Irrigation Water Consumption Research Articles

Synergetic optimization management of crop-biomass coproduction with food-energy-water nexus under uncertainties

Synergic management of the local crop-biomass coproduction system is the potential to increase resource efficiency and promote sustainable development. In this paper, an interval fuzzy linear fractional programming (IFLFP) model is developed for planning regional food production with the consideration of ecological protection, water resource conservation, biomass energy supply, and food-energy-water (FEW) nexus. The main advantages of the proposed IFLFP model are the abilities to reflect uncertainties with different characters as interval values and fuzzy sets and to provide system efficiency measurement by the ratio form of conflict objective functions. The IFLFP model is then tailored for the application of the crop-biomass coproduction management with FEW nexus in Jiangsu Province, China. The influences of different optimization goals (i.e. economic benefits and environmental benefits per unit irrigation water consumption) and multiple water resource scenarios under climate change are examined and discussed to provide more managerial insights. The results reveal that wheat, barley, and tuber crops would be more easily affected by water resource availability and optimization goals. Besides, recycle water would be considered as an important source for irrigation under scare water scenario, and gain the priority for the economic purpose. The results also imply that it is impossible to realize “double-win” of environmental and economic goals simultaneously, and decision makers should make compromises among different strategies.

An object-based image analysis approach to assess irrigation-water consumption from MODIS products in Ethiopia

Efficient water-resource management is essential with regard to food security, growing populations and climate change. This is especially important for low- and middle-income (LMC) countries where food is often locally produced by traditional smallholder farming. Detailed knowledge of the spatio-temporal distribution of irrigation-water consumption provides valuable information to anticipate local food shortages and water scarcity as a result of climate variability. Yet, adequate techniques to quantify irrigation-water consumption at field level over large areas are lacking. Irrigation estimates generally have a coarse resolution making them inadequate for field-level assessments.This study developed a remote-sensing-based approach to quantify spatio-temporal patterns of irrigation-water consumption at field level using the MODIS evapotranspiration product (MOD16A2) and existing land-use maps on the spatio-temporal distribution of irrigated agriculture. Object-based image analysis was used to establish local evapotranspiration differences between irrigated and rainfed fields on a monthly basis, which are the irrigation-water consumption rates of the irrigated fields. This novel method was applied to a study area in the Central Rift Valley in Ethiopia where smallholder farming is dominant and only a few large-scale farms are present. Comparison with irrigation-water-consumption values of a local irrigation scheme showed that the monthly temporal dynamics were captured quite well, but lower values were calculated compared to the scheme's field data. Comparison with two validated remote-sensing based studies in Africa showed good agreement as irrigation-water-consumption estimates were in the same order of magnitude. Irrigation-water consumption follows the temporal rainfall pattern, i.e. irrigation practices intensify with increased water availability. Surface water is commonly used for irrigation in the study area.Our study shows that smallholder practices have a lower irrigation-water consumption compared to modern large-scale farms by approximately a factor 3. Irrigation-water consumption in the area is considerable, especially during the dry season. On average 32 % of excess water (precipitation – evapotranspiration) is consumed for irrigation. For smallholder irrigation and large-scale irrigation specifically this is 28 % and 63 % respectively.The object-based approach presented here is an operational mapping method for field-level irrigation-water-consumption over large areas. MOD16A2 is a global open-source readily-available evapotranspiration product used here although an evapotranspiration product with a higher spatial resolution might be preferred. Our approach can provide irrigation-water-consumption estimates over large areas in data-poor regions, which will increase the understanding of spatio-temporal patterns of smallholder irrigation and provide information to optimize water use.

