FAO CROPWAT Research Articles

Assessment of Crop water requirement using FAO CROPWAT 8.0 for Groundnut in South Odisha

Water has a major impact on crop growth, output, and quality and increased production with less water consumption is crucial due to increased demand from domestic and industrial sectors. With evaporative demand-based irrigation scheduling the water consumption gets reduced and improves water productivity. The type of soil, growing season, weather, and crop type affect specific crops' water needs. To compute crop water requirement, irrigation requirement, and its schedule for groundnut cultivated during the rabi season in south Odisha, India, the FAO CROPWAT 8 program was used, with the meteorological data of Centurion University, Paralakhemundi, and NASA power. The water requirement for groundnut was 362.1 mm, the irrigation requirement for groundnut crops was 323.7 mm, and crop evapotranspiration (ETc) was 373.4 mm during rabi season. At 50% critical depletion of soil moisture and soil replenishment to field capacity, the yield did not decrease. These results indicate that irrigation schedules can be practiced for different regions' crops without experimental results by estimating crop water requirements and irrigation schedules obtained through the FAO CROPWAT 8 model.

Construction of the water balance model for the Bontanga irrigation dam in Northern Ghana

ABSTRACT Freshwater resources are essential for the sustenance of all living things, for crop production and socio-economic activities. The objective of this study was to construct a water balance model aimed at optimizing reservoir management by analyzing variations in water availability in the reservoir. This model will help dam operators to adopt water allocation strategies, timing of water releases and storage decisions. An echo sounder was used to measure the depth of water. Crop water requirements were computed using FAO CROPWAT 8 software, and the InVEST-SDR model was used to estimate sediments exported downstream of the watershed. Model construction utilized multiple linear regression, and the results were tested at a level of significance α = 0.05. Model performance was evaluated using a coefficient of determination (R2) and the ratio of the root mean square error to the standard deviation of measured data (RSR). The results revealed a coefficient of determination (R2) of 0.743 and a ratio of the root mean square error to the standard deviation of measured data (RSR) of 0.67. The constructed model will provide essential information to stakeholders on drought preparedness and mitigation, including water conservation measures and the management of water releases during critical periods.

Impact of reclaimed wastewater on alfalfa production under different irrigation methods

ABSTRACT The effect of different irrigation methods (sprinkler, surface, surface-drip, and subsurface-drip) using treated wastewater, on alfalfa yield quantity and quality, was studied under semi-arid conditions. Randomized complete block design considering irrigation methods on 5 × 5 m plots replicated four times. Applied irrigation water was based on the Penman–Monteith equation using the FAO Cropwat software and accounting for the efficiencies of used irrigation systems. Surface irrigation gave the highest alfalfa fresh yield without significant difference compared to subsurface-drip. Average fresh production was 123, 120, 109, and 91 tons/h for surface, subsurface-drip, surface-drip, and sprinkler irrigation, respectively. Alfalfa fresh weight from subsurface-drip irrigation was 32 and 10% higher compared to sprinkler and surface-drip irrigation. Alfalfa dry weight from subsurface-drip irrigation was 10, 21, and 47% higher compared to surface-drip, surface, and sprinkler irrigation, respectively. N percentage in alfalfa leaves was significantly lower by 12% under subsurface-drip irrigation as compared to the other irrigation methods. Escherichia coli (E. coli) and fecal coliform (FC) were not detected on alfalfa leaves using subsurface-drip irrigation. E. coli and FC counts were high on leaves using sprinkler and surface irrigation. Subsurface-drip irrigation may be adapted as an efficient irrigation method when using non-conventional water under semi-arid conditions.

