Erosion and Sedimentation of The Grey River of Haiti

Abstract

<b><sc>Abstract</sc></b> Fluvial erosion in Haiti, especially in the Rivière Grise, is a serious natural phenomenon that is aggravated day by day by human activities such as loss of riparian protection in agricultural land and new infrastructure located in vulnerable areas. According to a World Bank study on natural resource management in Haiti, in 1990 the estimates of soil loss in watersheds varies from 7.5 MT/ha/year to 750 MT/ha/year. In April 2015, the Ministry of Environment in Haiti estimated that more than a third of useful land is located at elevations between 200 m and 500 m, 40% above 500 m, and 17% above 800 m altitudes. Only 21% of the land has a slope gradient of less than 10%. Climatic factors, natural phenomena such as hurricanes and earthquakes, and human activities significantly affected the watersheds during the last 20 years. The Grey River has been impacted severely, threatening the existing agricultural land and biodiversity, which are often located along the riverbanks. This research focuses on the analysis of the main natural factors causing the phenomenon of soil water erosion in the Cul de Sac Plain basin, particularly the Grey River. The research focuses on the identification of downstream and upstream erosion risks and associated problems contributing to the estimation of erosion and sediment transport. Expected results aim at making proposals on soil conservation measures in the Grey River basin reduce the quantity of sediments. The methodology is based on digital mapping techniques including the acquisition and processing of satellite images combined with other geographic data in a Geographic Information System (GIS) tool. Modeling of annual soil loss (A) will be conducted using the U.S. Army Corps of Engineers (USACE) – Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) (USACE, 2022). The parameters to be estimated are related to environmental conditions such as the erosivity index (R), soil erodibility (K), topographic factor (LS), crop management (C), and conservation practice factor (P), then applying the Revised Universal Soil Loss Equation (RUSLE) formula as a basis for calculating annual erosion (A) (Renard et al., 1997). A= R K LS C P (1) A profile analysis along the Gray River will be performed by following the distribution of sub-basins, helping to determine sediment accumulation sites that are potential sites of water overflow into neighboring areas. The study will also reveal the major drivers of in-stream erosion related to land use, topography, and urbanization. This often leads to socio-economic consequences such as loss of agricultural land, infrastructure (roads, bridges, etc.), public facilities or loss of life and property, and environmental consequences such as depopulation of marine flora, and loss of animal species habitats.