Impacts of climate change and agricultural activities on water quality in the Lower Kaidu River Basin, China

In the context of climate change and over-exploitation of water resources, water shortage and water pollution in arid regions have become major constraints to local sustainable development. In this study, we established a Soil and Water Assessment Tool (SWAT) model for simulating non-point source (NPS) pollution in the irrigation area of the lower reaches of the Kaidu River Basin, based on spatial and attribute data (2010–2014). Four climate change scenarios (2040–2044) and two agricultural management scenarios were input into the SWAT model to quantify the effects of climate change and agricultural management on solvents and solutes of pollutants in the study area. The simulation results show that compared to the reference period (2010–2014), with a decline in streamflow from the Kaidu River, the average annual irrigation water consumption is expected to decrease by 3.84x108 m3 or 8.87% during the period of 2040–2044. Meanwhile, the average annual total nitrogen (TN) and total phosphorus (TP) in agricultural drainage canals will also increase by 10.50% and 30.06%, respectively. Through the implementation of agricultural management measures, the TN and TP in farmland drainage can be reduced by 14.49% and 16.03%, respectively, reaching 661.56 t and 12.99 t, accordingly, and the increasing water efficiency can save irrigation water consumption by 4.41 x108 m3 or 4.77%. The results indicate that although the water environment in the irrigation area in the lower reaches of the Kaidu River Basin is deteriorating, the situation can be improved by implementing appropriate agricultural production methods. The quantitative analysis results of NPS pollutants in the irrigation area under different scenarios provide a scientific basis for water environmental management in the Kaidu River Basin.

Effects of different irrigation frequencies and incorporation of rice straw on yield and water productivity of wheat crop

The current rapid increase in irrigation water consumption is considered unsustainable and threatens the world food production. Therefore, it is mandatory to promote modern techniques and to manage existing conventional irrigation methods. The present study was attempted to determine the effects of different irrigation frequencies and rice straw incorporation rates on yield and water productivity of the wheat crop. The experiment was arranged with randomize complete block design involving nine treatments (RS0I7, RS0I15, RS0I22, RS1I7, RS1I15, RS1I22, RS2I7, RS2I15 and RS2I22) under three replications. Results exposed that the incorporation of rice straw with different irrigation frequencies significantly improved physico-chemical properties of soil. Moreover, soil bulk density, infiltration rate, pH, electrical conductivity significantly decreased and soil porosity significantly increased under all treatments. Furthermore, maximum crop yield and crop water productivity of 7706.4 kg/hm2 and 1.92 kg/m3 respectively were found under RS1I15 treatment. Based on experimental results it can be concluded that irrigation frequency and incorporation of rice straw had significant effects on the physico-chemical properties of soil, total grain yield and water productivity of the wheat crop. However, this study suggested that the wheat crop yield and water productivity could be increased by incorporating 1 t/hm2 rice straw with 15 d of irrigation frequency. Keywords: physico-chemical, irrigation frequency, rice straw, wheat, crop water productivity DOI: 10.25165/j.ijabe.20201301.4790 Citation: Tunio M H, Gao J M, Talpur M A, Lakhiar I A, Chandio F A, Shaikh S A, et al. Effects of different irrigation frequencies and incorporation of rice straw on yield and water productivity of wheat crop. Int J Agric & Biol Eng, 2020; 13(1): 138–145.

Irrigation regimes and water consumption of soybeans and corn depending on irrigation methods

Irrigation regimes and water consumption of soybeans and corn depending on irrigation methods

Analysis of saline land and determination of the level of salinity of irrigated lands with use of the geographic information system technologies

In Uzbekistan, more than half of population lives in rural area, their well-being depends on quality of land and water resources availability. Quality of land is determined by ameliorative indicators: ground water depth level, ground water salt amount and salinity of soil. These factors do not appear naturally but rather due to the human activity. Inefficient irrigation and excessive consumption of irrigation water on irrigated land in Boyavut District of Syrdarya region of Uzbekistan within several decades have led to a salinization of soil. The primary objective of this article is determination of the level of salinity of soil for modelling spatial distribution of soil salinity throughout an irrigated land by using GIS technology. This technology is focused on automation of development and creation of ameliorative maps, while totally eliminating manual operations. Nowadays, ameliorative expedition specialists still create cadastral map using tracing paper over the marginal areas within irrigated lands based on their ameliorative conditions and by selecting from the three thematic maps and then selecting the poorest conditions of ameliorative indicators. The suggested technology is designed for professionals of cadastral subdivisions of regional ameliorative expeditions, who use the GIS-based software, such as ArcView 3.2. or ArcGIS 10x; their duties include creating of thematic maps based on salinity levels of irrigated lands. Exact coordinates of collection sites of soils samples (collected in 2018-2019) were determined using GPS. The Inverse Distance Weighting (IDW) interpolation method was applied to use that data to create ameliorative maps categorized by the salinity levels (non-saline, slightly saline, saline area and highly saline areas). Those maps were then analysed to develop procedures on how to improve ameliorative conditions of irrigated areas.

