Assessing water stress of desert vegetation using remote sensing : the case of the Tamarugo forest in the Atacama Desert (Northern Chile)
Chávez Oyanadel, R.O. - \ 2014
Wageningen University. Promotor(en): Martin Herold, co-promotor(en): Jan Clevers; E. Acevedo. - Wageningen : Wageningen University - ISBN 9789462570795 - 175
waterstress - woestijnen - vegetatie - remote sensing - bossen - waterbeheer - ecosystemen - droogte - adaptatie - chili - water stress - deserts - vegetation - remote sensing - forests - water management - ecosystems - drought - adaptation - chile
Water stress assessment of natural vegetation plays a key role in water management of desert ecosystems. It allows scientists and managers to relate water extraction rates to changes in vegetation water condition, and consequently to define safe water extraction rates for maintaining a healthy ecosystem. Previous research has shown that optical remote sensing constitutes a powerful tool for assessing vegetation water stress due to its capability of quantitatively estimating important parameters of vegetation such as leaf area index (LAI), green canopy fraction (GCF), and canopy water content (CWC). However, the estimation of these parameters using remote sensing can be challenging in the case of desert vegetation. Desert plants have to cope with high solar irradiation and limited water. In order to maintain an adequate water balance and to avoid photoinhibition, desert plants have evolved different adaptations. A common one is heliotropism or ‘solar tracking’, an ability of many desert species to move their leaves to avoid facing direct high solar irradiation levels during the day and season. This adaptation (paraheliotropism) can have an important effect on the canopy spectral reflectance measured by satellites as well as on vegetation indices such as the normalized difference vegetation index (NDVI). In this thesis, I propose a remote sensing based approach to assess water stress of desert vegetation, exemplified in the case of the Tamarugo (Prosopis tamarugo Phil) tree in the Atacama Desert (Northern Chile), a ‘solar tracker’ species, which is threatened by groundwater overexploitation.
In the first chapter of this thesis (general introduction), I explained the motivation of the PhD project and elaborated four research questions, which are later discussed in chapters 2, 3, 4, and 5. The thesis concluded with chapter 6, where I provide a synthesis of the main results, general conclusions and a final reflection and outlook.
In the second chapter, I studied the effects of water stress on Tamarugo plants under laboratory conditions and modelled the light-canopy interaction using the Soil-Leaf-Canopy radiative transfer model. I described for the first time pulvinar movement of Tamarugo and quantified its effects on canopy spectral reflectance with and without stress. I showed that different spectral indices have potential to assess water stress of Tamarugo by means of LAI and CWC. In the third chapter, I measured the effects of pulvinar movements on canopy reflectance for Tamarugos under field conditions and used high spatial resolution images to assess water stress at the tree level. I developed an automated process to first identify single trees and delineate their crowns, and secondly, to estimate LAI and GCF using spectral vegetation indices. These indices (NDVI and chlorophyll red-edge index) were negatively correlated to diurnal values of solar irradiation as a consequence of leaf pulvinar movements. For this reason, higher values of both vegetation indices are expected to occur in the morning and in winter (low solar radiation) than at midday or summer.
In the fourth chapter I studied the effects of diurnal pulvinar movements on NDVI time series from the MODIS-Terra satellite (acquired in the morning) and the MODIS-Aqua satellite (acquired at midday) for the period 2003-2012 and the seasonal effects of pulvinar movements on NDVI time series of Landsat images for the period 1998-2012 for Tamarugo areas with and without water stress. NDVI values measured by MODIS-Terra (morning) were higher than the NDVI values measured by MODIS-Aqua (afternoon) and the difference between the two, the ΔNDVImo-mi, showed good potential as water stress indicator. In a similar way, I observed a strong seasonal effect on the Landsat NDVI signal, attributed to pulvinar movements, and the difference between winter and summer, the ΔNDVIW-S, also showed good potential for detecting and quantifying water stress. The ΔNDVImo-mi, the ΔNDVIW-S and the NDVI itself measured systematically in winter time (NDVIW) were negatively correlated with in situ groundwater depth measurements.
In chapter five I used a dense NDVI time series of Landsat images for the period 1989-2013, combined with high spatial resolution satellite imagery and hydrogeological records, to provide a quantitative assessment of the water status of Tamarugo vegetation after 50 years of increasing groundwater extraction. The results showed that the NDVIW and ΔNDVIW-S of the Tamarugo vegetation declined 19% and 51%, respectively, as groundwater depleted (3 meters on average) for the period 1989-2013. Both variables were negatively correlated to groundwater depth both temporally and spatially. About 730.000 Tamarugo trees remained in the study area by 2011, from which 5.2% showed a GCF<0.25 which is associated to severe water stress. Based on this spatio-temporal analysis, I suggest that the survival of Tamarugo trees is limited to a maximum groundwater depth of 20 meters.
