Economic Valuation of the Protective Role of Tree Cover to the Roseries Dam and Gezira Scheme

Abstract

There are a number of environmental problems in Sudan, one of them is poor land use practices at the watersheds resulting in increased soil erosion and excessive soil deposition in Sudan Rivers, reservoirs and irrigation canals. This study hypothesizes that, there is a decline in the areas cultivated by some crops in Gezira Scheme in addition to their production and yield mainly due to water shortage as a result of high sediment amount precipitated in Roseries Dam Lake and in the irrigation canals due to land cover removal and mismanagement of land in the watershed areas. The objectives of this study is to estimate the economical losses resulting from declining of the areas cultivated by these crops and their production and yield as a result of irrigation problems, and to valuate the protective role of the vegetation cover to the dam and the irrigation canals . The study area comprises Roseries Dam and Gezira Scheme. This study completely relied on secondary data, which was collected from different relevant sources and some reports and studies. Regression analysis was conducted using SPSS program, where in the first step the area of each crop was taken as dependent variable and regressed on the sediment amount , actual capacity of the dam and sediment amount and actual capacity of the dam together as independent variables. Secondly the production of each crop was taken as dependent variable and regressed on the sediment xi amount, actual capacity and sediment amount and actual capacity together as independent variables. And thirdly the average area and average production for all crops were taken as dependent variables and regressed on the sediment amount, actual capacity and sediment amount and actual capacity together as independent variables. The results showed that: 1. Decline of the annual area cultivated by cotton and groundnut and their production as the sediment amount increased. 2. Increase of the annual area cultivated by sorghum as the sediment amount increased. 3. The effect of both sediment amount and actual capacity on the area cultivated by wheat and its production was almost neglible compared to effect on cotton and sorghum. A number of conclusions and recommendations were stated to improve policy and technical issues needed currently in this aspect. Among these issues are: 1. To minimize the soil erosion and maximize the life and duration of dams, the vegetation cover upstream must be conserved, protected and rehabilitated, also more attention must be given to canals sides plantation. Also the study identified a number of research topics needed to protect dams and irrigation canals.