АНАЛИЗ ИСПОЛЬЗОВАНИЯ ДИФФЕРЕНЦИРОВАННОГО ПОДХОДА ПРИ ОРОШЕНИИ СЕЛЬСКОХОЗЯЙСТВЕННЫХ КУЛЬТУР

Purpose: to analyze the experience of Russian scientists in the field of application of a differentiated approach to agricultural crops irrigation. The overview of research work of domestic scientists on the use of an irrigation system in agriculture, in which the provision of agricultural crops with water to maintain a given level of the minimum water capacity will be carried out during the most critical periods of their growth and development is presented. During irrigation, the timing, frequency, irrigation rates depend on the level of groundwater occurrence, agrochemical properties of soils, weather and climatic conditions, phases of growth and development of crops. The application of a differentiated irrigation regime to maintain a given level of pre-irrigation moisture allows increasing the productivity of agricultural crops, the quality of products obtained while reducing irrigation and watering rates, the number of waterings. Conclusions. The study of the results of research work of domestic scientists in the field of influence of irrigation and the fertilization system on the yield and quality of agricultural products allows concluding that obtaining the planned yields is possible only if irrigation regimes are observed and the level of soil fertility is maintained by applying various fertilizers. The use of a differentiated approach to irrigation while maintaining a given level of pre-irrigation soil moisture during critical periods of crop development allows reducing irrigation water consumption and optimizing irrigation rates and their quantity. The study of a differentiated irrigation regime is promising now and in the near future, taking into account the deteriorating water supply in the territory of our country, associated with a change in weather and climatic conditions.

Sustainability analysis of bioethanol promotion in Thailand using a cost-benefit approach

This study aims at analyzing the sustainability of bioethanol promotion in Thailand using cost-benefit analysis. The analysis is carried out based on the bioethanol production targets in Thailand’s Alternative Energy Development Plan 2015, covering cassava and molasses ethanol. The role of taxes and production efficiency improvement on the entire economy is presented via bioethanol promotion options. The socio-economic and environmental effects of bioethanol promotion are also considered. The effects of bioethanol promotion are derived via a hybrid approach including computable general equilibrium modeling and life cycle impact assessment. Environmental effects are converted into monetary units using the conversion factors for Thailand. The results show that increasing bioethanol production and use can bring about a net benefit to society of around 62 billion Thai Baht over 2016–2026. Improving the production efficiency of feedstock along with increasing bioethanol production can increase the net benefit to society. Furthermore, not only does bioethanol promotion enhance real Gross Domestic Product, but also creates more jobs in the society and leads to less environmental cost per unit of domestic production when air emissions and irrigation water consumption are considered. The study can thus support decision-making towards sustainable biofuel development in Thailand.

AVALIAÇÃO DO POTENCIAL DE REUSO DE EFLUENTES DE ETE EM ÁREAS IRRIGADAS DA BACIA HIDROGRÁFICA PIANCÓ-PIRANHAS-AÇU COM VISTAS A UNIVERSALIZAÇÃO

A Bacia Hidrográfica Piancó-Piranhas-Açu (PPA) abrange uma área total de 43.683 km² (ANA, 2016), com baixas precipitações, resultando em secas hídricas. O reuso de efluentes pode ser visto como uma prática que combate e minimiza os impactos sofridos pelas secas severas. Assim, uma vez que a região possui baixo atendimento ao tratamento de esgoto, neste trabalho, foi realizada uma avaliação do futuro potencial de reuso de efluentes de ETEs em áreas irrigadas. Assim, observou-se que, em relação à projeção para implantação das ETEs, em 2035, serão 131 ETEs em operação, com uma vazão total de 1,41 m3/s. A demanda de água para a agricultura irrigada na bacia é de 17,48 m³/s e com isso a oferta da água de reuso pode representar 8% da demanda de água para irrigação, a um custo estimado de transporte variando entre R$ 2,46/m3 e R$ 12,62/m3, em função do estado (PB e RN) e das distâncias de transporte (10 a 50 km). Comparando o custo da água de reuso com o valor do consumo da água bruta, constatou-se que os valores médios praticados atualmente para consumo de água na irrigação (0,02 R$/m3) inviabilizam financeiramente a prática e não se alinham com os objetivos instituídos pela lei das águas, já que os valores cobrados são ínfimos. Por fim, ficou ainda mais evidente a necessidade em se atingir a universalização do esgotamento sanitário, não somente para minimizar a poluição dos corpos d’água, mas também em propiciar efluentes tratados para a prática de reuso.
 

