Annual Irrigation Research Articles

Socio-economic Impact of Reducing Water Availability of Springs in Kandi Village, Devprayag, Uttarakhand: A People Perception Approach

Water is necessary for sustainable development, which includes safeguarding the environment and the reduction in hunger and poverty. Demand is rising quickly, which is posing issues for many countries due to population growth and economic expansion. The goal of the current study is to examine the state of spring and water resources in Kandi Village, Devprayag, Uttarakhand, India, and how they affect farmers’ agricultural productivity from a socioeconomic standpoint. The key data used in the study were gathered from farmers using questionnaires. Using a stratified random sampling technique, a sample of 100 farmers was chosen for the data collection. The conclusion of the study is that there is currently very little spring, and ground water available. It has been discovered that spring is sparse to fulfil the need of annual irrigation requirements for economic purposes like farming. Lack of springs resulted in a reduction in the amount of land used for farming, a decrease in farmer revenue, livestock losses, etc. According to the findings, some ways to lessen the strain on the water resources available to farmers include building new dams, rejuvenating springs, teaching them how to use highly efficient irrigation systems, and educating them about modern production techniques.

High-resolution land surface modeling of the irrigation effects on evapotranspiration over the Yellow River basin

Accurate estimation of irrigation-induced evapotranspiration (ET) is critical for understanding the terrestrial water cycle. However, current estimation has large uncertainties due to the model limitations and the lack of accurate water use data. In this study, a water-energy balanced irrigation scheme is incorporated into the Conjunctive Surface-Subsurface Process version 2 (CSSPv2) model to improve the hydrological simulations over the Yellow River basin (YRB) where irrigation is extensive. The coupled model (CSSPv2-IRR) is calibrated against long-term water use data from provincial survey, and it is used to perform a 6-km resolution simulation over the YRB during 1991–2017. The results show that the coupled model can well reproduce hydrological processes within the basin, and the simulated irrigation amount, ET and surface soil moisture largely agree with the validation datasets. Specifically, the annual irrigation amount and irrigation-induced ET changes from the CSSPv2-IRR are more reasonable than ISIMIP2a and reanalysis products, with a reduction in bias by 79.5–97.3 % and 81.2–98.8 % respectively. The CSSPv2-IRR model simulation suggests that irrigation-induced annual ET change is 26.4 mm/year during 1991–2017, contributing to an 8.9 % increase in annual ET over the YRB, and the increase can reach 44.3 % over major irrigation districts. In addition, the contribution of irrigation to long-term increasing trend in ET over the irrigation districts in the upper reach is greater than the contribution of climate change. This study suggests a growing control of irrigation on the ET over the YRB, which has implications for regional water cycle and water resources management.

Optimizing deficit irrigation in Monastrell vines grafted on rootstocks of different vigour under semi-arid conditions

A progressive irrigation reduction was applied during five years (from 2017 to 2021) by using regulated deficit irrigation (RDI) and partial root-zone drying irrigation (PRD) in field-grown mature Monastrell grapevines grafted on five different rootstocks (140Ru, 1103P 41B, 110R, and 161–49C) in the semi-arid wine-growing region of D.O. Bullas, South-Eastern (SE) Spain. The main goal was to adjust the irrigation volume applied during the growing season for each rootstock depending on the drought tolerance/vigour/productivity of the rootstock. Thus, the annual irrigation volume was progressively reduced (from 104 mm year−1 [2017] to 45 mm year−1 [2018‐2019] and 15 mm year−1 [2020‐2021] in the most drought-tolerant, vigorous, and productive rootstocks [1103P, 140Ru], and from 104 mm year−1 [2017] to 74 mm year−1 [2018‐2019] and 58 mm year−1 [2020‐2021] in the less drought-tolerant, vigorous, and productive rootstocks [110R, 161–49C, 41B]. A severe reduction of the irrigation in 140Ru and 1103P substantially reduced vigour, productivity, and berry weight and increased water productivity (WP) (220% and 97%, respectively) and phenolic berry quality (50% and 92%, respectively). Medium/low-vigour rootstocks also had a decrease in vigour, yield, and berry weight in response to an irrigation reduction, enhancing WP (between 17% [41B] and 41% [161‐49C] and phenolic berry quality (between 11% [161–49C] and 46% [110R] With a low water volume DI (53–77 mm year−1), vines grafted on 161–49C delivered the highest berry quality compared to other rootstocks. Physiological changes produced by very low water volume PRD were reflected in a reduced root water and nutrient uptake and leaf gas exchange and a slightly increased technological berry quality compared to RDI. However, PRD did not produce a significant improvement in WP, phenolic concentration, and global berry quality compared to RDI.

