Rwanda Agriculture – NASA DEVELOP Summer 2013 @ Langley Research Center & Wise County


>>[Martine]: Rwanda is one of the most densely
populated countries in Africa. With more than 90 percent its people engaged
in agricultural activities. Due to its steep topography, human settlement
and unmonitored agricultural practices are increasingly alarming soil degradation.
That has direct relationships with decreased agricultural yields and increased risk of
flood and landslides. With human settlement playing an integral
role in agricultural practices within the country,
the Rwanda Agriculture team hopes to identify possible resettlement areas for populations
living in the western part of the country. This will help prohibit overexploitation of
natural resources and thus reduce the risk of environmental disasters,
all of which are known to adversely affect the agriculture produced.>>[Abednego]: Our project end-user included
the World Bank Open Data Initative In which our results and data were actually
included in their actual result product. So that World Bank decision making regarding
Rwanda. Our team has also been in contact with officials for the Rwanda Ministry of
Agriculture in which they had expressed interest in mapping and researching soil erosion. The
partnership helped us get deeper understanding the needs and concerns of the agricultural
settler.>>[Angela]: In order to determine areas most
vulnerable to soil erosion we used RUSLE(the Revised Universal Soil Loss Equation ).
RUSLE is dependent upon the following factors: Erosivity, soil erodibility, slope length,
slope steepness and cover management. The separate factors were determined individually
and integrated together such that the average annual erosion per unit
land area is represented as linear function.>>[Dieudonne]: Soil Erosion is heavily dependent
on how much rainfall a region gets at any given point.
Rainfall data was collected from the NASA MERRA database by considering monthly rainfall
over 11 years from 2002 to 2012, using GIS and Python, monthly and annual averages
rainfall maps were created. The maps show that Rwanda receives between
1000 to 2000 millimeters of rain each year. The rainfall averages were used in the erosivity factor of the RUSLE soil
loss equation to identify places most effected by soil erosion and places for resettlement.>>[Angela]: In the soil loss scheme, soil
type plays an essential role. The soil erodibility factor of RUSLE takes
into account this essential aspect of soil erosion. The soil erodibility factor is generated through
a soil map supplied by the soil and terrain databases
for Central Africa as a joint effort of the International Soil Reference and Information
Center at the University of Ghent in 2007. This database included variables provided
as ArcGIS shapefiles that could in turn be used to derive the soil erodibility factor.>>[Emmanuel]: One of the factors responsible
for soil erosion is the elevation structure of land and the steepness and length of the
slope. The Western part of Rwanda is characterized by mountainous terrain making it liable for
soil erosion using ASTER we were able to obtain imagery that helped us classify land based
on its length and steepness. This information coupled with other factors
will help us in identifying areas for human resettlement.>>{Merna}: To derive landcover data, Landsat
8 image was acquired from April 2013 and computed supervised landcover classification
using ArcGIS.>>[Nirav]: By evaluating risk areas that are
a high risk for soil erosion and correlating that population distribution.
Calculated using various datasets from NASA including the Suomi NPP satellite�s VIIRS sensor specifically the Day Night Band
looking at Night Lights and correlating that with landcover
and how people are using the land to identify where the people are distributed. And by knowing where the people are distributed
on a 100 meter by 100 meter grid cell resolution we are able to make recommendations on redistributing
these people if they are in areas of soil loss.>>[Merna]: In conclusion our results show
the northwestern region of Rwanda is at the highest risk of soil erosion,
our population map points out dense settlements located near those high risk zones. In the future we would like to continue our
collaboration with the Rwandan Embassy and the Rwandan government
to pursue quantifying the risk of soil degradation and provide useful methodology that would
be in the government effort in soil conservation.

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