Irrigation Water Use in the Danube Basin: Facts, Governance and Approach to Sustainability

Abstract In this paper we assess the irrigation water use in the Danube Basin, highlight its complexity, identify future challenges and show the relevance for a basin-wide integrative irrigation management plan as part of a more holistic and coherent resource policy. In this sense, we base our integrative regional assessments of the water-food-energy nexus on insights from an extensive review and scientific synthesis of the Danube Basin and region, experimental field studies on irrigation and agricultural water consumption, current irrigation related policies and strategies in most of the Danube countries, and regulatory frameworks on resources at European Union level. We show that a basin-wide integrative approach to water use calls for the evaluation of resource use trade-offs, resonates with the need for transdisciplinary research in addressing nexus challenges and supports integrative resource management policies within which irrigation water use represents an inherent part. In this respect, we propose a transdisciplinary research framework on sustainable irrigation water use in the Danube Basin. The findings were summarized into four interconnected problem areas in the Danube Basin, which directly or indirectly relate to irrigation strategies and resource policies: prospective water scarcity and Danube water connectedness, agricultural droughts, present and future level of potential yields, and science based proactive decision-making.

Global unsustainable virtual water flows in agricultural trade

Recent studies have highlighted the reliance of global food production on unsustainable irrigation practices, which deplete freshwater stocks and environmental flows, and consequently impair aquatic ecosystems. Unsustainable irrigation is driven by domestic and international demand for agricultural products. Research on the environmental consequences of trade has often concentrated on the global displacement of pollution and land use, while the effect of trade on water sustainability and the drying of over-depleted watercourses has seldom been recognized and quantified. Here we evaluate unsustainable irrigation water consumption (UWC) associated with global crop production and determine the share of UWC embedded in international trade. We find that, while about 52% of global irrigation is unsustainable, 15% of it is virtually exported, with an average 18% increase between year 2000 and 2015. About 60% of global virtual transfers of UWC are driven by exports of cotton, sugar cane, fruits, and vegetables. One third of UWC in Mexico, Spain, Turkmenistan, South Africa, Morocco, and Australia is associated with demand from the export markets. The globalization of water through trade contributes to running rivers dry, an environmental externality commonly overlooked by trade policies. By identifying the producing and consuming countries that are responsible for unsustainable irrigation embedded in virtual water trade, this study highlights trade links in which policies are needed to achieve sustainable water and food security goals in the coming decades.

Climate smart agricultural technologies in rice-wheat water stressed regions of Punjab, India- A review

Intensively cultivated rice-wheat cropping sequence of Punjab, India responsible for many sustainability issues viz. declining underground water, declining soil health, arising micro-nutrient deficiencies etc. Around 1.3 M ha-m additional withdrawal of water from the ground is being taken place annually in Punjab and mainly it is used for the rice crop which is not a traditional crop of the region. Puddling, seepage and percolation losses are the main sources of water loss from the rice based cropping systems in the Indo-Gangetic plains (IGPs) and many Resource Conservation Technologies (RCTs) have been recommended for water saving. The real water saving techniques are those which hinder the water from going into those sinks from where it cannot be reused (Evaporation, E) and diverted greater fraction of water of ET toward transpiration (T) which is desired as greater transpiration, greater the inflow of water and nutrients andwhich ultimately increase the grain yield with the lesser consumption of irrigation water as interval in between two irrigation increases, which further increase the water productivity. Among different RCTs, short duration crop varieties and delaying transplanting time are the real water saving techniques for the regions where water table is already declining down, however other RCTs may be suitable for the regions facing water logging problems as these cut down the drainage losses and these energy saving rather than water saving techniques.

