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# Physical Geography - Science topic

Explore the latest questions and answers in Physical Geography, and find Physical Geography experts.
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Physical geography is includes the study of the earth spheres. Geographers usually working on geomorphology, climatology and biogeography. Why they don't work mostly in oceanography ?
Discussion.
Yes it is true that there is still a vast scope to work on life under the water, that is the part of Biological features of Oceanography. Most of the works are concerned with the geological or hydrological parts of Oceanography. May be it is due to the area of research interest. Jasem A Albanai
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I see huge discrepancy between researchers (difference for the same class is somewhere up to 0.2). What determines the choice of the appropriate value ? What is the role of spatial resolution of the research in this ? Thank you.
Manning's n or roughness coefficient is actually a measure of energy or head loss along a channel reach. The roughness of the channel, bank and floodplain is a major determinant of Manning's n. However, all mechanisms that contribute to energy loss should be considered in selecting its proper value. For example, flow velocity and associated turbulence are important (e.g., if velocity is near zero, the Manning's n will be zero even when the river has high roughness). Similarly flow depth is important. So is the season (e.g., more vegetation and thus higher roughness in summer).
I think engineers should think of Manning's n as more related to energy loss under specific flow conditions than to only roughness.
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Hi all,
i have a Before-After-Control-Treatment (2x2) design, resulting in two independent groups of scale data (samples in two water streams, in one a treatment has been installed at some point, both streams (two physical different locations) were sampled before and after at various occations). i would like to test for differences in distribution, the effect of this treatment.
My data are not-normal distributed, and some of the group combinations violate the assumption of equality of variance, as the output of the Modified Levene's test testified.
Initially I have performed Mann-whitney U tests on the groups so far, with several outputs resulting a significant difference across the treatment.
But MW-U assumes equality of variance.
1) How sensitive is MW-U to the violation of equality of variances?
2) To determine an effect size of the treatment, for instance eta squared, using the Z statistic of MW-U, is equality of variance needed?
3) Are there any alternative post-hoc tests similar to the univariate Games-Howell test (which does not assume equality of variance), that can be run on non-parametric 2x2 designs?
ps: i am working in SPSS
Many Thanks,
Taco
Sorry, both tests yield a very sign. effect of Location, a rather sign. effect of treatment, but no interaction.
Robust test:
------------------------------value ----------df1 -------- df2 -----------------p.value
Location 113.4956 ------1 ---------100.1808 -------0.0000 treatment 7.0434 -----------1 ----------- 97.6626 ------0.0093
Location:treatment 0.0001 -------1 ---------- 97.6626 ------0.9938
ARTool:
Table Type: Anova Table (Type III tests)
Model: No Repeated Measures (lm)
Response: art(VarX)
----------Df ---Df.res ----------- F value ----------- Pr(>F)
1 treatment --- ---1 326 ---------------4.67749 ----------- 0.031287 *
2 Location ---- 1 326 --------------45.48487 ------------7.0158e-11 ***
3 treatment:Location 1 326 ---------------0.25182 ------------ 0.616132
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
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Giant Underwater Craters May shed Light On Bermuda Triangle Mystery
We have been performing experiments in the laboratory for more than a year , and results are fascinating.
This may be a different explanation. See https://www.chinasona.org/Thiaoouba/Bermuda-triangle.html
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Data collection, river flow measurements, three height, cross sections of rivers, velocity of water flow, identification of rocks, geomorphology etc.
Dear Patrik,
I believe that you have to read in the literature of the science that is related to your field of interest. For example, if you are interested in geomorphology, you will find more applied details in geology books, etc..
Hope this will help.
Best wishes.
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I am aware of computational costs while working with high resolution data, so this question is more of hypotetical nature and is related to the relevance of friction parameter in inundation modeling. The question is also software(model)-dependent.
Thank you Chandan.
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Dear Dimitris Fotakis,
I am very pleased to write you this email.  I hope you are in good health. I am Ayaz F. Ali, doing PhD Physical Geography from Northwest Institute of Eco-Environment and Resources, CAS Lanzhou, China. I am writing this email regarding to acquire the Watershed Mapper software for the UBC watershed model.  Recently I published my article using HBV model. Now, for the comparison purpose of the hydrological models, I require your developed Watershed Mapper as it is ease and friendly to use with ARC GIS.    I shall be very thankful to you at this regard. Moreover the acknowledgement always will be for you, your institute and the publication. Thanks and regards Ayaz F. Ali PhD Scholar NIEER CAS Lanzhou +8618609447913
Dear Mr. Ayaz F. Ali,
thank you very much, I glad to meet you here, I hope you are in good health too. im PhD of environmental science from science and research islamic azad university of Tehran, Iran,
i use ROC model for camparision.
Best regard
elham goleiji
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Coriolis deflection for east-west moving objects
Not to resurrect an old question but the answers here are... deeply wrong. I'd be having sharp words with undergrads who turned out these answers.
Point 1: Yes obviously there is a Coriolis force for E-W travel at all latitudes. Look at the equation $\Omega \cross v$. Eastward travel gets pushed up from the Earth's surface, Westward travel pushed down. These forces are invariably pathetic compared to gravity but they do exist.
