[Objective] To address the mismatch between traditional rainfall analysis methods (April to October) for hilly irrigation areas in south China and actual intra-seasonal water demand during rice growth stages (late rice from July to October), this study focuses on intra-seasonal rainfall during the rice growth stages, integrating GIS technology to investigate the water supply reliability of the Maweizao irrigation area. [Methods] Using daily meteorological data from 1989 to 2019 in the irrigation area, the intra-seasonal rainfall frequency analysis method was employed to identify typical representative years and characteristic values for normal years (P=50%), moderately dry years (P=75%), and dry years (P=90%). The FAO Penman-Monteith method and water balance method were then used to calculate the crop water requirements and net irrigation water requirements for rice. [Results]The results showed that: (1) In dry years, the intra-seasonal rainfall during the late rice growth stages (160 mm) accounted for only 21.2% of the total rainfall from April to October (755 mm). Moreover, a mismatch was observed between the rainfall peak (August) and the critical water demand period (booting to heading stage, September). This led to 14% higher net field irrigation water requirements (560 mm) calculated by intra-seasonal rainfall frequency analysis compared to traditional methods, accurately reflecting the typical contradiction in hilly irrigation areas where there was “no rain during water demand periods but excessive rain during non-demand periods.” (2) GIS-based spatial simulations revealed a distinct bimodal structure in the irrigation area during dry years. Croplands near the main water source (Maweizao Reservoir) benefited from sufficient storage capacity (27.02 million m³) and a canal system integrity rate above 85%, achieving a water supply reliability rate greater than 80%, thus forming a high-yield and stable-production core zone. Areas dependent on small reservoirs for water regulation and storage, where storage capacity utilization declined to 60% due to sedimentation, had a water supply reliability rate of 60%-80%. Limited by scattered ponds (406 ponds), insufficient catchment areas (<5 km² per pond), and damaged main and lateral canals (integrity rate <40%), the overall reliability rates dropped below 40%, posing a high risk of yield reduction. (3) For every 10% increase in water supply reliability rate, late rice yield increased by 35-50 kg per mu(1mu≈666.67 m²), showing a significant positive linear correlation (R²=0.89). When the reliability rate exceeded 80%, soil water content remained stable at 18%-24% (optimal range for rice growth), resulting in yields of 400-500 kg per mu.When the reliability rate fell below 40%, soil water content dropped sharply below 10%, leading to plant wilting or even total crop failure (yield <200 kg per mu). Within the 60%-80% range of reliability rate, each 1 m³ irrigation water increase produced an extra 1.2-1.5 kg of rice, indicating optimal resource use efficiency. [Conclusion] By focusing on intra-seasonal rainfall during rice growth stages, this study reveals the underlying mechanism of irrigation water supply-demand imbalance in hilly irrigation areas and proposes the following three practical strategies. Over 70% irrigation water should be allocated during the booting to heading stages (September) based on crop water requirements, with priority given to areas maintaining water supply reliability rates above 60%. For areas with water supply reliability rates below 40%, the “pond desilting + intelligent water control” project should be implemented to increase small water source utilization rate from 45% to 75%, while restoring main and lateral canals to achieve an integrity rate above 60%. By focusing on intra-seasonal rainfall during rice growth stages, this study provides a scientific basis for precise irrigation management and confirmation of agricultural water use rights in hilly irrigation areas, holding important practical significance for optimizing water resource allocation and enhancing grain production capacity.

