Agricultural and Biosystems Engineering Agricultural and Biosystems Engineering Publications 9-2009 Impacts of Agricultural Expansion on Surface Runoff: A Case Study of a River Basin in the Brazilian Legal Amazon E. E. Maeda National Institute for Space Research A. R. Formaggio National Institute for Space Research Y. E. Shimabukuro National Institute for Space Researchers Amy L. Kaleita Iowa State University, [email protected] Follow this and additional works at: http://lib.dr.iastate.edu/abe_eng_pubs Part of the Agriculture Commons, Bioresource and Agricultural Engineering Commons, Geographic Information Sciences Commons, and the Water Resource Management Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ abe_eng_pubs/534. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Agricultural and Biosystems Engineering at Iowa State University Digital Repository. It has been accepted for inclusion in Agricultural and Biosystems Engineering Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Impacts of Agricultural Expansion on Surface Runoff: A Case Study of a River Basin in the Brazilian Legal Amazon Abstract This work presents an analysis of the Land Use and Land Cover (LULC) changes of a region in the Brazilian Legal Amazon, and an evaluation of their impacts on the surface runoff er gime. This case study took place at the Suiá-Miçu River basin, located in the northeast region of Mato Grosso State. LULC maps were produced for the years 1973, 1984 and 2005 using remote sensing data. After analyzing the agricultural expansion in the study area, the Automated Geospatial Watershed Assessment Tool (AGWA) was applied in performing the surface runoff modeling for each of the analyzed years using the SCS curve number method. The er sults showed that by 1984, 13% of the natural vegetation had been replaced by pasture in this drainage basin. These changes were responsible for a 5.7% increase in the annual average surface runoff ov lume when compared with the baseline values of 1973. In 2005, the agricultural areas increased to around 40% of the drainage basin, being 28% occupied by pasture and 12% by crop fields. In this last scenario, the annual average surface runoff was 37% higher than in 1973. Disciplines Agriculture | Bioresource and Agricultural Engineering | Geographic Information Sciences | Water Resource Management Comments This article is from International Journal of Geoinformatics 5 (2009): L. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/abe_eng_pubs/534 Impacts of Agricultural Expansion on Surface Runoff: A Case Study of a River Basin in the Brazilian Legal Amazon 1 2 1 1 Maeda, E. E., ' Formaggio, A. R., Shimabukuro, Y. E., and Kaleita, A. L./ 1National Institute for Space Research, Av dos Astronautas, 1758. Jd. Granja- CEP: 12227-010, Sao Jose dos Campos, Brazil, E-mail: [email protected] 2University of Helsinki, Department of Geography, Gustaf Hallstromin katu 2, 00014, Helsinki, Finland 3Towa State University, Agricultural and Biosystems Engineering, 211 Davidson Hall, 50011, Ames, TA, USA Abstract This work presents an analysis of the Land Use and Land Cover (LULC) changes of a region in the Brazilian Legal Amazon, and an evaluation of their impacts on the swjace runoff regime. This case study took place at the Suia-Mir;u River basin, located in the northeast region ofMato Grosso State. LULC maps were produced jar the years 1973, 1984 and 2005 using remote sensing data. Ajier analyzing the agricultural expansion in the study area, the Automated Geospatial Watershed Assessment Tool (AGWA) was applied in performing the surface runoff rnodeling for each of the analyzed years using the SCS curve number method. The results showed that by 1984, 13% of the natural vegetation had been replaced by pasture in this drainage basin. These changes were responsible jar a 5. 7% increase in the annual average surface runoff volurne when compared with the baseline values of 1973. In 2005, the agricultural areas increased to around 40% of the drainage basin, being 28% occupied by pasture and 12% by crop fields. In this last scenario, the annual average surface runoffwas 37% higher than in 1973. 