Ulrik Mårtensson Lund University Sweden. Methodology

Size: px

Start display at page:

Download "Ulrik Mårtensson Lund University Sweden. Methodology"

Dwayne Barber
6 years ago
Views:

1 Ulrik Mårtensson Lund University Sweden Department of Physical geography and Ecosystems Science Methodology Geomorphological applications Field work - GPS Remote sensing Geographical Information Systems (GIS) 1

Example of jobs and activities University teacher and consultant in GIS, RS and geomorphology Tunisia - Soil and water conservation, salinity, vegetation, socioeconomy Pakistan Water Resource

org Swedish national GIS implementation programme Physical Planning in Egypt data quality assessment IRBM Lake Victoria GIS implementation in Sri Lanka and Uganda Universities LAO PDR GIS in

sensing for forest fire area estimations Palestine accessibility to helth services Croatia mapping sea grass beds and coastal environment What could we use Physical Geography and Ecosystem modelling

2 Example of jobs and activities University teacher and consultant in GIS, RS and geomorphology Tunisia - Soil and water conservation, salinity, vegetation, socioeconomy Pakistan Water Resource Management Viet Nam and Thailand CSMP Nigeria & Kenya Land resource management (soil erosion) Ghana Country at a Glance Ghana & Uganda BPEIS BPEIS Synthesis report Swedish national GIS implementation programme Physical Planning in Egypt data quality assessment IRBM Lake Victoria GIS implementation in Sri Lanka and Uganda Universities LAO PDR GIS in Agriculture and forest research Tunisia & Lebanon Remote sensing for land degradation mapping Tanzania Remote sensing and GIS for studies of the relationship HIV/AIDS and agriculture Syria Remote sensing for forest fire area estimations Palestine accessibility to helth services Croatia mapping sea grass beds and coastal environment What could we use Physical Geography and Ecosystem modelling for? Green house gases Air pollution Atmosphere ozon, cloud, wind, storms, dust, precipitation Water pollution Oil spill Biosphere Vegetation type, forest fires, cropping, forest production Human Land use, infrastructure, urbanisation Hydrosphere Access to water, marine environment, algae blooming, sea level changes, snow and ice Land degradation desertification Lithosphere Rocks and minerals, soils and fertility, topography, vulcano eruptions Coastal erosion 2

3 Landscape dynamics and change Historical Landscape Current landscape Future landscape Landscapet at different scales Human influence Different approaches Field measurements and interviews Existing measurements Map data Air photo and satellite data Geographical Information Science GIS Modeling tools 3

4 What is geography? In Sweden divided since about 1965 Human, Social, Economic Physical Location Geographical information Science Soil science Geology Physics Chemistry Mathematics Computer science Statistics Physical Geography 4

5 Physical Geography Atmosphere science Climatology Meteorology Oceanography Plant geography Hydrology Geomorphology Ecology Cartography Surveying Science development Shape = function of (process and material) dt Level 1 Taxionomy, name shape, process and materials Level 2 Genesis explain shapes as a result of a process Level 3 process development over time Level 4 Quantify process speed => modelling 5

6 Geomorphology and Landscape evolution Davis 1909 Normal cycle of erosion Peneplane Penck 1924 Arid erosion cycle and pediplane 6

7 Climate morphology Tricart, Büdel, Dresch Tropical Tor Periglacial Talus 7

8 Weathering is an important process active in all environments but most prominent in tropical climates 8

9 Process importance Weathering Mass movements The shaping agents Running water fluvial processes Waves coastal processes Wind aeolian processes Ice Glacial and periglacial processes Resistance geology, soil and vegetation Climate Vegetation Water Process distribution 9

10 10

11 Mass movements (wasting) 11

12 gbvfffff 12

characteristic landforms on a developed floodplain The drainage basin

13 Fluvial Processes Davis conceptual model for landscape development is still very often referred to in textbooks Sub-picture E name several characteristic landforms on a developed floodplain The drainage basin Important area unit! Principle the same from meter scale to 1000 km scale 13

14 Different systems for classifying stream order Runoff = P I E Horton overland flow occur when P>I+E Saturated overland flow when the soil is saturated by water 14

erosion Sheet erosion Rill erosion Gully erosion

15 Once motion has been initiated it can be maintained by a lower flow velocity Erosion processes Rain drop erosion Sheet erosion Rill erosion Gully erosion Inter rill erosion Transport by: Saltation Suspension 15

Rain splash Sheet wash Rill Gully a) Orchard terrass Station "A" Station "B" b) 1 2 5 4 3 Station "C" Set-up of an erosion measurement station using erosion pins, normally planted in groups of

