Northwest Watershed Research Center

Boise, ID, United States

Northwest Watershed Research Center

Boise, ID, United States
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Green T.R.,Center for Agricultural Resources Research | Seyfried M.S.,Northwest Watershed Research Center | Jones A.S.,Cooperative Institute for Research in the AtmosphereColorado State UniversityFort Collins | Grazaitis P.J.,U.S. Army
Water Resources Research | Year: 2017

Soil moisture can be estimated at coarse resolutions (>1 km) using satellite remote sensing, but that resolution is poorly suited for many applications. The Equilibrium Moisture from Topography, Vegetation, and Soil (EMT+VS) model downscales coarse-resolution soil moisture using fine-resolution topographic, vegetation, and soil data to produce fine-resolution (10-30 m) estimates of soil moisture. The EMT+VS model performs well at catchments with low topographic relief (≤124 m), but it has not been applied to regions with larger ranges of elevation. Large relief can produce substantial variations in precipitation and potential evapotranspiration (PET), which might affect the fine-resolution patterns of soil moisture. In this research, simple methods to downscale temporal average precipitation and PET are developed and included in the EMT+VS model, and the effects of spatial variations in these variables on the surface soil moisture estimates are investigated. The methods are tested against ground truth data at the 239 km2 Reynolds Creek watershed in southern Idaho, which has 1145 m of relief. The precipitation and PET downscaling methods are able to capture the main features in the spatial patterns of both variables. The space-time Nash-Sutcliffe coefficients of efficiency of the fine-resolution soil moisture estimates improve from 0.33 to 0.36 and 0.41 when the precipitation and PET downscaling methods are included, respectively. PET downscaling provides a larger improvement in the soil moisture estimates than precipitation downscaling likely because the PET pattern is more persistent through time, and thus more predictable, than the precipitation pattern. © 2017. American Geophysical Union.

Li R.,Inner Mongolia Agricultural University | Shi H.,Inner Mongolia Agricultural University | Akae T.,Okayama University | Zhang X.,General Administration of Inner Mongolia Hetao Irrigation District | Flerchinger G.N.,Northwest Watershed Research Center
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2010

In accordance with the prevention of soil salination and water-saving irrigation in autumn in Inner Mongolia Hetao irrigation district, the reasonable water-saving irrigation scheme in autumn was quantificationally established by using SHAW model in theory, which aimed at the different salinized soils. For slight salinized soils, autumn irrigation quota was from 142 to183 mm between September 28 and October 23. For moderate salinized soils, autumn irrigation quota was from 180 to 200 mm between October 14 and 18. For serious salinized soils, planting sunflower instead of wheat, autumn irrigation quota was from 200 to 225 mm. In the studied irrigation district, autumn irrigation is supposed to be reasonably arranged according to the different salinized soils.

Li R.,Inner Mongolia Agricultural University | Shi H.,Inner Mongolia Agricultural University | Flerchinger G.N.,Northwest Watershed Research Center | Akae T.,Okayama University
Geoderma | Year: 2012

Inner Mongolia Hetao Irrigation District, in north of China, is typical of seasonal frozen soil areas in the region. Irrigation in autumn is required to leach soil salt and to provide a reserve of soil water for the next year's crop. However, improper autumn irrigation results in the secondary salinization of soil. The objective of this study is to simulate soil water and heat dynamics during winter period with the one-dimensional Simultaneous Heat and Water (SHAW) model to assess its capability for simulating overwinter water storage. SHAW model soil parameters were calibrated by data of 1995-1996 and 2002-2004 and validated by data of 1996-2001 and 2005-2006 using field measured soil water contents and temperatures during freezing and thawing periods. Using calibrated and validated soil parameters, the paper simulates the process of soil freezing-thawing, and the dynamic variation of moisture-heat transfer, including soil water content, temperature, frost depth, soil evaporation, and water flux in the seasonal freezing-thawing period. These are useful to determine proper autumn irrigation management, and can be used in future research to address overwinter solute migration to reduce soil secondary salinization. © 2012 Elsevier B.V.