Determination of Crop water Requirement and Irrigation Scheduling for Major Crops of Surendranagar, Gujarat Using CROPWAT 8.0

Abstract: Due to the growing need for water for uses such as hydropower, farming, and drinking purpose among others, water is becoming an endangered asset. Water is increasingly needed for a variety of reasons as the population grows. On the contrary, the accessibility of water resources is limited. To determine crop water requirement for any crop and evaluate irrigation scheduling for effective water management, crop coefficients and reference crop evapotranspiration must be calculated. The purpose of this research is to determine crop water requirement of Cotton, Wheat and Sesame for Surendranagar Region and Prepare Irrigation Scheduling using the FAO-56 Penman-Monteith Method using FAO CROPWAT 8.0 Software. Meteorological data for Surendranagar region such as maximum and minimum temperatures, mean relative humidity, sunshine hours, and wind speed, are obtained from Wadhwan taluka of Surendranagar used to calculate reference crop evapotranspiration. Crop water requirement for Cotton using CROPWAT 8.0 model is obtained 876.3 mm/dec Crop water Requirement for Wheat is obtained 543.9 mm/dec and Crop water Requirement for Sesame is obtained 529.6 mm/dec This finding may be helpful for agricultural planning and effective irrigation control in the growing of cotton, Wheat and Sesame.

ESTIMATING CROP WATER REQUIREMENTS AND CLIMATE-SMART FARMING IN CHEREPONI, GHANA

Globally, agricultural production depends on the quantity and quality of the available water. Still, in recent times, climate change has affected the amount of water needed for agriculture. This study assesses the water requirements for three selected crops (maize, rice and cabbage) mainly cultivated in the lean season in Nansoni in the Chereponi District. The study determined the crop water requirement and crop irrigation requirement of each of the crops using the FAO CROPWAT software. The study’s findings reveal that February and March have the highest ETo (5.9mm/day and 5.96mm/day). Again, results show that crop evapotranspiration (ETc) and crop water requirements varied in real; for two crops, for maize crop evapotranspiration (ETc) and crop water requirements ranged from 11.7 to 75.1mm/dec and 0.0 to 56.7mm/dec, for rice 3.7 to 75.7mm/dec and 3.4 to 136.3mm/dec, and age 24.7 to 58.1mm/dec and 5 to 45.6mm/dec respectively. Planting for Food and Jobs (PFJ), One Village One Dam (1V1D), and One District One Factory (1D1F) policies are geared towards helping rural farmers adapt to climate change and accelerate agriculture production to ensure food security, reduction of malnutrition and hunger and create jobs for the youths. The study will broaden farmers’ knowledge of water sustainability and increase their major crops’ farm sizes based on crop water needs.

A pragmatic approach to the combined effect of climate change and water abstraction on Lake Ziway water balance, Ethiopia

AbstractClimate change and ongoing human activity have been threatening Ethiopia's Lake Ziway's water balance. However, few studies have been conducted to investigate the combined effects of climate change and water withdrawal on the lake's water balance using climate change and water withdrawal for irrigation. We used high-resolution multiple climate models and Representative Concentration Pathways (RCP) scenarios to assess the impact of climatic variables for two future periods: 2021–2050 and 2051–2080. Rainfall and temperature data biases were corrected using power transformation and variance scaling methods, respectively. The Hydrologiska Byråns Vattenbalansavdelning (HBV) hydrological model was employed to simulate surface inflow into Lake Ziway from the Meki and Katar sub-catchments. The FAO CROPWAT model was used to estimate the irrigation water demand of major crops grown in the study area. The results indicate that future temperatures and wet season runoff levels are expected to rise. Under the worst climate change scenario, climate change and water withdrawal from the lake for agriculture may cause the lake level to drop by 25 cm per year, resulting in a 10 km2 surface area and 101 Mm3 volume reductions. Therefore, implementing preventive measures, proper planning and careful monitoring of lake water use is advised.