The main conclusions of this PhD thesis are summarized as follows:Heliotropism or leaf ‘solar tracking’, a common adaptation among desert plants, has an important impact on canopy spectral reflectance. As shown in the case of the Tamarugo trees, widely used vegetation indices such as the NDVI were negatively correlated to solar irradiation (the stimulus for leaf solar tracking), showing a distinct diurnal and seasonal cycle.An early symptom of water stress in paraheliotropic plants (leaves facing away the sun) is the decline of the amplitude of the diurnal and seasonal NDVI cycles. Thus, remote sensing estimations of this amplitude (e.g. the NDVI difference between winter and summer or the difference between midday and morning) can be used to detect and map early water stress of paraheliotropic vegetation.At the tree level, very high spatial resolution images combined with object based image analysis and in-situ data provided accurate estimations of the water status of small desert vegetation features, such as isolated trees. For monitoring purposes, careful consideration of the time during the day and the season at which the images are taken needs to be taken to avoid misleading interpretations.Time series analysis of historical satellite images combined with very high spatial resolution images and hydrogeological records can provide a quantitative spatio-temporal assessment of the effects of long-term groundwater extraction on desert vegetation.
EBONE in Mediterranean and desert sites in Israel, with notes on South Africa : report on field tests in LTER sites and habitat monitoring
Olsvig-Whittaker, L. ; Jobse, D. ; Gelder, A. de - \ 2011
Wageningen : Alterra (Alterra-rapport 2260) - 54 p.
habitats - biodiversiteit - remote sensing - woestijnen - israël - zuid-afrika - habitats - biodiversity - remote sensing - deserts - israel - south africa
Deserts and the planet - Linkages between deserts and non-deserts
Safriel, U. ; Ezcurra, E. ; Tegen, I. ; Schlesinger, W.H. ; Nellemann, C. ; Batjes, N.H. ; Dent, D. ; Groner, E. ; Morrison, S. ; Resenfeld, D. ; Avner, U. ; Briosch, N. ; Golan-Goldhirsh, A. ; Alpert, P. ; Portnov, B. ; Cates, R. ; White, R. ; Tsonis, A. ; Schwartz, M. ; Ayal, Y. ; Pinshow, B. ; Cohen, D. ; Demere, T. ; Shafir, H. ; Warren, A. ; Mazor, E. - \ 2006
In: Global Deserts Outlook / Ezcurra, E., Nairobi : UNEP - ISBN 9789280727227 - p. 50 - 72.
woestijnen - ecosystemen - biodiversiteit - cultureel erfgoed - milieu - natuurlijke hulpbronnen - conservering - wereld - deserts - ecosystems - biodiversity - cultural heritage - environment - natural resources - conservation - world
|Runoff and sediment transport in the arid regions of Argentina and India - a case study in comparative hydrology
Sharma, K.D. ; Menenti, M. ; Huygen, J. ; Fernandez, P.C. ; Vich, A. - \ 1996
Annals of Arid Zone 35 (1996)1. - ISSN 0570-1791 - p. 17 - 28.
argentinië - woestijnen - economische impact - economie - india - regen - relaties - oppervlakkige afvoer - gebruikswaarde - aride klimaatzones - argentina - deserts - economic impact - economics - india - rain - relationships - runoff - use value - arid zones
The arid zones of Argentina and India have been compared. In both regions run-off is often generated by the Hortonian infiltration surplus overland flow, and run-off response to precipitation input tends to be rapid. The sediment transport is governedby the transport capacity of run-off rather than by the availability of erodible material. The magnitude of hydrological processes is different in response to the different rainfall regimes.
|Modelling spatial sediment delivery in an arid region using Thematic Mapper data and GIS
Sharma, K.D. ; Menenti, M. ; Huygen, J. ; Vich, A. - \ 1996
Transactions of the ASAE 39 (1996)2. - ISSN 0001-2351 - p. 551 - 557.
toepassingen - woestijnen - geografische informatiesystemen - modellen - remote sensing - onderzoek - watererosie - aride klimaatzones - applications - deserts - geographical information systems - models - remote sensing - research - water erosion - arid zones
A distributed-parameter sediment delivery model is linked with a personal computer-based, low-cost geographical information system to facilitate preparation, examination, and analysis of spatially distributed input parameters and to link the sediment delivery from a micro-scale to the watershed scale. The model accurately predicts, even for the same values of flow shear stress, the higher sediment delivery from bare surfaces as compared to surfaces protected by vegetation cover. This study enables the identification of vulnerable regions within a watershed, thus facilitating improvements in the planning of soil conservation systems.
