A distributed agro-hydrological model for irrigation water demand assessment

Abstract The actual irrigation water demand in a district in Sicily (Italy) was assessed by the spatially distributed agro-hydrological model SIMODIS (SImulation and Management of On-Demand Irrigation Systems) . For each element with homogeneous crop and soil conditions, in which the considered area can be divided, the model numerically solves the one-dimensional water flow equation with vegetation parameters derived from Earth Observation data. In SIMODIS, the irrigation scheduling is set by means of two parameters: the threshold value of soil water pressure head in the root zone, h m , and the fraction of soil water deficit to be re-filled, Δ . This study investigated the possibility of identifying a couple of irrigation parameters ( h m , Δ ) which allowed to reproduce the actual irrigation water demand, given that the study area was adequately characterized with regard to the spatial distribution of the soil hydraulic properties and the vegetation conditions throughout the irrigation season. The spatial distribution of the soil and vegetation properties of the study area, covering an irrigation district of approximately 800 ha, was accurately characterized during the summer of 2002. The soil hydraulic properties were identified by an intensive undisturbed soil sampling, while the vegetation cover was characterized in terms of leaf area index, surface albedo and fractional soil cover by analysing multispectral LandSat TM imageries. Irrigation volumes were monitored at parcel scale. A reference scenario with h m  = −700 cm and Δ  = 50% (corresponding to a mean actual to potential transpiration ratio of 0.95) allowed to reproduce the spatial and temporal distribution of the actual irrigation demand at the district scale. The spatial variability of the crop conditions in the considered area had much more influence to assess the irrigation water demand than the soil hydraulic spatial variability. The proposed approach showed that, under the agro-climatic conditions typical for the Mediterranean region, SIMODIS may be a valuable tool in managing irrigation to increase water productivity.

[1]  Guido D'Urso,et al.  Earth Observation for Vegetation Monitoring and Water Management , 2006 .

[2]  G. D. Urso.  Simulation and management of on-demand irrigation systems: a combined agrohydrological and remote sensing approach , 2001 .

[3]  S. Idso,et al.  Analysis of an empirical model for soil heat flux under a growing wheat crop for estimating evaporation by an infrared-temperature based energy balance equation , 1987 .

[4]  Joop G Kroes,et al.  User's guide of SWAP version 2.0 : Simulation of water flow, solute transport and plant growth in the Soil-Water-Atmosphere-Plant environment , 1997 .

[5]  Van Genuchten,et al.  A closed-form equation for predicting the hydraulic conductivity of unsaturated soils , 1980 .

[6]  Guido D'Urso,et al.  Regional application of one-dimensional water flow models for irrigation management , 1999 .

[7]  W. L. Powers.  Physical Edaphology: The Physics of Irrigated and Non-irrigated Soils , 1974 .

[8]  Jose Moreno,et al.  Assessment of inputs to land surface processes models derived from hyperspectral multiangular data , 2002, SPIE Remote Sensing.

[9]  Mario Minacapilli,et al.  Crop And Irrigation Water Management Using High Resolution Remote Sensing And Agrohydrological Models , 2006 .

[10]  J. Bouma,et al.  Soil structure assessment. , 1986 .

[11]  Wim G.M. Bastiaanssen,et al.  Distributed agro-hydrological modeling of an irrigation system in western Turkey , 2000 .

[12]  Manfred Owe,et al.  Remote sensing for agriculture, ecosystems, and hydrology VIII : 11-13 September 2006, Stockholm, Sweden , 2004 .

[13]  Joe T. Ritchie,et al.  Model for predicting evaporation from a row crop with incomplete cover , 1972 .

[14]  C. Keyser.  Proceedings of the Congress , 1907 .

[15]  R. Feddes,et al.  Simulation of field water use and crop yield , 1978 .

[16]  R. Ragab,et al.  A holistic generic integrated approach for irrigation, crop and field management: the SALTMED model , 2002, Environ. Model. Softw..

[17]  N. U. Ahmed,et al.  Relations between evaporation coefficients and vegetation indices studied by model simulations , 1994 .

[18]  G. L. Ashcroft,et al.  Physical edaphology: The physics of irrigated and nonirrigated soils , 1972 .

[19]  L. S. Pereira,et al.  Crop evapotranspiration : guidelines for computing crop water requirements , 1998 .

[20]  J. Bouma,et al.  A procedure to identify different groups of hydraulic-conductivity and moisture-retention curves for soil horizons , 1986 .

[21]  Jiftah Ben-Asher,et al.  Irrigation of grapevines with saline water: II. Mathematical simulation of vine growth and yield , 2006 .

[22]  F. Baret,et al.  Potentials and limits of vegetation indices for LAI and APAR assessment , 1991 .

[23]  K. H. Hartge,et al.  Feddes, R. A., Kowalik, P. I. und Zaradny, H.: simulation of field water use and crop yield. Pudoc (Centre for agricultural publishing and documentation) Wageningen, Niederlande, 195 Seiten, 13 Abbildungen, Paperback. Preis: hfl 30,– , 1980 .

[24]  W. Bastiaanssen,et al.  Data management related to the application of two crop-water-environment- models in Argentina and Egypt , 1996 .

[25]  Joop G Kroes,et al.  Integrated modelling of the soil–water–atmosphere–plant system using the model SWAP 2·0 an overview of theory and an application , 2000 .

[26]  A. H. Bosma,et al.  THE WATER CONSUMPTION OF AGRICULTURAL CROPS: HOW CROP COEFFICIENTS ARE AFFECTED BY CROP GEOMETRY AND MICROCLIMATE , 1990 .

[27]  J. Doorenbos,et al.  Yield response to water , 1979 .

[28]  A. W. Warrick,et al.  13 – Spatial Variability of Soil Physical Properties in the Field , 1980 .

[29]  G. Campbell,et al.  An Introduction to Environmental Biophysics , 1977 .

[30]  Feike J. Leij,et al.  The RETC code for quantifying the hydraulic functions of unsaturated soils , 1992 .

[31]  J. Clevers.  Application of a weighted infrared-red vegetation index for estimating leaf Area Index by Correcting for Soil Moisture , 1989 .