Point 2: Without using equations, Coriolis is all about reference frames. For classic equator-to-pole travel, as you move away from the equator, the ground under your feet is moving West-to-East more slowly, so unless a force is applied to slow YOUR Westward velocity, you increasingly move west relative to the ground
For East-West travel, consider the Great circle corresponding to your latitude and your personal cartesian axes: North, East,Up. By heading "East" you move on a tangent to the great circle. The ground East of you has some component Downwards by your reference frame (and West ground moves "Upwards"). Thus, relative to the ground you seem to be accelerated Up as you go East and Down as you go West. Thus the Coriolis force we expect from the equation.
If you maintained an Eastward trajectory in your original cartesian frame, you start to have an Upward motion relative to the ground's reference frame and thus we get the third coriolis force direction, where you would appear to move East or West more slowly as your velocity vector is less and less aligned with the motion of the Earth's ground.
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The Bermuda Triangle is one of the amazing landmarks in the world And there are strange, interesting and horrible events in that area. Events such as the crash of planes, the sinking of ships, the collapse of the compass, and etc. Scientists express different ideas for these events Like hexagonal clouds, deep earthquakes, atmospheric disturbances, methane gas and etc. And each of these reasons justifies part of the events in that area . What really happens in this area ? Could this be the cause of the extraterrestrials? Is there another area like the Bermuda Triangle?
It is time for someone to do a serious study of these events. Not just one investigator, but many of various disciplines and specialties.
People have already solved the disappearance of dinosaurs, why not these phenomena?
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Urgent - trying to find a program that will convert a scanned pollen diagram into either graphs, a digital, clearer pollen diagram or data tables.
You can use the Getdata software, it could precisely get the point (x,y) from the pollen diagram, then use the data to draw another digital diagram.
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I currently work for the Swedish Geological Survey and am concurrently doing my MSc. thesis in Physical Geography.
I have a team of top UAV engineers (https://www.bitcraze.io/) helping me to develop a specialized UAV, I am confident it will be of interest to you. It is also likely that we will have some good funding opportunists connected to the project.
See my linked in profile if you would like to know more about my background.
I look forward to getting in touch.
All the best,
Levi Farrand
Hello,
There are many different companies and their models of UAV on the market. The type of the UAV is dependent on the purpose of utilization. So, as Kenneth and Vladimir mentioned, the objective of the research is important.
For example, in agriculture, we use SenseFly Ebee (single motor, fixed-wing). The system has GPS and a camera capable of acquiring images from different bands including RGB, green, red, NIR, and red edge. This type of UAV are used for yield estimation, plant emergence and count, stress detection, disease estimate, etc in agriculture.
Regards,
Muharrem Keskin
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I am searching about  a french researcher in the field of earth science and space interested in doing the work of a joint research project funded by STDF and the collaboration with the French Embassy in Egypt.
Regards
Hossam Ismael
Budyko, M.I. The effect of solar radiation variations on the climate
of the Earth. Tellus. 21(5)，611–619 (1969). doi:10.1111/j.2153-3490.
1969.tb00466.x.
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ii
Try to read more text on your research work and consult professionals on it.
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Needing current data for areas that are thaw sensitive or thaw stable along the Haul Road in Alaska. Preferably shapefiles or databases that can be imported into geodatabase.
Thanks!
ME
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Questionnaire is carried out in order to develop my master thesis: The impact of user-defined parameters on DEM accuracy. By using feedbacks from the users who works with DEMs the conclusion about users perception of the importance of user-defined parameters in digital terrain modelling will be performed.
Its well prepared questionnaire and i have added my response
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I tried viewing a GeoTIFF file using an ordinary photo viewer, and was curious as to why the GeoTIFF displayed differently compared to when it is loaded into a GIS software. Can anyone explain why this is so? Does this have to do with the amount of data stored per pixel in a GeoTIFF file or something?
(: Not from me. If you are using ArcMap you should export raster from it with the checkbox "Use renderer". TIFF will then be displayed correctly.
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The continental drift is a reality now, supported by the dynamics of plate tectonics and seafloor spreading. Continuous convergence (collision) and divergence (separation) of continental and oceanic plates from each other has been reshaping our Earth since the initiation of the process. Therefore, the absolute location (latitudinal and longitudinal) of places has been changing with the change of associated biotic and abiotic environments (tropics shift to equator, or polar regions being shifted to mid latitudes for example).
Then, how the shape of the earth arises due to the continuous movement of the continents and oceans is impacting the global climate? Does it also impact the paleoclimatic records which are being considered to understand the climate of the past?