Crop Water Requirements with Changing Climate in an Arid Region of Saudi Arabia

Agriculture is critical for a country’s population growth and economic expansion. In Saudi Arabia (SA), agriculture relies on groundwater, seasonal water, desalinated water, and recycled water due to a lack of surface water resources, a dry environment, and scanty rainfall. Estimating water consumption to plan crop water requirements (CWR) in changing environments is difficult due to a lack of micro-level data on water consumption, particularly in agricultural systems. High-resolution satellite data combined with environmental data provides a valuable tool for computing the CWR. This study aimed to estimate the CWR with a greater spatial and temporal resolution and localized field data and environmental variables. Obtaining this at the field level is appropriate, but geospatial technology can produce repeatable, time-series phenomena and align with environmental data for wider coverage regions. The CWR in the study area has been investigated through two methods: firstly, based on the high-resolution PlanetScope (PS) data, and secondly, using the FAO CROPWAT model v8.0. The analysis revealed that evapotranspiration (ETo) showed a minimum response of 2.22 mm/day in January to a maximum of 6.13 mm/day in July, with high temperatures (42.8). The humidity reaches a peak of 51%, falling to a minimum in June of 15%. Annual CWR values (in mm) for seven crops studied in the present investigation, including date palm, wheat, citrus, maize, barley, clover, and vegetables, were 1377, 296, 964, 275, 259, 1077, 214, respectively. The monthly averaged CWR derived using PS showed a higher correlation (r = 0.83) with CROPWAT model results. The study was promising and highlighted that such analysis is decisive and can be implemented in any region by using Machine Learning and Deep Learning for in-depth insights.

Estimation of crop water requirement and irrigation scheduling of rice in Shivamogga district of Karnatakausing FAO CROPWAT

Climate change is expected to have a significant impact on the water needs of rice crop worldwide in the upcoming decades. Proper water management is essential to enhance crop yield as well as maximising the region’s water use efficiency. The purpose of this study was to estimate the crop water requirement (CWR) and irrigation scheduling of rice in Shivamogga district of Karnataka using FAO CROPWAT model for a time span of 20 years (2001 to 2020). It was estimated that the crop water requirement of rice was 565.50 mm (average of 20 years) with the highest and lowest CWR (606.1 and 527.9 mm) in 2011 and 2001, respectively. Crop water requirement value showed a slight increasing trend (R2 = 0.0544) throughout the years from 2001 to 2020. Total gross irrigation (TGI) and total net irrigation (TNI) for rice was 491.61 and 344.12 mm, respectively during the study period. The present study is useful for effective planning and management of irrigation water needs of rice in Shivamogga district of Karnataka.

Estimation of Irrigation Requirement and Schedule in Southern Odisha for Major Rabi Cereal Crops using FAO CROPWAT 8.0 Model

Background: The increasing population and need for higher quantity of food grain production necessitates efficient use of limited water in the country, as agriculture sector alone uses 78% of water resources of India. During rabi season, mostly the crops are grown with irrigation in southern Odisha. There is no enough information on water and irrigation requirement of maize, sorghum and pearl millet crops grown in the region, which necessitated this study. Methods: The model-based study involving FAO CROPWAT 8.0 was used for the estimation of gross and net irrigation requirement and scheduling of maize, sorghum and pearl millet grown in southern Odisha. Result: The water requirement estimated with FAO CROPWAT 8.0 model during rabi for maize, sorghum and pearl milletgrown in Southern Odisha was 252.3, 197.9 and 172 mm and irrigation requirement was 231.2, 178.8 and 156.3 mm respectively.

Design of a photovoltaic solar irrigation system for the evaluation of phenology in jalapeño pepper

The need for higher crop productivity per unit area due to the growing population of the world is an extreme need, one of the possible approaches to cover this type of needs is photovoltaic solar irrigation systems. Considering the availability of solar radiation and the lack of electrical energy in the experimental study area, the design of a solar photovoltaic drip irrigation system is justified in an experimental area of ​​60 m² under shade mesh in Cosamaloapan, Veracruz, where the estimation of the solar radiation was carried out with the model provided according to the geographical location by means of the FAO CROPWAT software. For the calculation of evapotranspiration, the Penman-Monteith method was used, the data of the cultivation coefficient (Kc) were taken from the guide for the determination of the water requirements of the FAO crops and later these data were annexed to the aforementioned software for subsequent processing in the calculation of the water requirement of the crop. The main objective of this work was to design a photovoltaic solar irrigation system for the evaluation of phenology in the jalapeño pepper (Capsicum annuum, L.) under shade mesh. The analysis of the results indicates that during the months that included the development of the research, a daily average of 10.5 MJ/m² (2.91 Kwh/m²) was presented, which allowed charging the 9 A and 12 V battery in a time of 4 hours at 80 % charging efficiency through the 50 W solar panel used. The 70 W irrigation pump used was operated daily in a time of 16 minutes to cover the water demand of each plant (260 ml).

