainfall rates, suggesting a possible future scenario with a more frequent exceedance of the threshold triggering value and an increase of landslide risk.

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An Investigation into the Spatial and Temporal Variability of the Meteorological Drought in Jordan

Climate ◽

10.3390/cli7060082 ◽

2019 ◽

Vol 7 (6) ◽

pp. 82 ◽

Cited By ~ 5

Author(s):

Haitham Aladaileh ◽

Mohammed Al Qinna ◽

Barta Karoly ◽

Emad Al-Karablieh ◽

János Rakonczai

Keyword(s):

Regression Analysis ◽

Hierarchical Clustering ◽

Linear Regression Analysis ◽

Meteorological Drought ◽

Kendall Test ◽

Spatial And Temporal Variability ◽

Drought Event ◽

Mann Kendall Test ◽

The Impact

Following the impact of droughts witnessed during the last decade there is an urgent need to develop a drought management strategy, policy framework, and action plan for Jordan. This study aims to provide a historical baseline using the standardized precipitation index (SPI) and meteorological drought maps, and to investigate the spatial and temporal trends using long-term historical precipitation records. Specifically, this study is based on the statistical analysis of 38 years of monthly rainfall data, gathered from all 29 meteorological stations that cover Jordan. The Mann–Kendall test and linear regression analysis were used to uncover evidence of long-term trends in precipitation. Drought indices were used for calculating the meteorological SPI on an annual (SPI12), 6-months (SPI6), and 3-months basis (SPI3). At each level, every drought event was characterized according to its duration, interval, and intensity. Then, drought maps were generated using interpolation kriging to investigate the spatial extent of drought events, while drought patterns were temporally characterized using multilinear regression and spatial grouped using the hierarchical clustering technique. Both annual and monthly trend analyses and the Mann–Kendall test indicated significant reduction of precipitation in time for all weather stations except for Madaba. The rate of decrease is estimated at approximately 1.8 mm/year for the whole country. The spatial SPI krig maps that were generated suggest the presence of two drought types in the spatial dimension: Local and national. Local droughts reveal no actual observed trends or repeatable patterns of occurrence. However, looking at meteorological droughts across all time scales indicated that Jordan is facing an increasing number of local droughts. With a probability of occurrence of once every two years to three years. On the other hand, extreme national droughts occur once every 15 to 20 years and last for two or more consecutive years. Linear trends indicated significant increase in drought magnitude by time with a rate of 0.02 (p < 0.0001). Regression analysis indicated that draught in Jordan is time dependent (p < 0.001) rather than being spatially dependent (p > 0.99). Hierarchical clustering was able to group national draughts into three zones, namely the northern zone, the eastern zone, and the southern zone. This study highlights the urgent need for a monitoring program to investigate local and national drought impacts on all sectors, as well as the development of a set of proactive risk management measures and preparedness plans for various physiographic regions.

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Trend analysis of Icelandic discharge, precipitation and temperature series

Hydrology Research ◽

10.2166/nh.2006.020 ◽

2006 ◽

Vol 37 (4-5) ◽

pp. 365-376 ◽

Cited By ~ 6

Author(s):

Jóna Finndís Jónsdóttir ◽

Páll Jónsson ◽

Cintia B. Uvo

Keyword(s):

Time Series ◽

Kendall Test ◽

Temperature Series ◽

Energy Resources ◽

Renewable Energy Resources ◽

Energy Research ◽

Daily Discharge ◽

Spring Temperatures ◽

The Impact

This study is a part of a Nordic co-operative research project, Climate and Energy, funded by Nordic Energy Research and the Nordic energy sector. The project has the objective of a comprehensive assessment of the impact of climate change on Nordic renewable energy resources including hydropower, wind power, biofuels and solar energy. In this paper, the long term variability of precipitation, temperature and discharge of Icelandic rivers is analyzed with respect to trends. Trend is tested for two periods: 1941–2002, since the longest Icelandic discharge records reach 60 years back in time, and 1961–2000, so that a larger set of discharge records could be included, as only a few Icelandic discharge records extend more than 40 years back in time. An eventual trend in the time series is analyzed using the Mann–Kendall test. The test is applied to the time series of both annual and seasonal values, and also to the timing and volume of the maximum daily discharge in spring and autumn, respectively. The main conclusions from the study are that, despite significant increase in measured precipitation, discharge in non-glacial rivers has not increased. Meanwhile, spring temperatures have a negative trend and spring floods, therefore, are larger and delayed.

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Interactions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika – Kivu Rift region, Africa

10.5194/esurf-2020-87 ◽

2020 ◽

Author(s):

Arthur Depicker ◽

Gerard Govers ◽

Liesbet Jacobs ◽

Benjamin Campforts ◽

Judith Uwihirwe ◽

...