Multivariate Assessment of Groundwater Depletion and Recharge Prospect in a Sub-tropical Basin of Eastern India

Abstract The present study aims to highlight the groundwater-stress condition of the Quaternary 一 recent alluvial region escalated by anthropogenic extraction of water resources in the western Bengal Basin (Purba Bardhaman, West Bengal, India). With the rapid development of irrigation technology, high crop yield, water- consumed rice varieties, and high cropping intensity, the farmers of the river basin go to deeper underground aquifers (>180 m bgl) to extract water for summer rice (Boro) cultivation. In this study, the five semi-critical blocks (Mangolkote, Bhatai; Manteswai; Purbasthali II, and Memari II) of Purba Bardhaman district have experienced statistically significant pre-monsoon fall (0.404 m yr- 1 to 1.099 m yr-1) and post-monsoon fall of groundwater level from 0.486 m yr-1 to 2.214 m yr-1. Principal component analysis reflects that annual irrigation draft, annual replenishable groundwater unit, net groundwater availability, Boro rice cultivation area, area to be covered on each day irrigation for Boro, and daily pump discharge required for Boro irrigation are the key factors to escalate groundwater decline. This study reveals that Galsi II, Bardhaman I and II, Katwa I, and Purbasthali I blocks will experience a water-stress or groundwater drought in future. The model of groundwater recharge potential zone shows four principal categories of groundwater prospect area in the basin, viz., poor (0.08 %), moderate (5.78 %), good (68.96 %), and very good (25.18 %). These findings provide the relevant information for planners of groundwater resources to upscale groundwater management procedures and enhance the sustainability of agricultural systems in the study area.

Estimates of irrigation requirements throughout Germany under varying climatic conditions

As climate change brings about hotter and often drier summers, an improved understanding of how irrigation requirements vary according to climatic conditions is of increasing importance. Within Germany, temperate conditions have historically enabled most agriculture to be supplied solely by green water, but recent crop yield reductions and crop failures have demonstrated its increased vulnerability to climatic conditions. The raster-based mGROWA hydrological water balance model was implemented over all agricultural areas in Germany for the period 1961–2020 at a high spatial (200 m) and temporal (daily) resolution. Grid-cells were each assigned one of 10 major crop classes, which account for 86.7 % of all agricultural areas in Germany, and effectively all irrigated areas. Using crop-specific irrigation rules that reflect actual practices, irrigation requirements were simulated for all crop areas. To investigate the relationship between climatic water balance over the crop growing season and irrigation requirements, the simulated annual irrigation requirements were compared with the standardised precipitation-evapotranspiration index (SPEI-6), calculated at the end of September. Through this comparison, irrigation requirements could be characterised for near-normal and dry conditions, and results were aggregated to the district level. Additionally, using district-level data on the areas with irrigation infrastructure, the actual water used for irrigation was estimated. The results highlight marked increases in irrigation requirements in dry conditions compared to near-normal conditions (median increase of 72 %), which are more pronounced over crops in silty soils than in sandy soils. The results also demonstrate how the increased irrigation requirements in dry years are in many cases higher than what is suggested by guidelines for irrigation management in Germany. This study provides important information for actors related to the agricultural sector and water management and is based on a robust and transferable framework to quantify how irrigation requirements vary according to climatic variability and local soil conditions.

