Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 4 Renewable resources in rural areas: Vegetation, forestry, agriculture, soil survey, land and water use. Chairman: J. Besenicar, Liaisons: M. Molenaar, Th. A. de Boer

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Application of multispectral scanning remote sensing in agricultural water management problems. G. J. A. Nieuwenhuis, J. M. M. Bouwmans

Document type:: Multivolume work

Structure type:: Chapter

493 Figure 8. Ratio of cumulative actual to potential 24 hour évapotranspiration over the entire growing season of 1982 (ELE 24 /ELE 24 ) for grass and maize on Typic Haplaquod soil with drainage class V depending on groundwater table drawdown as calculated with the SWATRE-model (after Thunnissen 1984b) Water-tabel drawdown (cm) Figure 9. Relative 24 hour évapotranspiration rate (LE^^/LEp 4 ) on 30 July 1982 as calculated with the SWATRE-model. A. grass on Typic Haplaquod soil with drainage class V; B. for maize on the same soil with drainage class VI depending on groundwater table drawdown (after Thunnissen 1984b) water table is present under natural conditions (Fig ure 9A). For a relatively deep groundwater table crop évapotranspiration of maize is, even under natural conditions, low on 30 July 1982 and the effect of a lowering of the groundwater table is then limited (Figure 9B). The results obtained with the remote sensing ap proach are confirmed by the SWATRE-model calculations. According to the remote sensing approach crop évapo transpiration strongly decreases on 30 July 1982 in the direction of the centre of the extraction in case of shallow groundwater tables under natural conditions. This is shown in Figure 7A. Figure 9A shows that also according to SWATRE-model calculations for the con cerning conditions crop évapotranspiration strongly decreases with lowering of the groundwater table. Also for relatively deep groundwater tables under natural conditions both results show good agreement (Figures 7B and 9B). If no suppletion from groundwater occurs crop évapotranspiration is very low on 30 July 1982 and a lowering of the groundwater table has no perceptible influence on crop évapotranspiration. It can be concluded that with remote sensing de tailed information about the regional distribution of évapotranspiration on flight days is obtained. With SWATRE-model calculations the occurrence of drought damage can be explained. Thunnissen (1984b) concluded that an important improvement of the hy drological description of an area can be achieved by integrating SWATRE-model calculations with remote sensing. Information about the regional distribution of évapotranspiration can also be obtained with regional agrohydro logical simulation models like GELGAM (De Laat and Awater 1978). The applicability of such a model depends on the schematization. The size of the grid cell applied in the GELGAM-model has been in dicated in Figure 6. It can be seen that within grid cells large varia tions in évapotranspiration can occur. With model calculation for each grid cell separately mean val ues are obtained while with remote sensing informa tion is obtained about the deviations which may oc cur. In this way insight is obtained in the meaning of results obtained with a regional hydrological simulation model. As in the Netherlands we have to deal with inten sively used agricultural land an integrative ap proach based on the application of remote sensing and SWATRE-model calculations is preferred in water management above the application of a regional agro- hydrological simulation model as GELGAM. 4 CONCLUDING REMARKS With multispectral scanning remote sensing detailed information can be obtained about land use and crop water supply. A method has been developed for the mapping of évapotranspiration from digitally taken reflection and thermal images. The accuracy of an évapotranspiration map obtained with remote sensing is strongly dependent on the availability of an ac curate crop map. The possibilities to distinguish different crops is dependent on the growth stage. This being the case a multi-temporal approach has to be applied. With some examples the applicability of remote sensing techniques to determine effects of certain water management measures has been demonstrated. For a unique interpretation of remote sensing images additional information is, however, indispensable. The main advantage of remote sensing is, that the actual crop water supply is registrated for large areas. With models crop water supply can be simulat ed for certain locations during the entire growing season, while verification of the obtained results on a regional scale is nearly impossible with con ventional methods. Therefore an integrative approach based on the application of remote sensing tech niques and agrohydrological model simulations is propagated. The possibilities of remote sensing techniques to detect drought damage has been extensively investi gated. In the near future damage caused by excess of water has to be emphasized as in humid areas from economical point of view this is an important prob lem. The application of MSS-techniques in practice will mainly depend on the availability of useful and pay able images. The satellites SPOT and LANDSAT 5 pro vide reflection images with a spatial resolution useful for different small plots (10-30 m). The spatial resolution of thermal images obtained with the TM-scanner on board LANDSAT 5, however, is 120 m. Moreover, especially for humid areas the temporal resolution is questionable. The frequency is 16 days and the time of acquisition (about 9.30 AM local time) is far from optimal to detect drought damage. The increase in crop temperature because of a reduc tion in évapotranspiration is maximal in the early arteiuuon. Before 11.Ou AM une temperature dirter- ences caused by a lack of water in the root zone will be small. For operational applications it is neces sary that digital multi-spectral and thermal images are recorded with a frequency of at least once in every 5 days around midday with a spatial resolution of about 15-20 m. A space-borne system with these

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