DOI: 10.14393/SN-v32-2020-46916 Received: 06 February 2019|Accepted: 06 February 2020 Assessment of soil loss to vulnerability in the Boane District in Mozambique Euclides Délio Matule1 Lucrêncio Silvestre Macarringue1,2 Keywords Abstract Boane The soil lost vulnerability study of the landscape units constitutes one of the Stability mechanisms for the design of sustainable land use and cover and natural Geoprocessing resources. Therefore, this research aimed to evaluate the soil loss vulnerability Soil Loss in the Boane district in 2018. The materials used included OLI Landsat 8 and ASTER GDTM V2 images, through which we generated land use and cover and slope maps respectively, soils, lithology, and precipitation databases available in CENACARTA. This data was processed in a GIS environment. The results showed that 53.3% of the district had median stability, 34.7% moderately vulnerable, 11.4% moderately stable, 0.6% stable and 0% vulnerable. These results indicate a favorable situation, but not comfortable at the short term, due to the accelerated rhythm of urbanization and its consequences to the environment that is seen in the last decades, joined to the lack or non- implementation of the main planning plans, that can change this situation in short term. 1Instituto de Formação em Administração de Terras e Cartografia, Matola, Moçambique. [email protected] 2Universidade Estadual de Campinas, São Paulo, Brasil. [email protected] Soc. Nat. | Uberlândia, MG | v.32 | p.211-221 | 2020 | ISSN 1982-4513 211 MATULE; MACARRINGUE Assessment of Soil Loss Vulnerability in Boane District in Mozambique INTRODUCTION Crepani, et al. (1996). The scale of the vulnerability of basic To analyse a landscape unit, it is necessary to territorial units, from their morphodynamic know its genesis, physical constitution, form characterization, is made according to criteria and stage of evolution, as well as the type of developed from the principles of Tricart's vegetation cover that develops on it. This Ecodynamics (1977). information is provided by Geology, The criteria developed from these Geomorphology, Pedology and Phytogeography principles allow one to create a model where and needs to be integrated to have a faithful he can seek the assessment, relatively and picture of each unit's behaviour towards the empirically, of the stage of morphodynamic occupation. Finally, Climatology needs to help evolution of basic territorial units, assigning us to know some climatic characteristics of the stability values to morphodynamic categories region where the landscape unit is located, to (CREPANI et al., 2001). From this first predict its behaviour towards the changes approximation, a greater variety of imposed by the occupation (CREPANI et al., morphodynamic categories is sought, to 2001). construct a scale of vulnerability for situations The vulnerability to soil loss of landscape that occur naturally (CREPANI, 2001). units is linked to the imbalance in the natural In Mozambique, itinerant agriculture, dynamics of the environment. Each component wood exploitation, firewood and charcoal of the landscape, such as Geology, production and uncontrolled burning are Geomorphology, Pedology, Vegetation, Climate considered the main factors for the reduction and anthropic intervention, participates in of vegetation cover and consequently soil this dynamic in an integrated way. These erosion. components, participate in this dynamic in an The population of Boane uses forest integrated way (DE LA ROSA et al., 2000; LU resources such as pegs, reeds and other et al., 2004; CREPANI et al., 2008). material for house building and they take For Becker and Egler (1997) the advantage of trees for firewood, wood and vulnerability map to soil loss represents the charcoal production, which are the fuels most analysis of the physical and biotic used by the households. Because of this, the environment for the rational occupation and district presents serious problems of sustainable use of natural resources. Its deforestation and soil erosion. association with data of social, economic and In ten years the district has had a political potentiality offers subsidies to population increase of almost 50%. This territorial management (LU et al., 2004). This increase was due to the migration of the vulnerability is analysed from the population from the cities of Maputo and morphodynamic characterization of these Matola, causing the native vegetation cover to units, based on methodologies developed by be removed for the construction of their Soc. Nat. | Uberlândia, MG | v.32 | p.211-221 | 2020 | ISSN 1982-4513 212 MATULE; MACARRINGUE Assessment of Soil Loss Vulnerability houses. This fact precipitates, at first, the South and Southeast with Matutuine District district