[Objective] Taking inline cylindrical emitters as the research object, this study modifies the inclination angle of the emitter’s sidewall end face to investigate the effects of structural optimization on local head loss in drip irrigation pipes. [Methods] The end faces of the inline cylindrical emitters were structurally optimized, with inclination angles set as explanatory variables at four levels: 15°, 30°, 45°, and 90°. Irrigation experiments and numerical simulations were conducted, and the results were processed using the principle of dimensional homogeneity and multiple regression analysis. [Results] The results showed that the velocity and pressure gradients in the convergent and divergent sections of the drip irrigation pipe decreased as the inclination angle of the emitter end face decreased. Based on the principle of dimensional homogeneity and multiple regression analysis, a calculation model for local head loss in drip irrigation pipes incorporating the inclination angle of emitter end face was established. The local head loss was found to be inversely proportional to the 0.706 power of the cotangent of the inclination angle. Case analysis demonstrated that for a 60-m drip irrigation pipe with 0.6-m emitter spacing, the local head loss at inclination angles of 15°, 30°, and 45° decreased to 26.0%, 44.7%, and 65.0% of that at 90°, respectively. For a 60-m drip pipe with 1-m emitter spacing, the local head loss at inclination angles of 15°, 30°, and 45° decreased to 29.6%, 48.1%, and 74.1% of that at 90°, respectively. [Conclusion] In conclusion, the inclined design of the emitter’s end face can significantly reduce local head loss in drip irrigation pipes. Considering manufacturing complexity and cost, an inclination angle of 15° is recommended. These findings can provide references for drip irrigation design and pipe network optimization.

In order to explore the effect of mulching on soil aeration under drip irrigation,field experiment was carried out in the sub-humid area of Northeast China. In the experiments,four treatments,including mulched + fertilized,non-mulched + fertilized,mulched + unfertilized and non-mulched + unfertilized drip irrigation were tested. The results showed that soil redox potential in surface layer (0-10 cm)was increased by plastic film mulching with a difference of 2.7-10.0 mV (increasing by 0.5%-2.0%) compared with no plastic film mulching. Plastic film mulching had no significant effect on the distribution of soil redox potential in 0-30 cm layer,and the redox potential of each treatment increased with the increase of depth in the range of 0-30 cm. During the maize growth period,the soil under drip irrigation belonged to strong oxidizing soil with good aeration,and the redox potential of each treatment was higher than 500 mV. Plastic film mulching significantly improved soil aeration in the early growth stage,and the soil redox potential for mulching increased by 59.5-122.9 mV (9.7%-22.8%) compared with no mulching.

Rural water supply system is affected by geographical conditions, water resources endowment and regional differences in economic development level. In some areas, rural water supply projects exhibit weak resilience to risks, potentially leading to water shortage or contamination during emergencies. In this paper, the natural disaster risk theory is introduced into the analysis of rural water supply risk. An evaluation index system and the corresponding evaluation model were constructed from four aspects: disaster-causing factors, disaster-prone environment, disaster-bearing entities, and disaster prevention and mitigation capability. Based on data of rural water supply projects in 34 districts in Chongqing in 2020, the rural water supply risk at district level was assessed. According to the calculation results, the risk level was divided into three levels: low, medium and high, with the thresholds set at 0.336 6 and 0.558 1 respectively. Results indicate that five districts (Yongchuan, Beibei, Wansheng, Fengjie and Fuling), primarily located in the urban area, exhibited low risk. Two districts (Wushan and Youyang) were classified as high risk. Wushan is situated in the Three Gorges reservoir area in northeast Chongqing, while Youyang is in the Wuling Mountainous area in southeast Chongqing. The remaining 27 districts were categorized as medium risk. The risk assessment results offer technical support for early warning and response for rural water supply risks in Chongqing.

Under global climate warming, frequent extreme dry and wet events threaten crop growth, highlighting the importance of studying their impact on agricultural production for regional food security and water resource management. In this study, the Normalized Difference Vegetation Index (NDVI) was employed to assess rice growth in Hubei Province. Meteorological data spanning 1990 to 2020 from 32 stations and the Standardized Precipitation Evapotranspiration Index (SPEI) were employed to analyze spatial and temporal changes in extreme dry and wet events. Based on the NDVI from 2000 to 2020, the rice growth and its response to extreme dry and wet events were scrutinized. Correlation coefficients were computed to investigate the possible impacts on rice growth. Findings indicate a decline in extreme drought frequency, with 7 events occurring in 1990-1999, 4 in 2000-2009, and only 2 in 2010-2020. Conversely, extreme wet events numbered 5 in 1990-1999, 2 in 2000-2009, and 5 in 2010-2020, expanding in spatial extent without significant frequency change. Notably, the NDVI during the crucial growth period (June-August) exhibited a significant increase (p=0.012), growing at a rate of 0.007 8 per year, indicating improved growth conditions. Extreme dry and wet events in general exerted negative impacts on rice growth, with the coefficient of correlation between NDVI and SPEI reaching 0.418 and -0.358, respectively. To mitigate the impact of extreme dry and wet events, enhancing meteorological monitoring during rice’s critical growth phases is recommended. This proactive measure aims to bolster resilience against droughts and floods, ensuring consistent and robust agricultural production.

