Effectiveness of Conservation measures

Ethiopia

land use in the Blue Nile Basin

In Depth Coverage

Evaluation of effectiveness of Soil & Water conservation measures in the Blue Nile using MODIS image based disturbance index (DI)

The principal environmental problem in Ethiopia is land degradation, in the form of soil erosion, gully formation, soil fertility loss and severe soil moisture stress, which is partly the result of loss in soil depth and organic matter (Fitsum et al., 1999). The excessive dependence of the Ethiopian rural population on natural resources, particularly land, as a means of livelihood is an underlying cause for land and other natural resources degradation (EPA, 1998). The Ethiopian highlands, which are the center of major agricultural and economic activities, have been the victim of soil erosion for many years. It is concluded that about half of the highland‘s land area (about 27 Million hectares) is significantly eroded and over one-fourth (14 Million hectares) are seriously eroded. This has already resulted in a reduction in agricultural productivity of 2 to 3% per year, taking a considerable area of arable land out of production. With an aim to mitigate land degradation problems in Ethiopia, the federal and local governments and various NGO’s have undertaken taken different soil and water conservation measures. The effect of these conservation measures is to increase the biomass on the ground and thereby reduce soil loss by reducing the rain fall impact on the soil surface, reducing flow velocity of the surface run off and facilitating for infiltration of water. Nonetheless, the effect of these mitigation measures on soil and water conservation is not known. Hence there is the need to undertake a comprehensive assessment on the effectiveness of the conservation methods. This research will use the disturbance index (DI) (Mildrexler et al. 2007) to assess how effective the conservation measures are from the perspective of increasing the biomass and reducing the land surface temperature thereby minimizing evaporation from soil surface.

  • Link With Climate Change

    Open

    Evaluation of conservation measures helps to assess to what extent efforts to counter the effect of climate change are bearing results. It also helps to convince participating poor farmers to put more effort on conserving the environment so that their vulnerability will decrease. The resilence of the community to naturally occuring phenomenon such as drought or exessive rain and the like depends on the extent of conserving the biodiversity in which the ecosystem services pays back. As such this research will develop a monitoring tool to assess and if necessary correct the commonly practiced conservation practices to suit the situation on the ground.

  • Objectives

    Open

    Various soil and water conservation measures have been conducted in the Blue Nile basin. Various reports are also being released on the success of such measures. Yet no scientific methods are used to justify that conservation efforts are really bearing effort. Recent media releases by Ethiopian government claims that the national forest cover is increased to 9% from the 3% level. On the other hand vast tracts of land are being allotted to commercial farming and large infrastructure (more specifically hydropower) projects are underway. These activities pose a reversing effect on the claimed forest cover achieved. Thus developing a tool which will enable to assess the effectiveness of soil and water conservation measures are of paramount importance. In this regard remote sensing images are proved to be invaluable sources of information which will enable environmental decision makers to make an informed decision based on the facts onm the ground. The proposed assessment method will thus be used to evaluate effectiveness of soil and conservation methods by evaluating how much the ecosystem in the Blue Nile basin is positively or negatively disturbed in the past ten years.

  • Work plan

    Open

    Downloading 10 year MODIS images  Sep, 2011

    Data Analysis                                            Oct, 2011

    Collection of field validation data           Nov, 2011 - Mar, 2012

    Collection of SPOT images                    Oct, 2011

    Validation work                                          Apr-May, 2012

    Peer review                                                 Jun, 2012

    Report writing                                             Jul, 2012

    Submission for publication                      Aug, 2012

  • Schedule

    Open

    report on data Analysis                                 Nov, 2011

    Report on validation work                             June 2012

    Final report                                                       Aug, 2012

  • Technical and Scientific Approach & Methods Proposed

    Open

    The assessment of effectiveness of conservation measures will be made based on the biomass available on the ground and temperature measurements. The enhanced vegetation index (EVI) and the land surface temperature (LST) will be used in this assessment. Enhanced vegetation index is sensitive to vegetation change and thus remote sensing images can describe it on the basis of the reflectance measured on the near infrared (NIR) and red bands. Vegetated areas will generally yield high values because of their relatively high near-infrared reflectance and low visible reflectance and hence have higher EVI values.  Land surface temperature is strongly related to vegetation density due to the cooling effect of the vegetation through latent heat transfer. Thus higher vegetation density results in lower land surface temperature. Capitalizing on these phenomenons long term measurements in form of remote sensing images can be used to see how in time the biomass in the larger extent of the river basin gets on inclining or declining.

     

    The results of the image prodcts should be thoroughly verified on a field trip and other methodologies. The validation work will begin by compiling and thoroughly reviewing ancillary data which will be collected from agricultural bureaus of Amhara, Oromia and Beishangul regions and the federal government offices (Ministry of Agriculture, Ministry of Water and Energy, Disaster prevention and preparedness commission and the productive safety net program). The data may include locations of negative disturbance (Afforestation, physical soil conservation works and irrigated areas) and positive disturbance (drought prevalence, pest, fire, land slide and others) that occurred in the last ten years within the river basin. Agricultural statistics will also be used to validate the occurrence of drought or extensive rainy season. Comparison of the non-spatial agricultural statistics to the disturbance index will be made by summing up the area flagged by a disturbance index each year and comparing it with the area statistics of production for the corresponding year. Reports of forest fire will also be verified using MODIS fire products for the study period.

