Geospatial assessment on land-use changes of Home Gardens in Upper Mahaweli Catchment in Sri Lanka

Abstract

Land use changes are altering the hydrologic regimes in a catchment and have potentially large impacts on its water resources. Tree rich Home Gardens (HGs)in the Upper Mahaweli Catchment (UMC) play a vital role in catchment protection while providing other ecological services especially in areas where lack of forest cover. The main objective of this research study was to assess land-use changes of HGs in UMC and to analyze determinants for changes. An integrated approach was adopted for the methodology by integrating geo-spatial technologies with socio-economic modeling. Multi-temporal satellite imagery taken in 1990, 2005 and 2017 used for spatial assessment. Socioeconomic assessment was carried out to assess determinants for changes by developing a Binary logistic regression model using spatial, biophysical, and socio-economic determinants as predictor variables. According to spatial assessment a significant change has been revealed in Nuwara Eliya District of the UMC from 1990 to 2017. The most prominent changes have been occurred during 1990-2005 compared with to 2005 - 2017. During these periods HG land use has been increased by 14.85 % and 5.25%. In contrast, the distinct land use change was the increment of annual crop-based land use by 44.95% during 1990-2005 period. Spatial determinants were positively influenced for the conversion of HGs into other land uses. All other socio-economic determinants except age of the household head were significant for land use changes. Since conversion of HGs into annual crop-based land use would induce reduce tree cover of the UMC which lead to hinder ecological services of catchment protection function derived from HGs, policy strategies should focus on providing sufficient incentives to enhance tree cover of the HGs to control the conversion and to restore ecological services.