Li R.,Inner Mongolia Agricultural University | Shi H.,Inner Mongolia Agricultural University | Flerchinger G.N.,Northwest Watershed Research Center | Zou C.,Inner Mongolia Agricultural University
Geoderma | Year: 2013

Taking the Inner Mongolia Hetao Irrigation District (IMHID) agricultural production region as a background and based on field data and local meteorological data, the influence of antecedent soil water storage (ASWS) on water and heat status was simulated and analyzed using the SHAW model during the seasonal freezing-thawing period. The results showed that the amount of ASWS prior to soil freezing can influence the depth of freezing and penetration of low temperatures. When ASWS within the surface 1. m is less than or equal to 150. mm, soil water storage (SWS) was always increasing over the winter period. However, for ASWS greater than 150. mm, SWS went through 3 phases: at first it decreased, later it increased, and eventually it decreased again. During soil freezing, the amount of upward water transfer made up the deficit caused by evaporation and percolation for ASWS less than or equal to 150. mm. Conversely, the amount of percolation was greater than that of upward transfer for ASWS greater than 150. mm. During soil thawing, water continued to transfer from lower soil layers to upper layers and overtook evaporation and percolation for ASWS less than or equal to 210. mm. However, the amount of evaporation and percolation was greater than the upward transfer for ASWS larger 210. mm. These results may be used to assist in appropriate irrigation scheme in autumn, agricultural irrigation water management and research on reducing soil secondary salinization. © 2013 Elsevier B.V.

Tinkham W.T.,University of Idaho | Smith A.M.S.,University of Idaho | Marshall H.-P.,Boise State University | Link T.E.,University of Idaho | And 2 more authors.
Remote Sensing of Environment | Year: 2014

There is increasing need to characterize the distribution of snow in complex terrain using remote sensing approaches, especially in isolated mountainous regions that are often water-limited, the principal source of terrestrial freshwater, and sensitive to climatic shifts and variations. We apply intensive topographic surveys, multi-temporal LiDAR, and Random Forest modeling to quantify snow volume and characterize associated errors across seven land cover types in a semi-arid mountainous catchment at a 1 and 4. m spatial resolution. The LiDAR-based estimates of both snow-off surface topology and snow depths were validated against ground-based measurements across the catchment. LiDAR-derived snow depths estimates were most accurate in areas of low lying vegetation such as meadow and shrub vegetation (RMSE. = 0.14. m) as compared to areas consisting of tree cover (RMSE. = 0.20-0.35. m). The highest errors were found along the edge of conifer forests (RMSE. = 0.35. m), however a second conifer transect outside the catchment had much lower errors (RMSE. = 0.21. m). This difference is attributed to the wind exposure of the first site that led to highly variable snow depths at short spatial distances. The Random Forest modeled errors deviated from the field measured errors with a RMSE of 0.09-0.34. m across the different cover types. The modeling was used to calculate a theoretical lower and upper bound of catchment snow volume error of 21-30%. Results show that snow drifts, which are important for maintaining spring and summer stream flows and establishing and sustaining water-limited plant species, contained 30. ±. 5-6% of the snow volume while only occupying 10% of the catchment area similar to findings by prior physically-based modeling approaches. This study demonstrates the potential utility of combining multi-temporal LiDAR with Random Forest modeling to quantify the distribution of snow depth with a reasonable degree of accuracy. © 2013 Elsevier Inc.

Ma L.,U.S. Department of Agriculture | Flerchinger G.N.,Northwest Watershed Research Center | Ahuja L.R.,U.S. Department of Agriculture | Sauer T.J.,U.S. Department of Agriculture | And 3 more authors.
Transactions of the ASABE | Year: 2012

Correct simulation of surface energy balance in a crop canopy is critical for better understanding of soil water balance, canopy and soil temperature, plant water stress, and plant growth. One existing effort is to incorporate the surface energy balance in the Simultaneous Heat and Water (SHAW) model into the Root Zone Water Quality Model (RZWQM). In this study, an improved version of the RZ-SHAW (RZWQM-SHAW) hybrid model was tested for energy balance components, canopy and soil temperature, evapotranspiration (ET), and soil water content against eddy covariance data measured in a soybean canopy and against predictions of the original SHAW and RZWQM models. The experiment was first used previously to test the SHAW model for radiation energy fluxes within the canopy without examining the energy balance components, soil water balance, and soil temperature. The same parameters from that study were used in both the SHAW model and RZ-SHAW hybrid model without any modification in this study. In terms of root mean squared error (RMSE), both RZ-SHAW and SHAW simulated net radiation, sensible heat, and latent heat well. However, the ground heat flux simulated by RZ-SHAW was less accurate, with RMSE of 28.9 W m -2 compared to 22.6 W m -2 with SHAW, which could be due to differences in simulated soil evaporation. Simulated soil temperature at both 1.5 cm and 4.5 cm depths with RZ-SHAW was comparable to that of SHAW, with RMSE of 2.18°C and 2.23°C, respectively, compared to 2.13°C and 2.20°C with SHAW. Similarly, simulated canopy temperature was essentially the same, with RMSE values of 1.77°C with RZ-SHAW and 1.69°C with SHAW. Simulated surface soil water content was reasonable for both models. Simulated ET had an RMSE of 0.069 cm d -1 with RZ-SHAW and 0.074 cm d -1 with SHAW. The new RZ-SHAW model was an improvement over the original RZWQM model in simulating soil temperature and moisture, in addition to its ability to provide complete energy balance and canopy temperature. © 2012 American Society of Agricultural and Biological Engineers.