16 Rain splash Sheet wash Rill Gully a) Orchard terrass Station "A" Station "B" b) Station "C" Set-up of an erosion measurement station using erosion pins, normally planted in groups of five at different locations on the slopes Stony surface typical for a desert/semi arid climate Stone or desert pavement due to small particles transported away, courser materials left behind 16

starts with a rupture in vegetation that leads to the forming of a depression

17 Intense rainfall combined with lack of natural vegetation on the stony slopes leads to severe erosion, infrastructure rupture, cultivated soils disappear Gully development starts with a rupture in vegetation that leads to the forming of a depression eventually ending as a Gully. Note that the erosion starts down stream and work its way up-stream 17

Contour bonds build to prevent spreading Huge gully developing

18 Gullies in agriculture lands in central Tunisia. Feather-like pattern spreading upslope. Contour bonds build to prevent spreading Huge gully developing on flat cultivated ground at one single rain fall event Distance between trees in orchard 24 m 18

19 Badland formation USLE is used all over the world to estimate mean annual erosion intensity Critiziced of many but still good to demonstrate impact from different factors 19

20 Combined Erosion Model (case from Nigeria National soil erosion modelling ) Rainfall Erosivity Drainage Density Geology and Soils Soil Erodibility Depression Soils Slope Length (constant) Topography Watercourse Topography Slope Angle Land Cover Land Use & Vegetation Rubber Band Development Soil Management Input data from existing sources and satellite image interpretation, combined with field data collection MUSLE Modelling Wind Direction Soil Erodibility Universal soil loss equation Water Processes Eolian Processes Land Cover Wind Speed E R K L S C P Combined Erosion Modelling Soil Management Fetch Soil Erosion Intensity Soil Degradation Trend Rainfall erosivity index The R-factor 20

21 Soil map from satellite image The K-factor Digital elevation model The L and S-factors 21

22 Vegetation maps from 1975 and 1995 The C and P-factors Big variation in vegetation cover North West East South 22

GIS Geographical Information System Geology Land Use & R

Depression Soils Watercourse Topography Rubber Band

Length (constant) Slope Angle Land Cover Soil Management

Modelling erosion rate Used to prioritise actions, but

Processes Processes Soil Erodibility Land Cover D Wi

23 GIS Geographical Information System Geology Land Use & R Topography and Soils K L S C Vegetation P Drainage Density Depression Soils Watercourse Topography Rubber Band Development Rainfall Erosivity Soil Erodibility Slope Length (constant) Slope Angle Land Cover Soil Management MUSLE End result, brightere tone = higher estimated Modelling erosion rate Used to prioritise actions, but needs field verification for actual planning Water Eolian Processes Processes Soil Erodibility Land Cover D Wi Combined Erosion Modelling Soil Management Soil Soil Erosion Degradation Intensity Trend

24 Sediment transport in a river Suspension and saltation important Lag time important, e.g. inondations Depend on basin shape Pattern used to classify and may give information about rock type and tectonics 24

25 Flow velocity influenced by friction with river banks and bottom. Concept of Talweg, note meandering even in a straight channel (fig 12)! Concept of meandering important to understand development of the flood plain and its major shapes 25

Braided river sign of too heavy sediment

26 Braided river sign of too heavy sediment load. Very often glacier melt water and also associated with formation of alluvial fans Headward erosion could lead to River capture and completely change the hydrology of an area see Niger/Benue example 26

27 Alternate scouring and deposition depending on current regime. Dynamic environment with shifting depth and drifting material forming e.g. sand banks. Meander Levée Oxbow lake Backswamp Yazoo stream 27

28 Terraces indicate tectonic up lift or sea level shift (Base level shift) Extreme case in very soft rock Grand Canyon Frozen meanders Base level local could be a lake Base level global ocean water level Knick points see also Gully development 28

Nile, slow sedimentation, lots deposited on the delta, less at the mouth, strong long shore current B.

29 The death of a river when it meets the ocean (or a local lake) Delta growing sediment from river exceeds erosion from waves and currents Delta soils often very fertile, historical importance Delta shapes: A. Nile, slow sedimentation, lots deposited on the delta, less at the mouth, strong long shore current B. Good sediment supply to mouth, limited erosion except in extreme events C. Only one channel survive, strong erosion D. Inland delta due to very heavy tidal effects 29

30 Ulrik s comment to text figure 1: Vegetation binds soil on the slope. In arid climate stone pavement develops due to lack of vegetation 30

Ephermal streams are also braided streams.

clay soil particles, quick sand and qiuck clay, extremely slippery

Here a lake formed on the playa after a one day heavy rain it is

31 Ephermal streams are also braided streams. Illustration is also an alluvial fan Playa extremely flat, fine clay soil particles, quick sand and qiuck clay, extremely slippery and fragile when wet Satellite images - a good way to collect info Here a lake formed on the playa after a one day heavy rain it is the position in the landscape that would be a permanent lake in a temperate climate zone 31