1. Introduction The replacement of forests, wetlands, savannahs and compacted and the water that would otherwise have other native landscapes by agriculture is a severe infiltrated the soil would now be turned into runofl~ threat to the capacity of the environment to maintain which will cany out sediments and nutrients to the freshwater, sustain food production and other rivers, and decrease recharge of the groundwater ecosystem services (Foley et al., 2005). Cunently, reservoirs. This will have as consequence problems almost one-third of the world's land surface is under such as erosion, silting of the rivers, eutrophication, agricultural use and millions of hectares of natural water contamination, among others (Van Dessel et ecosystems are converted to croplands or pastures al., 2008, Bordman, 2006 and Szilassi et al., every year. In Brazil, the deforestation of the 2006).The identification and monitoring of areas Amazon forest due to the agricultural expansion and most susceptible to such environmental problems logging activities is one of the biggest problems are essential to allow improved planning and cunently faced in this important biome. Tardin et implementation of conservation practices. In al., ( 1980) showed that while the deforested area in addition, studies with the objective of measme and the 1970's was around 10 million hectares, by 2005 map the spatial distribution of the changes can not this area had increased to 67 million hectares (INPE, only help the development of public policies, but are 2006). Land use and land cover change modelling necessary to warn the society about the problem and studies predict that if cunent trends persist, by the its possible consequences. Several models year 2050 around 40% of the Brazilian Legal developed in the last few decades are contributing to Amazon will be deforested in favor of agricultural make this work possible and more efficient (Miller activities (Soares-Filho et al., 2006). One of the et al., 2007). However, little research has been done natural phenomena significantly affected by land with the objective of implementing hydrological and cover changes is the hydrological cycle. The forest erosion models within the Brazilian Legal Amazon protects the soil against the impacts of the and the impacts of the deforestation that has precipitation water and provides organic matter to occuned in the last few decades are still not well the soil. These factors improve infiltration and allow known. The objective of this work was to perform the recharging of groundwater reservoirs. When this an analysis of the land use and land cover changes vegetation cover is displaced the soil can be on a region in the Brazilian Legal Amazon, and to International Journal cfGeoirformatics, Vol5, No.3, September, 2009 ISSN 1686-6576 I© Geoinformatics International evaluate the impacts of these changes on the surface floodplains. One factor that enhances the runoff regime using remote sensing techniques and importance of this region is the presence of the a hydrological model. Xingu Indigenous Reserve in the Suia-Miyu River downstream (Figure 2). The Xingu Reserve is one 2. Study Area of the most important regions from the point of view The study was carried out at the Suia-Miyu River of its biodiversity and cultural significance to Brazil. Basin, located in the northeast region of Mato It is located at the banks of the Xingu River, an Grosso state, and pmt of the Amazon River Basin impottant tributary of the Amazon River. As (Figure 1). The drainage area of the basin comprises illustrated in Figure 2, most of the drainage area of approximately two million hectares, and is pmt of the watershed is located outside the indigenous six municipalities: Sao Felix do Araguaia, reserve. This contributed to the deforestation of Querencia, Alto da Boa Vista, Ribeirao Cascalheira, large areas next to the preservation area, mainly due Canarana and Born Jesus do Araguaia. The to the expansion of agricultural act1v11Ies. predominant soil types, according to the soil Consequently, besides the degradation in the Xingu taxonomy classification, are Rhodic Hapludox and River spring, the agricultural activities can impact Typic Hapludox. However, different types of soils the preservation area as a result of carrying can be found in some smaller regions, mainly in the sediments, nutrients and pesticides within it. southern part of the basin and in the rivers' 57"0'[1'\I"J srouw -~ ( '-·,~_.___f~ -~) '-.( Legend =:::J Mata Grasso State ~ ~ {) 50-Q 1{)00 / "¥--' km ~- ..... '-... /1'/ (..- Legend '/J - Suia-Mi~u River Basin ano km E 57"0'G''W 52~0'0'W Figure 1: Geographic location of the Suia-Miyu River Basin Legend ' L;-:-:;:2 Study Site · ·· ·1 Indigenous ParKs / i ;', . .j . ·: . !·-·· :-;.:: .)··. -.--·· Figure 2: Geographic location of the Indigenous areas close to the study site hnpacts of Agricultural Expansion on Surface Runoff: A Case Study of a River Basin in the Brazilian Legal Amazon 3. Methods al., 2002), which provides NDVI and EVI 16 days A comparative analysis was performed taking into composite images