Multi-purpose reservoir operation concomitant with estimating hydropower potential using multifarious hydrological models

The research aims at determining the optimal release rule to increase the capacity of Rib reservoir. The reservoir inflow using HBV-light hydrological model embracing optimal reservoir operation through HEC-ResSim model were used to prepare an optimum operational plan. The potential of the river for hydropower generation prioritise the demand at a specified level regarding storage capacity (m3), level of reservoir (m), and the relation between inflow and outflow of the reservoir. From the model performance features, the coefficient of correlation (R2) and Nash Sutcliffe Efficiency (NSE) were determined to be, respectively, 0.77 and 0.73 for calibration and 0.72 and 0.70 for validation. The Sobol approach was used for detailed sensitivity analysis of DROP model parameters based on the performance of C2M on outflows and volumes. The results suggest that the threshold coefficient characterizing the demand-controlled release level is the most significant parameter. According to the simulation's findings, the reservoir's average regulated release is calculated to be 22.86 m3/s, and its average monthly hydropower output is 6.73 MW. Average annual hydropower energy was estimated as 58.955 GW h/year and mean annual inflow of reservoir volume of water to be 223.54 Mm3. This volume of water is adequate to accommodate total annual irrigation demand, environmental obligation, and other respective requirements in the downstream. The demand for hydropower and irrigation and supply from reservoir capacity can be counterbalanced from the simulated result without any hindrance.

Impact of Groundwater Depletion on Irrigation Cost of Paddy and Maize Cropping System in the Anantapur District of Andhra Pradesh, India

The study was conducted to estimate the cost of groundwater irrigation and the impact of groundwater over-exploitation on the irrigation cost of paddy and maize in the Anantapur district of Andhra Pradesh. Based on the stage of groundwater extraction, the Central Groundwater Board divided the study area into safe and exploited areas. Primary data was collected from both these safe and exploited areas. The study found that the annual irrigation cost of groundwater in over-exploited areas for both paddy (₹4033.38/acre) and maize (₹3570.26/acre) were observed to be higher as against paddy (₹2697.01/acre) and maize (₹ 2524.76/acre) in safe areas. The added cost of groundwater irrigation in over-exploited areas for paddy (₹988.08/acre) and maize (₹838.34/acre) were preponderantly greater than paddy (₹216.60/acre) and maize (₹187.82/acre) in safe areas. This revealed that groundwater over-exploitation had a more significant impact on over-exploited regions. Marginal and small farmers are the primary victims of groundwater over-exploitation in terms of cost and groundwater resources. Free/subsidized electricity for irrigation and water-intensive crops, paddy and maize, are one of the reasons for depleting groundwater in the study area. There is a solid requirement for controlling groundwater over-exploitation in the study area.

Development and application of a new water-carbon-economy coupling model (WCECM) for optimal allocation of agricultural water and land resources

The optimal allocation of agricultural water and land resources is of great significance in ensuring sustainable food production and economic benefits of farmers. However, agriculture, as an important carbon cycle ecosystem, has paid limited attention to carbon sequestration in the optimal allocation of water and land resources. Therefore, this study developed a new water-carbon-economy coupling model (WCECM) for optimal allocation of agricultural water and land resources. In this model, the minimum water scarcity, maximum carbon sequestration and maximum economic benefits are taken as the optimization objectives. In addition, surface water volume and groundwater volume and planting area etc. were defined as constraints, respectively. Then, the model was solved using the Non-dominated Sorting Genetic Algorithm III (NSGA-III) and the Entropy-weighted-TOPSIS evaluation method. The developed model was demonstrated in the largest Farm, Youyi Farm, which is one of commercial grain production base in China to analyze the optimization of water and land resources from 2010 to 2019. We found that the new WCECM, based on the simulation of a complex coupled water-carbon-economy system, can realize the optimal allocation of agricultural water and land resources to protect regional water resources, increase carbon sequestration and adjust the agricultural planting structure. In detail, through the multi-objective optimization model, the planting structure and the allocation ratio of surface water and groundwater irrigation water consumption are more suitable for this study area. After the optimization, the area planted with Rice was significantly reduced, the area planted with Maize was increased, and the area planted with Soybean did not change significantly compared with the first two crops. The planting structure has changed from focusing on paddy cultivation to dryland cultivation, with the ratio of Rice area, Maize area and Soybean area being 3:6:1. The water consumption is constrained within manageable limits, with an average annual irrigation water consumption of 2.01 × 108 m3. The amount of carbon sequestered has increased significantly, with an average annual increase of 7.8 × 108 kg. Meanwhile, the optimized economic benefits increased slightly, with a value of ¥2.35 billion. In short, optimization of water and land resources is beneficial for improving farmers' incomes, increasing carbon sequestration in agriculture, and conserving water resources.

