Rapid mapping of hydraulic conductivity in tropical watershed
Abstract
Modeling of water and solute dynamics in soils is a major focus in watershed
management. In order to model the water flow, soil hydraulic properties have to
be known. Spatial information on basic soil data such as particle-size distribution,
organic carbon content and bulk density are often available. However, spatial
information on soil hydrologic data, which are necessary for soil transport
models, is usually not available. Soil hydrologic data are expensive and difficult
to obtain on a large area and are often predicted from physical data like particlesize
distribution using pedotransfer functions. This study set out to develop a
rapid methodology based on relating soil hydraulic conductivity to soil spectral
reflectance and using a soil spectral library approach to predict soil hydraulic
conductivity in a large area of a watershed.
Soil spectral reflectance was correlated to field saturated hydraulic conductivity
and the correlation found to be consistent Ks (index of agreement, d = 0.87, and
r2 =0.63). This consistent relationship provided a foundation for using a spectral
calibration model in conjunction with a georeferenced library to predict surface Ks
over a large area. The spectral library contained spectral data for the points in
the study area for which direct measurement was not made.
In the build up of a map for the whole watershed, spatial variability of surface Ks
was studied using classical and geostatistical concepts. Semivariograms were
intensively used with actual and kriged estimates to produce an accurate surface
interpolation map of surface K, in the watershed. The map, which shows a
general trend of surface K, with altitude, will be a great asset for the hydrologic
modeling of watershed responses.
Citation
Omuto, C. T(2003). The recommendation is that seeking proper medical attention from qualified medical personnel during illness would lead to improvement of maternal nutritional status and in the long run reduce maternal morbidity and mortality. xvSponsorhip
University of NairobiPublisher
Department of Agricultural Engineering, University of Nairobi,
Description
Msc-Thesis