vulnerability to soil loss. and the East with Matola Municipality (Figure Pereira and Pinto (2007) state that the 1). It has an approximate surface area of 860 speed and extent with which environmental Km2 and is home to a population of 210,498 problems have been occurring, resulting from inhabitants according to the 2017 Census the intense pressure generated by anthropic (INE, 2017). It is a district with a dry tropical occupation, require the use of data collection climate, with two well-defined seasons, the dry techniques and systematic monitoring of the season (between April and September) and the land surface, compatible with the speed of rainy season (between October and March). these changes. The average annual temperature is 23.7ºC and In recent decades, empirical modelling the average annual precipitation is around 752 techniques associated with geographic mm (MAE, 2005). information systems and satellite imaging The district is crossed by the Umbeluzi, with moderate to high spatial and temporal Tembe and Matola rivers belonging to the resolution have facilitated the monitoring and river basins of the same names, the Umbeluzi quantification of the conditions of changes river being born in the neighbouring e-Swatini occurring on the earth's surface and their (former Swaziland) over a length of 70 km degradation (PONZONI et al., 2014; VIJITH; (MAE, 2005), most important, it is the main DODGE-WAN, 2017). source of potable water for the cities of Maputo Thus, this article aims to assess (capital of the country) and Matola besides vulnerability to soil loss in the Boane district being the main source of water for irrigated in 2018. This analysis will serve as a basis or agriculture. subsidy for the preparation of the different In the past, Boane was dominated by territorial planning instruments (at the forests with high density of tree layer, thick district or municipality level), as well as the trunk trees with wide treetops that rose to a preparation of environmental planning, thus height of 10 to 20m, which was degraded contributing to the production of conservation giving way to pasture and agricultural areas, and preservation measures. with patches of secondary savannah and spontaneous or subspontaneous fruit trees METHODOLOGY (MUCHANGOS, 1999). Boane consists of Jurassic-Cretaceous Location and characterization of the study area basalt material (Volcanic Karroo of the Upper Series), Mananga sediments, pebbles and Boane District is located in the South of alluvial sediments. The basalts are of Maputo Province and borders in the North Jurassic-Cretaceous age, belonging to the with Moamba District in the West and Karroo Super Group, formed during the last Southeast with Namaacha District, in the phase, which of the volcanic emanations called Soc. Nat. | Uberlândia, MG | v.32 | p. 211-221 | 2020| ISSN 1982-4513 213 MATULE; MACARRINGUE Assessment of Soil Loss Vulnerability Superior Stormberg or Superior Series. These there are also quaternary coverings of sandy basalts are part of the Libombos chain with a materials consisting of alluvial deposits or north-south direction and more than 450km alluvial with gravel, quartz, rhyolites, some long and 20-25km wide and inclined towards minerals and rocks (TIQUE; DYKSHOORN, the east. On both banks of the Umbeluzi River, 1993; VASCONCELOS, 2014). Figure 1 Location of the study area. Source: CENACARTA Database (1999). The relief of the low course of the According to Tique; Dykshoorn (1993), Umbeluzi River basin is characterized, in five main soil units can be found in most parts general, by a slightly undulating landscape of the district: (i) derived from Basalts-Bv; (ii) without great differences in altitude. In the from Mananga with sandy cover of less than North, East and Southwest it presents a 25cm-Ml; (iii) from Post-Mananga-P; (iv) on landscape with small differences of level, rolled Pebbles-S; and (v) alluvial from forming a true plain. The altitude varies from Umbeluzi-F river. 0 to 300 meters (ALBINO, 2012). Soc. Nat. | Uberlândia, MG | v.32 | p. 211-221 | 2020| ISSN 1982-4513 214 MATULE; MACARRINGUE Assessment of Soil Loss Vulnerability MATERIAL AND METHOD (13-20%); Class E, Strong Wavy (20-45%) and Class F, Mountainous or Escarpment (> 45%) Images from the OLI sensor of the Landsat (RAMALHO-FILHO; BEEK, 1995). satellite, Path/Row 167/78 WRS-2, UTM At the second moment, the analysis and projection, Zone 36S and Datum WGS84 of generation of the thematic maps were made. June 15, 2018, were used; an ASTER GDTM In the case of the soil map, initially the V2 image, acquired through the following nomenclature of soil types was changed (from address: www.earthexplorer.usgs.gov. the FAO classification to the Embrapa The district/country digital cartographic