Dear Sumanta: the question you posed is a very complex one! The supercontinent cycle has been operating since at least the Paleoproterozoic or Neoarchean, assembling and disrupting continental masses, creating -and destroying- orogenic belts and ocean basins, volcanic belts, and the like. So it is unquestionable that such tectonic variarions had a strong influence on past climate, just as they have been doing since the Pangea disruption in the Jurassic. The problem is relatively easy to resolve in Mesozoic terrains, a bit more difficult in Paleozoic, and really a hard one in the Precambrian. Conditions for deposition of evaporitic basins were widespread during the Permian, but also in the Devonian and Proterozoic, where large evaporitic basins are found, also aeolian sandstones are frequent in this very dry period, and in older times too. Climate changes so profound as to be unimaginable to us happened when continental blocks collided to form supercontinents. Pangea was covered possibly by a desert three times larger that the actual Sahara, and by an enormous ice cover in its southern parts. The uplift of the Appalachian-Caledonian belt surely had a profound effect in the climate of this supercontinent and global Earth. Before this, in the Neoproterozoic, the uplift of the world-wide Greenvillian system of orogenic belts, which was probably even higher than the Himalaya and longer than the Andes..., due to the assembly of Rodinia, certainly had a marked influence in atmospheric and oceanic circulation, as to eventually lead he planet to the "Snow-ball Earth" global glaciation, just as the uplift of the Andes and Himalaya has done in more recent times, creating large deserts in South America and Central Asia. The problem in older terrains is the large uncertainties in the relative shape, positions and paleolatitudes adquired by land masses, this is relatively easy to solve during the Jurassic, but increasingly difficult to ascertain in older times. With regards, Sebastian.
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Global warming = Ice melting = Sea level rise = More water availability for evaporation and (possible) decrease of salinity = More evaporation = More clouds = Less solar radiation to earth = Global cooling = Fresh ice formation = Sea level fall = Less water availability for evaporation and (possible) increase of salinity = Less evaporation = Less atmospheric clouds = More incoming solar radiation = Global warming again.
(1) Are these consequences always true?
(2) If not, then what are the alternative circumstances?
(3) How does ever-changing Global Climate maintain its Dynamic Equilibrium with Global Water Cycle? Which one is the initiator of Change? Any evidence?
and,
(4) Is there any long term record of salinity of oceanic water?
**Note: Above are the physical factors (components) for global change and associated consequences... excluding biological factors such as changes of concentration of Oxygen/Carbon-dioxide/Methane etc. and their inter-relation which also influence the global cycle.
----------------------------------------------------------------------------------------------
UPDATE: Few Related & Interesting References (referred by the experts with their answers)
(IPCC Working Group Reports, referred by Harry ten Brink and Commenter)
http://isthereglobalcooling.com/ (referred by Yuri Yegorov)
https://nsidc.org/cryosphere/sotc/ (referred by Yuri Yegorov)
https://en.wikipedia.org/wiki/Past_sea_level   (referred by Yuri Yegorov)
http://www.antarcticglaciers.org/glaciers-and-climate/ (referred by Steingrimur Stefansson)
https://en.wikipedia.org/wiki/Greenhouse_gas  (referred by Henrik Rasmus Andersen)
http://www.giss.nasa.gov/research/ (referred by Alastair Bain McDonald)
https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/education-outreach [Click Introduction to Paleoclimatology] (Commenter)
http://www.ncdc.noaa.gov/sotc/ [For Global and Regional Analysis of (1) Climate, (2) Hazards, (3) Snow & Ice, (4) Upper Air, and (5) ENSO events .....during late 1990s to till date] (Commenter)
...for refence see the Global Major Climate Events (originally source & compiled map credit NOAA-NCDC and WMO) during year 2012, 2013, 2014, 2015 and some images related to historical trend of global temperature (Images collected from various webpages referred here)...
Dear Sumanta, you are asking a complex question for which there might be no exact answer today. While in economic literature the statement about temperature growth in the last 100 years by only anthropogenic influence dominates, physicists are still in doubt; see for example https://www.newscientist.com/article/dn11639-climate-myths-the-cooling-after-1940-shows-co2-does-not-cause-warming/ . There exists also a hypothesis about global cooling, but on much larger time scale; see http://isthereglobalcooling.com/ . The graph about global temperature and CO2 dynamics is the last 450,000 years is attached (from this source). If this graph is correct, we have an interesting observation: warming went faster (about 10,000 years) than cooling (100,000 years). It is unclear whether triggering is caused by some shocks or some mechanism of dynamic equilibrium on the Earth. But is is also clear that we observe anthropogenic contribution to this process for the 1st time.
The problem however is that we cannot wait too long without making actions to combat global warming. Less carbon emissions would indeed work towards speed reduction of this process, but it might happen that other greenhouse gases (like methane) will continue working in its favor while increase of volcanic activity (observed in the last 10 years) will work towards reduction.
As for the rise of ocean level, the effect is still small today, and is caused not so much by ice melting but more by change of water density with temperature and salinity. However, melting of all Antarctic ice will cause a catastrophic rise of the ocean level by 60 meters; see https://nsidc.org/cryosphere/quickfacts/icesheets.html . Melting of Greenland will have much lower effect (6 meters), but here we observe catastrophic melting in the last years.
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Generally we know the precipitation increases as altitude increases and along the orography of the mountains also. How do you calculate this gradient in precipitation?
