Effects of deforestation and afforestation on water availability for dry bean production in Haiti

Haitian watersheds suffer from a lack of environmental management and the absence of conservation practices, which impairs natural resources and agricultural productivity. This is aggravated by harvesting trees to compensate for reduced crop production and income. Deforestation can further deteriorate the natural and agricultural systems by increasing the temporal variability of water availability, often realized in the forms of floods and droughts. The goal of this study was to determine the effects of both deforestation and afforestation on water resources and agricultural productivity. We selected the Courjolle River watershed and its downstream irrigation districts because they represent the linkage between the upstream forest and downstream agricultural areas. Watershed hydrology and dry bean growth were simulated with the Soil and Water Assessment Tool (SWAT) model and the CSM-CROPGRO-Dry bean model of the Decision Support System for Agrotechnology Transfer (DSSAT). The parameters for both models were calibrated to streamflow and dry bean growth measurements that were made in the study areas. Deforestation and afforestation scenarios were developed based on an understanding of the local landscape. The modeling experiment showed that deforestation could decrease water availability and stability, causing a decrease in dry bean production, while afforestation had the opposite effect. An increase of the afforested areas from 25% to 100% of the watershed increased the streamflow by 2-7%, compared to the current land cover, during dry periods. On the other hand, an increase in deforested areas decreased the amount of available water for downstream agricultural areas by 6-24%. Potential changes in the water availability due to the land cover changes then affected the yield of dry bean grown in the downstream irrigation areas, from - 42-24% under the deforestation and afforestation scenarios. The study demonstrated how improved hydrologic stability due to an increase in tree cover could promote agricultural production. It also showed that afforestation could be an effective way to manage both the natural and agricultural resources in Haiti, improving the environmental sustainability of the watershed and the economic sustainability of local smallholder farmers.

Automated summary

The lack of environmental management and conservation practices in Haitian watersheds leads to impaired natural resources and agricultural productivity. Deforestation to compensate for reduced crop production worsens the situation. The study demonstrates that afforestation can improve water availability and stability, increasing agricultural production.