FAO-CROPWAT 8.0 Used for Analysis of Water Requirements and Irrigation Schedule in the Kutch Region of Gujarat

Abstract: Water is an important input for agriculture so this valuable resource is designed properly and deliverable. Reasonable information on evapotranspiration, crop water requirements, and net irrigation requirements is required for effective planning of this resource. To use optimum amount of water for crops and reduce irrigation quantity, some form of irrigation scheduling should be used by the farming community. Unscientific and injudicious application of groundwater in this region resulted in depletion of the groundwater table. To achieve effective utilization of the groundwater resources, there is a need to estimate the crop water requirement for different crops at different management levels to accomplish effective irrigation management. Crop water requirements of different crop in districts of Kutch was calculated using FAO CROPWAT 8.0 a computer simulation model. The simulation study was conducted with the objectives of determining irrigation water requirement and irrigation scheduling for some major crops. The Penman - Monteith method was used for evapotranspiration calculation in the model. The model predicted the daily, decadal as well as monthly crop water requirement at different growing stages of crops. Keywords: crop water requirement, irrigation scheduling, CROPWAT 8.0

An integrated assessment approach for fossil groundwater quality and crop water requirements in the El-Kharga Oasis, Western Desert, Egypt

Study regionThe El-Kharga Oasis in the Western Desert of Egypt is selected as the study area due to its hyberarid climate condition and water scarcity. In this region, the fossil groundwater is the main water source; therefore, preserving groundwater quality and quantity is mandatory. Study focusThis study evaluated groundwater suitability for irrigation purposes and assessed the water requirements of cultivated crops to optimize the water supply in hyperarid climate regions. In total, 79 deep groundwater samples were hydrochemically tested to determine the suitability for irrigation by assessing the key water quality parameters. Spatial distribution maps of all chemical parameters, such as pH, EC, SAR, RSC, SSP, TDS, total hardness, Na+, K+, Ca++, Mg++, Fe, Mn, Cl-, and SO4—, were developed. The FAO CROPWAT 8.0 model, based on the Penman–Monteith equation, was used to forecast agricultural water requirements for three years, 2010, 2011, and 2012. New hydrological insights for the regionThe groundwater had medium salinity and low sodium in 84% of the cases. In comparison, high salinity was found in 16% of the samples, indicating that groundwater can be used for many soil types with a low risk of exchangeable sodium. Except for 15 of the 79 wells, all groundwater samples had chloride concentrations less than 100 mg/l. The sulfate ion distribution map showed a low sulfate ion content in the extreme western south. The total annual irrigation water requirements of all crops for 2010, 2011 and 2012 were 199.4, 215.1, and 231.7 million m3/year, respectively, reflecting a gradual increase of approximately 16.57 million m3/total area/year due to the expansion of the cultivated area. The analysis showed that modern irrigation systems reduced the amount of irrigation water by 32% and increased the cultivated area by 45% compared to conventional irrigation methods. Severe groundwater depletion occurred during the dry season from March to July, which exacerbated the water stress in the study region. The results confirmed that the region is under water stress. Accordingly, water conservation is urgently recommended.

Investigating effects of deficit irrigation levels and fertilizer rates on water use efficiency and productivity based on field observations and modeling approaches

