In order to clarify the infiltration characteristics of the soil at different locations in the field at Hetao Irrigation District，the infiltration process of the soil at different locations in the experimental area were analyzed based on the soil infiltration model to fit the infiltration process. The results show that infiltration characteristics of soil at different locations are closely related with its physical and chemical properties；the infiltration rate of the head of border is 1.42 and 1.81 times of that of the middle and the tail of border，respectively. The infiltration coefficient and the stable infiltration rate show the change characteristics of the head of the border > the tail of the border > the middle of the border，and the cumulative infiltration volume and the initial infiltration rate show the change characteristics of the head of the border > the middle of the border > the tail of the border. The results also show that Horton model simulation parameters have a smaller deviation from the measured values，and is suitable for describing the soil infiltration process in the field.

Precipitation is an important climate variable. In order to improve the prediction accuracy of precipitation， a time series prediction model of precipitation based on Prophet algorithm was established in this paper. Based on the monthly precipitation data of Hubei province from January 1960 to May 2006， the monthly precipitation of 139 months from June 2006 to December 2017 was predicted， and compared with the traditional SVR， BP and ARIMA prediction models， in order to explore the feasibility of this model in precipitation prediction. The experimental results show that the Prophet model is better than the other three models in predicting precipitation in Hubei Province， and its RMSE and MAE are 18.402 and 16.189 lower than the average of other models. Moreover， the Prophet model is more accurate in predicting the fluctuation of monthly precipitation time series. In terms of spatial distribution， the predicted value of Prophet model obtained by Kriging interpolation method is similar to the spatial distribution of the actual monthly average precipitation value， indicating that the model can accurately predict the monthly precipitation of various regions in Hubei Province and has universal applicability in precipitation prediction.

In order to solve the problem of saline-alkali land improvement in the arid area of southern Xinjiang, the law of soil water and salt transport during spring irrigation with different powder ridge depth and irrigation amount was discussed. In this study, 12 treatments, including three furrow depths of S1(40 cm), S2(60 cm) and S3(80 cm), and three irrigation amounts of W1(2 400 m³/hm²), W2(3 000 m³/hm²) and W3(3 600 m³/hm²), were set up in the saline and alkali land test field in Tumushuke city, Xinjiang, with CK(20 cm) as the control, to conduct experiments to analyze the dynamic changes of water content and salt content in 0~150 cm soil layer after spring irrigation. The results showed that spring irrigation could change the distribution of soil water in cotton field, effectively leach and reduce the soil salt content in cultivated layer. Compared with traditional CK tillage, powder ridge tillage could reduce the soil bulk density, increase the soil saturated water content and total porosity. The salt content of 0~100 cm soil layer was lower than that of traditional tillage, and the effect in 0~40 cm root layer soil was particularly significant. The desalting rate of 0~40 cm root layer soil after S1, S2 and S3 irrigation treatment was increased by 24.80%, 39.05% and 44.17%, respectively, compared with CK treatment. It is concluded that the depth of powdery ridge and water quota of spring irrigation have obvious improvement effect on the distribution and content of water and salt in cotton field soil.

In order to explore the effects of drip irrigation quota and fertilizer amount on apple growth， photosynthesis， yield and quality， three factors (water quality Q， irrigation quota W， fertilizer amount F) three levels (low， medium and high) orthogonal test， range analysis， variance analysis and principal component analysis were used. The primary and secondary order， significance， optimal combination scheme and the scheme with the highest comprehensive score of each index of domestic reclaimed water drip irrigation on apple were obtained. The results showed that the primary and secondary order of the effects of the three factors on apple shoot length， stem diameter， Pn and yield was W>F>Q， the effects of irrigation quota W and fertilizer amount F on the above indexes were significant， and the above indexes increased with the increase of irrigation quota and fertilizer amount； The primary and secondary order of the effects of the three factors on apple soluble solids were F>Q>W， and the effects were significant， and soluble solids first increased and then decreased with the increase of irrigation quota and fertilization； The primary and secondary order of the effects of the three factors on apple total sugar and vitamin C were F>W>Q， and the effects of irrigation quota and fertilization were significant. Principal component analysis results showed that the cumulative variance contribution rate of the first three principal components was 95.333%. According to the comprehensive score ranking， T3 treatment was a better combination scheme for drip irrigation of apples with domestic reclaimed water. That is， under the condition of gravel soil and 180.4 mm rainfall during the growth period， for the 4-year-old dense planting of Liquan Duanfu apple with dwarf rootstock， the irrigation quota of 6 480 m³ / hm² and the fertilization amount of 317 kg/hm² is better for domestic reclaimed water drip irrigation. The study lays a theoretical foundation for the water and fertilizer management scheme of apple production with domestic reclaimed water drip irrigation in Ningxia and realizes the high-quality and efficient production of apple.

