In situ soil moisture measurements are few and far between, yet soil moisture is an important contributing factor in landslides.
Do we use rainfall-runoff models to simulate soil moisture, make satellite-based estimates, or what are other possibilities?
Very interesting question. I'm also interested on that.
Actually, the important role of initial soil moisture conditions for slope stability models has still to be fully understood. In two studies, we used a soil water balance model (Ponziani et al., 2012; Landslides journal) and satellite soil moisture data (Brocca et al., 2012; Remote Sensing journal) as initial conditions for predicting landslides triggering and movement (you can find the papers on "Research Gate").
Likely, the integration of in situ, satellite and modelled data will provide the best options for predicting the soil moisture conditions in regional slope stability models.
We are working on this direction and we have a poster at the next EGU conference (http://meetingorganizer.copernicus.org/EGU2013/EGU2013-8004.pdf).
Satellite-based method is the best approach for obtaining the soil moisture at regional scale.
which is the Satellite based method? 1:50.000 is in your opinion regional scale? Thanks
i think the hydrology model VIC can simulated the soil moisture that can be put into your slope model. Google 'VIC' can give a lot of imformation.
You can use NASA quantitative precipitation estimates(QPE) products, i.e. 3B42RT and 3B42 as input into VIC model to simulate the soil moisture.
Actually, there exist several satellite soil moisture products.
See at previous RG questions/answers:
https://www.researchgate.net/post/What_is_the_best_satellite_soil_moisture_product_for_land_surface_modelling
https://www.researchgate.net/post/How_to_monitor_estimate_soil_moisture_over_large_areas
https://www.researchgate.net/post/How_can_I_get_the_soil_moisture_products_freely_online
The current soil moisture product based on Aqua and Terra is an alternative, but its algorithm is not very robust mathematically. The upcoming SMAP satelling launch expected in 2014 will have exciting product meet demands in a lot of communities.
Please, have a look to the ASCAT soil moisture products operationally delivered from EUMETAT through satellites METOP-A and METOP-B.
Depending on your data needs, uou could also try the Soil Wetness Index derived from a Digital Elevation Model: http://watershed.for.unb.ca/files/NAFSCcatena2.pdf
Hi Eric and thanks for Your interesting question. I generally agree with my previous contributors. However, i'd like to complement that You should not disregard "geogenic" water content as influence factor on soil moisture (which of course also correlates with rainfall - but certainly will not react immediately). Depending on your area of investigation You might have information about spring horizons, existent soil movements or wells as indicative information to spring horizons. Maybe using this supplement information You can generate important indicators on "high risk landlide areas". Regards from a Swiss practitioner!
... and by the way: In eastern Switzerland, the authorities provide You with (measured) soil moisture information (soil moisture = german "Bodenfeuchte"); see for example http://www.bodenfeuchte-ostschweiz.ch/
Great!
In Switzerland, you are really ahead.
It would be very interesting to see at your soil moisture data, not only for landslides prediction but also for other applications (satellite products validation, flood modelling, ...).
Dear Eric,
I recently wrote a few papers on the subject together with my former Ph.D. student Cristiano Lanni and others. They try to use simple methods to assess soil moisture content in a hillslope, using variations on the topographic index approach. You can find these papers at:
#1
http://abouthydrology.blogspot.it/2012/09/my-past-research-on-shallow-landslide.html
(see the reference J33, J35, J36).
You can certainly also get information and details from the Ph.D thesis by Cristiano himself at:
#2
http://eprints-phd.biblio.unitn.it/779/
These methods were implemented with the idea to simplify as much as possible the estimation of soil misture.
As you can see from link #1, this is just one part of my research on the topics, where I and coworkers developed different models and methods to obtain the required results.
In particular, for small areas, we prefer actually to use the full capability of the GEOtop model
#3
http://abouthydrology.blogspot.it/search/label/GEOtop
For having the code presented in Dr. Lanni work, you have to ask himself to cristiano.lanni gmail.com.
Said that, based on my experience, I exclude that VIC can provide a fairly accurate soil moisture content that could be used for the task. VIC acts properly at very large scale and very corse resolution compared to what is needed for a serious work on (shallow) landslides. We implemented a version of the SHALSTAB model
for the same scope in the Horton Machine:
#4
http://abouthydrology.blogspot.it/2013/04/the-horton-machine.html
However, in my work, I spent most of the time trying to show that a method based on stationary hydrological fluxes cannot work properly (and therefore simply using the topographic index does not work very much).
Regarding the use of remote sensed data, it is a VERY promising field. However, keep in mind that remote sensing usually returns just the sil moisture in the very top most centimeters of the soil, while, even shallow landslides, can be a few meters deep. Moreover, the sensors I had the occasion to work with (but I cannot be considered an expert as the previous commenters are) gives different results from those brought by Richards equation solvers. This could be partially due to the fact that the "soil moisture" seen by satellites is not just soil moisture, but also water on canopies, and water in vegetation. Obviously I have also some criticism about the way usually the satellite "products" are actually made (which is, this operation involve different degrees of hydrological assumptions ... without any explicit hydrological modelling).
I think that you could also have some isight by reading:
#5
http://abouthydrology.blogspot.it/2012/10/guidelines-for-mapping-of-triggering-of.html
A reference that I also recommend is:
#6
Hillslope hydrology and stability by Lu and Godt
http://www.amazon.com/Hillslope-Hydrology-Stability-Ning-Lu/dp/1107021065
All the best,
riccardo
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