State–space prediction of field–scale soil water content time series in a sandy loam

1999 ◽  
Vol 50 (1) ◽  
pp. 85-93 ◽  
Author(s):  
O Wendroth ◽  
H Rogasik ◽  
S Koszinski ◽  
C.J Ritsema ◽  
L.W Dekker ◽  
...  
2012 ◽  
Vol 9 (7) ◽  
pp. 8027-8062 ◽  
Author(s):  
X. Pan ◽  
J. Zhang ◽  
P. Huang ◽  
K. Roth

Abstract. We explore the feasibility to quantify the field-scale soil water dynamics through time series of GPR (ground-penetrating radar) measurements. They bridge the gap between accurate and well-established point measurements and the field-scale where soil hydrology issues are addressed. Working on a 40 m × 50 m area in a heterogeneous agricultural field, we obtain a time series of radargrams after a heavy rainfall event. On the one hand, these yield a three-dimensional representation of the subsurface architecture, in particular of the layer boundary that originates from paleo-sand dunes and of a number of clay inclusions in an otherwise rather uniform sand. On the other hand, the total soil water volume between the surface and the layer boundary is obtained. We assess the precision and the accuracy of these quantities and conclude that the method is sensitive enough to capture the spatial structure of the changing soil water content. While the sensitivity of the method still needs to be improved, it already produced useful information to understand the observed patterns in crop height and it yielded insight into the dynamics of soil water content at this site including the effect of evaporation.


2012 ◽  
Vol 16 (11) ◽  
pp. 4361-4372 ◽  
Author(s):  
X. Pan ◽  
J. Zhang ◽  
P. Huang ◽  
K. Roth

Abstract. We explore the feasibility to quantify the field-scale soil water dynamics through time series of GPR (ground-penetrating radar) measurements, which bridge the gap between point measurements and field measurements. Working on a 40 m × 50 m area in a heterogeneous agricultural field, we obtain a time series of radargrams after a heavy rainfall event. The data are analysed to simultaneously yield (i) a three-dimensional representation of the subsurface architecture and (ii) the total soil water volume between the surface and a reflection boundary associated with the presence of paleo sand dunes or clay inclusions in a rather uniform sand matrix. We assess the precision and the accuracy of these quantities and conclude that the method is sensitive enough to capture the spatial structure of the changing soil water content in a three-dimensional heterogeneous soil during a short-duration infiltration event. While the sensitivity of the method needs to be improved, it already produced useful information to understand the observed patterns in crop height and it yielded insight into the dynamics of soil water content at this site including the effect of evaporation.


2013 ◽  
Vol 8 (2) ◽  
pp. 99
Author(s):  
Ali Rahmat ◽  
Afandi ◽  
Tumiar K Manik ◽  
Priyo Cahyono

Irigasi pada tanaman nanas sangat penting karena mempengaruhi pertumbuhan dan produksi namun biayanya sangat mahal. Penelitian ini bertujuan untuk mengetahui pengaruh irigasi dan mulsa organik pada kadar air tanah dan pertumbuhan nanas. Penelitian ini dilakukan menggunakan perlakuan faktorial (5 x 2) dalam rancangan acak kelompok dengan tiga ulangan. Faktor pertama adalah panjang waktu irigasi (I), yang terdiri dari 5 waktu yaitu tanpa irigasi (I0), irigasi 1 bulan (I1), irigasi 2 bulan (I2), irigasi 3 bulan (I3), dan irigasi 4 bulan (I4). Faktor kedua adalah dosis kulit singkong (mulsa organik) terdiri dari 2 level 0 ton/ha (M0) dan 50 ton/ha (M1). Kadar air tanah diukur menggunakan Diviner 2000. Data kadar air tanah dianalisis dengan time series. Pertumbuhan tanaman dianalisis keragamannya dan diuji BNT pada taraf 5 %. Hasil penelitian menunjukkan kulit singkong 50 ton/ha pada umumnya hanya bertahan 2,5 bulan untuk mempertahankan kadar air. Mulsa kulit singkong lebih berperan ketika tanah mulai mengering. Pemberian mulsa kulit singkong berpengaruh terhadap tinggi dan berat basah tanaman sedangkan perlakuan, irigasi secara terpisah hanya berpengaruh terhadap berat basah tanaman. Interaksi antara irigasi dan kulit singkong berpengaruh terhadap berat basah tanaman. Meskipun kadar air tanah tersedia cukup saat memasuki musim hujan, namun tidak efektif dalam memulihkan keragaan tanaman nanas. Pemulihan terjadi setelah memasuk musim hujan dimana kadar air tanah tinggi.


2012 ◽  
Vol 111 ◽  
pp. 105-114 ◽  
Author(s):  
Basem Aljoumani ◽  
Jose A. Sànchez-Espigares ◽  
Nuria Cañameras ◽  
Ramon Josa ◽  
Joaquim Monserrat

2017 ◽  
pp. 1.9-1.19 ◽  
Author(s):  
Afua Mante ◽  
Ramanathan Sri Ranjan

The HYDRUS (2D/3D) modeling tool was used to simulate water flow through subsurface-drained sandy loam soil under potato (Solanum tuberosum) cultivation in Southern Manitoba. The model was used to simulate water flow through a 2-D model domain of dimensions, 15 m width × 2.5 m depth. The model was calibrated and validated with field data measured during the growing season of year 2011 at the Hespler Farms, Winkler, Manitoba. Field measurements, including soil water content and watertable depth, for two test plots under subsurface free drainage were used for the calibration and validation. Weather data were also obtained to estimate reference crop evapotranspiration, which was used as input data in the model. Based on the reference crop evapotranspiration, and crop coefficient of the potato crop, the actual crop evapotranspiration was estimated and compared to the simulated actual crop evapotranspiration results. The results showed that the model was able to account for 50% to 78% of the variation in the estimated actual crop evapotranspiration. With respect to water flow through the soil, the observed soil water content and the simulated soil water content were compared using graphical and quantitative analysis. Based on the coefficient of determination (R2), the model accounted for 68% to 89% variation in the observed data. The intercept of the regression line varied from 0.01 to 0.08, and the slope, 0.75 to 0.99. The Nash–Sutcliffe modeling efficiency coefficient (NSE) varied from 0.62-0.89, the Percent bias (PBIAS) values varied from -1.99% to 1.16%. The root mean square error-observations standard deviation ratio (RSR) values varied from 0.33 to 0.61. The values for the evaluation parameters show that the model was able to simulate the water flow through the soil profile reasonably well.


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