Comparing water requirements of urban landscape plants in an arid environment: An application of the WUCOLS method in the National Botanical Garden of Iran

Water scarcity is a pressing issue in many arid and semi-arid regions worldwide, requiring effective water resource management. To address this challenge in the National Botanical Garden of Iran, we analyzed the water requirements for the irrigation of ten tree species over the entire growth period, spanning from January 2021 to January 2022. We employed the Water Use Classification of Landscape Plants (WUCOLS) method, and used remote and on-site measurements to obtain the required data (i.e., enhanced vegetation index, leaf area index, rainfall, and site and species characteristics) for the analysis. We found that Ficus carica L., Cercis siliquastrum L., and Ulmus glabra Hudson had high landscape evapotranspiration (ETL) values, showing their elevated water requirements. Among all the species studied, F. carica, C. siliquastrum, and U. glabra showed the highest total ETL, reaching 1033, 1031, and 1002 mm respectively, highlighting their overall greater water needs throughout the study period. Further, we computed the annual net water requirement (IRn) for each plant species, taking into account the effective rainfall of 123.5 mm during the growth period of the study garden. We found that F. carica, C. siliquastrum, and U. glabra had the highest IRn among all the species with values of 950, 948, and 919 mm respectively. In contrast, Olea europaea L., and Quercus robur L. had the lowest IRn values of 681, and 711 mm, respectively. Additionally, we assessed the difference between annual irrigation values (AI) and gross water requirement values (IRg). Cercis siliquastrum and F. carica with values of −519 mm and − 511 mm had the largest negative differences, indicating that these species received the least irrigation water in comparison with their gross water requirements among all the species. In contrast, Cotinus coggygria, and O. europaea, with values of 182 mm and 125 mm had the largest positive differences, suggesting that these species received the most irrigation water in comparison with their gross water requirements among all the species. Our findings hold significance for the management of urban green spaces, including botanical gardens, parks, and street trees, contributing to the well-being of urban residents and visitors.

Effects of full and deficit irrigation on the growth and quality of cool-season turfgrasses under subsurface drip irrigation

Irrigation is necessary in terms of achieving high-quality turfgrass. However, it is evident that more efficient and cost effective irrigation methods should be adapted for the sake of water conservation strategies since water consumption is high during turf irrigation. The objective of this study is to determine the effects of full and deficit irrigation with subsurface drip irrigation on growth and quality of perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinaceae Schreb) in a sub-humid climate of Turkey. Three irrigation treatments [I1 (full irrigation), I2 (mild water deficit, 75%), and I3 (moderate water deficit, 50%) were applied to the plants. Turf color and quality of each plot were rated visually, and clipping yields were collected. The amount of irrigation applied varied between 457.3 - 833.9 mm and 356.7 - 710.1 mm and seasonal crop evapotranspiration (ETa) values ranged from 578.4 to 1053.0 mm for tall fescue and 551.2 to 1044.0 mm for perennial ryegrass in 2018 and 2019, respectively. Among the species, tall fescue showed higher visual color, quality ratings and clipping yields. In cases where it does not matter for one or two weeks to be below the acceptable quality (<6) minimum annual irrigation amounts required to maintain quality was 689.1 mm for perennial ryegrass and 578.4 for tall fescue. The results have suggested that acceptable visual color and quality are sustainable in the tall fescue with mild water deficit application in regions where irrigation water is limited in sub-humid climates. Studies on water-saving strategies to turfgrass in regions where the climates varies from year to year are lacking in literature.

