Sensitivity of the agro-hydrological model CRITERIA-1D to the Leaf Area Index parameter (original) (raw)
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In the context of major changes (climate, demography, economy, etc.), the southern Mediterranean area faces serious challenges with intrinsically low, irregular, and continuously decreasing water resources. In some regions, the proper growth both in terms of cropping density and surface area of irrigated areas is so significant that it needs to be included in future scenarios. A method for estimating the future evolution of irrigation water requirements is proposed and tested in the Tensift watershed, Morocco. Monthly synthetic crop coefficients (K c) of the different irrigated areas were obtained from a time series of remote sensing observations. An empirical model using the synthetic K c and rainfall was developed and fitted to the actual data for each of the different irrigated areas within the study area. The model consists of a system of equations that takes into account the monthly trend of K c , the impact of yearly rainfall, and the saturation of K c due to the presence of tree crops. The impact of precipitation change is included in the K c estimate and the water budget. The anthropogenic impact is included in the equations for K c. The impact of temperature change is only included in the reference evapotranspiration, with no impact on the K c cycle. The model appears to be reliable with an average r 2 of 0.69 for the observation period (2000-2016). However, different subsampling tests of the number of calibration years showed that the performance is degraded when the size of the training dataset is reduced. When subsampling the training dataset to one-third of the 16 available years, r 2 was reduced to 0.45. This score has been interpreted as the level of reliability that could be expected for two time periods after the full training years (thus near to 2050). The model has been used to reinterpret a local water management plan and to incorporate two downscaled climate change scenarios (RCP4.5 and RCP8.5). The examination of irrigation water requirements until 2050 revealed that the difference between the two climate scenarios was very small (< 2 %), while the two agricultural scenarios were strongly contrasted both spatially and in terms of their impact on water resources. The approach is generic and can be refined by incorporating irrigation efficiencies.
Leaf area index as a function of precipitation within a hydrological model
Hydrology Research, 2014
The Leaf Area Index (LAI) was derived from the Normalised Difference Vegetation Index (NDVI) obtained from Advanced Very High Resolution Radiometer (AVHRR) data for the years 1982–2004. The NDVI-derived LAI showed a very good agreement (correlation coefficient r up to 0.96) with MODIS LAI. To address the relation between precipitation and LAI, linear correlation analysis between gridded precipitation and the NDVI-derived LAI was conducted for several land uses and each month of the year. Based on the regression coefficients, LAI could be simulated as a function of precipitation. During validation, the simulated LAI showed a very good agreement (r ≥ 0.75) with the NDVI-derived LAI. The simulated dynamic LAI was thereafter implemented in a hydrological model. For comparison, a model run with a static LAI without any inter-annual variations was also conducted. During abnormally dry conditions, the dynamic LAI was lower than the static LAI and less transpiration was therefore simulated....
Water Practice and Technology
The world is facing an acute water shortage. The present irrigation techniques used in the Hyderabad district, Pakistan, are not demand-driven. The present study was carried out to determine the crop water requirement (CWR), irrigation water requirement (IWR), and irrigation scheduling for major crops grown in the Hyderabad district using the CROPWAT model based on climatic, soil, and crop data. The analysis revealed that the total CWR for the entire growing season for sugarcane, banana, cotton, and wheat were 3,127.0; 2,012.3; 1,073.5; and 418.9 mm, respectively. However, the IWR for sugarcane, banana, cotton, and wheat for the entire growing season was found to be 2,964.0; 1,966.7; 1,052.7; and 407.6 mm, respectively. However, the contribution of rainfall was 163.0, 45.6, 20.8, and 11.3 mm during sugarcane, banana, cotton, and wheat, respectively. The CWR and IWR were higher during the dry season due to high temperatures and low relative humidity. However, the IWR of each crop was...
