Biophysical and anthropic factors of the Mandinga River basin and its influence on the destruction of the mangrove ecosystem of Barra Salada, Sonsonate, El Salvador

Abstract

The mangrove forest of Barra Salada with 454 ha, located in the department of Sonsonate, is an ecosystem of environmental and socioeconomic importance; however, it is being altered by physical-chemical and anthropic factors. This forest is located in the southern part of the Mandinga basin, with an extension of 86.51 km², a maximum elevation of 600 masl and is drained by the Mandinga and Pululuya rivers, which extend through the municipal territories of San Julián, Cuisnahuat and Sonsonate. The basin presents 92% of its area for agricultural production (basic grains include: 29.1 km², this being the most representative area, established on slopes between 15% to more than 70%), there is a population density of 173 hab. / km²; These, among other factors, are the causes that prevent the development of environmental goods and services, important for the proper functioning of ecosystems in this territory. For example, the Water Quality Index (ICA, for its acronym in English), which drains into the mangrove, is from regular to very poor; The rivers, without flow in the dry season, facilitate the plugging of the mouth of the estuary, raising (30-33 ‰) or decreasing (0.15-0.45 ‰) periodically the concentration of salt in the estuary water, in addition to increasing the water temperature, for long periods of time. To the foregoing, the usurpation of the mangrove is added, for the construction of houses (13.1 ha) or agricultural growth (22.01 ha). These factors are promoting the development of a monospecific forest of Avicennia germinans, with a Holdrige complexity index (ICH) that reaches a value of 0.094 and is also underdeveloped and deteriorated. Similarly, the salty forest has been reduced in area, from 1954 to 2018 by 33.21% (260.01 ha.), that is, 620.41 ha. to 414.4 ha. respectively; an area smaller than that officially managed by the Ministry of the Environment and Natural Resources (MARN).