Assessment of surface water resource and allocation optimization for diverse demands in Ethiopia's upper Bilate Watershed

Water planning and management is very crucial for all computing sectors for water uses to maximize the scarce and allocated water uses based on their demands sustainably in Ethiopia's upper Bilate watershed. The shortage of surface water, especially during dry months, has become a major point of contention between upstream and downstream water users in the upper Bilate River. Therefore, the key objectives of the study are to evaluate the surface water resources and determine the best distribution for a range of requirements in the watershed. The historical climatic and stream flow daily data for the period of 2010–2019 have been used for the analysis. Hydrologic Engineering Center Hydrologic Modeling System-Geospatial Hydrologic Modeling Extension with the Hydrologic Engineering Center Hydrologic Modeling System was used for rainfall-runoff analysis. The model output further represents that the yearly overall surface water of the watershed is 502 MC M. Estimated annual environmental requirement is 75.32MCM which is 15% of the average annual available flow in watershed. Current annual irrigation, livestock, and domestic water demand were estimated to be 19.34 MC M, 12.39 MC M, and 79.4 MC M, respectively. The net amount of water delivered was 19.25 MC M, 79.28 MC M, and 12.36 MC M for irrigation, domestic, and Livestock demands, respectively, in the reference scenario. In the currently available (reference) scenario, 99.8% of the water supply need had been fulfilled, yet only 0.2% of the requirements for water were unmet. Average annual water demand of 111.13 MC M in the current scenario growth to 176.08 MC M when the future growth scenario. In contrast, for the future irrigation development and population projections scenario, 69.8% of the supply-demand became acquainted, and 30.2% of the demand for water remained unfulfilled in 2035. Therefore, to realize good water availability for productive use and allocate water optimal manner constructing a hydraulic structure (dam) upstream of the watershed was recommended.

Telecoupled urban demand from West African cities causes social-ecological land use transformation in Saharan oases.

Little is known about the long-distance telecoupling effects of urban food demands on land use changes (LUCs) in remote oases of the Southern Sahara. Using the example of two typical oasis settlements on Mont Bagzam in the southern Aϊr Mountains of Niger which are linked to regional and global markets by an unpaved road since 2015, this study aimed at analyzing time trajectories of LUCs and related changing agricultural production patterns. LUCs were quantified for 1955 to 2022 using GIS-based mapping of agriculture and natural vegetation based on historical aerial photographs, CORONA and multi-spectral satellite images, and high resolution drone-based surveys. The results show a major increment in actively used agricultural land in the 850 ha watershed of the two oases from 11 ha in 1955 to 13 ha in 2003 and 68 ha in 2022 as well as the addition of 92 irrigation wells to 16 existing ones between 2003 and 2022. LUCs and evapotranspiration calculated from climatic data of a local weather station allowed to estimate changes of irrigation water needs in the selected watershed. While annual precipitation averages only 214 mm, local reference evapotranspiration may reach 1,476 mm year-1. Therefore, the additional annual irrigation water needs for the newly established fields between 2003 and 2022 cultivated to cash crops rose by 696 million l. To detect LUC effects on soil quality, soil samples of onion and garlic fields of different ages were collected employing a false-time-series approach. Results reveal increasing soil pH and salt concentrations and falling ground water tables, which reflects a negative water balance and ground water extraction above recharge levels. Our study provides evidence that the newly established telecoupled production systems on Mont Bagzam threaten the sustainability of existing local agricultural production and related livelihoods of agro-pastoralists.