Furrow and ridge planting and sprinkler irrigation technology is an integration water-saving cultivation. In this study， four treatments were set with different irrigation quota (24 mm， 30 mm， 36 mm， 42 mm， irrigating 5 times)， and conventional film-covered sprinkler irrigation was used as the CK treatment (42 mm， irrigating 5 times). By measuring the root growth and distribution characteristics of ridge and furrow planting oil sunflower under different irrigation treatments， the longitudinal and transverse growth of oil sunflower root and the distribution of root in soil under different irrigation treatments were analyzed， and the effects on the root growth of oil sunflower were compared. The results showed that the vertical infiltration of irrigation water was deeper in ridge and furrow planting treatment， and the vertical root growth length was higher than that in the control treatment. The lateral root growth of the control treatment was concentrated in 0~20 cm underground， and the growth length was all longer than that of the ridge and furrow planting treatment， but there were fewer roots below 20 cm， and the growth length was lower than that of the ridge and furrow planting treatment. The ratio of root dry weight to total root dry weight in 0~10 cm of CK treatment was higher than that of ridge and furrow planting treatment， while that below 20 cm of ridge and furrow planting treatment was significantly higher than that of CK treatment. The distribution of root weight density in vertical soil showed a "T" shape with the growth period. The greater the irrigation amount， the greater the root weight density. With the increase of soil depth， the root weight density gradually decreased. Compared with conventional film-covered sprinkler irrigation method， furrow and ridge planting and sprinkler irrigation technology can promote the root growth of oil sunflower， increase the root dry matter， make full use of water and fertilizer resources and promote the growth of the above ground part of oil sunflower， which has a positive effect on improving the yield. So it is worth promoting gradually.

In order to explore the optimal combination of different reclaimed water ratios and different fertilization amounts，the two-factor three-level random segment test method was used to study the effects different irrigation water (W3 is reclaimed water，W2 is 1∶1 mixture of reclaimed water and tap water， W1 is tap water) and different fertilizer quota (F1 is 60 kg / hm²， F2 is 90 kg / hm²， F3 is 120 kg / hm²) on the growth， photosynthesis and yield of pepper. The results showed that the mean values of plant height， stem diameter， photosynthetic indexes (Pn， Gs， Ci， Tr and WUE)， yield and partial fertilizer productivity of pepper increased with the increase of reclaimed water proportion in irrigation water under certain fertilization amount. Under certain irrigation water quality conditions， the mean values of plant height and stem diameter of pepper increased with the increase of fertilization amount， while the mean values of photosynthetic indexes and yield increased first and then decreased， and the mean values of fertilizer partial productivity decreased with the increase of fertilization amount. The yield of pepper under reclaimed water irrigation was significantly higher than that under tap water irrigation at low (F1) and medium (F2) fertilization levels. The plant height， stem diameter， yield and instantaneous net photosynthetic rate of pepper of W3F2 treatment were 29.73%，13.39%，36.18% and 49.60% higher than those of W1F1 treatment，respectively. The principal component analysis showed that W3F2 treatment had the highest comprehensive score. In other words，under the conditions of 174.30 mm rainfall，2 820 m3/hm² irrigation quota (15 times of irrigation)， reclaimed water as irrigation water and 900 kg/hm² fertilization (10 times of fertilization)，the pepper grew well and had the highest net photosynthetic rate and yield.

