Q

Figure 2 Modelled values of the omega factor (Q) as a function of canopy resistance, for different values of aerodynamic resistance. Figure 2 Modelled values of the omega factor (Q) as a function of canopy resistance, for different values of aerodynamic resistance. 2.2 Methods to Measure ET in Stands of Woody Plants The methods for ET measurement that have been currently used, in field conditions, can be classified in two main categories hydrological and micrometeorological methods....

Inside The North African Oasis Mohamed Habib Sellami

Laboratory of Thermal Radiation, Department of Physics, University of Sciences of Tunis, 1060, Tunis, Tunisia, Mh.sellami planet.tn, sellamimohamedhabib yahoo.com, In this chapter I am presenting a methodology and basic equations permitting to establish models to monitor water, nutrient and salt distribution in the oasis soil under different irrigation system, to determine the best oasis architecture for an efficient use of resources, to estimate the amount of water really needed by plants and...

Material and Methods

This experience was carried out in season 2005 06 in an experimental orchard of 'Algerie' loquat trees located at the Experimental Station of Cajamar Foundation Las Palmerillas, in Almer a (SE, Spain). The area presents a semi-arid subtropical climate with an average rainfall of 231 mm and evaporation from an A pan (Epan) of 1922 mm per year. Mean annual temperature and humidity is 18 C and 68 , respectively. Orchard soil is a well-aerated sandy-loam (72.4 sand, 14.6 loam, and 13.0 clay), pH...

References

Allen, R.G., Pereira, L.S., Raes, D. et al. (1998). Crop Evapotranspiration (Guidelines for Computing Crop Water Requirements). FAO Irrig. Drain. 56. Rome, Italy FAO. ASAE S330.1 (2004). Procedure for sprinkler distribution testing for research purposes. Standard ASAE (pp. 845-848). St Joseph, MI, USA ASAE. ASAE S398.1 (2004). Procedure for sprinkler testing and performance reporting. Standard ASAE (pp. 876-879). St Joseph, MI, USA ASAE. ASAE S436.1 (2004). Test procedure for determining the...

Evapotranspiration Components Measuring Transpiration

None of the ET measurement methods mentioned in the previous section allows differentiation between T and Es or can be applied in heterogeneous stands (natural landscapes, for instance), when a distinction between species is required. New opportunities for the estimation of T, typically the main component of ET, especially in arid environments, are offered by sap flow methods, usually based on correlated heat transport. These methods can be applied to investigate the responses of T to different...

Plant Water Stress and Irrigation Scheduling3

Water is more and more becoming a precious resource and deficit irrigation strategies, such as partial root zone drying (PRD), regulated deficit irrigation (RDI) and others, have been increasingly studied, in different contexts (e.g. Naor, 2006). The starting point to link water use and water stress indicators is the understanding and quantification of stomatal behavior. Quantifying rs is important for ET estimation but also through its relationship with CO2 assimilation rate, affected by water...

ArjVJ AlATVi Vj VVpa

LL is the longitudinal dispersivity of the medium is the transversal dispersivity of the medium Vi is the component of the average interstitial solution velocity V in the direction i Op(ro) is the soil diffusion coefficient Many authors (Brandt et al. (1971) Bresler (1975) Lomen and Warrick (1976)) consider that in presence of a trickle source the water flow and solute transport can be treated as a two-dimensional problem using axi-symmetric cylindrical model where the cylindrical coordinates...

Materials and Methods

The experiments were carried out, between 1992 and 1998, at CIHEAM - Mediterranean Agronomic Institute (Bari, Italy), in the frame of a long-term experiment to study the crop response to soil salinity. Species behaviour of the species in saline environment was analyzed in previous studies by van Hoorn et al. (1993) and by Katerji et al. (1996, 1997, 1998a and b). The experimental data in this paper synthesize the observations obtained on the control treatments that were kept in well-watered...

Rb z

Oc> 1 is the sensible heat flux the canopy layer i Ov> 1 is the latent heat flux for the vegetation layer i inside the oasis r-net, i flux of net radiation received by the vegetation layer i pcp is the volumetric heat capacity of air, Ti,i is the temperature of the leaves corresponding to canopy layer i Tai is the temperature of the air corresponding to canopy layer i e(Tli) is water vapour pressure of the air at the canopy layer i for Tli e(Tai) is the water vapour pressure of the air at...