EFFECT OF IRRIGATION REGIMES, NITROGEN, AND MULCHING TREATMENTS ON WATER PRODUCTIVITY OF TOMATO UNDER DRIP IRRIGATION SYSTEM

A field experiment was conducted at El-Intelaq area, West Nubaria region, Behaira Governorate (31o 02' N, 30o 28' E, and 6.7 m above mean sea level), Egypt during the 2012 and 2013 summer growing seasons to study the effect of three irrigation treatments (i.e., I1=75%, I2 = 100%, and I3 = 125% of reference ETo, which was estimated from class ‘A’ pan evaporation and Kpan=0.75, two nitrogen fertilizer levels (i.e., N1= 75%, and N2=100% of recommended nitrogen rate), and two crop residuals mulching treatments (i.e., M0 = without mulch, and M = with mulch) on tomato yield, amounts of applied irrigation water, water consumption, applied water productivity (AWP), leaf water potential, and to develop a local tomato crop coefficient (Kc) and yield response factor (Ky) under the experimental conditions. Results indicated that, the tested variables had significant effect on tomato yield in the two growing seasons. The highest tomato fruit yields of 80.57 and 64.42 ton/ha were obtained as a result of the interaction of I3 (125%ETo) and N2 treatment in the two growing seasons, respectively. Total depths of applied irrigation water and water consumption of 816.2 and 838.0mm and 573 and 574mm were recorded in the 1st and 2nd growing seasons, respectively, for the I3 irrigation treatment. In both seasons, the highest AWPs values were 9.73 and 9.42 kg/m3 due to the combined effect of irrigation treatment I1 (75% Epan) and N2 (100% of recommended nitrogen fertilizer). Leaf water potential values were lower with the high applied water treatment than with the stressed irrigation treatment. Average crop coefficient values were 0.51 at initial growth stage during June and reached its maximum value of 0.98 during August, and then decreased to 0.71 during October. The local seasonal average tomato crop coefficient (KC=ETc/ETo) and yield response factor (Ky) values under the experimental conditions were 0.74 and 0.82, respectively. It was concluded that, under similar field conditions, applying a depth of water equal to 125% of ETo and 100% of the recommended nitrogen fertilizer, and adding plant residue mulch is recommended for maximum tomato yield in the studied sandy soils under drip irrigation systems.

Water Requirement for Irrigation of Complicated Agricultural Land by Using Classified Airborne Digital Sensor Images

Land use of irrigated areas nearby the metropolitan is complex. On fields, crop growth may differ with variations in the water demand. Among the image classification methods, combined object-oriented classification is currently preferred over conventional pixel-based classification. Compared with the traditional pixel-based method, which generally exhibits a spot-like salt-and-pepper effect, object-based classification can significantly reduce the salt-and-pepper effect and amount of data required for analysis. To obtain improved spectral recognition, maximum image information is described using color, texture, and shape to enhance image recognition. In this study, image information extraction and crop interpretation were performed using the airborne digital sensor ADS40 to obtain experimental data, and the traditional supervised image and image object classification methods were compared. The results indicate that both the image classification methods could yield an overall accuracy of more than 80%, and the accuracy of object-based classification (88.68%) was higher than that of the other classification. The daily water requirement of crops in the study area, calculated using a high-precision image object classification method, was approximately 2585 m3. The current results may aid in the effective estimation of agricultural irrigation water consumption.

Quantification of irrigation water using remote sensing of soil moisture in a semi-arid region