Wilcox B.P.,Texas A&M University | Turnbull L.,Arizona State University | Young M.H.,University of Texas at Austin | Williams C.J.,Northwest Watershed Research Center | And 7 more authors.
Ecohydrology | Year: 2012

Across the globe, native savannas and woodlands are undergoing conversion to exotic grasslands. Here we summarize the current state of knowledge concerning the ecohydrological consequences of this conversion for the cold deserts (Great Basin, Colorado Plateau) and the warm deserts (Mojave, Sonoran, Chihuahuan) of North America. Our analysis is based on a synthesis of relevant literature, complemented by simulation modelling with a one-dimensional, soil water redistribution model (HYDRUS-1D) and a hillslope runoff and erosion model (MAHLERAN). When shrublands are invaded by grasses, many changes take place: rooting depths, canopy cover, species heterogeneity, water use, and fire regimes are radically altered. These changes then have the potential to alter key ecohydrological processes. With respect to the processes of runoff and erosion, we find that grass invasion influences cold and warm deserts in different ways. In cold deserts, runoff and erosion will increase following invasion; in particular, erosion on steep slopes (>15%) will be greatly accelerated following burning. In addition, evapotranspiration (ET) will be lower and soil water recharge will be higher-which after several decades could affect groundwater levels. For warm deserts, grass invasion may actually reduce runoff and erosion (except for periods immediately following fire), and is likely to have little effect on either ET fluxes or soil water. Significant gaps in our knowledge do remain, primarily because there have been no comprehensive studies measuring all components of the water and energy budgets at multiple scales. How these changes may affect regional energy budgets, and thus weather patterns, is not yet well understood. © 2011 John Wiley & Sons, Ltd.

Reba M.L.,Northwest Watershed Research Center | Marks D.,Northwest Watershed Research Center | Seyfried M.,Northwest Watershed Research Center | Winstral A.,Northwest Watershed Research Center | And 2 more authors.
Water Resources Research | Year: 2011

A modeling data set (meteorological forcing data, geographic information system data, and validation data) is presented for water years 1984 through 2008 for a snow-dominated mountain catchment. The forcing data include hourly precipitation, wind speed and direction, air and soil temperature, relative humidity, dew point temperature, and incoming solar and thermal radiation from two sites. Validation data include stream discharge, snow water equivalent, snow depth, soil moisture, and groundwater elevation. These data will improve the development, testing, and application of the next generation of hydrologic models. Copyright 2011 by the American Geophysical Union.

Alkhaier F.,University of Twente | Su Z.,University of Twente | Flerchinger G.N.,Northwest Watershed Research Center
Hydrology and Earth System Sciences | Year: 2012

The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS) to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012). The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous. © 2012 Author(s). CC Attribution 3.0 License.

Alkhaier F.,University of Twente | Flerchinger G.N.,Northwest Watershed Research Center | Su Z.,University of Twente
Hydrology and Earth System Sciences | Year: 2012

Understanding when and how groundwater affects surface temperature and energy fluxes is significant for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To investigate the shallow groundwater effect under bare soil conditions, we numerically exposed two soil profiles to identical metrological forcing. One of the profiles had shallow groundwater. The different responses that the two profiles manifested were inspected regarding soil moisture, temperature and energy balance at the land surface. The findings showed that the two profiles differed in three aspects: the absorbed and emitted amounts of energy, the portioning out of the available energy and the heat fluency in the soil. We concluded that due to their lower albedo, shallow groundwater areas reflect less shortwave radiation and consequently get a higher magnitude of net radiation. When potential evaporation demand is sufficiently high, a large portion of the energy received by these areas is consumed for evaporation. This increases the latent heat flux and reduces the energy that could have heated the soil. Consequently, lower magnitudes of both sensible and ground heat fluxes are caused to occur. The higher soil thermal conductivity in shallow groundwater areas facilitates heat transfer between the top soil and the subsurface, i.e. soil subsurface is more thermally connected to the atmosphere. For the reliability of remote sensors in detecting shallow groundwater effect, it was concluded that this effect can be sufficiently clear to be detected if at least one of the following conditions occurs: high potential evaporation and high contrast between day and night temperatures. Under these conditions, most day and night hours are suitable for shallow groundwater depth detection. © 2012 Author(s). CC Attribution 3.0 License.

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