32 Two weeks after an innondation flamingos, 300 km from the closest known resort Before After Decrease in ground water level on the Gammouda plain April December Station 1 Station 2 Station

33 Irrigation in hot areas high risk of salinisation Pumping groundwater High evaporation Salty groundwater intrusion Referring back to similar graph for running water but density differences are bigger so transport requires higher wind speed 33

34 Same modes of transportation as running water Erosion by wind 34

35 45 million tons to Amazonas every year Wind erosion a global process Present in all climates, particualrly on cultivated fields, these iamges is from just outside Lund 35

36 Dune classification done according to wind direction(s) and availability of sand Elements in an arid landscape Mountain ranges Alluvial fans/bajada Playa 36

In the mountains suitable land for cultivation is also a problem.

37 Alluvial fan High mountains where India is pushing against Asia In Pakistan it is very dry and water availaility is an issue. In the mountains suitable land for cultivation is also a problem. Traditionall issigation use surface water, and the alluvial fans are a good way to profit from the water. 37

Analysis of satellite recordings 1980-1999 demonstrate a strong increase

conservation Check dam Orchard terrace Contour bond Tabia and Yessour

38 Analysis of satellite recordings demonstrate a strong increase of vegetation Seasonal variation could be strong Soil and water conservation Check dam Orchard terrace Contour bond Tabia and Yessour Re-plantation of vegetation Shelter belt plantation or mechanical Perennial crops 38

39 Set-up of an erosion measurement station using erosion pins, normally planted in groups of five at different locations on the slopes a) Orchard terrass Station "A" Station "B" b) Station "C"

40 40

41 41

42 Dry year wet year Desertification??? 42

43 THE FUTURE??? Overexploitation of the land leads to erosion, irrigation to salinisation, but at the same time on short-term basis the crop yield increases and thus revenue for farmers. Should WE tell them to not do that? Long term solutions return to animal husbandry? 43

44 Water harvesting??? Coastal processes Mechanical waves (Tsunami) Tide water waves (Pororoka in Amazone) Wind generated waves Sea vindvåg Swell dyning Wind speed Fetch the distance Duration the time Wavelength Wave height = wavelength (distance between two wave peaks) = frequency (number of cycles passing a fixed point per unit time) 44

Currents Wind generated Salinity differences Temperature Near shore circulation cell wave generated Some numbers Sea Short and relatively steep, h/λ = 0.

45 Currents Wind generated Salinity differences Temperature Near shore circulation cell wave generated Some numbers Sea Short and relatively steep, h/λ = 0.03 Ocean h = 2-5 m, extreme 10-15, λ = m The Baltic h = m Max measured 9 m Swell λ increase and h decrease, crest regularised, smaller waves are eaten by bigger due to interference λ = 300 m, up to 750 m 45

46 Breakers Deep water wave Circular movement of water molecules Diameter h at surface; 0.043h at depth = ½ wave length; 0.002h at depth = wave length Bottom contact from about depth < ½ wave length Spilling breaker Plunging breaker Surging breaker Depends on steepness (h/ λ) and the slope of the ocean bottom Spilling breaker summer waves that normally build on the beach Plunging breaker winter waves that erode the beach collapsing wave disturb the forward motion under the crest => outward net transport and deposition of sand bars Surging breaker last brake on the beach it self => long shore drift and sorting on the beach 46

$refraction$ due to

47 Near shore circulation system Wave refraction due to bottom contact of waves Sand bars 47

48 48

49 follow link to LUMA-GIS 49

50 50

51 51

52 Weathering is an important process active in all environments but most prominent in tropical climates 52

53 Depending on rock resistance, weathering is affecting also arid landscapes Standard erosion plot that may be used to calibrate USLE to new environments Width 7 m Fenced Erosion plot Length 23 m Sediment collection ditch Evacuation tube Width 0.4 m Water collection tank (2 x 2 x 2 m) 53

54 A B C D Soil sampling sites (three per plot (A - D) Test plot Metal sheet border of the plot preventing runoff from entering from outside areas Four test plots with different treatment Runoff concentration and subdivision Concrete surface to eliminate unwanted sedimentation before collection 50% 50% Sampling from each plot only 25 % of the total run off 25% to be sampled 75% of total to be spilled 54

Ulrik Mårtensson Lund University Sweden. Methodology

www.nateko.lu.se www.giscentrum.lu.se www.cmes.lu.se ulrik.martensson@nateko.lu.se Ulrik Mårtensson Lund University Sweden Department of Earth and Ecosystems Science Lund University GIS Centre Centre for