Irrigated agriculture is the principal consumer of fresh water resources. Most countries do not have a precise measurement of water consumption for irrigation. In this study, an innovative approach is proposed that allows for estimation of irrigation water use at the catchment scale based on satellite soil moisture data. To this end, the SM2RAIN algorithm, which had been originally developed for estimation of rainfall from the soil moisture observations, is adopted. The satellite soil moisture observations obtained from Advanced Microwave Scanning Radiometer 2 (AMSR2) along with different rainfall and evapotranspiration (ET) products in the period 2012–2015 are used as the input to the model. The methodology is tested in the agricultural plains of southern Urmia Lake, which is one of the main agricultural plains in Iran for which actual irrigation data is available.The results reveal that the proposed approach can capture the overall irrigation pattern, although; it is systematically overestimating irrigation volume compared to observed irrigation data. Thus the bias is calculated over largely non-irrigated pixels and used to modify the model estimates. The bias-corrected results show good agreement with the in situ irrigation data. In particular, the average model performance in the irrigated pixels in terms of R and RMSE (mm/month) are (0.86 and 12.895) respectively. Accuracy varied depending on the inputs, with improvement in order of 11% and 42% in R and RMSE depending on the inputs chosen. The method is also applied to less irrigated areas that result in obtaining significantly lower irrigation rates.The low spatial resolution of soil moisture products (i.e. ~50 km) makes it difficult to capture the irrigation water of small irrigated croplands. Unreliable rainfall and ET data can also lead to the over/underestimation of irrigation. In spite of the above limitations (particularly lack of reliable ET dataset), the proposed model can still capture the irrigation pattern, given that strong soil moisture signal from irrigation is detected by the satellite.

Change of winter wheat planting area and its impacts on groundwater depletion in the North China Plain

The North China Plain is one of the most water-stressed areas in China. Irrigation of winter wheat mainly utilizes groundwater resources, which has resulted in severe environmental problems. Accurate estimation of crop water consumption and net irrigation water consumption is crucial to guarantee the management of agricultural water resources. An actual crop evapotranspiration (ET) estimation model was proposed, by combining FAO Penman-Monteith method with remote sensing data. The planting area of winter wheat has a significant impact on water consumption; therefore, the planting area was also retrieved. The estimated ET showed good agreement with field-observed ET at four stations. The average relative bias and root mean square error (RMSE) for ET estimation were −2.2% and 25.5 mm, respectively. The results showed the planting area and water consumption of winter wheat had a decreasing trend in the Northern Hebei Plain (N-HBP) and Southern Hebei Plain (S-HBP). Moreover, in these two regions, there was a significant negative correlation between accumulated net irrigation water consumption and groundwater table. The total net irrigation water consumption in the N-HBP and S-HBP accounted for 12.9×109 m3 and 31.9×109 m3 during 2001–2016, respectively. Before and after 2001, the decline rate of groundwater table had a decreasing trend, as did the planting area of winter wheat in the N-HBP and S-HBP. The decrease of winter wheat planting area alleviated the decline of groundwater table in these two regions while the total net irrigation water consumption was both up to 28.5×109 m3 during 2001–2016 in the Northwestern Shandong Plain (NW-SDP) and Northern Henan Plain (N-HNP). In these two regions, there was no significant correlation between accumulated net irrigation water consumption and groundwater table. The Yellow River was able to supply irrigation and the groundwater table had no significant declining trend.

The Shadow Price of Irrigation Water in Major Groundwater‐Depleting Countries

AbstractIn many semiarid regions with irrigation, the depletion rate of groundwater resources has increased substantially during the last decades. A possible reason for this is that the price that users pay for their water does not reflect its scarcity and value. An alternative way to assess the perceived value of water is calculating its shadow price, which is defined here as the marginal value produced, and relates to the efficiency gain from current reallocation. Here we determine the shadow price of water used for irrigation for the most important groundwater‐depleting countries and for four staple crops and one cash crop. To quantify the shadow price, the relation between the output and the water input is represented using production functions. We use globally available panel data on country‐specific crop yields and prices together with crop‐specific water consumption, calculated with the global hydrological model PCR‐GLOBWB, to parameterize the production function by country and crop with econometric analyses. Our results show that the variation of shadow prices for staple crops within several countries is high, indicating economically inefficient use of water resources, including nonrenewable groundwater. We also analyze the effects of reallocating irrigation water between crops, showing that changes in water allocation could lead to either an increase in the economic efficiency of water use or large reductions in irrigation water consumption. Our study thus provides a hydroeconomic basis to stimulate sustainable use of finite groundwater resources globally.