  • Results

    Open

    The result of this research will be series of maps showing how the environmental disturbance had decreased because of conservation works or a result showing the in effectiveness of the conservation works shown as expanded disturbance in the study area. The result will be submited to a journal for possible publication and further enrichment of the content. The maps will be provided to the Blue Nile River Authority for use in palnning their future conservation activities.

  • Deliverables

    Open

    Maps of environmetal disturbances showing the level of positive/negative disturbance on the environment

    Graphs showing how the disturbance (i.e. positive/negative) had evolved with time

  • Use of Satellite Imagery and GIS Solutions

    Open

    The result of the analysis of the image products will be validated using field visit and high resolution images. High resolution images will be used for the validation work as such part of the validation will be made using SPOT images and part of it will be through actual field trip. The SPOT images will be used to assess how vegetated areas created as part of a conservation program expand with time with in the same time span of the MODIS images used in the analysis (i.e. 2000 to 2010).

  • Local Actions

    Open

    Decision makers at the Blue Nile River Authority will be given an on job training on how to develope the index for use in environmetal monitoring. As our university had established a ground station for satellite image reception a web page will be developed for downloading the images for use by the professionals at the river basin authority and the disturbance index map will be contneously updates. The disturbance index maps will also be distributed for local development agents for awareness on modern monitoring tools.

  • Miscellaneous information / interesting details on project

    Open

    The assessment of level of disturbance in the ecosystem (mainly through measuring total biomass available on the ground) is based on two indicators: the enhanced vegetation index (EVI) and the land surface temperature (LST). Enhanced vegetation index is sensitive to vegetation change and thus remote sensing images can describe it on the basis of the reflectance measured on the near infrared (NIR) and red bands. Vegetated areas will generally yield high values because of their relatively high near-infrared reflectance and low visible reflectance and hence have higher EVI values.  Land surface temperature is strongly related to vegetation density due to the cooling effect of the vegetation through latent heat transfer. Thus higher vegetation density results in lower land surface temperature. Capitalizing on these phenomenons long term measurements in form of remote sensing images can be used to see how in time the biomass in the larger extent of the river basin gets on inclining or declining. The cause for the disturbance must however be properly justified as there are various causes for disturbance. Disease, fire, drought, land slide, urbanization, infrastructure expansion, resettlement, clear cutting and climate change effects are among the factors causing a reduction in the biomass and hence results in positive disturbance whereas reforestation and irrigation result in negative disturbance. Physical conservation measures (bund) retain part of the water from precipitation making it available for vegetation growth thereby increases the total biomass on the ground. The availability of the biomass on the long term basis may be used as an indicator to the effectiveness of the conservation measures specifically in terms of reducing rainfall impact, breaking surface runoff velocity and facilitating infiltration.

    Disturbance may be short lived or prolonged. The usual cycle of cropping and harvesting will eventually cause in increased EVI and reduced LST during the peak vegetation season. This is usually followed by a reduced EVI and increased LST at harvest. On the other hand drought, disease and urbanization result in prolonged reduction in the EVI and thereby an increase in LST. Thus the length of prevalence of the disturbance index tells the type of phenomena causing the disturbance (Positive or negative). Seasonal increase or decreases in DI that occur mainly due to vegetation phenology fall within an explainable range of variability. Both instantaneous phenomenon (fire, disease and the like) and prolonged (drought, urbanization and the like) extends out of the natural range of variability. Values within +/-1 standard deviation of the long term mean are considered to be within the natural variability. A departure higher than this will be considered a flag for potential disturbance areas.


    The ability of the calculated disturbance index to catch these phenomenon should however be verified in the field. The validation work will begin by compiling and thoroughly reviewing ancillary data which will be collected from agricultural bureaus of Amhara, Oromia and Beishangul regions and the federal government offices (Ministry of Agriculture, Ministry of Water and Energy, Disaster prevention and preparedness commission and the productive safety net program). The data may include locations of negative disturbance (Afforestation, physical soil conservation works and irrigated areas) and positive disturbance (drought prevalence, pest, fire, land slide and others) that occurred in the last ten years within the river basin. Agricultural statistics will also be used to validate the occurrence of drought or extensive rainy season. Comparison of the non-spatial agricultural statistics to the disturbance index will be made by summing up the area flagged by a disturbance index each year and comparing it with the area statistics of production for the corresponding year. Reports of forest fire will also be verified using MODIS fire products for the study period.

  • Region Name

    Open
    Horn of Africa
  • Partners involved in project

    Open
    Blue Nile Water Institute