Please be concentrated towards remote sensing data for precipitation measurement in a mountain belt latitudinal and longitudinal to reach the conclusion.
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The definition of RDLS varies for its discrepant application in different fields. In this paper, RDLS is defined as the relative height difference within a certain region. According to pre- vious research (Niu, 1996), the RDLS of China is extracted by the following equation:
RDLS ?? ??1??? 2 ?? (1)? Max Min H P A A? H / ? /500
where Max(H) and Min(H) are the highest and lowest altitudes of a region respectively and P(A) and A are the flat area and total land area of the region respectively. In this paper, we choose a 10 km×10 km grid size as the basic study unit, so A equals 100 km2
If we could take a 'flat land' as a given surface unit area with low variance in altitude range (expressed by DEM pixel values), I'd simply aggregate that DEM to a given factor using a variance function. Establish a threshold and reclass your 1st raster. This could be achieved using R.
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Phisical Geography, Astronomy
I don't work for Nasa, but the latest news- from news bulletins - is that the 2036 encounter would be safe, but there will be some effects by the close encounter of 2029. If some people know more, they will not say in public.
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HI im looking for Aphonopelma chalcodes distribution data for use in a gis, i need the data in geotiff or shape format.
The recent revision of the genus Aphonopelma will give you most of the data you need, certainly the best data available before you seek to add records and distributional data for any of the species..
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Physical Geography
For up-to-date instrumental seismicity www.gii.co.il
For preinstrumental see Agnon 2014, in Springer Dead Sea Transform book (edited by Garfunkel, Ben-Avraham, Kagan)
DOI 10.1007/978-94-017-8872-4_8
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I am working on RUSLE, So I need this information.
Thank you.
You can check out the attached MSc Project of M.W. Esther. She has used ILWIS 3.3 to derive the LS factor of 'RUSLE'. There are other tutorials which you might find helpful via the ITC website. Links are attached.
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I am writing to overcome a problem that I am facing while using data. I am willing to use the optimal fingerprinting method and the problem pops up when I want to use the downscaled historical data of CORDEX as I want to use the historical simulations of CMIP5 including ALL, NAT and GHG forcing but as I have noticed the only forcing of historical that has been downscaled is ALL . Would you mind telling me if other forcings of historical (NAT, GHG) and control run data are to be used as they are (not downscaled), and if I can simultaneously use downscaled historical ALL (CORDEX) with historical (NAT, GHG) of CMIP5 which have not been downscaled? If the case is that these should all be downscaled to be used, would you please lead me to the right track of how to downscale them to be used with historical ALL (CORDEX).
Hi Tofigh,  I am not an expert in this process, but doing spatial analysis all comes down to similar problems-missing data. Would using the average of both controls work?
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Please suggest me about the good literatures available on the relationship between Bouguer Gravity Anomaly and the planform of alluvial channels.
Dear All..
is it possible to calculate potential area (reserve) with gravity ?
Thanks
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I want to know whether my research site (red star in attached figure) is located in or out of the canyon system.
Dear Tielidze, Thanks, it is a nice map.
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You can access the page of Landslides of the USGS, they have many publications of problems and solutions:
And I attached to you an interesting paper about the theme.
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Recent defomation responsible of faulted folds
I am not fully aware about rockwork. Rockwork software may be useful for this analysis
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I want to georeference topographic features located in two adjacent UTM zones of 36P and 37P. The areas where I am interested are located in the extreme bottom right corner of 36P which has  a UTM value of 827000m while its adjacent bottom left corner point from 37P has a UTM value of 173000m. They are adjacent but with different UTM values. How to reconcile the two adjacent projection UTM values? How much will be the progressive eastward error in meters from the zone 36P to 37P projections? Is there a possibility of merging the two adjacent zones and consider them as one to work with?
Zone-to-Zone Extension accuracies are dependent on the derivative power employed by the transformation software.  Most software packages have truncations of the infinite series at the 7th derivative.  The U.S. Army had Extension Tables truncated at the 14th derivative and had/has accuracies better than 3 millimeters (Forward and Inverse) at plus or minus 45 degrees from the Central Meridian.  ESRI implemented the closed-form of the elliptic integrals several years ago, and their transformations are now good to fractions of a millimeter up to plus or minus 89 degrees from the central meridian.  See: (NOAA Technical Report NESS 81. Improved Algorithm for Calculation of UTM and Geodetic Coordinates. Jeff Dozier. Washington, DC. September 1980.)  However, there are numerous "typos" in the equations.
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Gravitation
Delta\tau_g = \frac{g}{c^2} \sum_{i=1}^{k} (h_i - h_0) \Delta t_i
How the difference between 0m and 5000m on Earth should be today (after for example 4.5 billion years):
\Delta\tau_g = \frac{~10}{9*10^{16}} (5000m - 0m) 4.5*10^9 years = 21.9 hours
Following the theory, shouldn't we see a difference of 21.9 hours between two picture of the sky taken at 0m and 5000m?
Have a look on my book "ESSAI (version V2) - L’univers pourrait-il être un réseau 3D et la matière ordinaire en être des singularités topologiques ?". You could find some interesting answers!