Keyword(s):

Slope Failure ◽

Land Use Changes ◽

Extreme Rainfall ◽

Google Earth ◽

Shallow Landslides ◽

Extreme Rainfall Events ◽

Landslide Activity ◽

Erosion Rates ◽

The North ◽

The Impact

Abstract. Deforestation increases landslide activity over short, contemporary timescales. However, over longer timescales the location and timing of landsliding is controlled by the interaction between uplift and fluvial incision. Yet, the interaction between (human-induced) deforestation and landscape evolution has hitherto not been explicitly considered. We address this issue in the North Tanganyika-Kivu Rift region (East African Rift). In recent decades, the regional population has grown exponentially and the associated expansion of cultivated and urban land has resulted in widespread deforestation. On a much longer time scale, tectonic uplift has forged two parallel mountainous Rift shoulders that are continuously rejuvenated through knickpoint retreat, enforcing topographic steepening. In order to link deforestation and rejuvenation to landslide erosion, we compiled an inventory of nearly 8,000 recent shallow landslides in Google Earth© imagery from 2000–2019. To accurately calculate landslide erosion rates, we developed a new methodology to remediate inventory biases linked to the spatial and temporal inconsistency of this satellite imagery. We find that erosion rates in rejuvenated landscapes are roughly 40 % higher than in the surrounding relict landscapes, upstream of retreating knickpoints and outside of the Rift shoulders. This difference is due to the generally steeper relief in rejuvenated landscapes which more than compensates for the fact that rejuvenated slopes, when compared to similarly angled slopes in relict zones, often display a somewhat lower landslide erosion rate. These lower rates in the rejuvenated landscapes could be the result of a drier climate, the omission of earthquake-induced landslide events in our landslide inventory, and potentially a smaller regolith stock. More frequent extreme rainfall events in the relict zones, and possibly the presence of a thicker regolith, cause a stronger landslide response to deforestation compared to rejuvenated landscapes. Overall, deforestation initiates a landslide peak that lasts approximately 15 years and increases landslide erosion by a factor 2 to 8. Eventually, landslide erosion in deforested land falls back to a level similar to that observed under forest conditions, most likely due to the depletion of the most unstable regolith. Landslides are not only more abundant in rejuvenated landscapes but are also smaller in size, which may be a consequence of the seismic activity that fractures the bedrock and reduces the minimal critical area for slope failure. With this paper, we highlight the importance of considering the geomorphological context when studying the impact of recent land use changes on landslide activity.

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Considerations on the prediction of hazards (mainly landslides) and their consequences

10.5194/egusphere-egu21-641 ◽

2021 ◽

Author(s):

Fausto Guzzetti

Keyword(s):

Early Warning Systems ◽

Landslide Hazard ◽

Landslide Risk ◽

Visual Interpretation ◽

Landslide Forecasting ◽

Length Width ◽

Hazard And Risk ◽

Short Term Forecasting ◽

The Impact

<p>The general assumptions and the most popular methods used to assess landslide hazard and for landslide risk evaluation have not changed significantly in recent decades. Some of these assumptions have conceptual weaknesses, and the methods have revealed weackneses and limitations. After an introduction on what we need to predict in order to assess landslide hazard and risk, I introduce the strategies and main methods currently used to detect and map landslides, to predict landslide populations in space and time, and to anticipate the number and size characteristics of expected landslides. For landslide detection and mapping, I consider traditional methods based on visual interpretation of aerial photography, and modern approaches that exploit visual, semi-automatic or automatic analysis of remotely sensed imagery. For spatial landslide prediction, I discuss the results of a review of classification-based statistical methods for evaluating landslide susceptibility. For temporal forecasting, drawing on a review of geographical landslide forecasting and early warning systems, I discuss short-term forecasting capabilities and their limitations. Then, I discuss the long-term landslide projections considering the impact of climate variations on landslide projections. Regarding the numerosity and size of landslides, I discuss existing statistics on the length, width, area, and volume of landslides obtained from populations of event-triggered landslides. This is followed by an analysis of the consequences of landslides. I conclude by offering recommendations on what I imagine we should do to make significant progress in our collective ability to predict the risk posed by landslide populations and to mitigate their risk. My understanding, but also my feeling and hope, is that some - perhaps many - of the recommendations are general, and may be applicable to other hazards as well.</p>

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Interactions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika–Kivu rift region, Africa

Earth Surface Dynamics ◽

10.5194/esurf-9-445-2021 ◽

2021 ◽

Vol 9 (3) ◽

pp. 445-462

Author(s):

Arthur Depicker ◽

Gerard Govers ◽

Liesbet Jacobs ◽

Benjamin Campforts ◽

Judith Uwihirwe ◽

...