An intercomparison of techniques to determine the area-averaged latent heat flux from individual in situ observations: a remote sensing approach using the European Field Experiment in a Desertification-Threatened Area data
Pelgrum, H. ; Bastiaanssen, W.G.M. - \ 1996
Water Resources Research 32 (1996)9. - ISSN 0043-1397 - p. 2775 - 2786.
toepassingen - woestijnen - interacties - microklimaat - remote sensing - bodemtemperatuur - thermische bodemeigenschappen - thermische geleiding - vegetatie - aride klimaatzones - applications - deserts - interactions - microclimate - remote sensing - soil temperature - soil thermal properties - thermal conductivity - vegetation - arid zones
Different procedures to obtain the area-averaged latent heat flux as a weighted average of ground-based observations of latent heat flux are described. Weighting coefficients are obtained from remote sensing data. A newly developed remote sensing algorithm, SEBAL, which solves the energy budget on a pixel-by-pixel basis, was successfully applied with EFEDA data. Two other methods for retrieving weighting coefficients were tested against SEBAL. The second method combines satellite images of surface temperature, surface albedo and Normalized Difference Vegetation Index (NDVI) into an index on a pixel-by-pixel basis. The third method uses a supervised classification.
|A methodology for the assessment of surface resistance and soil water storage variability a mesoscale based on remote sensing measurements. A case study with HAPEX-EFEDA data.
Bastiaanssen, W.G.M. ; Hoekman, D.H. ; Roebeling, R.A. - \ 1994
Wallingford : IAHS - ISBN 9780947571931 - 66
toepassingen - woestijnen - evaporatie - land - remote sensing - bodem - bodemwatergehalte - oppervlakten - aride klimaatzones - applications - deserts - evaporation - land - remote sensing - soil - soil water content - surfaces - arid zones
|Groundwater monitoring in (semi-) arid regions. A general outline.
Lanen, H.A.J. van - \ 1994
In: International workshop on groundwater monitoring and recharge in semi - arid areas, Hyderabad, India, January 18-20, 1994 - p. SI1 - SI13.
woestijnen - grondwater - hydrologie - instrumenten (meters) - meting - monitoring - pampa's - semi-aride klimaatzones - steppen - waterbeheer - waterkwaliteit - aride klimaatzones - netwerken - deserts - groundwater - hydrology - instruments - measurement - pampas - semiarid zones - steppes - water management - water quality - arid zones - networks
Spectral reflectance in the Tunesian desert
Epema, G.F. - \ 1992
Agricultural University. Promotor(en): S.B. Kroonenberg; M. Molenaar. - S.l. : Epema - 150
remote sensing - toepassingen - absorptie - reflectie - ruimtelijke ordening - landgebruik - zonering - woestijnen - tunesië - aride klimaatzones - remote sensing - applications - absorption - reflection - physical planning - land use - zoning - deserts - tunisia - arid zones
Satellites provide the possibility to give a synoptical view of the earth surface at regular time intervals. Satellites operating in the optical wavelengths have however as disadvantage that monitoring of the surface characteristics becomes impossible as soon as clouds are present. Deserts and desert margins are for that reason much more appropriate for monitoring by optical satellites than temperate and wet tropical areas. Potential hazards, possibilities and often inaccessibility makes use of optical remote sensing very reasonable.
Landsat Thematic Mapper (TM) satellites provide a much better spectral resolution than other satellites at reasonable spatial and temporal resolution. Ile presented research was hence focused on the spectral possibilities of Landsat Thematic Mapper for determining surface characteristics and their dynamics in desert areas. Field measurements of reflectance in different seasons were performed to evaluate the effect of different factors and their dynamics on reflectance. A field radiometer (MMR) with TM compatible bands was used. The study was performed in southern Tunisia in an area with large variation: footslopes, dunes and dynamical salt plains, all with few or absent vegetation cover. Dominant mineralogy is representative for many and areas and comprises gypsum, carbonate, quartz and halite.
In order to compare results of field reflectance measurements with Landsat Thematic Mapper data, adequate processing of both data sets is necessary.