A field experiment of water and fertilizer regulation was conducted at the Jiangxi Provincial Irrigation Experiment Center Station from 2020 to 2022 to investigate the impacts of water and fertilizer regulation on rice growth and water demands across varying hydrological conditions. The findings revealed that intermittent irrigation resulted in reduced irrigation (by 20.82%), drainage (by 3.93%), leakage (by 16.68%), and evapotranspiration (by 6.77%) compared to conventional irrigation methods during different hydrological years. Evapotranspiration during the late tillering and jointing-booting stages accounted for 40.2% of the total evapotranspiration throughout the growth period. Rice plant height, tiller number, leaf area index (LAI), and dry matter accumulation exhibited consistent dynamic changes across different hydrological years, all being greater under fertilization treatments compared to non-fertilized conditions, with fertilizer application notably affecting yield. However, in drought years, rice yield under intermittent irrigation was lower than that under submerged irrigation, and plant height, tiller number, LAI, dry matter accumulation, rice yield, and evapotranspiration were all restrained. Average irrigation amounts were higher in drought years compared to wet and normal years, while average drainage, leakage, and plant height were lower. Average evapotranspiration of paddy fields was lower in drought years compared to wet years but higher than in normal years, while tiller number, LAI, dry matter accumulation, and rice yield were lower in drought years compared to normal years but higher than in wet years.

To investigate the impact of regulated deficit irrigation (RDI) on soil temperature, maize growth and yield with different mulching methods, we conducted field mulching and RDI experiment at an experimental base in Yongdeng county, Lanzhou City, in 2021. A total of eight treatments were arranged with four mulchings, namely white film-mulch (M1), ground fabric (M2), biodegradable plastic film (M3), and liquid film (M4), each under two supplemental irrigation scenarios, that is, sufficient irrigation (D1) and mild water stress (D2). The impact of each treatment on soil temperature and maize growth and yield were examined, with white film-mulch under sufficient irrigation (D1M1) serving as the control group throughout the growth period. Results indicated that white film-mulch demonstrated the most effective increase in surface soil temperature, while liquid film performed the least favorably in this regard. Soil temperature did not show significant differences among various water stress scenarios given the same mulching method. Maize growth and yield varied significantly dependent on the mulching methods employed. Mild water stress did not notably affect maize yield, but a combination of mulching methods and water-film interaction significantly boosted yield (P＜0.01), with the former outperforming the latter. The highest yield was achieved with treatment D2M1 at 19 761.32 kg/hm², significantly surpassing yields from other treatments. Yield under D1M3 was slightly higher than that of the control treatment. Being environmental friendly, the D1M3 treatment is the most conducive for regional sustainable development.

Precise estimation of meteorological yield is a premise of accurately assessing the impact of meteorological conditions on rice yield. This study delves into the time series variation of meteorological yield for single-season rice in the irrigated areas of Zhanghe, Hubei Province. Four methods, in specific, three-point moving average method, HP filtering method, single exponential smoothing method, and quadratic exponential smoothing method, were applied to decompose the rice yield data from 1975 to 2020 into trend yield and meteorological yield. Through correlation analysis, eight meteorological factors associated with rice growth stages were identified and used to construct a rice prediction model alongside the separated meteorological yield. The findings indicate that the four methods effectively capture the regional consistency between meteorological yield series and productivity level in Hubei Province. The annual average meteorological yield accounted for approximately 3.39% of the total output, and after 2008 the figure exceeded 10.1%. Via correlation analysis, the key factors influencing meteorological yield were identified as follows: minimum temperature at heading and flowering stage, maximum temperature at jointing and booting stage, average temperature at late tiller stage, minimum temperature at returning-green stage, evaporation at milk grain stage, and minimum temperature at seedling raising stage. During calibration period (1976-2014) and validation period (2015-2020), the model exhibited relative errors less than 5%, and a determination coefficient (R²) reaching 0.994. The proposed model holds potential for facilitating the study of regional rice production under future climate change scenarios.