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For my study I have six different DEMs of a glacier. The DEMs are all from different years and I want to calculate the volume changes over a timeperiod. Including the six DEMs I have one subglacial DEM with low resolution (100 meter). In ArcMap, I use raster calculator to subtract the DEMs from the subglacial DEMs to get the volume results. The problem is that the DEMs with high resolution gets converted to 100 meter resolution. Is there any way to derive results with better resolution?
Another thought I have.
Do you roughly know the thickness of the ice sheet? And how rough is the subglacial DEM and the surface of the ice?
Maybe it would be useful to take the 3D surface into account. There are tools available in ArcMap (or extensions) to calculate first the surface of each cell based on the topography. During the volume calculation you multiply then the surface of the cell by the thickness of the ice instead of using 100x100m.
This approach could be more accurate depending of the terrain roughness and the relation between thickness and cell size.
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I have GPS data reference to WGS84 (lat,long,ellipsoid height) - I can transform to projected coordinates (e.g. UTM), but not sure how to achieve a vertical transformation too.
Hi Helene,
To convert ellipsoidal height to mean sea level you need a geoid undulations model of the region you are working on. Depending on the required precision, you can use a global model like EGM2008 ondulation data (N). (http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/Und_min1x1_egm2008_isw=82_WGS84_TideFree.gz). You then need to subtract N from the ellipsoidal height (h) to obtain an estimation of the orthometric height (mean sea level, for practical purposes). More info here: http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/egm08_wgs84.html
If you need more precision or data tied to a particular datum (e.g. a national leveling network), you will have to get a "local" geoid undulations model. Not sure where to get it for South Africa. I hope this helps you. Let me know if you have other questions.
Cheers,
Demián
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Our research group is trying to estimate the quantity of sediment blowing off of cultivated fields during the winter in the Canadian Prairie region. It is a common-held belief that this sediment is a significant loss of soil from farm fields and a major source of sediment and associated nutrients being delivered to adjacent field boundaries, to roadside ditches in particular. It is a very conspicuous phenomenon, but the magnitude of sediment transport is being questioned. Our plan is to collect the dirty snow (referred to a “snirt” in this region) in one-meter-wide strips extending out from the field boundaries into the adjacent ditches.  We have only found reference to one other study trying to make such measurements, and it was a small study carried out in this region about 15 years ago. Any information of advice would be appreciated.
In order to look at more local effects, such as relations between area of snow-cover & the amount of sediment in the snow, it might be worth to make a few Sarre traps, similar to those used to measure sand transport on beaches.
Perhaps snow Sarre traps should be taller with some guy ropes to hold them still... But actual measurements of transport rates and more detailed  analyses of causes for the dust/sand content would be very interesting to see.
Admittedly, it could be rather cold work to collect a good dataset. Those traps need emptying out regularly (10 min- 2 hours on the beach). Let me know if you need a few more suggestions along this line.
Good luck
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I've recently seen air temperature data acquired from 1984 to 2014 from a meteorological station in central Italy. Such data show a mean temperature trend from 15 to 18°C !!! I know that global warming caused an increase of about 0.7°C in the same time, while the trend in Italy was +1.5°C. But I wonder if locally the trend could reach +3°C in south Latium region.
Did the land cover around the station changed since the 80's? The change in temperature could be related to the change in land cover around the station (e.g. from agricultural land to urban and built-up). In my paper I showed that changes in land cover classes in a grid cell impact the temperature (due to the changes in the heat fluxes), wind speed and precipitation (De Meij and Vinuesa, Impact of SRTM and Corine Land Cover data on meteorological parameters using WRF, Atmos. Res., 2014). I guess that such impact would be visible in a sharp increase in temperature trend line.
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Refer me any article from where i can get the geological, geomorphological and soil map of Kullu, lahaul and spiti district of Himachal Pradesh, India.
Dear Mritunjay,
For Geological, geomorpholocial map contact GSI. For soil please contact NBSSLUP. They publish soil maps and its properties for each state.
Vaibhav
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Law of erosion of the river.
The "equilibrium" of a riverbed can be reached when the Lane equation is satisfied...
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Load is one of the controlling factors of river erosion, however, how does rate of erosion minimise when a river has maximum load?
Relationship of fluvial erosion and river load.
There is no straightforward answer to your question, all depends on the sediment conditions in suspension and in the river bed. For instance, when a river is heavily loaded with suspended mud (there is no such thing as a predictable “maximum”), the maximum erosion velocity of a sandy bed is hindered by the reduced penetration velocity of water-mud mixture to dilate of the grain packing necessary for erosion from the bed. On the other hand, a high suspended sediment concentration reduces the difference of the bulk sediment density of the bed with the overlying fluid, which in case of a bed that consists of cohesive material, or silt, may enable large pieces of the bed to be ripped off and carried away with the flow while disintegrating. A nice example of this is the Yellow River (see Van Maren, D.S., Winterwerp, J.C., Wang, Z.Y., Pu, Q. (2009) Suspended sediment dynamics and morphodynamics in the Yellow River, China. Sedimentology, 56 (3), pp. 785-806).