A distributed agroecosystem model (RegWHCNS) for water and N management at the regional scale: A case study in the North China Plain

Process-based agroecosystem model is difficult to apply at the regional scale due to the complexity of model parameterization and execution efficiency. Thus, developing a regional agroecosystem model is challenging. In this study, a parallel computing framework is introduced to upscale an agroecosystem model (WHCNS model) from field to regional scale by integrating parallel computing, inversing modeling, and spatial calculation. The newly developed model was tested in the North China Plain (NCP) for modeling water consumption, N fate, and crop growth for winter wheat–summer maize rotation system under different water and N management practices. The optimum irrigation water and fertilizer N demands of winter wheat–summer maize system was estimated based on the auto-irrigation and auto-fertilization component in the model. Multisite testing showed that the model well reproduced soil water and N dynamics, crop biomass, LAI, yield, and crop N uptake, with R2 exceeding 0.886. The estimated annual average irrigation water and fertilizer N demands of winter wheat–summer maize rotation system was 395.8 mm and 529.5 kg N ha−1, respectively. Winter wheat was the major consumer of irrigation water and fertilizer N, accounting for 79.2 % and 54.4 % of annual irrigation water and chemical N fertilizer use, respectively. These results suggested that winter wheat was a crop with high water and fertilizer N demand in the NCP. The RegWHCNS model has potential value to assess and optimize regional water and N management for intensive agricultural-production systems. This study can provide as a scientific reference to upscale agroecosystem models from field to region for other agroecosystem models.

Are we saving water? Simple methods for assessing the effectiveness of groundwater conservation measures

Substantial storage reductions by irrigation pumping in many of the world’s major aquifers jeopardize future food production. As a result, new conservation measures are being utilized to reduce pumping and extend aquifer lifespans. The key question is how effective are these practices in attaining true water conservation (i.e., water use reduction) for a given area? Relationships between pumping and precipitation help provide an answer, as precipitation explains most of the variation in annual irrigation water use for aquifers in semi-arid to sub-humid climates when surface water supplies are limited. Our objective is to utilize correlations between radar precipitation and irrigation groundwater use at a range of spatial scales to assess the effectiveness of conservation approaches in the High Plains aquifer in the central USA. Linear regressions between pumping and precipitation for a conservation area established in 2013 in northwest Kansas indicate that water use and water use per irrigated area were over 27 % less and 25 % less, respectively, during 2013–2021 compared to the same climatic conditions during 2005–2012. Similar regressions found over a 38 % reduction and 23 % reduction in irrigation water use and use per irrigated area, respectively, during 2018–2021 compared to the same conditions during 2005–2017 in a west-central Kansas county with conservation areas. A decrease in irrigated area accounted for most of the difference between these reductions. Higher R2 values after conservation area establishment imply that irrigation tracks precipitation better due to use of soil moisture sensors and other measures as part of increased irrigation efficiency and enhanced water management. The precipitation and water use relationships, which are statistically significant for a wide range of spatial scales, have great potential for assessing the effectiveness of conservation practices in areas with high-quality water use and precipitation data.

Irrigation Water Requirements in Regions along Euphrates River in Iraq: Role and implications of Climate Change

This research aimed to predict how projected climate change will affect the quantity of water needed for irrigation. The case study focused on the Iraqi cities of Anbar and Babylon, located in the Euphrates River Basin (ERB). The CROPWAT model was fed by current and future climate data. Three climate change scenarios for the reference period from 1995-2014, SSP1-2.6 (2020-2039) and SSP2- 4.5 (2040-2059), were implemented in this research. The obtained results showed that annual increases in the temperature for Anbar are 1.1 and 1.85 °C, and for Babylon, they are 0.9 and 1.88 °C for the two scenarios SSP1- 2.6 and SSP2-4.5 concerning the reference period scenario. In addition, the annual decrease in precipitation is 3.61 and 4.63 mm for Anbar and 3.61 and 2.66 mm for Babylon Province. The average annual reference evapotranspiration for the three climate scenarios is 157, 202, and 206 mm for Anbar and 187.5, 195.6, and 224 mm for Babylon Province. The total annual irrigation water requirements for the crop growth cycle are 1.10, 1.43, and 1.46 for Anbar and 3.96, 4.13, and 4.76 billion cubic meters for Babylon.

