Complex landscape analysis for satellite and field estimations of soil water content
Giraldo, Mario Andres
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Landscape assessment of soil moisture content is critical in understanding the hydrological cycle at the regional scale. In the hydrological cycle, soil moisture, is the amount of water present within the soil profile. Developing a global soil moisture observing system is of critical importance to the long term monitoring of the water cycle, in areas such as hydrology, climatology, ecology, agriculture, among others. In this research, landscape complexity caused by soil and landuse classes and their relationships with the spatial and temporal variation of soil moisture and ground temperature are analyzed within areas equivalents to the pixel sizes of four environmental satellites. Under the principle that landscape fragments are spatial units in which biophysical factors interact, this research builds in the concept that the integration of remote sensing, hydrology, geostatistics, GIScience and landscape ecology is a valid methodological approach to explore the relationships between fragments and process expanding the inferential capabilities of remote sensing research in complex landscapes. Throughout a GIS- remote sensing analysis of fragmentation I investigate the contribution of soil and landuse classes to landscape complexity as a way to understand the environmental factors influencing the soil moisture point readings of the in situ network at the Little River Watershed (LRW) south Georgia US. Also through a year long field data collection, I established the spatial and temporal variation of soil moisture and ground temperature within and among adjacent homogeneous fields and five landuses (orchard, peanuts, cotton, grass and bare land) to the stations of the in situ network at the LRW. The most important results include: 1. Criteria to define the appropriate pixel sizes of a satellite instrument to capture homogeneous expressions of soil moisture or ground temperature at the LRW. 2. Understanding the contribution to landscape and local complexity added by soil and landuse classes and their weight in point readings. 3. The assessment of soil moisture responds by different soils and land cover combinations. 4. The study of temporal stability of soil moisture in homogeneous fields matching the size of a Lansat TM pixel size. 5. The correlation between point readings and adjacent homogeneous fields under different landuses. 6. The assessment of temporal and spatial variation of soil moisture and ground temperature within and among homogeneous fields matching the size of a Lansat TM pixel size at the LRW. Overall, this research contribute to satellite study of the water cycle by proposing a landscape ecology-hydrology approach to the problems of remote sensing of soil moisture and interpolation of soil moisture-soil temperature point reading within complex landscapes. This work contributes to the knowledge of the variation of biophysical variables for the remote sensing study of energy fluxes and the water cycle within complex landscapes.