Use of calibration coefficients given for Landsat Thematic Mapper data processed in Fucino will cause large errors in calculating reflectance data. It turned out that these coefficients were not updated for deterioration of the sensors during the flight and that calculations were made based on two different definitions of bandwidth. In order to achieve adequate values of reflectance these errors were evaluated and corrected (Chapter 8).
The evaluation of factors affecting field reflectance can be separated in external and internal ones.
Influence of atmosphere on field reflectance is limited. The evaluation of the external factors leads to the conclusion that all measurements with a solar zenith angle less than 65 degrees and on clear days could be used for obtaining a field data reference set.
Field measurements showed that Landsat TM-like bands are very useful in detecting the surface characteristics ( internal factors ) in this area (Chapters 5 - 7).
Presence of halite on the playas could be detected by relatively high reflectance in the visible part of the spectrum, especially in the blue band. Field reflectance on plots showed that moisture content induces a relatively low reflectance in all bands with an extra low reflectance in the middle infrared bands. Linear relations between volumetric moisture content and reflectance in individual bands in near and middle infrared turned out to be feasible.
Most dynamical parts of the area turned out to be the playas, where after storms moisture contents of the top layer were affected for a long time and halite efflorescences occurred shortly after the storms. Although dust slowly covering the surface, even in spring plots with higher halite content could be derived from the spectral signature. Field plots in dune parts showed a large variation in reflectance between November and May too due to changes by wind. Dynamics on footslopes were much less important than in other areas. Variation in vegetation appears to be relatively small, while also effect of storms was not visible for more than a few days after a storm.
Results of field reflectance were extrapolated to Landsat TM satellite data (Chapter 9). It was possible to derive directly from Landsat TM data a number of useful classes for playas, footslopes and eolian material, having variation in surface mineralogy (gypsum, carbonate, quartz, halite) and variation in surface type. Also dynamics of factors like moisture and halite could be derived using multitemporal Landsat TM data.
The presented methodology, implementing an extensive field reflectance measurement campaign, gives insight in possibilities of Landsat TM under a range of conditions. It corroborates that for operational application in and areas Landsat TM data will be a useful source of information in addition to other types of remote sensing as for instance aerial photography.
Bio-economic capability of West-African drylands
Wolf, J. ; Breman, H. ; Keulen, H. van - \ 1991
Wageningen : CABO-DLO (Report / Centre for Agrobiological Research 147) - 83
teelt - cultuurmethoden - agrarische bedrijfsvoering - landbouw - landbouwproductie - woestijnen - west-afrika - aride klimaatzones - cultivation - cultural methods - farm management - agriculture - agricultural production - deserts - west africa - arid zones
A new simulation model of bare soil evaporation in arid regions (EVADES)
Bastiaanssen, W.G.M. ; Kabat, P. ; Menenti, M. - \ 1989
Wageningen : ICW (ICW note 1938) - 74
woestijnen - evaporatie - land - modellen - onderzoek - oppervlakten - aride klimaatzones - deserts - evaporation - land - models - research - surfaces - arid zones
Mapping evaporation from playa's in the Western Desert : approach and practical examples
Abd El Karim, M.H. - \ 1989
Wageningen : ICW (ICW nota 1972) - 39
toepassingen - watervoerende lagen - woestijnen - egypte - evaporatie - hydrologie - remote sensing - aride klimaatzones - applications - aquifers - deserts - egypt - evaporation - hydrology - remote sensing - arid zones
|Introduction to the landscape ecology of southern Texel.
Doing, H. - \ 1989
In: Perspectives in coastal dune management : proceedings of the European Symposium, Leiden, September 7 - 11, 1987, The Netherlands / van der Meulen, F., Jungerius, P.D., Visser, J., - p. 279 - 285.