The effects of different irrigation conditions on nutrient absorption of maize plants were studied. The experiment was carried out in Moshan， Shandong Province. On the basis of the integration of water and fertilizer， the law of nutrient absorption of maize plants under different irrigation methods was investigated. Four irrigation methods， including non-irrigation (CK)， gully irrigation (T1)， spray irrigation (T2) and drip irrigation (T3)， were set up. The results showed that the dry matter accumulation of maize at jointing stage， wire-drawing stage and maturity stage showed a trend of T3 > T2 >T1> CK. The absorption of N，P and K showed a trend of T3 > T2 > T1 > CK. The absorption of calcium and magnesium was T3 > T2 > T1 > CK. The absorption of Fe，Mn，Cu and Zn showed a trend of T3 > T2 > T1 > CK. In addition，the dry matter accumulation in the whole growth period of maize was the highest in T3 treatment，which was 14 447.20 kg/hm². The nutrient accumulation of N，P and K was the highest in T3 treatment，which were 207.73 kg/hm²，178.18 kg/hm² and 204.65 kg/hm²，respectively. The nutrient accumulation of calcium and magnesium in T3 treatment was the highest，which were 22.55 kg/hm² and 7.62 kg/hm²，respectively. The nutrient accumulation of Fe，Mn，Cu and Zn was the highest in T3 treatment，which were 8 967.55 g/hm²，1 040.53 g/hm²，406.65 g/hm² and 1 182.65 g/hm²，respectively. In conclusion，compared with furrow irrigation and sprinkler irrigation，drip irrigation is better for nutrient absorption of maize plants，can better promote dry matter accumulation and nutrient absorption during maize growth. So it is an appropriate irrigation method for maize planting.

In this study，5 kinds of 4-year-old shrubs commonly used in urban afforestation in Urumqi were used as test materials，and three treatments，including stop irrigation for 5 d，10 d and rewatering，were set and normal irrigation was used as contrast treatment (CK). Soil water content，gas exchange parameters and chlorophyll content were measured and photosynthetic characteristics of five kinds of shrubs under drought stress were studied to provide theoretical basis for selection of drought-tolerant garden plants. The results showed that with the extension of irrigation stop time，the soil water content of the treatment of stop irrigation for 5d and 10d decreased continuously，and was significantly lower than the normal irrigation level from the 5^th day to the 10^th day，and the soil water content recovered after rehydration treatment. After 10 days of drought stress， the photosynthetic rates of Amygdalus triloba，Prunus x cistena，Syringa oblata，Ligustrum obtusifolium and Ulmus pumila decreased by 51.33%，71.92%，13.12%，71.45% and 83.78%，respectively，compared with CK. The photosynthetic rate of five garden plants was restored to some extent by rehydration treatment， among which， the photosynthetic rate of Amygdalus triloba and Syringa oblate returned to the level of normal irrigation. Drought stress significantly reduced the stomatal conductance of five garden plants， especially at the 10th day of drought stress， the lowest value was 0.02 mol/（m²·s），0.06 mol/（m²·s），0.08 mol/（m²·s），0.03 mol/（m²·s） and 0.03 mol/（m²·s）， respectively. However， rehydration did not restore stomatal conductance of shrubs. The concentrations of intercellular CO₂ of Prunus×cistena，Syringa oblate， Ligustrum obtusifolium and ulmus pumila remained relatively unchanged，while that of Amygdalus triloba increased significantly after 10 days of drought stress，and decreased significantly after rehydration treatment. Similarly，the transpiration rate of five shrubs decreased to the lowest point after 10 days of drought stress，and decreased by 86.95%，61.15%，19.51%，77.43% and 81.64% compared with the control，respectively. After rehydration treatment，that of Amygdalus triloba and Syringa oblate returned to normal irrigation level. Except for the chlorophyll a/b of Amygdalus triloba，the chlorophyll and carotenoid contents of the 5 kinds of shrubs were relatively unchanged. Comprehensive analysis of the changes of chlorophyll content and photosynthetic parameters of the 5 kinds of shrubs under drought stress and re-watering showed that the comprehensive drought resistance ability of Syringa oblata and Amygdalus triloba was stronger. The two kinds of shrubs are very suitable for landscaping plants in arid cities like Urumqi with long winters，hot summers and lack of water.