Recent Global Cropland Water Consumption Constrained by Observations

AbstractUnder current global warming and accelerated population growth scenarios, cropland irrigation water consumption has become a central issue limiting the sustainability of coupled human‐natural systems. This study proposes a new estimate of recent global cropland water consumption constrained by observations and provides attributions for its recent trend. By incorporating observations, including extracted cropland leaf area index and irrigation threshold data, this study provides improved estimates of recent global cropland evapotranspiration and transpiration as well as irrigation water consumption and withdrawal. The global annual consumption and withdrawal of irrigation water are estimated to be approximately 874 and 1,867 km3 (in 2005), respectively. From 2000 to 2014, a rapid increase in cropland irrigation was detected, especially in water‐deficient areas (i.e., hyperarid, arid, and semiarid regions). Climate change, which mainly consists of rising temperature and reduced moisture conditions, is usually distinguished as the major driving factor. Human‐induced increases in crop canopy cover have also contributed to more irrigation in hyperarid and arid regions. This study also provides suggestions for water‐savings‐targeted cropland management in water‐deficient areas based on the transpiration ratio (i.e., ratio of transpiration to evapotranspiration).

Mathematical programming model (MMP) for optimization of regional cropping patterns decisions: A case study

The economic, technical and strategic factors are the three most important factors in examining the cropping patterns in Iran. Iran is geographically located in a part of the planet with specific climate constraints. Drought is one of the constraints that has been a major challenge to agricultural development for many years and has always been the subject of discussions and investigations. On the other hand, constraints such as agricultural soils, economic factors, climate change, agricultural workforce, etc., multiply the production challenges in the country. Despite such constraints, planning a coherent and targeted program for the cultivation of crops and overcome the existing problems is inevitable. The present study introduced a model for optimization of regional cropping pattern decisions, which is one of the subsets of the Multi-Objective Structural Planning (MOSP) approach, and addressed different objectives, such as economic, social and environmental objectives, separately and jointly. However, it is important to address the exchange of crops in different areas in order to achieve the fundamental objectives of determining the optimal cropping pattern. Therefore, in the proposed model of optimal regional cropping pattern, issues such as the transportation of crops and, consequently, virtual water and energy exchanges were also considered. In order to evaluate the proposed model, agricultural arable lands located in the political-geographic divisions of 23 counties of Isfahan province (Iran) were selected for examination. The results showed that in the main groups of grains and forage, a significant reduction was observed in the optimal crop area of the multi-objective model by 26% and 5%, respectively. Increasing the crop area of horticultural products by 10% in the optimal pattern of multi-objective model was another important factor in the analysis of the results. In general, in order to achieve the economic, social and environmental objectives mentioned in this study within the framework of a multi-objective planning, a 16% reduction in the level of the crop area in Isfahan province is inevitable. The results of this measure are reduction in the irrigation water consumption by 17%, increase in the profit by 58% and increase in the production by 11%. Regarding the fact that in the structural planning of cropping pattern, different and sometimes conflicting objectives are considered and the compromise between the objectives is possible in the multi-objective structural planning model, the decision makers are recommended to use this model.

Environmental burdens of groundwater extraction for irrigation over an inland river basin in Northwest China

Crop production is expected to increase by more than 50% to meet the demand of population growth in China in 2050 (FAO, 2017). Crop production in North China largely depends on irrigation, which is mainly from groundwater in Northwest China. Over-extraction of groundwater is decreasing groundwater levels, and threatening the fragile ecological systems of arid regions. How groundwater levels will change in order to meet the irrigation water requirement in Northwest China has not been extensively investigated to evaluate sustainability of agriculture and the cost to maintain groundwater levels. Here, we examine the dynamic relations between groundwater levels and the amount of irrigation water, by employing the Variable Infiltration Capacity model and an irrigation scheme, for the last three decades in Heihe River basin of China. The results show that on the average about 1.86 m decline of groundwater is attributable to the irrigation water consumption for the farmland area in Heihe River over the past three decades. In the scenario of ceasing irrigation activities, the groundwater level will be prevented to further decline about 3.06 ± 0.4 m under the future climate scenarios till 2050, but at the cost of crop production valued 64.2 ± 8.4 billion CNY. Effective water-saving measures and strategies are expected to adopt to maintain both groundwater levels and agricultural productivity for the coming decades.