Impact of climate change on shumbrite small scale irrigation project, South Gojjam subbasin, Ethiopia

Climate change has the potential to affect climate parameters like rainfall and temperature which lead to a change in the irrigation water requirement of the irrigation system. As irrigation water requirement is highly dependent on precipitation and potential evapotranspiration, climate change impact studies are necessary. Therefore, this study aims to assess the impact of climate change on the irrigation water requirement of the Shumbrite irrigation project. For this study, climate variables of precipitation and temperature were generated from CORDEX-Africa simulations downscaled from MPI Global Circulation Model (GCM) under three emission scenarios (RCP2.6, RCP4.5, and RCP8.5). The climate data covers from 1981 to 2005 for the baseline period and 2021–2045 for the future period for all scenarios. Future precipitation shows a decrease for all scenarios with a maximum decrease under RCP2.6 (4.2%) and temperature show an increase in the future as compared to the baseline period. The reference evapotranspiration and Irrigation Water Requirements (IWR) were calculated by using CROPWAT 8.0 software. Results showed that the mean annual reference evapotranspiration is expected to increase in the future by 2.7%, 2.6%, and 3.3% for RCP2.6, RCP4.5, and RCP8.5 respectively as compared to the baseline period. Mean annual irrigation water requirement shows an increase of 2.58%, 0.74%, and 8.4% for the future under RCP2.6, RCP4.5, and RCP8.5 respectively. The Crop Water Requirement (CWR) also increases for the future period under all RCP scenarios, with maximum CWR for tomato, potato, and pepper crops. To ensure the sustainability of the project, crops with high irrigation water requirements should be replaced by other crops with low water requirements.

基于 Hdyrus-2D 和 Stewart 模型的半干旱区灌溉制度优化及其应用

Water scarcity has been a critical constraint to economic development in semi-arid areas of China, so optimizing irrigation scheduling has become essential. This study obtained quantitative relationships between crop yield, crop water consumption, and irrigation quantity based on the Hydrus-2D and Stewart models. Different irrigation scheduling scenarios were evaluated to obtain the best irrigation scheduling based on the principle of simultaneous water conservation and crop productivity improvement with the evaluation indicators of crop yield, water use efficiency (WUE), irrigation water use efficiency (IWUE), and Critic-Topsis method. Taking drip irrigation under mulch as an example, the problem of optimizing the irrigation scheduling for different typical years was calculated. The optimization results showed that in the wet, normal, dry, and very dry years the annual irrigation quantity should be 49.68 mm, 49.68 mm, 85.38 mm, and 123.72 mm, when the WUE as well as IWUE, increases significantly, which had less impact on the crop yield and can save irrigation quantity by 30.00%, 30.00%, 35.00%, 27.00%. This study used Hydrus-2D to make a new attempt in irrigation scheduling optimization, giving full play to the model's high accuracy in soil water transport simulation and flexibility in boundary condition simulation. The optimization results can provide a reference for achieving accurate control of irrigation quantity during the crop growth period and reasonable irrigation scheduling formulation for regional crops.

Spatio-Temporal Study on Irrigation Guarantee Capacity in the Northwest Arid Region of China

Irrigation guarantee capacity is the critical factor in evaluating the development level of irrigated agriculture and is also a future development trend. It is necessary to carry out scientific planning and reasonable allocation of irrigation water resources to ensure the sustainable development of irrigated agriculture and improve the efficiency and effectiveness of water resource utilization. This study is based on remote sensing meteorological data and the principles of the Miami model and water balance. We calculated the annual irrigation water requirement and effective irrigation water, and used the ratio between the effective irrigation water and irrigation water requirement as the basis for evaluating an irrigation guarantee capability index. By using irrigation guarantee capability evaluation indicators from multiple years, we evaluated and assessed the irrigation guarantee capability in the arid region of northwest China. In addition, we analyzed three indicators (i.e., irrigation water requirement IWR, effective irrigation water EIW, and irrigation guarantee capacity index IGCI) to explore the rational allocation of water resources in the northwest arid area. IWR, EIW, and ICGI in northwest China from 2001 to 2020 were analyzed, and the average values were 379.32 mm, 171.29 mm, and 0.50, respectively. Simultaneously, an analysis was conducted on the temporal and spatial distribution of IWR, EIW, and IGCI in the northwest region of China from 2001 to 2020. The results indicated that the rainfall in the southwestern edge of the Yellow River Basin and the eastern part of the Qaidam Basin could meet the irrigation water demand. The northwest edge of the Yellow River Basin, the central Hexi Inland River Basin, most of Northeast Xinjiang, central and southeastern Xinjiang, and other regions mainly rely on irrigation to meet agricultural water requirements. The rest of the region needs to rely on irrigation for supplementary irrigation to increase crop yield. All districts in the ‘Three Water Lines’ area of northwest China should vigorously develop sprinkler irrigation, micro-irrigation, pipe irrigation, and other irrigation water-saving technologies and support engineering construction. Under the premise of ensuring national food security, they should reduce the planting area of rice, corn, and orchards, and increase the planting area of economic crops such as beans and tubers in the ’Three Water Lines’ area. That is conducive to further reducing the agricultural irrigation quota and improving the matching degree of irrigation water resources. It provides a scientific reference for optimizing water resource allocation and improving irrigation water-use efficiency in northwest arid areas.