Evapotranspiration is the main way of water consumption in agricultural oasis in the middle reach of Heihe River Basin. Estimating the actual evapotranspiration and analyzing its changes are of great significance for scientifically guiding local agricultural irrigation and optimizing water resource allocation. This study mainly focused on the estimation of the actual evapotranspiration in the middle reach of Heihe River basin from 2006 to 2015 based on Budyko theory and the improved Fubaopu empirical formula applicable to oasis. The trend and change point characteristics of the actual evapotranspiration series were analyzed by using Mann Kendall test. The contribution rates of different factors affecting the variation of actual evapotranspiration series were analyzed by elastic coefficient method. The results showed that the average annual actual evapotranspiration in the study area was 293 mm； the annual scale and the actual evapotranspiration in spring and autumn showed no significant downward trends， and those in summer and winter showed no significant upward trend. The actual evapotranspiration series was detected to have a change point in 2010， and compared with period I (from 2006 to 2010)， the actual evapotranspiration of period II (from 2011 to 2016) was decreased by 7.3%. The decrease in precipitation contributed the most to the decrease of actual evapotranspiration. The decrease in precipitation led to a decrease in actual evapotranspiration by 8.94%， and the increase in incoming water led to an increase in actual evapotranspiration by 1.68%. The change in potential evapotranspiration has the smallest contribution to the reduction of actual evapotranspiration， and the reduction of potential evapotranspiration led to a decrease of about 0.04% in actual evapotranspiration. Therefore， the water supply condition was the dominant factor affecting the changes of actual evapotranspiration in the study area.

A total of four development scenarios considering many factors affecting water demand and their interaction， namely trend maintaining (S1)， economic development (S2)， water saving (S3) and sustainable development (S4)， were designed in a system dynamics model according to the social economy and water resources utilization of North China Plain (NCP) in order to predict the water demand and water resources supply-demand balance of the NCP from 2019 to 2050. The results show that：①the average total water demands of the NCP under four scenarios during the simulation period are 38.356， 43.079， 32.173 and 35.975 billion m³， respectively， while the average supply-demand balances are 0.068， 4.162， -5.885 and -2.588 billion m³ respectively；②the scenario S4 is the best scenario for the future development of the NCP from the aspects of the economic development scale， total water demand， water shortage and environmental protection；③the sustainable development of water resources in the NCP needs not only the policy guidance of the government， but also the participation of the public. Only the coordination between the government and the public can ensure the sustainable development of water resources and social economy.

In order to reveal the applicability of the Root Zone Water Quality Model (RZWQM2) for the simulation of the soil water content and growth of vegetable crops in the Bashang Area of Hebei Province, in this study, taking Chinese cabbage under drip irrigation under membrane as the research object, the databases of meteorological, soil and crop were established to simulate the dynamic changes of soil moisture, crop plant height and final yield during the growth period of Chinese cabbage in 2018 and 2019, and compared with the measured values. The results showed that: ①after calibration of the model parameters, the RMSE (root mean square error) and d (consistency index) values of simulated soil water content of each soil layer (20 cm, 40 cm and 60 cm) ranged from 1.00% to 3.03% and 0.50 to 0.78, respectively. ② In 2018 and 2019, RMSE values of plant height simulation results were 0.87 cm and 0.90 cm, respectively, and d values were both greater than 0.85. The d values of yield reached 0.99 and 0.98. The calibrated RZWQM2 model has good applicability in Bashang Area of Hebei Province, which can lay a foundation for further researches on water efficient utilization and different irrigation systems for Chinese cabbage in this area.

In order to improve the hardware configuration and network speed of agricultural irrigation system， realize the diversification of client functions， and achieve the purpose of real-time remote monitoring and management， a set of intelligent agricultural irrigation system based on Internet of Things was designed. The system takes the collected farm environmental parameters， such as soil temperature， humidity and PH， and compares them with predetermined values to make corresponding actions. Data is transmitted to the cloud through 4G communication module. App is designed at the remote monitoring and control end to make visual data interface of farm production environment and irrigation， providing a more friendly management mode for the system. The test shows that the irrigation system network is stable and fast response， the economic benefit is increased by 3.5%， the overall goal of intelligent sprinkler irrigation is achieved， and the intelligent level of agricultural irrigation is improved. It can be widely used in large-scale agricultural irrigation scenarios.