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Nigeria does not lie within the globally recognized seismically active zones, such as the continental plate boundaries and right zones. The country lie within the West African Craton, where inter-plate seismic disturbance are not common. However, South Eastern Nigeria is situated between two major tectonic trends. The first, has a North West - South East direction and is expressed in the Okitipupa basement complex of Western Nigeria and the Oban Massif and Mamfe embayments to the Southeast. The second, has a direction which is approximately Southwest- Northeast and is expressed in the trend of the Cameroon volcanic zone, the Benue trough, The Abakaliki Anticlinorium and the Afikpo Syncline (Hospers 1965). Now between these two tectonic trends lies the greatest threat of gully erosion in Nigeria.
Two issues on this topic: First: yes of course, mainly on the cratons several parts of the fluvial systems follow the structures of the basement; and second: There were several approaches by Italian geomorphologists linking stream order to tectonic activity, e.g. Belisario et al. (1999) stated that linear river courses of a higher order represent older structures and first order rivers younger ones. Ciccacci et al. (1987) assumed that also first order rivers can follow older structures due to their remobilization. However, the mentioned authors worked mainly in Italy in a distinct “younger” environment, but it’s an interesting approach.
Belisario, F., DelMonte, M., Fredi, P., Funiciello, R., Lupia, E., Salvini, P. & Salvini, F. (1999): Azimuthal Analysis of stream orientations to define regional tectonic lines. Z. Geomorph. N.F., Suppl.-Bd. 118: 41-63.
Ciccacci, S., Fredi, P., Lupia Palmieri, E. & Salvini, F. (1987): An approach to the quanti¬tative analysis of the relations between drainage pattern and fracture trend. International geomorphology, Part II: 49-68.
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I am conducting a study that aims to detect the trends of hydro-meteorological conditions in the basin using the non-parametric Mann-Kendall test.
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Some years ago, some specialist propose different methods to calculate the amount of mountains all around the world in order to make comparisons within countries of different latitude. The data are very coarse and I think we need more specific values. How to calculate this in any specific region or country?
One approach is calculating the fractal dimension of the surface. This is a form of roughness. See a classic paper on the topic: http://www.dtic.mil/dtic/tr/fulltext/u2/a129664.pdf - there are many more modern versions of this an even some tool boxes & APIs out there to help.
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Some geochemical data are available in a given area around a landfill site. geology, geomorphology maps/information are not available. In such a situation how can remote sensing or satellite image be used to generate more data to assist in soil pollution mapping?
I'm going to stick my neck out and answer the question in one word. No.
Now to qualify this.
Brian's answer sets you on the right track, with phenomenology as the first step. Can the sensor you are using detect the effect you are looking for? Immediately you need ancillary data, even if it is simply descriptive of the phenomenon.
An approach which can work and may help you, in the way you pose the question is to look at unsupervised classification methods/PCA etc. Does this identify anomalies around your landfill? Now you have anomalies. Nothing more. In some cases you can characterise them using your data, but eventually you are going to need to get onto the ground for some sort of cal/val exercise.
I'm answering this as I have experienced a number of studies where remote sensing has been employed to produce results which look great, while not answering the question which needs to be answered. It's important to guard against this as it is bad for the image of remote sensing.
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It is now widely admitted that climate change impacts on water resources are occurring and are expected to amplify in the future. However, these impacts are highly uncertain and usually scientist and decision makers prefer to have a quantitative assessment of these associated uncertainties. How can we assess future uncertainty related to climate change in the absence of observations? Then, how can decision makers consider these uncertainties in their future plan management of water resources for instance?
Haykel, you have asked a question which in many ways highlights the different "world views" of scientists and decision/policy makers. As you point out, decision makers would like to minimize the uncertainty while scientists, especially climate scientists, live with uncertainty. Part of the problem stems from the two communities not always understanding the needs, capabilities, and limitations of each other. In this particular case the problem is compounded since it is uncertainty upon uncertainty - climate projections contain inherent uncertainty and, as you point out, the impact of climate on water resources is also not well understood. Nevertheless the tools that we have available today, mainly global and regional climate models, are much more powerful and useful than simpler statistical methods of extrapolation. As our understanding of the system improves, so will the models, and thereby the uncertainty will be reduced, although it will never be completely eliminated due to the inherent nature of the system. Certain approaches such as multi-model, ensemble projections, or some type of statistical postprocessing of the model results can further reduce the uncertainty. At the same time new approaches in decision making and management need to be developed which are able to account for and deal with the inherent uncertainty. And perhaps most important, a common "language" needs to be developed that will allow scientists and decision makers communicate more effectively.
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Does anyone know how to make in GIS software (Quantum GIS or ArcGIS) parallels and meridians appear on the extreme limits of a polygon? <br />
I was on the sidelines latitude and longitude. How to make the GIS program to appear?<br />
I will put a photo so you know what I want to do.