Surface water estimation in Sewell watershed

This study was conducted in the field of hydrology, through which the researcher analysed the hydrological characteristics of the waters of the Sewell Basin, depending on the file of the digital elevation model (DEM12.5m) for the study area, and the use of the hydrological GIS program to find the morphometric characteristics affecting the hydrology of the region. The researcher also resorted to a method Conservation of American soils and curve number In order to obtain the volume of running water during the year and in this way, it lies between two latitudes(35o 34- 29= - 35o 55- 23=)N and two longitudes (45o 26- 01= - 46o 20- 49=)to the east, the water channels of the Sewell Basin are six (6) ranks in an area of ​​about (1545 km2), its length is (82.6 km) and its width is (18.70 km), and the highest point in the basin is (2770 m) in the north of the region. The lowest point in the study area is located at an altitude of (816 m) above sea level. The objective of this study is to analyses the hydrological characteristics of the main Sewell Basin and the secondary basins in order to estimate the water flow in it. There are 11 secondary water basins in the study area. The hydrological characteristics of these basins have a direct impact on the amount of water accumulation. The study concluded that the basins have large areas of water resources, and the expected annual water volume in the main Sewell Basin (1.113 billion / m3), and the average annual irrigation during the period (2012-2015) was (6.69 m 3 / sec).

High resolution annual irrigation water use maps in China based-on input variables selection and convolutional neural networks

Water use and available water resources are the prerequisites for optimal water resources allocation, which is an efficient way to alleviate water scarcity all over the world. However, the spatial scales of water use and available water resources are often not matched due to their different ways for data surveying or observing. The spatial distributed (grid-scale) water use map is one of the ways to convert the spatial scales of the water use and available water resources. As irrigation is essential to guarantee sustainable development of agriculture, food security and economy, and accounts for most water use in China. A framework to generate high resolution (1 km) annual irrigation water use maps has been proposed. An iterative input variables selection (IIS) algorithm is adopted to select the optimal input variables among candidate input variables. After determining the optimal input variables, the convolutional neural network (CNN) is built to establish the relationship between the selected input variables and the irrigation water use. The spatial distributed irrigation water use maps can be produced by the trained CNN with the selected input variables at grid scale. The spatial distributed annual irrigation water use maps in China is produced at 1 km resolution from 1998 to 2013, and the performance of the framework has been proven to be credible with three metrics (i.e., root mean squared error, Nash Sutcliffe efficiency coefficient and relative error). Based on the spatial distributed annual irrigation water use maps, the spatial autocorrelation of annual irrigation water use in China is weak and the clustered pattern is random with 99% confidence. The temporal changing pattern mainly depends on precipitation and soil moisture in most prefectures, and the change of the cultivated area can also lead to dramatic change of the annual irrigation water use in China. The proposed framework can generate high resolution spatial distributed annual irrigation water use maps at grid scale, and the maps can be applied to ensure the optimal water resources allocation to realize efficient utilization of water resources and the agricultural policy-making.