Based on the daily data of 8 meteorological stations in Shaoguan City from 1971 to 2020， SPEI drought index， MMK test and crop coefficient method were used to analyze the variation characteristics of drought and tobacco evapotranspiration in the city. The results showed that：①The degree of drought and drought affected areas was increasing after 2000；②The frequency of drought in the north was larger than that in the south. And droughts occurred more frequently in Qujiang in four seasons；③The drought in Shaoguan City was mainly caused by air temperature and precipitation， and precipitation was the dominant factor；④The water requirement of tobacco in Nanxiong increased at the rate of 5.98mm/10a， which was negatively correlated with SPEI drought index. In general， the drought in Shaoguan City was becoming more severe， which was characterized by frequent occurrence in all year round， severe disaster in midlands and sudden changing from drought to waterlogging in spring and winter. Because of the intensification of drought in Nanxiong， it’s necessary to focus on water resources allocation and planning management during tobacco growth stages.

In order to explore the effect of irrigation water quality on sensor performance in the irrigation control system， this paper selected three commonly used soil moisture sensors (5TE， CSF13， FDS100) based on dielectric principles at home and abroad for their key performance such as accuracy and consistency. The evaluation and analysis show that： in terms of measurement accuracy， the 5TE and FDS100 sensors have better accuracy， and the R² between the tested and actual values of soil moisture content reaches 0.892 and 0.914； in terms of consistency， the readings of the 5TE and CSF13 sensors are more stable and their variation coefficients C_v are 0.031 and 0.026 respectively， while the readings of the FDS100 sensor fluctuate greatly， and the variation coefficients C_v reaches 0.051； the typical irrigation water quality will affect the performance of the three sensors， and the measured values of the three sensors are all positive correlated with the salinity of the irrigation water. The sensitivity of 5TE， CSF13， and FDS100 sensors for measuring soil moisture content are 0.52%， 1.51%， and 1.18%， respectively. When reclaimed water is used for irrigation， the measurement error of 5TE sensor increases at high water content (higher than 0.15 cm³/cm³)， while CSF13 and FDS100 sensors are not significantly affected by reclaimed water. The results can provide a basis for the selection of soil moisture sensors under different water source irrigation conditions.

The seasonal drought is serious and water resources are scarce in the karst faulted basin. Efficient water-saving irrigation is an important way to solve the shortage of water resources in the region. In this study， four water-saving irrigation modes， including drip irrigation under plastic film (DI)， percolation irrigation (PI)， subsurface drip irrigation (SDI) and alternate partial root-zone subsurface drip irrigation (PDSI) were used for tomato planting. The TOPSIS method was used to evaluate the comprehensive benefits of tomato quality， yield and irrigation use efficiency by setting different lower limits of irrigation (55%~65%，65%~75% and 75%~85% of field water capacity， respectively). The results showed that the comprehensive benefits of PDSI were the best， followed by SDI. Tomato quality and water use efficiency of these two irrigation modes were higher. The best comprehensive benefits were under the PDSI irrigation method when the lowest limiting of irrigation soil moisture was 65%~75% of field capacity. While for DI under the condition of higher water consumption， the yield was improved， but the quality and utilization efficiency of irrigation water were low， and the comprehensive benefit was the worst. It is suggested that PDSI and SDI should be used in the water-scarce area of karst faulted basin， and the lower limiting of soil moisture should be controlled at 65%~75% of the field capacity. The research provides scientific support for solving the problem of water resources utilization in karst faulted basin.

At present， the total water quantity in the lysimeter of underground automatic water supply and drainage device is calculated by using a single fixed water quantity and the movement times value of the electromagnetic. This method ignores the difference of the inner diameter of the water supply and drainage column (PMMA material) along the height direction and the error caused by the water level fluctuation in the water column， which affects the water level holder. At the same time，the service life of automatic control of the electrical components is reduced for its poor environment in the underground， resulting in a large initial investment and high maintenance costs. In order to solve this problem， the existing device is improved by using a high-precision flow meter to directly measure the amount of water entering the horizontal tank， and a hydraulic automatic control method is used to keep the water level of the lysimeter fluctuating in a certain range. The device can perform all the functions of the existing device. The experimental results show that the measuring accuracy of the improved device is close to or better than that of the existing device， the initial investment can be saved by 20%~30%，and the operation and maintenance are simple.