The advancement of intelligent agriculture has made informatization a vital catalyst for agricultural development. Investigating the influence of informatization on agricultural industrial structure is crucial for facilitating adjustment and upgrade in agricultural restructuring. We utilized the quadratic term of agricultural informatization development level to explore the nonlinear relationship between agricultural informatization and upgrading of agricultural industrial structure based on China's inter-provincial panel data. Furthermore, we employed the panel smooth regression model to analyze the threshold effect between agricultural informatization and upgrading of agricultural industrial structure. Results reveal that the development level of agricultural informatization exhibits an “inverted U-shaped” impact on upgrading the agricultural industry structure. The turning point of this inverted U-shaped curve represents the threshold value, which distinguishes a single threshold within the nonlinear relationship. Taking into account the actual situation of China's agricultural development, we found that the level of agricultural informatization promotes the development of the agricultural industrial structure upgrading. However, as agricultural informatization gradually rises, the driving effect would diminish marginally.

Cloud model offers a quantitative representation of the randomness and fuzziness associated with reference crop evapotranspiration (ET₀). To provide valuable insights for agricultural irrigation, flood, and drought studies in Yunnan Province, we employed cloud model to analyze the spatiotemporal distribution of ET₀ in the region based on daily meteorological data from 31 meteorological stations in Yunnan spanning the period from 1958 to 2013. ET₀ was calculated and examined using linear trend, partial correlation analysis, and the M-K methods. Results revealed a lack of consistency in the homogeneity of the temporal-spatial distribution of ET₀ in Yunnan. The temporal variation exhibited lower homogeneity and stability compared to the spatial distribution. Over the 56 years, no significant increasing trend in ET₀ was observed. However, after the year 2000, a significant upward trend in ET₀ became evident, accompanied by a decrease in homogeneity and stability. Seasonally, spring exhibited the highest ET₀, while winter displayed the lowest values. Notably, ET₀ distribution in winter and spring appeared uneven and unstable. Spatially, the middle and south region exhibited higher ET₀ values than the eastern and western and northern areas. Further analysis highlighted an increasing trend in ET₀ in western Yunnan, while the middle and eastern regions experienced a decrease. The high-value areas in central Yunnan exhibited uneven and unstable variations in ET₀. Additionally, our analysis identified humidity, sunshine duration, and wind speed as the primary influencing factors on ET₀.

In this study, we aim to simulate the groundwater level in irrigation area by utilizing sequential observation data from ground-based and remote sensing platforms. A deep learning model based on a multi-layer GRU network was developed for this purpose. Precipitation, soil moisture, historical measurements of groundwater levels, and Sentinel-2 remote sensing observations were used as simulation factors. Furthermore, groundwater level simulation experiments and result analyses are conducted for two irrigation areas located in North and South China. The experimental findings reveal that the groundwater level simulation model, which incorporates the synergy between sky-earth observations and deep learning, effectively establishes the intrinsic relationship between external environmental factors and groundwater levels within the irrigation area. The model is apparently superior to comparative models that merely considers groundwater level as it demonstrates impressive simulation performance, exhibits applicability in diverse geographical environments, and holds promising potential for practical applications. It can provide valuable decision-making support for crop cultivation and water resources management in irrigation area.

In the aim of enhancing the efficiency of utilizing water resources in agriculture, we studied the spatial and temporal evolution of water footprint of summer maize in Hebei Province as well as the factors affecting the change of water footprint based on meteorological data from 17 meteorological stations and related agricultural data in Hebei Province from 2002 to 2018. Results revealed that in the study period, the water footprint of summer maize production in Hebei Province declined in a fluctuating mode, averaging 759.03 m³/t annually. By comparing the spatial evolution characteristics of green water footprint and blue water footprint of summer maize in Hebei Province among the year 2002 (low flow), 2003 (normal flow), and 2013 (high flow), we found that the green water footprint in different periods remained approximately the same level, while the blue water footprint differed significantly. Correlation analysis of 13 factors also suggest that the water footprint of summer maize is positively correlated with evapotranspiration and effective irrigation area; but significantly negatively corrlated with the total output value of summer maize.