Investigating the effects of optimized fertilizer and irrigation levels on water use efficiency and productivity of wheat crop at small farms is of great importance for precise and sustainable agriculture in Pakistan's irrigated areas. However, traditional farmer practices for wheat production are inefficient and unsustainable. This study aimed to investigate the effects of deficit irrigation and nitrophos fertilizer levels on bread wheat grain yield, yield parameters, nutrient use and water use efficiencies in bed planting wheat compared to traditional farmers' practices in the flat sowing method. The two-year field experiment followed a randomized complete block design of three replications, taking three irrigation treatments according to the requirement of crop estimated by CROPWAT model (100% of ETC), deficit irrigation (80% of ETC), and deficit irrigation 60% of ETC and three nitrophos fertilizer treatments (farmer practice 120 kg N ha-1, optimized 96 kg N ha-1, and 84 kg N ha-1) at different growth stages. Crop ETC was calculated using the FAO CROPWAT 8.0 model from the last ten years (2003-2013) average climate data of the experimental station. The traditional farmer practice treatment was included as a control treatment with a flat sowing method compared with other sown-by-bed planter treatments. All treatments were provided with an equivalent amount of fertilizer at the basal dose. Before the first and second irrigation, top-dressing fertilizer was used in traditional farmers' treatment at the third leaf and tillering stages. It was applied in optimized treatments before the first, second, and third irrigation at the third leaf, tillering and shooting stages, respectively, under the bed planting method. The deficit level of irrigation (80% of ETc) and optimized fertilizer (96 kg N ha-1) showed the optimum grain yield, nutrient use, and water use efficiencies, with 20% reduced irrigation water and fertilizer levels than traditional farming practice. The results suggest that bread wheat should be irrigated with 80% of ETC and applied 96 kg N ha-1 nitrophos fertilizer at the third leaf, tillering, and shooting stages to achieve higher grain yield and water and nutrient use efficiencies under bed planting.

Spatial Variations in Water-Holding Capacity as Evidence of the Need for Precision Irrigation

Malaysia receives a lot of water from its two main monsoon periods. Generally, there is a lot of precipitation throughout the year, with drought periods lasting less than three months. To date, irrigation has been treated homogenously, even though soil properties can vary spatially over a field, requiring site-specific applications. The aim of this study was to establish an irrigation management zone (IMZ) covering 23.4 ha, which was previously determined under the same soil series. Soil sampling was done according to a grid system over an area of 100 m × 100 m. Three soil depth ranges were examined for every sampling point, namely 0–30, 30–60, and 60–90 cm from the soil surface. Samples were taken to a laboratory for physical analysis and determination of the available water-holding capacity (AWHC). Delineation of AWHC values was achieved using GIS software and the Kriging method. Estimated irrigation depth (EID) data for the plantation were collected for the years 2016 and 2017. Afterward, EID and total net irrigation (TNI) data were simulated in the FAO Cropwat model and compared. The results showed that clay, sand, and organic matter (OM) distributions varied with soil depth; however, no strong correlation was found between these variable with AWHC. The IMZ was classified into three areas named zones A, B, and C, ranging from 79 to 167 mm. The crop water requirement (CWR) was 667 mm in 2016 but only 260 mm in 2017. Based on the AWHC values, the EID for 2016 was found to be below the TNI requirement range of about 106 to 110 mm. In contrast, the EID range was approximately 34 to 62 mm and above TNI requirements for 2017. This study indicates that water inputs for irrigation can be optimized with knowledge of the water-holding capacity of a specific soil. Subsequently, this can be related to crop yield and the impact on sustainable agriculture.

Proposal of an empirical model to estimate the productivity of ‘Valencia’ orange (Citrus sinensis L. Osbeck) in the Colombian low tropics

The response of the citrus crop to environmental supply largely determines the speed and intensity of the plant's ecophysiological processes, which affect the development and production of the crop. The main objective was to analyze the effects of climatic conditions on the productivity of the ‘Valencia’ orange agroecosystems (Citrus sinensis L. Osbeck) previously typified in the department of Meta, Colombia. The climatological variables precipitation (PPT), maximum and minimum temperatures (Tmax and Tmin), wind speed, relative humidity and solar brightness were analyzed in an observation window spanning the years 2013 to 2015. Using the FAO CropWat model, the crop reference evapotranspiration (ETo) was obtained to applied agroclimatic indices. Using the statistical software STATGRAPHICS Centurion XVI v. 16.2.04, an empirical model was proposed that relates productivity according to agroclimatic indices, for the vegetative and reproductive phenological phases. It was found that the proposed empirical model explains 49% (P=0.0233) of the oscillation of productivity in study area agroecosystems. The model, based on agroclimatic indices associated with PPT, ETo, Tmax and Tmin, found that the relationship between productivity and agroclimatic indices is non-linear. It was established that productivity variation is mainly influenced by PPT, the occurrence and magnitude of which determines the volume of production and quality of the fruit. On the other hand, whereas increases in air temperature and the occurrence of water deficits in the pre-flowering and flowering phases positively favor crop production, the same factors produce a negative effect in the setting phase.