Result Variables

The Bn is structured as an annual balance, subtracting water inputs from the requirements for the different uses. In this manner, it is possible to estimate the available volume for the following HU and the groundwater extracted from the aquifer. Explaining the meaning of each individual variable would be arduous and descriptions are therefore limited to groups 4 and 5. Group 4 'Agricultural consumption'. This group is made up of five subgroups. The combination of these subgroups provides an...

S

SA, 3, 60, 126, 169, 255, 256, 257, 263, 265, 266 sales, 262, 263, 265 salinity, vii, 28, 128, 173, 174, 175, 177, 180, 183, 187, 188, 207, 225, 226, 275, 287, 289 salt(s), ix, 20, 27, 62, 171, 172, 175, 176, 179, 181, 186, 187, 188, 189, 207, 210, 225, 226 sample, 6, 42, 115, 141, 202 sampling, 4, 25, 151, 159, 165, 202, 231, 277 satellite, 119, 139, 194 saturation, 22, 133, 141, 184, 188, 226, 278, 285 savings, 15 scaling, 67, 133, 138, 139, 159, 160, 163, 178, 186, scarcity, viii, ix, 10,...

Sampling Frequency and Others

Sampling frequency must be at 10 Hz or higher and data loggers that are not able to sample at this or higher frequencies should not be used with eddy covariance equipment. In addition to the above corrections, some other corrections may be needed also. Details may be found at n_files _frame.htm).

Stress Coefficients

The use of plant and soil-water-status indicators, thought useful to identify the moment for water applications does not provide information about the amounts needed to replenish the soil reservoir. Usually (see Allen at al, 1998) this is obtained by a daily soil water balance that, under non-restricted water application, that includes the estimation of cumulated ET from the previous irrigation (E ETa), provided ETo and Kc are available. Under restricted water application, when a moderate water...

The Agridema Pilot Assessments Results

According to the AGRIDEMA goals, the Pilot assessments should comprise the two following tasks 1. Downscaling the provided GCM-outputs and or seasonal-forecasts. 2. Simulating impacts (such as crop growth and yield, drought stress level etc.) under the locally-obtained climate scenarios, evaluating several management options, which might mitigate the probable climate impact. Scientific quality of the assessments is quite variable, which can be expected from the wide irregularity of AGRIDEMA...

The Agridema Proposal General Description

AGRIDEMA comprises the following specific objectives 1. To identify European human resources that developed, improved and tested simulating tools such as GCM, seasonal forecasts, regional downscaling techniques and agricultural-impact simulation models inviting them to participate in the SSA proposal activities for implementing their tools and Know-How. 2. To identify and to invite attending the SSA activities to potential users of the European-provided modelling tools. 3. To conduct short...

The Spanish Climate Change Adaptation Plan

Additionally to the EU concerns, the Spanish government and the National institutions are also ready to introduce Climate-Change adaptation actions, taking into account that Spain is one of the most risky countries within Europe. The huge assessment comprised in the Preliminary Evaluation of Climate Change effects in Spain (Moreno, 2005), including the risks of Spanish agriculture (Minguez et al., 2005), has been an important guidelines to develop Climate-change adaptation strategies at the...

Total

In CLM there are more than 90 reservoirs, with a total capacity in excess of 6,741 hm3, with approximately 60 of them having a very limited capacity i.e. less than 5 hm3. Among the reservoirs, emphasized are those of Entepe as and Buend a, in the Tajo river basin, which can store more than 2,440 hm3. These reservoirs are well known, as from them originates the Tajo-Segura Aqueduct (Acueducto Tajo-Segura, ATS). Other important reservoirs are those of Alarc n and Contreras, in the river basin of...

Water Management In The

A water right is a legal authorization to take water from a water source. However, the terminology used for defining water rights varies significantly in all the jurisdictions in the MDB they may be locally referred to as rights, licenses, permits, allocations or entitlements. Water rights are granted for specific users (e.g., irrigators), for specific purposes (e.g., stock and household consumption, environmental flows), for an individual (e.g., diversion licences), or for a group of users...