landschap - landschapsecologie - plantengemeenschappen - woestijnplanten - woestijnen - duinen - eolisch zand - landschapsbouw - ruimtelijke ordening - cartografie - noord-holland - thematische cartografie - nederlandse waddeneilanden - landscape - landscape ecology - plant communities - desert plants - deserts - dunes - aeolian sands - landscaping - physical planning - mapping - thematic mapping - dutch wadden islands
Diurnal variation of bare soil reflectance
Bastiaanssen, W.G.M. - \ 1988
Wageningen : ICW (Nota / Instituut voor Cultuurtechniek en Waterhuishouding 1854) - 28
fysische bodemeigenschappen - remote sensing - absorptie - reflectie - woestijnen - aride klimaatzones - soil physical properties - remote sensing - absorption - reflection - deserts - arid zones
New empirical aspects of the Bowen-ratio energy balance method : a study of evaporation losses in arid regions
Bastiaanssen, W.G.M. - \ 1988
Wageningen : ICW (ICW note 1914) - 41
watervoerende lagen - woestijnen - energiebalans - evapotranspiratie - hydrologie - methodologie - sahel - aride klimaatzones - aquifers - deserts - energy balance - evapotranspiration - hydrology - methodology - sahel - arid zones
Desert environment and agriculture in the Central Negev and Kadesh-Barnea during historical times
Bruins, H.J. - \ 1986
Landbouwhogeschool Wageningen. Promotor(en): L.J. Pons; A.M. van der Woude. - Wageningen : Bruins - ISBN 9789071666018 - 219
landbouw - regenwateropvang - landbouw met waterafvoer - water - watervoorziening - bodemkarteringen - nomadisme - pastoralisme - woestijnen - geschiedenis - israël - aride klimaatzones - agriculture - water harvesting - runoff farming - water - water supply - soil surveys - nomadism - pastoralism - deserts - history - israel - arid zones
A description is given of historic land-use and ancient agriculture in the arid desert environment of the central Negev and adjacent northeastern Sinai, based on archeaeological research and soil research.
Relationships between the landscape, climatic and agricultural history are evaluated.
Production and water use of several food and fodder crops under irrigation in the desert area of Southwestern Peru
Alberda, T. - \ 1984
Wageningen : Pudoc (Agricultural research reports no. 928) - 50
irrigatie - veldgewassen - akkerbouw - landbouw met irrigatie - woestijnen - peru - aride klimaatzones - irrigation - field crops - arable farming - irrigated farming - deserts - peru - arid zones
|Irrigatie van boomkwekerijen en boomaanplantingen in droge gebieden
Romijn, M.M.E. - \ 1984
Wageningen : De Dorschkamp (Rapport / Rijksinstituut voor Onderzoek in de Bos- en Landschapsbouw 'De Dorschkamp' no. 382) - 94
bosbouw - boomkwekerijen - irrigatie - woestijnen - aride klimaatzones - forestry - forest nurseries - irrigation - deserts - arid zones
Physical aspects and determination of evaporation in deserts applying remote sensing techniques
Menenti, M. - \ 1984
Landbouwhogeschool Wageningen. Promotor(en): L. Wartena, co-promotor(en): W.H. van der Molen. - Wageningen : Menenti - 202
remote sensing - toepassingen - bodemtemperatuur - thermische geleiding - thermische bodemeigenschappen - atmosfeer - straling - temperatuur - geomorfologie - reliëf - hydrologie - evaporatie - libië - woestijnen - aride klimaatzones - eolische processen - remote sensing - applications - soil temperature - thermal conductivity - soil thermal properties - atmosphere - radiation - temperature - geomorphology - relief - hydrology - evaporation - libya - deserts - arid zones - aeolian processes
In the deserts of the world groundwater losses by evaporation are shown to be a very important and almost unknown quantity in the water balance of aquifers present.After establishing a new combination formula to calculate actual evaporation from within the soil, the evaporational soil physical aspects are discussed in detail. It is shown that under specified conditions vapour flow can take place against the direction of heat flow. A new, fundamental, definition of evaporation sites is given and its bearing on a model of heat and moisture flow is discussed. A theory of heat exchange at the soil - air interface is presented in terms of the apparent soil thermal admittance. Equations to relate the latter soil property to soil layering and to the frequency of the surface temperature wave are given. A theory of evaporation in terms of multi-dimensional geometry is proposed and it is shown how to derive approximate formulae to calculate actual evaporation by making use of satellite data only. For more accurate results point ground reference measurements have been used to calibrate the satellite-based calculations.After describing a particular desert area in Libya, the accuracy of a number of satellite data of that area is discussed on the basis of ground reference measurements and numerical correction procedures.Finally, the theory is combined with satellite and point ground reference data to calculate the different terms of the surface energy balance and the actual evaporation for some 36,000 km 2of the Libyan desert.
|A new geophysical approach using remote sensing techniques to study groundwater table depths and regional evaporation from aquifers in deserts
Menenti, M. - \ 1983
Wageningen : I.C.W. (Report / Institute for Land and Water Management Research no. 09) - 15
toepassingen - klimaat - woestijnen - evaporatie - grondwaterstand - land - remote sensing - oppervlakten - applications - climate - deserts - evaporation - groundwater level - surfaces