Evaluation of irrigation suitability potential of brewery effluent post treated in a pilot horizontal subsurface flow constructed wetland system: implications for sustainable urban agriculture

The use of untreated or partially treated wastewater reuse for urban and peri-urban agricultural irrigation is a common practice in developing countries like Ethiopia. Such practices, however, pose significant environmental and public health risks. The objective of this study was to evaluate the irrigation suitability of anaerobic digestion brewery effluent (ADBE) and two-stage horizontal subsurface constructed wetland post-treated ADBE (CWPBE). A series of pot experiments were conducted in a plastic - greenhouse system arranged in three sets of irrigation schemes: Treatment Group1 (TG1): municipal pipe tap water (MPTW) irrigated pots; Treatment Group2 (TG2): ADBE irrigated pots, and Treatment Group3 (TG3): CWPBE irrigated pots. Pots packed with the same amount of sandy clay loam soil and local tomato seeds sown were irrigated following an updated tomato irrigation schedule derived from the FAO CROPWAT stimulation model for 120 days. The findings from key irrigation water quality parameters showed that the CWPBE achieved the prescribed irrigation water standards with values of pH (7.4 ± 0.15), electrical conductivity (1.9 ± 0.11 dS.m−1), total suspended solids (25 ± 4.17 mgL-1), chemical oxygen demand (185.1 ± 1.66 mgL-1), total nitrogen (17.4 ± 0.7 mgL-1), total phosphorous (8.8 ± 0.26 mgkg-1), calcium (10.5 ± 3.6 mgkg-1), magnesium (4.9 ± 0.98 mgkg-1), sodium (4.4 ± 1.51 mgkg-1), potassium (2.3 ± 1.15 mgkg-1), sodium adsorption ratio (1.6 ± 0.34), and total coliform (8 ± 0.16×10−5 CFU/100 mL). Moreover, tomato plants grown in TG3 attained higher growth such as number of leaves (85.6 ± 4.68), plant height (92.2 ± 1.29 cm), stem diameter (13.1 ± 2.35 cm) and leaf area (35.5 ± 1.03 cm2) as well as higher biomass (61.2 ± 1.33 kgm−2) and fruit (46.4 ± 3.51 kgm−2) yields over other treatment groups. The results revealed that irrigation waters significantly improved both growth and yield parameters of tomato plants with the ascending order of TG1 < TG2 < TG3. Moreover, CWPBE showed minima short-term residual effect on soil physicochemical properties as compared to ADBE, and thus, it has potential suitability for agricultural irrigation reuse.

Estimation of Crop Water Requirement using CROPWAT Model for Maize, A Case Study of Raya Azebo District, Ethiopia

Water is the major limiting factor for crop production. A lot of water resources have been exploited for irrigation purpose. Irrigation systems essential to enhance crop productivity in order to meet future food demand and ensure food security. Unscientific and injudicious application of groundwater in this district resulted in depletion of the groundwater table. To achieve effective utilization of the groundwater resources, there is a need to estimate the crop water requirement for different crops at different management levels to accomplish effective irrigation management. Crop water requirements of maize crop in Raya Azebo districts was calculated using FAO Cropwat 8.0 a computer simulation model. The simulation study was conducted with the objectives of determining irrigation water requirement maize. The study was carried out to estimate the crop water requirement of maize by using the climatic data, crop evapotranspiration (ETc) and reference crop evapotranspiration (ETo) for each crop were determined using CROPWAT 8.0. The study shows that crop water requirement of maize with a growing period of 125 days to maturity requires 504.0 mm depth of water on off season and 457.8 mm on main season respectively. The result shows that in off season the crop water requirement of maize was needed more water than the main season, due to the climatic condition and in the main season the effective rainfall is more available than the off season. This study proved that the CROPWAT model is useful for calculating the crop irrigation needs for the proper management of water resources. Keywords: CROPWAT, Model, Crop water requirement, Maize, Eto DOI: 10.7176/JRDM/74-03 Publication date: March 31 st 2021

