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" Applications of remote sensing and GIS in surface hydrology: Snow cover, soil moisture and precipitation "
Xianwei Wang
X. Wang
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Latin Dissertation
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English
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| Record Number
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55506
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TL25460
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3303907
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| Main Entry
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Xianwei Wang
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| Title & Author
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Applications of remote sensing and GIS in surface hydrology: Snow cover, soil moisture and precipitation\ Xianwei Wang
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| College
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The University of Texas at San Antonio
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| Date
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2008
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| Degree
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Ph.D.
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2008
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| Page No
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245
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| Abstract
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Studies on surface hydrology can generally be classified into two categories, observation for different components of surface water, and modeling their dynamic movements. This study only focuses on observation part of surface water components: snow cover, soil moisture, and precipitation. Moreover, instead of discussion on the detailed algorithm and instrument technique behind each component, this dissertation pours efforts on analysis of the standard remotely sensed products and their applications under different settings. First in Chapter 2, validation of MODIS Terra 8-day maximum snow cover composite (MOD10A2) in the Northern Xinjiang, China, from 2000-2006, shows that the 8-day MODIS/Terra product has high agreements with in situ measurements as the in situ snow depth is larger or equal to 4 cm, while the agreement is low for the patchy snow as the in situ snow depth less than 4 cm. According to the in situ observation, this chapter develops an empirical algorithm to separate the cloud-covered pixels into snow and no snow. Continued long-term production of MODIS-type snow cover product is critical to assess water resources of the study area, as well as other larger scale global environment monitoring. Terra and Aqua satellites carry the same MODIS instrument and provide two parallel MODIS daily snow cover products at different time (local time 10:30 am and 1:30 pm, respectively). Chapter 3 develops an algorithm and automated scripts to combine the daily MODIS Terra (MOD10A1) and Aqua (MYD10A1) snow cover products, and to automatically generate multi-day Terra-Aqua snow cover image composites, with flexible starting and ending dates and a user-defined cloud cover threshold. Chapter 4 systematically compares the difference between MODIS Terra and Aqua snow cover products within a hydrologic year of 2003-2004, validates the MODIS Terra and Aqua snow cover products using in situ measurements in Northern Xinjiang, and compares the accuracy among the standard MODIS Terra and Aqua snow cover products, and the new combined daily and multi-day composite from both MODIS Terra and Aqua daily products. In Chapter 5, utilizing the new cloud-low multi-day composite of MODIS Terra and Aqua snow cover products, several new methods are developed to study the spatiotemporal variation of snow cover conditions from different aspects at the Northern Xinjiang and on the Central Tianshan Mountains, mainly in China, partly covering Kazakhstan and Kyrgyzstan. Secondly, Chapter 6 investigates the feasibility to indirectly map root-zone soil moisture using optical remote sensing techniques and in situ measurements. Specifically, covariation of root-zone soil moisture with the normalized difference of vegetation index (NDVI) from MODIS observation is studied at three sites (New Mexico, Arizona, and Texas). The three sites represent two types of vegetation (shrub and grass) and two types of climate conditions: arid/semi-arid (New Mexico and Arizona) and humid (Texas). Results show that the root-zone soil moisture has significant linear correlation with vegetation (NDVI). Finally, Chapter 7 validates and compares the NEXRAD Stage III and MPE precipitation products using a high density rain gauge network on the Upper Guadalupe River Basin of the Texas Hill Country in 2001 and 2004. (Abstract shortened by UMI.)
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Health and environmental sciences; Earth sciences; GIS; Precipitation; Remote sensing; Snow cover; Soil moisture; Hydrology; Environmental science; 0799:Remote sensing; 0768:Environmental science; 0388:Hydrology
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X. Wang
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The University of Texas at San Antonio
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