Hi Ana-Maria:
I think you can use Print Composer tools in QGIS.
look at Extents dialog to configure how to how them. I hope you find it usefull
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An agronomist colleague and I are looking for known sites to test a field reconnaissance methodology for rapid verification, so we are looking for sites for which local "dark earths" have been verified as being anthropogenic in origin.
Thank you once again, Wenceslau. I sent Dr. Neves a message last night, but these contacts in Rondonia may be better able to help me in the time that I have left here. I did not know about Zimpel before, but will try to contact him here. I had intended to talk to UNIR archaeologists, so this provides a more specific person to contact.
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Concerned about the degree of sediment compaction at depth in the Wax Lake Delta in the Atchafalaya Basin, Louisiana.
Deltaic systems are so dynamic (on a spatio-temporal scale) to a level that it is near impossible to estimate their variations. Further, 5km is too great a distance that may show numerous variations.
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Perhaps, the steeper the gradient the slower the rate of infiltration?
Dear Philip Tieh
It's an interesting question, but do not have a definitive answer.
Fox et al (1997) highlights the problem:
D.M. Fox, R.B. Bryan, A.G. Price. 1997. The influence of slope angle on final infiltration rate for interrill conditions. Geoderma, 80(1–2): 181–194. Doi:10.1016/S0016-7061(97)00075-X.
They says: “Despite numerous studies, the relationship between slope angle and infiltration rate remains unclear. Under different experimental conditions, new processes may be introduced which influence the relationship.”
And they comment also:
“The results showed that sealing intensity did not vary with slope angle, and the dominant influence of slope angle on infiltration rate resulted from changes in overland flow depth and surface storage. The results also suggest that small changes in seal hydraulic conductivity with microrelief play an important role in the infiltration process.”
More recently:
O. Ribolzi, J. Patin, L.M. Bresson, K.O. Latsachack, E. Mouche, O. Sengtaheuanghoung, N. Silvera, J.P. Thiébaux, C. Valentin. 2011. Impact of slope gradient on soil surface features and infiltration on steep slopes in northern Laos. Geomorphology, 127(1–2): 53-63. Doi:10.1016/j.geomorph.2010.12.004.
They say: “Three main conclusions can be drawn from this work: (1) high intensity rainfall can rapidly transform soil surface features of steep bare soil; (2) on steeper slopes, the micro-relief tends to form micro-terraces much more pervious and less erodible than the ripple-like roughness that formed on gentler slopes; and (3) there was a more pronounced lowering of the soil surface due to compaction and denser microlayers on gentler slopes. The latter conclusion confirms the hypothesis that higher effective rainfall intensity is responsible for the formation of less permeable erosion crusts under 30% slope gradients while more permeable structural crusts develop under 75% slope gradients.”
And other articles analyzed partial aspects:
S. Assouline, M. Ben-Hur. 2006. Effects of rainfall intensity and slope gradient on the dynamics of interrill erosion during soil surface sealing. CATENA, 66(3):211–220. doi:10.1016/j.catena.2006.02.005
They say: “Soil erosion during rainfall is strongly affected by runoff and slope steepness. “
And:
M. Koulouri, Chr. Giourga. 2007. Land abandonment and slope gradient as key factors of soil erosion in Mediterranean terraced lands. CATENA, 69(3): 274–281
Good luck
Best regards
Ofelia Gutiérrez
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Limestone islands are very interesting in terms of karstic landscape, coastal process, ecosystems, etc. A limestone island named Cat Ba of 144 sq.km in northern Vietnam is one such island. Which limestone islands are larger than Cat Ba island? I would ultimately like to have a list of the largest limestone islands in the world.
Hello, Cres and Krk (Adriatic sea, Croatia) are 405,8 sq. km each. And there is another 6 islands >100 sq. km, all of them fully karstic or mostly (>90%) karstic islands.
Source: Statistical Yearbook 2013, Croatian Bureau of Statistics, http://www.dzs.hr/default_e.htm
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In order to protect the mountain forest ecosystems in Armenia, from the mining industry and non-regulated utilization one way might be to demonstrate the mountain forest ecosystem services potential in Armenia.
A good overview is also the following discussion paper: http://www.cifor.org/publications/pdf_files/Books/BNasi0201.pdf
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I have an open gully from which I created a triangulated mesh in Agisoft. Now I want to compute volumes in 3D (not 2.5D which fills undercut hollows), anyone any ideas?
I would try Jewel Suite software or GRASS GIS functions for volumes.
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I'm using it for a chapter on my thesis, I have read the relevant literature but I'm not convince about it.
That your judgement according to the record of two cores can not be revealed in the third one is not to say that's wrong. the third one should be the case very local and interrupted once formed. Then, grain size can be surely used to understand the origin of the deposits.
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If we interpret the landslide points based on aerial images, when we want to get landslide susceptibility mapping, in case we extract non-landslide as training samples, how could we extract non-landslides points, because the landslide points not only one landslide?