Water Resources Issues in CastillaLa Mancha

2.1.1 Edafoclimatic Conditions and Water Resources Due to CLM being situated in the center of the Iberian Peninsula the sources of important rivers are located within this region, such as the Tajo and Guadiana, of the Atlantic side, the Jucar and the Segura of the Mediterranean, as well as, some tributaries of the Duero, Ebro and Guadalquivir (CES, 2006). Since not one of the aforementioned rivers is completely included within the territory of CLM, this denotes that hydrological planning is a...

Oasis of Tozeur

The models established and experimentations realised for the oasis of Tozeur deal with many subject that concern the agricultural water management solar radiation intercepted and shared between canopy species inside the oasis, plant productivity and transpiration, heat and mass transfer, biodiversity conservation by simulating the water really needed by every species and by detecting the eventual diseases that can emerge at hours scale, the optimal arrangement between plants, there orientations...

Water Use in Chilean Agriculture

Legal Context of the Water Resources Use in Chile The management of water in Chile and its consequences correspond to a case of administration of a scarce natural resource within a neo-liberal economical and political context, represented by the 1981 Water Code. Such legal body diminished the Government attributions and transferred the ownership of rights for water use, and therefore its usage, exploitation and disposal, to private entities, generating the power to freely negotiate and use the...

Crop Growth Oriented Simulation Models

According to Stockle et al. (2003), the initial crop-growth simulation models, mainly theoretical approaches, appeared in the 1970s (de Wit et al., 1970 Arkin et al., 1976). Applications oriented models appeared during the 1980s (Wilkerson et al., 1983 Swaney et al., 1983). Models such as SUCROS and others associated with the Dutch 'School of de Wit' (Bouman et al., 1996) as well as those produced in the US as the CERES (Ritchie, 1998) and CROPGRO (Boote et al., 1998) families of models had a...

Dssat

Several work agreements were achieved between the AGRIDEMA consortium and most of the contacted developers, pointing out the developers participation in the AGRIDEMA courses, as well as their future support of the Pilot Assessments to be conducted by the users in the framework of AGRIDEMA. 4.3.2 Identifying and Contacting Users Mediterranean countries could face the highest negative consequences of global warming within Europe, through water-shortage and crop-water requirements increments....

Hydrus Model

An important modelling approach, aimed to simulate water and solute transport through the soil vadose zone is the model HYDRUS-1D Simunek et al., 2005 . The model consists of the HYDRUS computer program, and the HYDRUS 1D interactive graphics-based user interface. According to Simunek et al. 2005 , the HYDRUS program numerically solves the Richards equation for saturated-unsaturated water flow and convection-dispersion type equations for heat and solute transport. The water flow equation...

Simulating Crop Growth and Crop Water Use

On the other hand, many crop simulation models have been appeared in the last 20 years. Those models are able to estimate crop water-use and growth under any weather and cop management conditions. Those models, combined with downscaled GCM scenarios, can be a reliable approach to support decision-making under climate change conditions Hoogenboom, 2000 . Despite many models are available, Mechanistic models i.e. those based in the physical laws of the soil-water-plant-atmosphere continuum, are...

Biodiversity Reserve

5.1 Application of the Radiative Transfer Equations Inside the Oasis A vegetation canopy is a porous medium for the radiation. In more specific term it is considered as semi-transparent to solar radiation. At macro-scale, the plants intercept a part of the incoming radiation and diffuse ascendant flux and descendant flux the others. This is done by the participation of all the vegetation components leaf, fruit, branch, trunk . At micro-scale molecule level the plant canopy absorb a share of the...

Weather Generators

Weather generators have been very used in agriculture climate-change impact assessments Hoogenboom, 2000 Sivakumar, 2001 . A weather generator produces synthetic daily time series of climatic variables statistically equivalent to the recorded historical series, as well as daily site-specific climate scenarios that could be based on regional GCM results Semenov and Jamieson, 2001 . The weather generator usually mimics correctly the mean values of the climatic variables, although underestimates...

Climate Scenarios Seasonal Forecasts and Downscaling Issues

Complex Models regarding general atmospheric circulation GCM have been developed to predict the future earth climate. Those models are able to simulate the energy and mass exchanges between the atmosphere and the earth surface, according to several man-due scenarios of greenhouse gases emissions IPCC, 2007 . The HadCM3 model, developed by the United-Kingdom Meteorological Office, and the German ECHAM4 model were considered in the IPCC 2007 report, among other non-European GCM's. On the other...