КОЛИЧЕСТВЕННАЯ ОЦЕНКА ВЛИЯНИЯ ИЗМЕНЕНИЙ КЛИМАТА НА ЭВАПОТРАНСПИРАЦИЮ И УРОЖАЙНОСТЬ СЕЛЬСКОХОЗЯЙСТВЕННЫХ КУЛЬТУР В ЦЕНТРАЛЬНОМ РАЙОНЕ ИНДИИ

The present work focuses on estimation of future evapotranspiration of paddy, maize, soybean and assessment of yields of these crops under RCP scenarios 2.6, 4.5, and 8.5 for years 1997-2099 using FAO Cropwat and AquaCrop yield simulating models for the Sehore district, in central state of India. Statistically downscaled General Circulation Model CanESM2 data were used as input to Cropwat and AquaCrop tools for generation of future crop evapotranspiration and crop yield data. The AquaCrop yield model was first checked for its suitability and accuracy in prediction of yield for years 1997-2010. The future scenario RCP 8.5 shows the highest reduction in the yield of paddy (-8.5%), maize (-4.52%), and soybean (-3.93%) during the future period. It was concluded that the FAO AquaCrop model can be applied to many other crops as well as in the other regions to formulate proper cropping strategies that will help to decrease the risks due to future climate change.

Estimation of Crop Water Requirement for Sugarcane in Coimbatore District using FAO CROPWAT

The present study aimed to evaluate the software CROPWAT 8.0 that isused for estimation of the crop water requirement forsugarcane. With theseapproach the net irrigation requirement of sugarcane is calculated and themonthly water requirement is calibrated to meet out the requirement. Itincludes a simple water balance model that allows the simulation of cropwater stress conditions and estimation of yield reductions based on wellestablished methodologies. The use of modern irrigation techniques will goa long way in reducing water use and conservation. This will put wider areasunder cultivation and potentially contribute to greater agricultural production.The results showed that the Net and Gross Irrigationare 1394 and 1991.5mm, repectively. The crop water requirement of sugarcane in Coimbatorewas estimated to be 1438.7 mm.

GIS-Based Irrigation Potential Assessment for Surface Irrigation: The Case of Birbir River Watershed, Oromia, Ethiopia

The assessment process of surface irrigation has to integrate information about the suitability of the land; water resource availability and water requirements of irrigate able areas in time and place. Birbir River is one of well-known river found in western Ethiopia. The Birbir River is a tributary of the Baro-Akobo river basin, which creates Baro River when it joins with Gebba River. Ethiopia has immense potential in expanding irrigation using available water resources. But due to lack of information related to cultivable and irrigation suitability of the land, its agricultural system does not yet fully productive. Geographic Information System can be an effective tool in identifying irrigable land and mapping of suitable land for irrigation. Therefore, the objective of the present study was to assess the surface irrigation potential of the Birbir river watershed using ArcGIS 10.3. Different methods of data processing and analysis have been employed in this study. The main suitability factors used to identify the potential irrigable land for surface irrigation were slope, soil texture, soil depth, soil type, soil drainage characteristics, land use, land cover and distance to water source. The consistency of rainfall and stream flow data were checked by double mass curve and the areal mean of rainfall and temperature data were determined by using Theissen polygon method whereas the irrigation water demands of the selected two crops (maize and potato) were calculated separately using FAO cropwat model. By weighting values of the seven factors using Analytic Hierarchy Process and overlaying by weighted overlay in ArcGIS 10.3, the irrigation suitability map was developed and potential irrigable land for surface irrigation was found to be 17%, 63% and 20% for highly suitable (S1), moderately suitable (S2), and marginally suitable (S3) respectively. Irrigation potential of the Birbir river watershed was obtained by comparing monthly gross irrigation requirements of the identified land suitable for surface irrigation and the available 80% mean monthly dependable flows in the river catchments. The potential irrigable land that can be irrigated without provision of storage structures was found to be around 68,000 ha from the total of 106,223 ha suitable land for surface irrigation.