Keyword(s):

Slope Failure ◽

Land Use Changes ◽

Google Earth ◽

Shallow Landslides ◽

Extreme Rainfall Events ◽

Landslide Occurrence ◽

Landslide Activity ◽

Erosion Rates ◽

The North ◽

The Impact

Abstract. Deforestation is associated with a decrease in slope stability through the alteration of hydrological and geotechnical conditions. As such, deforestation increases landslide activity over short, decadal timescales. However, over longer timescales (0.1–10 Myr) the location and timing of landsliding is controlled by the interaction between uplift and fluvial incision. Yet, the interaction between (human-induced) deforestation and landscape evolution has hitherto not been explicitly considered. We address this issue in the North Tanganyika–Kivu rift region (East African Rift). In recent decades, the regional population has grown exponentially, and the associated expansion of cultivated and urban land has resulted in widespread deforestation. In the past 11 Myr, active continental rifting and tectonic processes have forged two parallel mountainous rift shoulders that are continuously rejuvenated (i.e., actively incised) through knickpoint retreat, enforcing topographic steepening. In order to link deforestation and rejuvenation to landslide erosion, we compiled an inventory of nearly 8000 recent shallow landslides in © Google Earth imagery from 2000–2019. To accurately calculate landslide erosion rates, we developed a new methodology to remediate inventory biases linked to the spatial and temporal inconsistency of this satellite imagery. Moreover, to account for the impact of rock strength on both landslide occurrence and knickpoint retreat, we limit our analysis to rock types with threshold angles of 24–28∘. Rejuvenated landscapes were defined as the areas draining towards Lake Kivu or Lake Tanganyika and downstream of retreating knickpoints. We find that shallow landslide erosion rates in these rejuvenated landscapes are roughly 40 % higher than in the surrounding relict landscapes. In contrast, we find that slope exerts a stronger control on landslide erosion in relict landscapes. These two results are reconciled by the observation that landslide erosion generally increases with slope gradient and that the relief is on average steeper in rejuvenated landscapes. The weaker effect of slope steepness on landslide erosion rates in the rejuvenated landscapes could be the result of three factors: the absence of earthquake-induced landslide events in our landslide inventory, a thinner regolith mantle, and a drier climate. More frequent extreme rainfall events in the relict landscapes, and the presence of a thicker regolith, may explain a stronger landslide response to deforestation compared to rejuvenated landscapes. Overall, deforestation initiates a landslide peak that lasts approximately 15 years and increases landslide erosion by a factor 2 to 8. Eventually, landslide erosion in deforested land falls back to a level similar to that observed under forest conditions, most likely due to the depletion of the most unstable regolith. Landslides are not only more abundant in rejuvenated landscapes but are also smaller in size, which may again be a consequence of a thinner regolith mantle and/or seismic activity that fractures the bedrock and reduces the minimal critical area for slope failure. With this paper, we highlight the importance of considering the geomorphological context when studying the impact of recent land use changes on landslide activity.

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A Comparative Analysis of Relationship Between Innovation and Transport Sector Carbon Emissions in Developed and Developing Mediterranean Countries

10.21203/rs.3.rs-206436/v1 ◽

2021 ◽

Author(s):

Nigar Demircan Çakar ◽

Ayfer Gedikli ◽

Seyfettin Erdoğan ◽

Durmuş Çağrı Yıldırım

Keyword(s):

Developing Countries ◽

Carbon Emissions ◽

Negative Impact ◽

Empirical Test ◽

Patent Application ◽

Developed Countries ◽

Transport Sector ◽

Mediterranean Countries ◽

The Impact

Abstract Innovation technologies have been recognized as an efficient solution to alleviate carbon emissions stem from transport sector. The aim of this study is to investigate the impact of innovation on carbon emissions stemming from the transportation sector in the Mediterranean countries. Based on the available data, Albania, Algeria, Bosnia and Herzegovina, Croatia, Egypt, Morocco, Tunisia, and Turkey are selected as the 8 developing countries; and Cyprus, France, Greece, Israel, Italy, Spain are selected as the 6 developed countries and included in the analysis. Due to data constraints, the analysis period has been determined as 1997-2017 for the developing Mediterranean countries, and 2003-2017 for the developed Mediterranean countries. After determining the long-term relationship with the panel cointegration method, we obtained the long-term coefficients with FMOLS and DOLS methods. The empirical test results indicated that the increments in the level of innovation in developing countries have a negative impact on carbon emissions due to transportation if the innovation results from an increase in patents. However, the trademark increase does not have a statistically significant effect on carbon emissions. In developed countries, it is observed that both the patent application increases and the trademark increases have a positive effect on carbon emissions.

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Suppressed, but Not Forgotten

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000033 ◽

2011 ◽

Vol 70 (1) ◽

pp. 5-11 ◽

Cited By ~ 8

Author(s):

Beat Meier ◽

Anja König ◽

Samuel Parak ◽

Katharina Henke

Keyword(s):

Memory Trace ◽

Thought Suppression ◽

Test Phase ◽

Indirect Test ◽

Final Test ◽

Test Experiment ◽

And Control ◽

Cue Words ◽

The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

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