The aim of this research is to optimize the combination mode of pipe network in agricultural pipeline irrigation, improve irrigation efficiency and cut irrigation costs. Support vector machine (SVM) coupled with genetic algorithm (GA) was employed to optimize the model, and the optimal combination of the number of standard sections of branch pipes with different diameters that met the constraints and the objective function was obtained. The objective function was to minimize the cost per unit area of pipeline under the assumption of unlimited irrigation area; the decision variables were the number of standard sections of branch and capillary; the constraint conditions were the maximum allowable pressure difference of the system and the minimum number of pipes constituting the pipe network. Results showed that when capillary pipes were laid in both directions, the cost of pipes per unit area was the lowest, 8 755.7 yuan/hm², the irrigation area was 24.15 hm², and the water head difference of the pipe network reached 97.6%-99.7% allowed by the system. Compared with one-way laying, the cost of pipe per hectare of two-way laying was reduced by about 6.5%, and the irrigation area was increased by about 103%. Compared with the results in existing literature, the cost per hectare of pipeline decreased by 5%, and the irrigation area increased by 23%. In conclusion, support vector machine coupled with genetic algorithm can better optimize the design of pipe network, and provides a reference for agricultural water-saving irrigation.

The effects of two different extrogenous humic acids on the activity of Cd in clayey farmland were examined by measuring the content of total Cd, DTPA-Cd and MgCl₂-Cd after leaching treatment. After two humic acid treatments, the total content of Cd content in the soil remained unchanged in general, the content of DTPA-Cd decreased from 0.421 mg/kg to 0.313 mg/kg, and the content of MgCl₂-Cd declined from 0.2 mg/kg to 0.169 mg/kg. When leaching time increased from 1 day to 5 days, the total content of Cd also remained unchanged overall, DTPA-Cd decreased from 0.325 mg/kg to 0.265 mg/kg, and MgCl₂-Cd reduced from 0.196 mg/kg to 0.165 mg/kg. In conclusion, both the exogenous humic acids could remove Cd in the soil of clayey farmland.

In this study, three types of Ti-based single/composite oxide nanotube arrays are prepared by anodic oxidation of Ti and typical Ti alloys (Ti-0.2Pd and Ti-6Al-4V). The different fabrication processes and properties of these oxide nanotube arrays are analyzed using SEM, EIS, XRD, EDS, ICP, XPS and UV-Vis DRS. Their photocatalytic activities are determined by degradation of p-nitrophenol in aqueous solution under UV light irradiation. Al and V inside the Ti-6Al-4V alloy-derived nanotube arrays are detected by EDS or XPS. Pd inside the Ti-0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Al and V significantly deteriorates the photoreactivity of the resultant nanotube arrays, while incorporation of Pd remarkably improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the sulfur poison resistance and the separation of photogenerated charge carriers. Excessive dosage of Al and V element results in structure defect as recombination center and limits the separation of photogenerated charge carriers. This study suggests that anodization of Ti-0.2Pd alloy, rather than pure Ti metal, allows to produce high-performance photocatalysts for environmental and energy applications.

Climate change has brought about alteration in rice water consumption, and thus affected the demand for irrigation water in paddy field. In this study, the changes in rice water consumption and irrigation water demand from 1955 to 2013 in Gaoyou irrigation area under water-saving irrigation (WSI) and flood irrigation (FI) were investigated by means of water balance calculation in the paddy field and Mann-Kendall analysis. Results indicated that air temperature presented significant increasing trends during the past six decades, and rainfall presented slight decreasing trends. Rice evapotranspiration and percolation under WSI and FI both presented gradual increasing trends, but rice water consumption decreased significantly under WSI; irrigation water demand in paddy field declined gradually under WSI while increased slightly under FI. Moreover, precipitation utilization efficiency has remarkably improved under WSI regimes. We conclude that the adverse effects of climate change on rice production can be effectively mitigated by using WSI technology, which would be an important measure of sustainable development for irrigation areas under changing environment.