Well, a point is a very approximative representation of a landslide and will have an uncertainty, that is correct. If you have an idea about the mean size of the landslide bodies you could define the uncertainties of the landslides location represented by a point. Then it is appropriate to generate a buffer around the landslide points according to the uncertainty ( e.g. 20-50 m). After you can use the remaining area (ouside the buffers) for random sampling.Otherwise, even if you have no information of the landslide size you could still try the buffering, but then the buffer distance should be selected carefully. So you would most likely avoid to have landslide points in a non-landslide sample.
But a I have also a question, why are you using points to charcterize landslides from aerial images? What kind of images do you use (in which ground resolution)? What is the expected scale of analysis? Since you generate a sample for non-landslides points I guess you're giong to do a statistical analysis, logistic regression?
I'm asking because, if the resolution of the images allows the direct mapping of the landlide extent I would use polygons instead of points to do that. For high resolution images even a separation into source and deposition areas is recomended, since after you could gain additional information via magnitude-frequency statistics.
Best Regards,
Jewgenij
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Symbols or a legend used in geomorphological mapping varies significantly from map to map and place to place and they are not consistent. The legend and mapping symbols in geomorphological maps are likely to be chosen on the basis of purpose of the output, and hence the legend is not pretty standard with compared to that in other maps like geological. I am planning to compile a geomorphological map in an area where is largely covered with alluvial fills and fluvial erosional landforms. Is there any standard protocol or guideline or any good article on geomorphological mapping that could be useful for reading?
Dear Tilak,
I have worked a lot in this issue. I have compiled references since geomorphological mapping starts to be used in geomorphologic surveys, data collection and results presentation. I have some reviews but mostly were published in portuguese language. Indeed the last publication on this matter (I didn´t agree with all the ideas in the book) belongs to Jan Otto and Mike Smith (eds.) published by Elsevier "Geomorphological mapping: methods and applications".
But what I can say to you is that there are no standard symbols and legends apply by everybody. That was the aim of the Subcommission on Geomorphological Mapping of the IGU, that started its activity in 1962. Although the work done, namely the publication of the "Manual of Detailed Geomorphological Mapping", edited by Demek, in 1972, establish the modern concept of geomorphologic mapping and represents in our point of view a sort of revolution in the way how geomorphologic studies are done, the "Project of the Unified Key to the Detailed Geomorphological Map of the World" for maps at 1:25 000 and 1:50 000 scales, failed completely its pourpose. The Unified Key was not applied by the different country researcher and we can say that, nowadays, are the objectives of each work, the habits of each researcher and personal conotations about graphic symbols, that prevail.
In my opinion, we are quite far from the adoption of commum methodologies and legends in the survey of landforms, deposits and processes. On the contrary, it seems that the prevailing tendency it's for the diversification of legends and procedures.
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How can use paleoclimatic to determine bauxite origin?
These 'old' references might be useful starting points:
Schwarz, T. (1997). Lateritic bauxite in central Germany and implications for Miocene palaeoclimate. Palaeogeography, Palaeoclimatology, Palaeoecology, 129(1), 37-50.
DArgenio B, Mindszenty A(1995) Bauxites and related paleokarst: Tectonic and climatic event markers at regional unconformities. ECLOGAE GEOLOGICAE HELVETIAE 88:(3) 453-499
best wishes,
Zoltan
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This assumption makes certain planform measurements applicable to thalweg
variability studies. Workers in the related field are using this assumption. But I am a bit sceptical about it and would like to get concrete studies, references from the researchers. Can anybody help?
You could check out the very interesting and thorough research over the last 10 years on braided channel dimensions, evolution and dynamics in some of the world's largest rivers (e.g. South Saskatchewan River, Canada; the Parana etc.) by Gregory H. Sambrook Smith, Philip J. Ashworth, Jim Best and Stuart N. Lane. You could search on Google Scholar, for example. That body of work would give you a good start in establishing the evidence base to test out answers to your question on width and depth of braid channels. They often use GIS, digital elevation models and ground-penetrating radar approaches.
For example, see this recent paper below on the South Saskatchewan River, Canada - and its large reference list too:
"Quantification of the relation between surface morphodynamics and subsurface sedimentological product in sandy braided rivers"
by
Natalie O. Parker1,
Gregory H. Sambrook Smith1,
Philip J. Ashworth2,
James L. Best3,
Stuart N. Lane4,
Ian A. Lunt5,
Christopher J. Simpson6,
Roberte. Thomas7
published in Sedimentology, Volume 60, Issue 3, pages 820–839, April 2013
Hope this helps to get you started!
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Without using ARC GIS
You may have a look to shapelib (http://shapelib.maptools.org/) or gdal/ogr ( http://www.gdal.org/ ). Shapelib provides a C - API for vector GIS data, and GDAL/OGR a C++ library for both, raster and vector data, rsp., where, as far as I know, the OGR shapfile driver uses shapelib. Depends also on the input format of your raster files (e.g. ASCII grids are quite easy to read), type of classification and coordinate reference system (proj4 library can do conversions and transformations, if needed).
If you are not coding within your own programming projects, you may also consider GRASS or M4SW (see http://www.maptools.org/ ), which contains a couple of command line utilities that might do what you need.
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