Modelling for water supply of irrigated cropping systems on climate change
Italian Journal of Agronomy, 2012
The vulnerability of Mediterranean environment due to climatic changes makes necessary to define the effects of the increase of CO2 atmospheric concentration and the consequent alterations of temperature and precipitation variations upon the processes which regulate the plants water supply. The traditional research can not meet the needs of this information because of the difficulty of carrying out the experiments. Therefore, it is necessary to use models based upon mathematical representation of the processes and interactions between climatic scenarios, plant and soil, with which to simulate different agronomic situations. The integration of global circulation models with water balance models is a valid tool for studying the influence of climatic changes on water supply. This study took into account the influence of climatic changes on water supply of poly-annual (artichoke and asparagus) and annual (potato and broccoli) crops with the CRITERIA simulation model of water balance. The simulations were performed with two future climate scenarios (A2 and B1). The results of the simulations highlight how the A2 scenario gives a greater influence on cycle length of crops which develop in summer time determining a reduction of crop cycle from 15-20% compared to the observed data, and so, as a consequence in the future, the crops with a summer crop cycle will be subjected to reductions of water supply up to 25%.
Model parameters of four important vegetable crops for improved water use and yield estimation
Water SA, 2018
High-value vegetable crops are typically grown under irrigation to reduce production risk. For water resource planning it is essential to be able to accurately estimate water use of irrigated crops under a wide range of climatic conditions. Crop water use models provide a means to make water use and yield estimates, but need crop- and even cultivar-specific parameters. There is generally a lack of crop-specific model parameters for some important commercially grown vegetable crops, especially parameters determined over both summer and winter seasons. The experimental site used in this study was on the Steenkoppies Aquifer, a catchment under stress and an important vegetable production area in South Africa. Crop-specific growth parameters and water use for 4 selected high-value vegetable crops (beetroot, cabbage, carrots and broccoli) were measured over multiple seasons (two summers and one winter). These were used to parameterise the Soil Water Balance (SWB) generic crop growth mode...
Use of Agrometrological Data to Calculate Irrigation Requirement
International Symposium on The Horizons of Using Organic Matter and Substrates in Horticulture, 2003
IRRI_CLAC is a software developed by the Central Laboratory for Agricultural Climate (CLAC) aiming at calculating either daily irrigation requirement or irrigation scheduling for a given growing season. The software is divided into three major screens. The first Screen deals with the crop groups that include vegetables, fruits, field crops and greenhouses. Each group include a list of crops belonging to it. Knowing the plant age, or planting date, the program picks a crop coefficient (Kc) and root depth as a function of plant age. The second screen is related to the location and includes the farm area and the nearest weather station to calculate the potential evapotranspiration (ETo) utilizing one of ten different equation according to the availability of weather parameters. It also includes an options to select soil type select soil field capacity and permanent wilting point. The program then calculates the maximum amount of water that could be given to fill the soil down to a given root depth. The program can estimate the frequency and amount of water should be given to a certain crop at a certain location according to plant soil and crop age; i.e. how much and how often to irrigate. The last section is related to the irrigation system type, efficiency and discharge per unit length as well as distance between laterals. This section allows the program to estimate the duration of irrigation, i.e. how long to irrigate.
Water
Water is one of the most important natural resources and is widely used around the globe for various purposes. In fact, the agricultural sector consumes 70% of the world’s accessible water, of which about 60% is wasted. Thus, it needs to be managed scientifically and efficiently to maximize food production to meet the requirements of an ever-increasing population. There is a lack of information on water requirements of crops and irrigation scheduling concerning the Shaheed Benazirabad district, Pakistan. Thus, the present study was conducted to determine the irrigation water requirements (IWR) and irrigation scheduling for the major crops in the Shaheed Benazirabad district, Sindh, Pakistan, using agro-climatic data and the CROPWAT model. Agro-climatic data such as rainfall, maximum and minimum temperature, sunshine hours, humidity, and wind speed were obtained from the NASA website, CLIMWAT 2.0, and world weather However, data about studied crops and soils were obtained from FAO (F...