The aim of this research is to evaluate and analyze the forecasting of short-term daily reference crop evapotranspiration by Hargreaves-Samani equation based on temperature forecast. The observed daily meteorological data from 2002 to 2013 at Nanjing Station and the daily weather forecast data for 7-day forecast period from 2012 to 2013 are collected, and the daily ET₀ was calculated by using the FAO-56 Penman-Monteith (PM) equation according to daily meteorological data from 2002 to 2012. Furthermore, parameters in the HS equation are calibrated with 2002-2012 PM ET₀ values and the calibrated HS equation is adopted for forecasting the 7-day ET₀ with weather forecast data from 2012 to 2013. The precision and sensitivity of the forecast results are evaluated and analyzed. Results showed that the forecast result of ET₀ based on minimum temperature is more accurate than that on maximum temperature; the statistical indicators of calibrated HS equation are good, indicating the accuracy has improved; and the ET₀ estimated from calibrated HS equation are in accordance with the ET₀ estimated from PM equation, the accuracy of the HS equation has been significantly improved. Moreover, the accuracy of ET₀ declines with the increase of forecast period; the error in ET₀ is usually more sensitive to maximum temperature than that to minimum temperature, and the error in ET₀ is most sensitive to temperature forecasts in summer, while least sensitive to temperature forecasts in winter.

An SCS-MIKE11 coupled model was built to calculate the drainage moduli of plain lake area with different land-use patterns, and the effect of land-use change on drainage modulus was analyzed. Drainage measures in the background of land-use change were simulated and optimized by setting different combinations among proportions of paddy field to dry land area, water surface ratio, and ground hardening rate. The Luoshan drainage area in the Four-lake Drainage Basin in Hubei Province was selected as study area. Results revealed that the drainage modulus in 2011 was larger than that in 1994 under the same land-use pattern. According to the water logging control standards (10-year rainstorm for one day and draining for three days, 10-year rainstorm for three days and draining for five days), the drainage modulus increased by 159.3% and 33.6% respectively from 1994 to 2011. When water surface ratio and proportion of paddy field to dry land area kept unchanged, the drainage modulus under one-day rainstorm and three-day rainstorm increased by 0.005 m³/(s·km²) and 0.003 m³/(s·km²) respectively as ground hardening rate increased by 1%; the drainage modulus under one-day rainstorm and three-day rainstorm decreased by 0.016 m³/(s·km²) and 0.012 m³/(s·km²) as water surface ratio increased by 1% when ground hardening rate and proportion of paddy field to dry land area kept unchanged; the drainage modulus under one-day rainstorm and three-day rainstorm decreased by 0.004 m³/(s·km²) and 0.003 m³/(s·km²) as proportion of paddy field to dry land area increased by 0.1 when ground hardening rate and water surface ratio remained unchanged. Therefore, reducing the ground hardening rate by permeable pavement for example, and increasing the water surface ratio and proportion of paddy field to dry land area in addition to increasing the drainage discharge of pumping stations are effective measures of reducing waterlogging disaster loss. The research results could be used as a reference for reasonable determination of the drainage modulus and formulation of waterlogging control measures under the condition of land-use change in plain lake areas.

The effective utilization of water resources has been an urgent issue to be addressed. According to the composition of agricultural ecosystem, factors affecting the efficiency of agricultural water use can be categorized into natural condition (climate, water resources condition and soil texture), type and size of the irrigation area, crop growth structure, engineering measures and irrigation technology, infrastructure and water saving configuration in the irrigation area, management level, economic policy and water price, etc. The influence mechanisms of these factors are different. Some are controllable, and some are hard to change. The mechanisms of these factors affecting the coefficient of effective utilization of farmland irrigation water are analyzed. Furthermore, measures to improve agricultural water use efficiency are put forward from aspects of facilities, regime, structure and technology.

Irrigation is required in the north of Hubei Province as scarce water resource and limited precipitation could not meet the water demand of rice growth. In view of this, we built a paddy rice growth model for northern Hubei Province based on ORYZA 2000 model according to the results of irrigation test at Changqu irrigation station. By using the proposed model, we simulated the variation rules of water demand and yield of paddy rice in different drought conditions (different growth periods and drought levels). Results revealed that the water demand and yield of paddy rice decreased with the aggravation of drought. On this basis, we obtained the sensitivity coefficients at different stages, and established the water production function of paddy rice in association with the Jensen model and the least squares theory. The results could guide the irrigation of paddy rice in northern Hubei Province.